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uvm32/apps/agnes/src/agnes.c
Toby Jaffey 035608b04a Add agnes NES emulator (very slow). 
Add -W <n> -H <n> width and height options to host-sdl
2025-12-15 00:37:12 +00:00

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/*
SPDX-License-Identifier: MIT
agnes
https://http://github.com/kgabis/agnes
Copyright (c) 2022 Krzysztof Gabis
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#define AGNES_AMALGAMATED
#ifdef _MSC_VER
#ifndef _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
#endif /* _CRT_SECURE_NO_WARNINGS */
#endif /* _MSC_VER */
#include "agnes.h"
//-----------------------------------------------------------------------------
// Headers
//-----------------------------------------------------------------------------
//FILE_START:common.h
#ifndef common_h
#define common_h
#include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
#ifdef AGNES_AMALGAMATED
#define AGNES_INTERNAL static
#else
#define AGNES_INTERNAL
#endif
#define AGNES_GET_BIT(byte, bit_ix) (((byte) >> (bit_ix)) & 1)
#endif /* common_h */
//FILE_END
//FILE_START:agnes_types.h
#ifndef agnes_types_h
#define agnes_types_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#include "agnes.h"
#endif
/************************************ CPU ************************************/
typedef enum {
INTERRPUT_NONE = 0,
INTERRUPT_NMI = 1,
INTERRUPT_IRQ = 2
} cpu_interrupt_t;
typedef struct cpu {
struct agnes *agnes;
uint16_t pc;
uint8_t sp;
uint8_t acc;
uint8_t x;
uint8_t y;
uint8_t flag_carry;
uint8_t flag_zero;
uint8_t flag_dis_interrupt;
uint8_t flag_decimal;
uint8_t flag_overflow;
uint8_t flag_negative;
uint32_t stall;
uint64_t cycles;
cpu_interrupt_t interrupt;
} cpu_t;
/************************************ PPU ************************************/
typedef struct {
uint8_t y_pos;
uint8_t tile_num;
uint8_t attrs;
uint8_t x_pos;
} sprite_t;
typedef struct ppu {
struct agnes *agnes;
uint8_t nametables[4 * 1024];
uint8_t palette[32];
uint8_t screen_buffer[AGNES_SCREEN_HEIGHT * AGNES_SCREEN_WIDTH];
int scanline;
int dot;
uint8_t ppudata_buffer;
uint8_t last_reg_write;
struct {
uint16_t v;
uint16_t t;
uint8_t x;
uint8_t w;
} regs;
struct {
bool show_leftmost_bg;
bool show_leftmost_sprites;
bool show_background;
bool show_sprites;
} masks;
uint8_t nt;
uint8_t at;
uint8_t at_latch;
uint16_t at_shift;
uint8_t bg_hi;
uint8_t bg_lo;
uint16_t bg_hi_shift;
uint16_t bg_lo_shift;
struct {
uint16_t addr_increment;
uint16_t sprite_table_addr;
uint16_t bg_table_addr;
bool use_8x16_sprites;
bool nmi_enabled;
} ctrl;
struct {
bool in_vblank;
bool sprite_overflow;
bool sprite_zero_hit;
} status;
bool is_odd_frame;
uint8_t oam_address;
uint8_t oam_data[256];
sprite_t sprites[8];
int sprite_ixs[8];
int sprite_ixs_count;
} ppu_t;
/********************************** MAPPERS **********************************/
typedef enum {
MIRRORING_MODE_NONE,
MIRRORING_MODE_SINGLE_LOWER,
MIRRORING_MODE_SINGLE_UPPER,
MIRRORING_MODE_HORIZONTAL,
MIRRORING_MODE_VERTICAL,
MIRRORING_MODE_FOUR_SCREEN
} mirroring_mode_t;
typedef struct mapper0 {
struct agnes *agnes;
unsigned prg_bank_offsets[2];
bool use_chr_ram;
uint8_t chr_ram[8 * 1024];
} mapper0_t;
typedef struct mapper1 {
struct agnes *agnes;
uint8_t shift;
int shift_count;
uint8_t control;
int prg_mode;
int chr_mode;
int chr_banks[2];
int prg_bank;
unsigned chr_bank_offsets[2];
unsigned prg_bank_offsets[2];
bool use_chr_ram;
uint8_t chr_ram[8 * 1024];
uint8_t prg_ram[8 * 1024];
} mapper1_t;
typedef struct mapper2 {
struct agnes *agnes;
unsigned prg_bank_offsets[2];
uint8_t chr_ram[8 * 1024];
} mapper2_t;
typedef struct mapper4 {
struct agnes *agnes;
unsigned prg_mode;
unsigned chr_mode;
bool irq_enabled;
int reg_ix;
uint8_t regs[8];
uint8_t counter;
uint8_t counter_reload;
unsigned chr_bank_offsets[8];
unsigned prg_bank_offsets[4];
uint8_t prg_ram[8 * 1024];
bool use_chr_ram;
uint8_t chr_ram[8 * 1024];
} mapper4_t;
/********************************* GAMEPACK **********************************/
typedef struct {
const uint8_t *data;
unsigned prg_rom_offset;
unsigned chr_rom_offset;
int prg_rom_banks_count;
int chr_rom_banks_count;
bool has_prg_ram;
unsigned char mapper;
} gamepack_t;
/******************************** CONTROLLER *********************************/
typedef struct controller {
uint8_t state;
uint8_t shift;
} controller_t;
/*********************************** AGNES ***********************************/
typedef struct agnes {
cpu_t cpu;
ppu_t ppu;
uint8_t ram[2 * 1024];
gamepack_t gamepack;
controller_t controllers[2];
bool controllers_latch;
union {
mapper0_t m0;
mapper1_t m1;
mapper2_t m2;
mapper4_t m4;
} mapper;
mirroring_mode_t mirroring_mode;
} agnes_t;
#endif /* agnes_types_h */
//FILE_END
//FILE_START:cpu.h
#ifndef cpu_h
#define cpu_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct agnes agnes_t;
typedef struct cpu cpu_t;
AGNES_INTERNAL void cpu_init(cpu_t *cpu, agnes_t *agnes);
AGNES_INTERNAL int cpu_tick(cpu_t *cpu);
AGNES_INTERNAL void cpu_update_zn_flags(cpu_t *cpu, uint8_t val);
AGNES_INTERNAL void cpu_stack_push8(cpu_t *cpu, uint8_t val);
AGNES_INTERNAL void cpu_stack_push16(cpu_t *cpu, uint16_t val);
AGNES_INTERNAL uint8_t cpu_stack_pop8(cpu_t *cpu);
AGNES_INTERNAL uint16_t cpu_stack_pop16(cpu_t *cpu);
AGNES_INTERNAL uint8_t cpu_get_flags(const cpu_t *cpu);
AGNES_INTERNAL void cpu_restore_flags(cpu_t *cpu, uint8_t flags);
AGNES_INTERNAL void cpu_set_dma_stall(cpu_t *cpu);
AGNES_INTERNAL void cpu_trigger_nmi(cpu_t *cpu);
AGNES_INTERNAL void cpu_trigger_irq(cpu_t *cpu);
AGNES_INTERNAL void cpu_write8(cpu_t *cpu, uint16_t addr, uint8_t val);
AGNES_INTERNAL uint8_t cpu_read8(cpu_t *cpu, uint16_t addr);
AGNES_INTERNAL uint16_t cpu_read16(cpu_t *cpu, uint16_t addr);
#endif /* cpu_h */
//FILE_END
//FILE_START:ppu.h
#ifndef ppu_h
#define ppu_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct agnes agnes_t;
typedef struct ppu ppu_t;
AGNES_INTERNAL void ppu_init(ppu_t *ppu, agnes_t *agnes);
AGNES_INTERNAL void ppu_tick(ppu_t *ppu, bool *out_new_frame);
AGNES_INTERNAL uint8_t ppu_read_register(ppu_t *ppu, uint16_t reg);
AGNES_INTERNAL void ppu_write_register(ppu_t *ppu, uint16_t addr, uint8_t val);
#endif /* ppu_h */
//FILE_END
//FILE_START:instructions.h
#ifndef opcodes_h
#define opcodes_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef enum {
ADDR_MODE_NONE = 0,
ADDR_MODE_ABSOLUTE,
ADDR_MODE_ABSOLUTE_X,
ADDR_MODE_ABSOLUTE_Y,
ADDR_MODE_ACCUMULATOR,
ADDR_MODE_IMMEDIATE,
ADDR_MODE_IMPLIED,
ADDR_MODE_IMPLIED_BRK,
ADDR_MODE_INDIRECT,
ADDR_MODE_INDIRECT_X,
ADDR_MODE_INDIRECT_Y,
ADDR_MODE_RELATIVE,
ADDR_MODE_ZERO_PAGE,
ADDR_MODE_ZERO_PAGE_X,
ADDR_MODE_ZERO_PAGE_Y
} addr_mode_t;
typedef struct cpu cpu_t;
typedef int (*instruction_op_fn)(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
typedef struct {
const char *name;
uint8_t opcode;
uint8_t cycles;
bool page_cross_cycle;
addr_mode_t mode;
instruction_op_fn operation;
} instruction_t;
AGNES_INTERNAL instruction_t* instruction_get(uint8_t opcode);
AGNES_INTERNAL uint8_t instruction_get_size(addr_mode_t mode);
#endif /* opcodes_h */
//FILE_END
//FILE_START:mapper.h
#ifndef mapper_h
#define mapper_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct agnes agnes_t;
AGNES_INTERNAL bool mapper_init(agnes_t *agnes);
AGNES_INTERNAL uint8_t mapper_read(agnes_t *agnes, uint16_t addr);
AGNES_INTERNAL void mapper_write(agnes_t *agnes, uint16_t addr, uint8_t val);
AGNES_INTERNAL void mapper_pa12_rising_edge(agnes_t *agnes);
#endif /* mapper_h */
//FILE_END
//FILE_START:mapper0.h
#ifndef mapper0_h
#define mapper0_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct mapper0 mapper0_t;
typedef struct agnes agnes_t;
AGNES_INTERNAL void mapper0_init(mapper0_t *mapper, agnes_t *agnes);
AGNES_INTERNAL uint8_t mapper0_read(mapper0_t *mapper, uint16_t addr);
AGNES_INTERNAL void mapper0_write(mapper0_t *mapper, uint16_t addr, uint8_t val);
#endif /* mapper0_h */
//FILE_END
//FILE_START:mapper1.h
#ifndef mapper1_h
#define mapper1_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct mapper1 mapper1_t;
typedef struct agnes agnes_t;
AGNES_INTERNAL void mapper1_init(mapper1_t *mapper, agnes_t *agnes);
AGNES_INTERNAL uint8_t mapper1_read(mapper1_t *mapper, uint16_t addr);
AGNES_INTERNAL void mapper1_write(mapper1_t *mapper, uint16_t addr, uint8_t val);
#endif /* mapper1_h */
//FILE_END
//FILE_START:mapper2.h
#ifndef mapper2_h
#define mapper2_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct mapper2 mapper2_t;
typedef struct agnes agnes_t;
AGNES_INTERNAL void mapper2_init(mapper2_t *mapper, agnes_t *agnes);
AGNES_INTERNAL uint8_t mapper2_read(mapper2_t *mapper, uint16_t addr);
AGNES_INTERNAL void mapper2_write(mapper2_t *mapper, uint16_t addr, uint8_t val);
#endif /* mapper2_h */
//FILE_END
//FILE_START:mapper4.h
#ifndef mapper4_h
#define mapper4_h
#ifndef AGNES_AMALGAMATED
#include "common.h"
#endif
typedef struct mapper4 mapper4_t;
typedef struct agnes agnes_t;
AGNES_INTERNAL void mapper4_init(mapper4_t *mapper, agnes_t *agnes);
AGNES_INTERNAL uint8_t mapper4_read(mapper4_t *mapper, uint16_t addr);
AGNES_INTERNAL void mapper4_write(mapper4_t *mapper, uint16_t addr, uint8_t val);
AGNES_INTERNAL void mapper4_pa12_rising_edge(mapper4_t *mapper);
#endif /* mapper4_h */
//FILE_END
//-----------------------------------------------------------------------------
// C files
//-----------------------------------------------------------------------------
//FILE_START:agnes.c
//#include <stdlib.h>
//#include <string.h>
#ifndef AGNES_AMALGAMATED
#include "agnes.h"
#include "common.h"
#include "agnes_types.h"
#include "cpu.h"
#include "ppu.h"
#include "mapper.h"
#endif
#define AGNES_IMPL_VERSION_MAJOR 0
#define AGNES_IMPL_VERSION_MINOR 2
#define AGNES_IMPL_VERSION_PATCH 0
#if (AGNES_VERSION_MAJOR != AGNES_IMPL_VERSION_MAJOR)\
|| (AGNES_VERSION_MINOR != AGNES_IMPL_VERSION_MINOR)\
|| (AGNES_VERSION_PATCH != AGNES_IMPL_VERSION_PATCH)
#error "Version mismatch"
#endif
typedef struct {
uint8_t magic[4];
uint8_t prg_rom_banks_count;
uint8_t chr_rom_banks_count;
uint8_t flags_6;
uint8_t flags_7;
uint8_t prg_ram_banks_count;
uint8_t flags_9;
uint8_t flags_10;
uint8_t zeros[5];
} ines_header_t;
typedef struct agnes_state {
agnes_t agnes;
} agnes_state_t;
static uint8_t get_input_byte(const agnes_input_t* input);
static agnes_color_t g_colors[64] = {
{0x7c, 0x7c, 0x7c, 0xff}, {0x00, 0x00, 0xfc, 0xff}, {0x00, 0x00, 0xbc, 0xff}, {0x44, 0x28, 0xbc, 0xff},
{0x94, 0x00, 0x84, 0xff}, {0xa8, 0x00, 0x20, 0xff}, {0xa8, 0x10, 0x00, 0xff}, {0x88, 0x14, 0x00, 0xff},
{0x50, 0x30, 0x00, 0xff}, {0x00, 0x78, 0x00, 0xff}, {0x00, 0x68, 0x00, 0xff}, {0x00, 0x58, 0x00, 0xff},
{0x00, 0x40, 0x58, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff},
{0xbc, 0xbc, 0xbc, 0xff}, {0x00, 0x78, 0xf8, 0xff}, {0x00, 0x58, 0xf8, 0xff}, {0x68, 0x44, 0xfc, 0xff},
{0xd8, 0x00, 0xcc, 0xff}, {0xe4, 0x00, 0x58, 0xff}, {0xf8, 0x38, 0x00, 0xff}, {0xe4, 0x5c, 0x10, 0xff},
{0xac, 0x7c, 0x00, 0xff}, {0x00, 0xb8, 0x00, 0xff}, {0x00, 0xa8, 0x00, 0xff}, {0x00, 0xa8, 0x44, 0xff},
{0x00, 0x88, 0x88, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff},
{0xf8, 0xf8, 0xf8, 0xff}, {0x3c, 0xbc, 0xfc, 0xff}, {0x68, 0x88, 0xfc, 0xff}, {0x98, 0x78, 0xf8, 0xff},
{0xf8, 0x78, 0xf8, 0xff}, {0xf8, 0x58, 0x98, 0xff}, {0xf8, 0x78, 0x58, 0xff}, {0xfc, 0xa0, 0x44, 0xff},
{0xf8, 0xb8, 0x00, 0xff}, {0xb8, 0xf8, 0x18, 0xff}, {0x58, 0xd8, 0x54, 0xff}, {0x58, 0xf8, 0x98, 0xff},
{0x00, 0xe8, 0xd8, 0xff}, {0x78, 0x78, 0x78, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff},
{0xfc, 0xfc, 0xfc, 0xff}, {0xa4, 0xe4, 0xfc, 0xff}, {0xb8, 0xb8, 0xf8, 0xff}, {0xd8, 0xb8, 0xf8, 0xff},
{0xf8, 0xb8, 0xf8, 0xff}, {0xf8, 0xa4, 0xc0, 0xff}, {0xf0, 0xd0, 0xb0, 0xff}, {0xfc, 0xe0, 0xa8, 0xff},
{0xf8, 0xd8, 0x78, 0xff}, {0xd8, 0xf8, 0x78, 0xff}, {0xb8, 0xf8, 0xb8, 0xff}, {0xb8, 0xf8, 0xd8, 0xff},
{0x00, 0xfc, 0xfc, 0xff}, {0xf8, 0xd8, 0xf8, 0xff}, {0x00, 0x00, 0x00, 0xff}, {0x00, 0x00, 0x00, 0xff},
};
agnes_t* agnes_make(void) {
agnes_t *agnes = (agnes_t*)malloc(sizeof(*agnes));
if (!agnes) {
return NULL;
}
memset(agnes, 0, sizeof(*agnes));
memset(agnes->ram, 0xff, sizeof(agnes->ram));
return agnes;
}
bool agnes_load_ines_data(agnes_t *agnes, const void *data, size_t data_size) {
if (data_size < sizeof(ines_header_t)) {
return false;
}
ines_header_t *header = (ines_header_t*)data;
if (strncmp((char*)header->magic, "NES\x1a", 4) != 0) {
return false;
}
unsigned prg_rom_offset = sizeof(ines_header_t);
bool has_trainer = AGNES_GET_BIT(header->flags_6, 2);
if (has_trainer) {
prg_rom_offset += 512;
}
agnes->gamepack.chr_rom_banks_count = header->chr_rom_banks_count;
agnes->gamepack.prg_rom_banks_count = header->prg_rom_banks_count;
if (AGNES_GET_BIT(header->flags_6, 3)) {
agnes->mirroring_mode = MIRRORING_MODE_FOUR_SCREEN;
} else {
agnes->mirroring_mode = AGNES_GET_BIT(header->flags_6, 0) ? MIRRORING_MODE_VERTICAL : MIRRORING_MODE_HORIZONTAL;
}
agnes->gamepack.mapper = ((header->flags_6 & 0xf0) >> 4) | (header->flags_7 & 0xf0);
unsigned prg_rom_size = header->prg_rom_banks_count * (16 * 1024);
unsigned chr_rom_size = header->chr_rom_banks_count * (8 * 1024);
unsigned chr_rom_offset = prg_rom_offset + prg_rom_size;
if ((chr_rom_offset + chr_rom_size) > data_size) {
return false;
}
agnes->gamepack.data = (const uint8_t *)data;
agnes->gamepack.prg_rom_offset = prg_rom_offset;
agnes->gamepack.chr_rom_offset = chr_rom_offset;
bool ok = mapper_init(agnes);
if (!ok) {
return false;
}
cpu_init(&agnes->cpu, agnes);
ppu_init(&agnes->ppu, agnes);
return true;
}
void agnes_set_input(agnes_t *agn, const agnes_input_t *input_1, const agnes_input_t *input_2) {
if (input_1 != NULL) {
agn->controllers[0].state = get_input_byte(input_1);
}
if (input_2 != NULL) {
agn->controllers[1].state = get_input_byte(input_2);
}
}
size_t agnes_state_size() {
return sizeof(agnes_state_t);
}
void agnes_dump_state(const agnes_t *agnes, agnes_state_t *out_res) {
memmove(out_res, agnes, sizeof(agnes_t));
out_res->agnes.gamepack.data = NULL;
out_res->agnes.cpu.agnes = NULL;
out_res->agnes.ppu.agnes = NULL;
switch (out_res->agnes.gamepack.mapper) {
case 0: out_res->agnes.mapper.m0.agnes = NULL; break;
case 1: out_res->agnes.mapper.m1.agnes = NULL; break;
case 2: out_res->agnes.mapper.m2.agnes = NULL; break;
case 4: out_res->agnes.mapper.m4.agnes = NULL; break;
}
}
bool agnes_restore_state(agnes_t *agnes, const agnes_state_t *state) {
const uint8_t *gamepack_data = agnes->gamepack.data;
memmove(agnes, state, sizeof(agnes_t));
agnes->gamepack.data = gamepack_data;
agnes->cpu.agnes = agnes;
agnes->ppu.agnes = agnes;
switch (agnes->gamepack.mapper) {
case 0: agnes->mapper.m0.agnes = agnes; break;
case 1: agnes->mapper.m1.agnes = agnes; break;
case 2: agnes->mapper.m2.agnes = agnes; break;
case 4: agnes->mapper.m4.agnes = agnes; break;
}
return true;
}
bool agnes_tick(agnes_t *agnes, bool *out_new_frame) {
int cpu_cycles = cpu_tick(&agnes->cpu);
if (cpu_cycles == 0) {
return false;
}
int ppu_cycles = cpu_cycles * 3;
for (int i = 0; i < ppu_cycles; i++) {
ppu_tick(&agnes->ppu, out_new_frame);
}
return true;
}
bool agnes_next_frame(agnes_t *agnes) {
while (true) {
bool new_frame = false;
bool ok = agnes_tick(agnes, &new_frame);
if (!ok) {
return false;
}
if (new_frame) {
break;
}
}
return true;
}
agnes_color_t agnes_get_screen_pixel(const agnes_t *agnes, int x, int y) {
int ix = (y * AGNES_SCREEN_WIDTH) + x;
uint8_t color_ix = agnes->ppu.screen_buffer[ix];
return g_colors[color_ix & 0x3f];
}
void agnes_destroy(agnes_t *agnes) {
free(agnes);
}
static uint8_t get_input_byte(const agnes_input_t* input) {
uint8_t res = 0;
res |= input->a << 0;
res |= input->b << 1;
res |= input->select << 2;
res |= input->start << 3;
res |= input->up << 4;
res |= input->down << 5;
res |= input->left << 6;
res |= input->right << 7;
return res;
}
//FILE_END
//FILE_START:cpu.c
//#include <string.h>
#ifndef AGNES_AMALGAMATED
#include "cpu.h"
#include "ppu.h"
#include "agnes_types.h"
#include "instructions.h"
#include "mapper.h"
#endif
static uint16_t cpu_read16_indirect_bug(cpu_t *cpu, uint16_t addr);
static uint16_t get_instruction_operand(cpu_t *cpu, addr_mode_t mode, bool *out_pages_differ);
static int handle_interrupt(cpu_t *cpu);
static bool check_pages_differ(uint16_t a, uint16_t b);
void cpu_init(cpu_t *cpu, agnes_t *agnes) {
memset(cpu, 0, sizeof(cpu_t));
cpu->agnes = agnes;
cpu->pc = cpu_read16(cpu, 0xfffc); // RESET
cpu->sp = 0xfd;
cpu_restore_flags(cpu, 0x24);
}
int cpu_tick(cpu_t *cpu) {
if (cpu->stall > 0) {
cpu->stall--;
return 1;
}
int cycles = 0;
if (cpu->interrupt != INTERRPUT_NONE) {
cycles += handle_interrupt(cpu);
}
uint8_t opcode = cpu_read8(cpu, cpu->pc);
instruction_t *ins = instruction_get(opcode);
if (ins->operation == NULL) {
return 0;
}
uint8_t ins_size = instruction_get_size(ins->mode);
bool page_crossed = false;
uint16_t addr = get_instruction_operand(cpu, ins->mode, &page_crossed);
cpu->pc += ins_size;
cycles += ins->cycles;
cycles += ins->operation(cpu, addr, ins->mode);
if (page_crossed && ins->page_cross_cycle) {
cycles += 1;
}
cpu->cycles += cycles;
return cycles;
}
void cpu_update_zn_flags(cpu_t *cpu, uint8_t val) {
cpu->flag_zero = val == 0;
cpu->flag_negative = AGNES_GET_BIT(val, 7);
}
void cpu_stack_push8(cpu_t *cpu, uint8_t val) {
uint16_t addr = 0x0100 + (uint16_t)(cpu->sp);
cpu_write8(cpu, addr, val);
cpu->sp--;
}
void cpu_stack_push16(cpu_t *cpu, uint16_t val) {
cpu_stack_push8(cpu, val >> 8);
cpu_stack_push8(cpu, val);
}
uint8_t cpu_stack_pop8(cpu_t *cpu) {
cpu->sp++;
uint16_t addr = 0x0100 + (uint16_t)(cpu->sp);
uint8_t res = cpu_read8(cpu, addr);
return res;
}
uint16_t cpu_stack_pop16(cpu_t *cpu) {
uint16_t lo = cpu_stack_pop8(cpu);
uint16_t hi = cpu_stack_pop8(cpu);
uint16_t res = (hi << 8) | lo;
return res;
}
uint8_t cpu_get_flags(const cpu_t *cpu) {
uint8_t res = 0;
res |= cpu->flag_carry << 0;
res |= cpu->flag_zero << 1;
res |= cpu->flag_dis_interrupt << 2;
res |= cpu->flag_decimal << 3;
res |= cpu->flag_overflow << 6;
res |= cpu->flag_negative << 7;
return res;
}
void cpu_restore_flags(cpu_t *cpu, uint8_t flags) {
cpu->flag_carry = AGNES_GET_BIT(flags, 0);
cpu->flag_zero = AGNES_GET_BIT(flags, 1);
cpu->flag_dis_interrupt = AGNES_GET_BIT(flags, 2);
cpu->flag_decimal = AGNES_GET_BIT(flags, 3);
cpu->flag_overflow = AGNES_GET_BIT(flags, 6);
cpu->flag_negative = AGNES_GET_BIT(flags, 7);
}
void cpu_trigger_nmi(cpu_t *cpu) {
cpu->interrupt = INTERRUPT_NMI;
}
void cpu_trigger_irq(cpu_t *cpu) {
if (!cpu->flag_dis_interrupt) {
cpu->interrupt = INTERRUPT_IRQ;
}
}
void cpu_set_dma_stall(cpu_t *cpu) {
cpu->stall = (cpu->cycles & 0x1) ? 514 : 513;
}
void cpu_write8(cpu_t *cpu, uint16_t addr, uint8_t val) {
agnes_t *agnes = cpu->agnes;
if (addr < 0x2000) {
agnes->ram[addr & 0x7ff] = val;
} else if (addr < 0x4000) {
ppu_write_register(&agnes->ppu, 0x2000 | (addr & 0x7), val);
} else if (addr == 0x4014) {
ppu_write_register(&agnes->ppu, 0x4014, val);
} else if (addr == 0x4016) {
agnes->controllers_latch = val & 0x1;
if (agnes->controllers_latch) {
agnes->controllers[0].shift = agnes->controllers[0].state;
agnes->controllers[1].shift = agnes->controllers[1].state;
}
} else if (addr < 0x4018) { // apu and io
} else if (addr < 0x4020) { // disabled
} else {
mapper_write(agnes, addr, val);
}
}
uint8_t cpu_read8(cpu_t *cpu, uint16_t addr) {
agnes_t *agnes = cpu->agnes;
uint8_t res = 0;
if (addr >= 0x4020) { // moved to top because it's the most common case
res = mapper_read(agnes, addr);
} else if (addr < 0x2000) {
res = agnes->ram[addr & 0x7ff];
} else if (addr < 0x4000) {
res = ppu_read_register(&agnes->ppu, 0x2000 | (addr & 0x7));
} else if (addr < 0x4016) {
// apu
} else if (addr < 0x4018) {
int controller = addr & 0x1; // 0: 0x4016, 1: 0x4017
if (agnes->controllers_latch) {
agnes->controllers[controller].shift = agnes->controllers[controller].state;
}
res = agnes->controllers[controller].shift & 0x1;
agnes->controllers[controller].shift >>= 1;
}
return res;
}
uint16_t cpu_read16(cpu_t *cpu, uint16_t addr) {
uint8_t lo = cpu_read8(cpu, addr);
uint8_t hi = cpu_read8(cpu, addr + 1);
return (hi << 8) | lo;
}
static uint16_t cpu_read16_indirect_bug(cpu_t *cpu, uint16_t addr) {
uint8_t lo = cpu_read8(cpu, addr);
uint8_t hi = cpu_read8(cpu, (addr & 0xff00) | ((addr + 1) & 0x00ff));
return (hi << 8) | lo;
}
static uint16_t get_instruction_operand(cpu_t *cpu, addr_mode_t mode, bool *out_pages_differ) {
*out_pages_differ = false;
switch (mode) {
case ADDR_MODE_ABSOLUTE: {
return cpu_read16(cpu, cpu->pc + 1);
}
case ADDR_MODE_ABSOLUTE_X: {
uint16_t addr = cpu_read16(cpu, cpu->pc + 1);
uint16_t res = addr + cpu->x;
*out_pages_differ = check_pages_differ(addr, res);
return res;
}
case ADDR_MODE_ABSOLUTE_Y: {
uint16_t addr = cpu_read16(cpu, cpu->pc + 1);
uint16_t res = addr + cpu->y;
*out_pages_differ = check_pages_differ(addr, res);
return res;
}
case ADDR_MODE_IMMEDIATE: {
return cpu->pc + 1;
}
case ADDR_MODE_INDIRECT: {
uint16_t addr = cpu_read16(cpu, cpu->pc + 1);
return cpu_read16_indirect_bug(cpu, addr);
}
case ADDR_MODE_INDIRECT_X: {
uint8_t addr = cpu_read8(cpu, (cpu->pc + 1));
return cpu_read16_indirect_bug(cpu, (addr + cpu->x) & 0xff);
}
case ADDR_MODE_INDIRECT_Y: {
uint8_t arg = cpu_read8(cpu, cpu->pc + 1);
uint16_t addr2 = cpu_read16_indirect_bug(cpu, arg);
uint16_t res = addr2 + cpu->y;
*out_pages_differ = check_pages_differ(addr2, res);
return res;
}
case ADDR_MODE_ZERO_PAGE: {
return cpu_read8(cpu, cpu->pc + 1);
}
case ADDR_MODE_ZERO_PAGE_X: {
return (cpu_read8(cpu, cpu->pc + 1) + cpu->x) & 0xff;
}
case ADDR_MODE_ZERO_PAGE_Y: {
return (cpu_read8(cpu, cpu->pc + 1) + cpu->y) & 0xff;
}
case ADDR_MODE_RELATIVE: {
uint8_t addr = cpu_read8(cpu, cpu->pc + 1);
if (addr < 0x80) {
return cpu->pc + addr + 2;
} else {
return cpu->pc + addr + 2 - 0x100;
}
}
default: {
return 0;
}
}
}
static int handle_interrupt(cpu_t *cpu) {
uint16_t addr = 0;
if (cpu->interrupt == INTERRUPT_NMI) {
addr = 0xfffa;
} else if (cpu->interrupt == INTERRUPT_IRQ) {
addr = 0xfffe;
} else {
return 0;
}
cpu->interrupt = INTERRPUT_NONE;
cpu_stack_push16(cpu, cpu->pc);
uint8_t flags = cpu_get_flags(cpu);
cpu_stack_push8(cpu, flags | 0x20);
cpu->pc = cpu_read16(cpu, addr);
cpu->flag_dis_interrupt = true;
return 7;
}
static bool check_pages_differ(uint16_t a, uint16_t b) {
return (0xff00 & a) != (0xff00 & b);
}
//FILE_END
//FILE_START:ppu.c
//#include <stdlib.h>
//#include <string.h>
//#include <stdio.h>
#ifndef AGNES_AMALGAMATED
#include "ppu.h"
#include "agnes_types.h"
#include "cpu.h"
#include "mapper.h"
#endif
static void scanline_visible_pre(ppu_t *ppu, bool *out_new_frame);
static void inc_hori_v(ppu_t *ppu);
static void inc_vert_v(ppu_t *ppu);
static void emit_pixel(ppu_t *ppu);
static uint16_t get_bg_color_addr(ppu_t *ppu);
static uint16_t get_sprite_color_addr(ppu_t *ppu, int *out_sprite_ix, bool *out_behind_bg);
static void eval_sprites(ppu_t *ppu);
static void set_pixel_color_ix(ppu_t *ppu, int x, int y, uint8_t color_ix);
static uint8_t ppu_read8(ppu_t *ppu, uint16_t addr);
static void ppu_write8(ppu_t *ppu, uint16_t addr, uint8_t val);
static uint16_t mirror_address(ppu_t *ppu, uint16_t addr);
static unsigned g_palette_addr_map[32] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x00, 0x11, 0x12, 0x13, 0x04, 0x15, 0x16, 0x17, 0x08, 0x19, 0x1a, 0x1b, 0x0c, 0x1d, 0x1e, 0x1f,
};
void ppu_init(ppu_t *ppu, agnes_t *agnes) {
memset(ppu, 0, sizeof(ppu_t));
ppu->agnes = agnes;
ppu_write_register(ppu, 0x2000, 0);
ppu_write_register(ppu, 0x2001, 0);
}
void ppu_tick(ppu_t *ppu, bool *out_new_frame) {
bool rendering_enabled = ppu->masks.show_background || ppu->masks.show_sprites;
// https://wiki.nesdev.com/w/index.php/PPU_frame_timing#Even.2FOdd_Frames
if (rendering_enabled && ppu->is_odd_frame && ppu->dot == 339 && ppu->scanline == 261) {
ppu->dot = 0;
ppu->scanline = 0;
ppu->is_odd_frame = !ppu->is_odd_frame;
} else {
ppu->dot++;
if (ppu->dot > 340){
ppu->dot = 0;
ppu->scanline++;
}
if (ppu->scanline > 261) {
ppu->scanline = 0;
ppu->is_odd_frame = !ppu->is_odd_frame;
}
}
if (ppu->dot == 0) {
return;
}
bool scanline_visible = ppu->scanline >= 0 && ppu->scanline < 240;
bool scanline_pre = ppu->scanline == 261;
bool scanline_post = ppu->scanline == 241;
if (rendering_enabled && (scanline_visible || scanline_pre)) {
scanline_visible_pre(ppu, out_new_frame);
}
if (ppu->dot == 1) {
if (scanline_pre) {
ppu->status.sprite_overflow = false;
ppu->status.sprite_zero_hit = false;
ppu->status.in_vblank = false;
} else if (scanline_post) {
ppu->status.in_vblank = true;
*out_new_frame = true;
if (ppu->ctrl.nmi_enabled) {
cpu_trigger_nmi(&ppu->agnes->cpu);
}
}
}
}
static void scanline_visible_pre(ppu_t *ppu, bool *out_new_frame) {
bool scanline_visible = ppu->scanline >= 0 && ppu->scanline < 240;
bool scanline_pre = ppu->scanline == 261;
bool dot_visible = ppu->dot > 0 && ppu->dot <= 256;
bool dot_fetch = ppu->dot <= 256 || (ppu->dot >= 321 && ppu->dot < 337);
if (scanline_visible && dot_visible) {
emit_pixel(ppu);
}
if (dot_fetch) {
ppu->bg_lo_shift <<= 1;
ppu->bg_hi_shift <<= 1;
ppu->at_shift = (ppu->at_shift << 2) | (ppu->at_latch & 0x3);
switch (ppu->dot & 0x7) {
case 1: {
uint16_t addr = 0x2000 | (ppu->regs.v & 0x0fff);
ppu->nt = ppu_read8(ppu, addr);
break;
}
case 3: {
uint16_t v = ppu->regs.v;
uint16_t addr = 0x23C0 | (v & 0x0C00) | ((v >> 4) & 0x38) | ((v >> 2) & 0x07);
ppu->at = ppu_read8(ppu, addr);
if (ppu->regs.v & 0x40) {
ppu->at = ppu->at >> 4;
}
if (ppu->regs.v & 0x02) {
ppu->at = ppu->at >> 2;
}
break;
}
case 5: {
uint8_t fine_y = ((ppu->regs.v) >> 12) & 0x7;
uint16_t addr = ppu->ctrl.bg_table_addr + (ppu->nt << 4) + fine_y;
ppu->bg_lo = ppu_read8(ppu, addr);
break;
}
case 7: {
uint8_t fine_y = ((ppu->regs.v) >> 12) & 0x7;
uint16_t addr = ppu->ctrl.bg_table_addr + (ppu->nt << 4) + fine_y + 8;
ppu->bg_hi = ppu_read8(ppu, addr);
break;
}
case 0: {
ppu->bg_lo_shift = (ppu->bg_lo_shift & 0xff00) | ppu->bg_lo;
ppu->bg_hi_shift = (ppu->bg_hi_shift & 0xff00) | ppu->bg_hi;
ppu->at_latch = ppu->at & 0x3;
if (ppu->dot == 256) {
inc_vert_v(ppu);
} else {
inc_hori_v(ppu);
}
break;
}
default:
break;
}
}
if (ppu->dot == 257) {
// v: |_...|.F..| |...E|DCBA| = t: |_...|.F..| |...E|DCBA|
ppu->regs.v = (ppu->regs.v & 0xfbe0) | (ppu->regs.t & ~(0xfbe0));
if (scanline_visible) {
eval_sprites(ppu);
} else {
ppu->sprite_ixs_count = 0;
}
}
if (scanline_pre && ppu->dot >= 280 && ppu->dot <= 304) {
// v: |_IHG|F.ED| |CBA.|....| = t: |_IHG|F.ED| |CBA.|....|
ppu->regs.v = (ppu->regs.v & 0x841f) | (ppu->regs.t & ~(0x841f));
}
if (ppu->masks.show_background && ppu->masks.show_sprites) {
if ((ppu->ctrl.bg_table_addr == 0x0000 && ppu->dot == 270) // Should be 260 but it caused glitches in Kirby
|| (ppu->ctrl.bg_table_addr == 0x1000 && ppu->dot == 324)) { // Not tested so far.
// https://wiki.nesdev.com/w/index.php/MMC3#IRQ_Specifics
// PA12 is 12th bit of PPU address bus that's toggled when switching between
// background and sprite pattern tables (should happen once per scanline).
// This might not work correctly with games using 8x16 sprites
// or games writing to CHR RAM.
mapper_pa12_rising_edge(ppu->agnes);
}
}
}
#define GET_COARSE_X(v) ((v) & 0x1f)
#define SET_COARSE_X(v, cx) do { v = (((v) & ~0x1f) | ((cx) & 0x1f)); } while (0)
#define GET_COARSE_Y(v) (((v) >> 5) & 0x1f)
#define SET_COARSE_Y(v, cy) do { v = (((v) & ~0x3e0) | ((cy) & 0x1f) << 5); } while (0)
#define GET_FINE_Y(v) ((v) >> 12)
#define SET_FINE_Y(v, fy) do { v = (((v) & ~0x7000) | (((fy) & 0x7) << 12)); } while (0)
static void inc_hori_v(ppu_t *ppu) {
unsigned cx = GET_COARSE_X(ppu->regs.v);
if (cx == 31) {
SET_COARSE_X(ppu->regs.v, 0);
ppu->regs.v ^= 0x0400; // switch horizontal nametable
} else {
SET_COARSE_X(ppu->regs.v, cx + 1);
}
}
static void inc_vert_v(ppu_t *ppu) {
unsigned fy = GET_FINE_Y(ppu->regs.v);
if (fy < 7) {
SET_FINE_Y(ppu->regs.v, fy + 1);
} else {
SET_FINE_Y(ppu->regs.v, 0);
unsigned cy = GET_COARSE_Y(ppu->regs.v);
if (cy == 29) {
SET_COARSE_Y(ppu->regs.v, 0);
ppu->regs.v ^= 0x0800; // switch vertical nametable
} else if (cy == 31) {
SET_COARSE_Y(ppu->regs.v, 0);
} else {
SET_COARSE_Y(ppu->regs.v, cy + 1);
}
}
}
#undef GET_COARSE_X
#undef SET_COARSE_X
#undef GET_COARSE_Y
#undef SET_COARSE_Y
#undef GET_FINE_Y
#undef SET_FINE_Y
static void eval_sprites(ppu_t *ppu) {
ppu->sprite_ixs_count = 0;
const sprite_t* sprites = (const sprite_t*)ppu->oam_data;
int sprite_height = ppu->ctrl.use_8x16_sprites ? 16 : 8;
for (int i = 0; i < 64; i++) {
const sprite_t* sprite = &sprites[i];
if (sprite->y_pos > 0xef || sprite->x_pos > 0xff) {
continue;
}
int s_y = ppu->scanline - sprite->y_pos;
if (s_y < 0 || s_y >= sprite_height) {
continue;
}
if (ppu->sprite_ixs_count < 8) {
ppu->sprites[ppu->sprite_ixs_count] = *sprite;
ppu->sprite_ixs[ppu->sprite_ixs_count] = i;
ppu->sprite_ixs_count++;
} else {
ppu->status.sprite_overflow = true;
break;
}
}
}
static void emit_pixel(ppu_t *ppu) {
const int x = ppu->dot - 1;
const int y = ppu->scanline;
if (x < 8 && !ppu->masks.show_leftmost_bg && !ppu->masks.show_leftmost_sprites) {
set_pixel_color_ix(ppu, x, y, 63); // 63 is black in my default colour palette
return;
}
uint16_t bg_color_addr = get_bg_color_addr(ppu);
int sprite_ix = -1;
bool behind_bg = false;
uint16_t sp_color_addr = get_sprite_color_addr(ppu, &sprite_ix, &behind_bg);
uint16_t color_addr = 0x3f00;
if (bg_color_addr && sp_color_addr) {
if (sprite_ix == 0 && x != 255) {
ppu->status.sprite_zero_hit = true;
}
color_addr = behind_bg ? bg_color_addr : sp_color_addr;
} else if (bg_color_addr && !sp_color_addr) {
color_addr = bg_color_addr;
} else if (!bg_color_addr && sp_color_addr) {
color_addr = sp_color_addr;
}
uint8_t output_color_ix = ppu_read8(ppu, color_addr);
set_pixel_color_ix(ppu, x, y, output_color_ix);
}
static uint16_t get_bg_color_addr(ppu_t *ppu) {
if (!ppu->masks.show_background || (!ppu->masks.show_leftmost_bg && ppu->dot < 9)) {
return 0;
}
bool hi_bit = AGNES_GET_BIT(ppu->bg_hi_shift, 15 - ppu->regs.x);
bool lo_bit = AGNES_GET_BIT(ppu->bg_lo_shift, 15 - ppu->regs.x);
if (!lo_bit && !hi_bit) {
return 0;
}
uint8_t palette = (ppu->at_shift >> (14 - (ppu->regs.x << 1)) & 0x3);
uint8_t palette_ix = ((uint8_t)hi_bit << 1) | (uint8_t)lo_bit;
uint16_t color_address = 0x3f00 | (palette << 2) | palette_ix;
return color_address;
}
static uint16_t get_sprite_color_addr(ppu_t *ppu, int *out_sprite_ix, bool *out_behind_bg) {
*out_sprite_ix = -1;
*out_behind_bg = false;
const int x = ppu->dot - 1;
const int y = ppu->scanline;
if (!ppu->masks.show_sprites || (!ppu->masks.show_leftmost_sprites && x < 8)) {
return 0;
}
int sprite_height = ppu->ctrl.use_8x16_sprites ? 16 : 8;
uint16_t table = ppu->ctrl.sprite_table_addr;
for (int i = 0; i < ppu->sprite_ixs_count; i++) {
const sprite_t *sprite = &ppu->sprites[i];
int s_x = x - sprite->x_pos;
if (s_x < 0 || s_x >= 8) {
continue;
}
int s_y = y - sprite->y_pos - 1;
s_x = AGNES_GET_BIT(sprite->attrs, 6) ? 7 - s_x : s_x; // flip hor
s_y = AGNES_GET_BIT(sprite->attrs, 7) ? (sprite_height - 1 - s_y) : s_y; // flip vert
uint8_t tile_num = sprite->tile_num;
if (ppu->ctrl.use_8x16_sprites) {
table = tile_num & 0x1 ? 0x1000 : 0x0000;
tile_num &= 0xfe;
if (s_y >= 8) {
tile_num += 1;
s_y -= 8;
}
}
uint16_t offset = table + (tile_num << 4) + s_y;
uint8_t lo_byte = ppu_read8(ppu, offset);
uint8_t hi_byte = ppu_read8(ppu, offset + 8);
if (!lo_byte && !hi_byte) {
continue;
}
bool lo_bit = AGNES_GET_BIT(lo_byte, 7 - s_x);
bool hi_bit = AGNES_GET_BIT(hi_byte, 7 - s_x);
if (lo_bit || hi_bit) {
*out_sprite_ix = ppu->sprite_ixs[i];
if (AGNES_GET_BIT(sprite->attrs, 5)) {
*out_behind_bg = true;
}
uint8_t palette_ix = ((uint8_t)hi_bit << 1) | (uint8_t)lo_bit;
uint16_t color_address = 0x3f10 | ((sprite->attrs & 0x3) << 2) | palette_ix;
return color_address;
}
}
return 0;
}
uint8_t ppu_read_register(ppu_t *ppu, uint16_t addr) {
switch (addr) {
case 0x2002: { // PPUSTATUS
uint8_t res = 0;
res |= ppu->last_reg_write & 0x1f;
res |= ppu->status.sprite_overflow << 5;
res |= ppu->status.sprite_zero_hit << 6;
res |= ppu->status.in_vblank << 7;
ppu->status.in_vblank = false;
// res |= ppu->status_in_vblank
// w: = 0
ppu->regs.w = 0;
return res;
}
case 0x2004: { // OAMDATA
return ppu->oam_data[ppu->oam_address];
}
case 0x2007: { // PPUDATA
uint8_t res = 0;
if (ppu->regs.v < 0x3f00) {
res = ppu->ppudata_buffer;
ppu->ppudata_buffer = ppu_read8(ppu, ppu->regs.v);
} else {
res = ppu_read8(ppu, ppu->regs.v);
ppu->ppudata_buffer = ppu_read8(ppu, ppu->regs.v - 0x1000);
}
ppu->regs.v += ppu->ctrl.addr_increment;
return res;
}
}
return 0;
}
void ppu_write_register(ppu_t *ppu, uint16_t addr, uint8_t val) {
ppu->last_reg_write = val;
switch (addr) {
case 0x2000: { // PPUCTRL
ppu->ctrl.addr_increment = AGNES_GET_BIT(val, 2) ? 32 : 1;
ppu->ctrl.sprite_table_addr = AGNES_GET_BIT(val, 3) ? 0x1000 : 0x0000;
ppu->ctrl.bg_table_addr = AGNES_GET_BIT(val, 4) ? 0x1000 : 0x0000;
ppu->ctrl.use_8x16_sprites = AGNES_GET_BIT(val, 5);
ppu->ctrl.nmi_enabled = AGNES_GET_BIT(val, 7);
// t: |_...|BA..| |....|....| = d: |....|..BA|
ppu->regs.t = (ppu->regs.t & 0xf3ff) | ((val & 0x03) << 10);
break;
}
case 0x2001: { // PPUMASK
ppu->masks.show_leftmost_bg = AGNES_GET_BIT(val, 1);
ppu->masks.show_leftmost_sprites = AGNES_GET_BIT(val, 2);
ppu->masks.show_background = AGNES_GET_BIT(val, 3);
ppu->masks.show_sprites = AGNES_GET_BIT(val, 4);
break;
}
case 0x2003: { // OAMADDR
ppu->oam_address = val;
break;
}
case 0x2004: { // OAMDATA
ppu->oam_data[ppu->oam_address] = val;
ppu->oam_address++;
break;
}
case 0x2005: { // SCROLL
if (ppu->regs.w) {
// t: |_CBA|..HG| |FED.|....| = d: |HGFE|DCBA|
// w: = 0
ppu->regs.t = (ppu->regs.t & 0x8fff) | ((val & 0x7) << 12);
ppu->regs.t = (ppu->regs.t & 0xfc1f) | ((val >> 3) << 5);
ppu->regs.w = 0;
} else {
// t: |_...|....| |...H|GFED| = d: HGFED...
// x: CBA = d: |...|..CBA|
// w: = 1
ppu->regs.t = (ppu->regs.t & 0xffe0) | (val >> 3);
ppu->regs.x = (val & 0x7);
ppu->regs.w = 1;
}
break;
}
case 0x2006: { // PPUADDR
if (ppu->regs.w) {
// t: |_...|....| |HGFE|DCBA| = d: |HGFE|DCBA|
// v = t
// w: = 0
ppu->regs.t = (ppu->regs.t & 0xff00) | val;
ppu->regs.v = ppu->regs.t;
ppu->regs.w = 0;
} else {
// t: |_.FE|DCBA| |....|....| = d: |..FE|DCBA|
// t: |_X..|....| |....|....| = 0
// w: = 1
ppu->regs.t = (ppu->regs.t & 0xc0ff) | ((val & 0x3f) << 8);
ppu->regs.t = ppu->regs.t & 0xbfff;
ppu->regs.w = 1;
}
break;
}
case 0x2007: { // PPUDATA
ppu_write8(ppu, ppu->regs.v, val);
ppu->regs.v += ppu->ctrl.addr_increment;
break;
}
case 0x4014: { // OAMDMA
uint16_t dma_addr = ((uint16_t)val) << 8;
for (int i = 0; i < 256; i++) {
ppu->oam_data[ppu->oam_address] = cpu_read8(&ppu->agnes->cpu, dma_addr);
ppu->oam_address++;
dma_addr++;
}
cpu_set_dma_stall(&ppu->agnes->cpu);
break;
}
}
}
static void set_pixel_color_ix(ppu_t *ppu, int x, int y, uint8_t color_ix) {
int ix = (y * AGNES_SCREEN_WIDTH) + x;
ppu->screen_buffer[ix] = color_ix;
}
static uint8_t ppu_read8(ppu_t *ppu, uint16_t addr) {
addr = addr & 0x3fff;
uint8_t res = 0;
if (addr >= 0x3f00) { // $3F00 - $3FFF, palette reads are most common
unsigned palette_ix = g_palette_addr_map[addr & 0x1f];
res = ppu->palette[palette_ix];
} else if (addr < 0x2000) { // $0000 - $1FFF
res = mapper_read(ppu->agnes, addr);
} else { // $2000 - $3EFF
uint16_t mirrored_addr = mirror_address(ppu, addr);
res = ppu->nametables[mirrored_addr];
}
return res;
}
static void ppu_write8(ppu_t *ppu, uint16_t addr, uint8_t val) {
addr = addr & 0x3fff;
if (addr >= 0x3f00) { // $3F00 - $3FFF
int palette_ix = g_palette_addr_map[addr & 0x1f];
ppu->palette[palette_ix] = val;
} else if (addr < 0x2000) { // $0000 - $1FFF
mapper_write(ppu->agnes, addr, val);
} else { // $2000 - $3EFF
uint16_t mirrored_addr = mirror_address(ppu, addr);
ppu->nametables[mirrored_addr] = val;
}
}
static uint16_t mirror_address(ppu_t *ppu, uint16_t addr) {
switch (ppu->agnes->mirroring_mode)
{
case MIRRORING_MODE_HORIZONTAL: return ((addr >> 1) & 0x400) | (addr & 0x3ff);
case MIRRORING_MODE_VERTICAL: return addr & 0x07ff;
case MIRRORING_MODE_SINGLE_LOWER: return addr & 0x3ff;
case MIRRORING_MODE_SINGLE_UPPER: return 0x400 | (addr & 0x3ff);
case MIRRORING_MODE_FOUR_SCREEN: return addr - 0x2000;
default: return 0;
}
}
//FILE_END
//FILE_START:instructions.c
#ifndef AGNES_AMALGAMATED
#include "instructions.h"
#include "agnes_types.h"
#include "cpu.h"
#endif
static int op_adc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_and(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_asl(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bcc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bcs(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_beq(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bit(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bmi(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bne(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bpl(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_brk(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bvc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_bvs(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_clc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_cld(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_cli(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_clv(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_cmp(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_cpx(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_cpy(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_dec(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_dex(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_dey(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_eor(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_inc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_inx(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_iny(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_jmp(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_jsr(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_lda(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_ldx(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_ldy(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_lsr(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_nop(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_ora(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_pha(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_php(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_pla(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_plp(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_rol(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_ror(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_rti(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_rts(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sbc(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sec(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sed(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sei(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sta(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_stx(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_sty(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_tax(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_tay(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_tsx(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_txa(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_txs(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int op_tya(cpu_t *cpu, uint16_t addr, addr_mode_t mode);
static int take_branch(cpu_t *cpu, uint16_t addr);
#define INS(OPC, NAME, CYCLES, PCC, OP, MODE) { NAME, OPC, CYCLES, PCC, MODE, OP }
#define INE(OPC) { "ILL", OPC, 1, false, ADDR_MODE_IMPLIED, NULL }
static instruction_t instructions[256] = {
INS(0x00, "BRK", 7, false, op_brk, ADDR_MODE_IMPLIED_BRK),
INS(0x01, "ORA", 6, false, op_ora, ADDR_MODE_INDIRECT_X),
INE(0x02),
INE(0x03),
INE(0x04),
INS(0x05, "ORA", 3, false, op_ora, ADDR_MODE_ZERO_PAGE),
INS(0x06, "ASL", 5, false, op_asl, ADDR_MODE_ZERO_PAGE),
INE(0x07),
INS(0x08, "PHP", 3, false, op_php, ADDR_MODE_IMPLIED),
INS(0x09, "ORA", 2, false, op_ora, ADDR_MODE_IMMEDIATE),
INS(0x0a, "ASL", 2, false, op_asl, ADDR_MODE_ACCUMULATOR),
INE(0x0b),
INE(0x0c),
INS(0x0d, "ORA", 4, false, op_ora, ADDR_MODE_ABSOLUTE),
INS(0x0e, "ASL", 6, false, op_asl, ADDR_MODE_ABSOLUTE),
INE(0x0f),
INS(0x10, "BPL", 2, true, op_bpl, ADDR_MODE_RELATIVE),
INS(0x11, "ORA", 5, true, op_ora, ADDR_MODE_INDIRECT_Y),
INE(0x12),
INE(0x13),
INE(0x14),
INS(0x15, "ORA", 4, false, op_ora, ADDR_MODE_ZERO_PAGE_X),
INS(0x16, "ASL", 6, false, op_asl, ADDR_MODE_ZERO_PAGE_X),
INE(0x17),
INS(0x18, "CLC", 2, false, op_clc, ADDR_MODE_IMPLIED),
INS(0x19, "ORA", 4, true, op_ora, ADDR_MODE_ABSOLUTE_Y),
INE(0x1a),
INE(0x1b),
INE(0x1c),
INS(0x1d, "ORA", 4, true, op_ora, ADDR_MODE_ABSOLUTE_X),
INS(0x1e, "ASL", 7, false, op_asl, ADDR_MODE_ABSOLUTE_X),
INE(0x1f),
INS(0x20, "JSR", 6, false, op_jsr, ADDR_MODE_ABSOLUTE),
INS(0x21, "AND", 6, false, op_and, ADDR_MODE_INDIRECT_X),
INE(0x22),
INE(0x23),
INS(0x24, "BIT", 3, false, op_bit, ADDR_MODE_ZERO_PAGE),
INS(0x25, "AND", 3, false, op_and, ADDR_MODE_ZERO_PAGE),
INS(0x26, "ROL", 5, false, op_rol, ADDR_MODE_ZERO_PAGE),
INE(0x27),
INS(0x28, "PLP", 4, false, op_plp, ADDR_MODE_IMPLIED),
INS(0x29, "AND", 2, false, op_and, ADDR_MODE_IMMEDIATE),
INS(0x2a, "ROL", 2, false, op_rol, ADDR_MODE_ACCUMULATOR),
INE(0x2b),
INS(0x2c, "BIT", 4, false, op_bit, ADDR_MODE_ABSOLUTE),
INS(0x2d, "AND", 4, false, op_and, ADDR_MODE_ABSOLUTE),
INS(0x2e, "ROL", 6, false, op_rol, ADDR_MODE_ABSOLUTE),
INE(0x2f),
INS(0x30, "BMI", 2, true, op_bmi, ADDR_MODE_RELATIVE),
INS(0x31, "AND", 5, true, op_and, ADDR_MODE_INDIRECT_Y),
INE(0x32),
INE(0x33),
INE(0x34),
INS(0x35, "AND", 4, false, op_and, ADDR_MODE_ZERO_PAGE_X),
INS(0x36, "ROL", 6, false, op_rol, ADDR_MODE_ZERO_PAGE_X),
INE(0x37),
INS(0x38, "SEC", 2, false, op_sec, ADDR_MODE_IMPLIED),
INS(0x39, "AND", 4, true, op_and, ADDR_MODE_ABSOLUTE_Y),
INE(0x3a),
INE(0x3b),
INE(0x3c),
INS(0x3d, "AND", 4, true, op_and, ADDR_MODE_ABSOLUTE_X),
INS(0x3e, "ROL", 7, false, op_rol, ADDR_MODE_ABSOLUTE_X),
INE(0x3f),
INS(0x40, "RTI", 6, false, op_rti, ADDR_MODE_IMPLIED),
INS(0x41, "EOR", 6, false, op_eor, ADDR_MODE_INDIRECT_X),
INE(0x42),
INE(0x43),
INE(0x44),
INS(0x45, "EOR", 3, false, op_eor, ADDR_MODE_ZERO_PAGE),
INS(0x46, "LSR", 5, false, op_lsr, ADDR_MODE_ZERO_PAGE),
INE(0x47),
INS(0x48, "PHA", 3, false, op_pha, ADDR_MODE_IMPLIED),
INS(0x49, "EOR", 2, false, op_eor, ADDR_MODE_IMMEDIATE),
INS(0x4a, "LSR", 2, false, op_lsr, ADDR_MODE_ACCUMULATOR),
INE(0x4b),
INS(0x4c, "JMP", 3, false, op_jmp, ADDR_MODE_ABSOLUTE),
INS(0x4d, "EOR", 4, false, op_eor, ADDR_MODE_ABSOLUTE),
INS(0x4e, "LSR", 6, false, op_lsr, ADDR_MODE_ABSOLUTE),
INE(0x4f),
INS(0x50, "BVC", 2, true, op_bvc, ADDR_MODE_RELATIVE),
INS(0x51, "EOR", 5, true, op_eor, ADDR_MODE_INDIRECT_Y),
INE(0x52),
INE(0x53),
INE(0x54),
INS(0x55, "EOR", 4, false, op_eor, ADDR_MODE_ZERO_PAGE_X),
INS(0x56, "LSR", 6, false, op_lsr, ADDR_MODE_ZERO_PAGE_X),
INE(0x57),
INS(0x58, "CLI", 2, false, op_cli, ADDR_MODE_IMPLIED),
INS(0x59, "EOR", 4, true, op_eor, ADDR_MODE_ABSOLUTE_Y),
INE(0x5a),
INE(0x5b),
INE(0x5c),
INS(0x5d, "EOR", 4, true, op_eor, ADDR_MODE_ABSOLUTE_X),
INS(0x5e, "LSR", 7, false, op_lsr, ADDR_MODE_ABSOLUTE_X),
INE(0x5f),
INS(0x60, "RTS", 6, false, op_rts, ADDR_MODE_IMPLIED),
INS(0x61, "ADC", 6, false, op_adc, ADDR_MODE_INDIRECT_X),
INE(0x62),
INE(0x63),
INE(0x64),
INS(0x65, "ADC", 3, false, op_adc, ADDR_MODE_ZERO_PAGE),
INS(0x66, "ROR", 5, false, op_ror, ADDR_MODE_ZERO_PAGE),
INE(0x67),
INS(0x68, "PLA", 4, false, op_pla, ADDR_MODE_IMPLIED),
INS(0x69, "ADC", 2, false, op_adc, ADDR_MODE_IMMEDIATE),
INS(0x6a, "ROR", 2, false, op_ror, ADDR_MODE_ACCUMULATOR),
INE(0x6b),
INS(0x6c, "JMP", 5, false, op_jmp, ADDR_MODE_INDIRECT),
INS(0x6d, "ADC", 4, false, op_adc, ADDR_MODE_ABSOLUTE),
INS(0x6e, "ROR", 6, false, op_ror, ADDR_MODE_ABSOLUTE),
INE(0x6f),
INS(0x70, "BVS", 2, true, op_bvs, ADDR_MODE_RELATIVE),
INS(0x71, "ADC", 5, true, op_adc, ADDR_MODE_INDIRECT_Y),
INE(0x72),
INE(0x73),
INE(0x74),
INS(0x75, "ADC", 4, false, op_adc, ADDR_MODE_ZERO_PAGE_X),
INS(0x76, "ROR", 6, false, op_ror, ADDR_MODE_ZERO_PAGE_X),
INE(0x77),
INS(0x78, "SEI", 2, false, op_sei, ADDR_MODE_IMPLIED),
INS(0x79, "ADC", 4, true, op_adc, ADDR_MODE_ABSOLUTE_Y),
INE(0x7a),
INE(0x7b),
INE(0x7c),
INS(0x7d, "ADC", 4, true, op_adc, ADDR_MODE_ABSOLUTE_X),
INS(0x7e, "ROR", 7, false, op_ror, ADDR_MODE_ABSOLUTE_X),
INE(0x7f),
INE(0x80),
INS(0x81, "STA", 6, false, op_sta, ADDR_MODE_INDIRECT_X),
INE(0x82),
INE(0x83),
INS(0x84, "STY", 3, false, op_sty, ADDR_MODE_ZERO_PAGE),
INS(0x85, "STA", 3, false, op_sta, ADDR_MODE_ZERO_PAGE),
INS(0x86, "STX", 3, false, op_stx, ADDR_MODE_ZERO_PAGE),
INE(0x87),
INS(0x88, "DEY", 2, false, op_dey, ADDR_MODE_IMPLIED),
INE(0x89),
INS(0x8a, "TXA", 2, false, op_txa, ADDR_MODE_IMPLIED),
INE(0x8b),
INS(0x8c, "STY", 4, false, op_sty, ADDR_MODE_ABSOLUTE),
INS(0x8d, "STA", 4, false, op_sta, ADDR_MODE_ABSOLUTE),
INS(0x8e, "STX", 4, false, op_stx, ADDR_MODE_ABSOLUTE),
INE(0x8f),
INS(0x90, "BCC", 2, true, op_bcc, ADDR_MODE_RELATIVE),
INS(0x91, "STA", 6, false, op_sta, ADDR_MODE_INDIRECT_Y),
INE(0x92),
INE(0x93),
INS(0x94, "STY", 4, false, op_sty, ADDR_MODE_ZERO_PAGE_X),
INS(0x95, "STA", 4, false, op_sta, ADDR_MODE_ZERO_PAGE_X),
INS(0x96, "STX", 4, false, op_stx, ADDR_MODE_ZERO_PAGE_Y),
INE(0x97),
INS(0x98, "TYA", 2, false, op_tya, ADDR_MODE_IMPLIED),
INS(0x99, "STA", 5, false, op_sta, ADDR_MODE_ABSOLUTE_Y),
INS(0x9a, "TXS", 2, false, op_txs, ADDR_MODE_IMPLIED),
INE(0x9b),
INE(0x9c),
INS(0x9d, "STA", 5, false, op_sta, ADDR_MODE_ABSOLUTE_X),
INE(0x9e),
INE(0x9f),
INS(0xa0, "LDY", 2, false, op_ldy, ADDR_MODE_IMMEDIATE),
INS(0xa1, "LDA", 6, false, op_lda, ADDR_MODE_INDIRECT_X),
INS(0xa2, "LDX", 2, false, op_ldx, ADDR_MODE_IMMEDIATE),
INE(0xa3),
INS(0xa4, "LDY", 3, false, op_ldy, ADDR_MODE_ZERO_PAGE),
INS(0xa5, "LDA", 3, false, op_lda, ADDR_MODE_ZERO_PAGE),
INS(0xa6, "LDX", 3, false, op_ldx, ADDR_MODE_ZERO_PAGE),
INE(0xa7),
INS(0xa8, "TAY", 2, false, op_tay, ADDR_MODE_IMPLIED),
INS(0xa9, "LDA", 2, false, op_lda, ADDR_MODE_IMMEDIATE),
INS(0xaa, "TAX", 2, false, op_tax, ADDR_MODE_IMPLIED),
INE(0xab),
INS(0xac, "LDY", 4, false, op_ldy, ADDR_MODE_ABSOLUTE),
INS(0xad, "LDA", 4, false, op_lda, ADDR_MODE_ABSOLUTE),
INS(0xae, "LDX", 4, false, op_ldx, ADDR_MODE_ABSOLUTE),
INE(0xaf),
INS(0xb0, "BCS", 2, true, op_bcs, ADDR_MODE_RELATIVE),
INS(0xb1, "LDA", 5, true, op_lda, ADDR_MODE_INDIRECT_Y),
INE(0xb2),
INE(0xb3),
INS(0xb4, "LDY", 4, false, op_ldy, ADDR_MODE_ZERO_PAGE_X),
INS(0xb5, "LDA", 4, false, op_lda, ADDR_MODE_ZERO_PAGE_X),
INS(0xb6, "LDX", 4, false, op_ldx, ADDR_MODE_ZERO_PAGE_Y),
INE(0xb7),
INS(0xb8, "CLV", 2, false, op_clv, ADDR_MODE_IMPLIED),
INS(0xb9, "LDA", 4, true, op_lda, ADDR_MODE_ABSOLUTE_Y),
INS(0xba, "TSX", 2, false, op_tsx, ADDR_MODE_IMPLIED),
INE(0xbb),
INS(0xbc, "LDY", 4, true, op_ldy, ADDR_MODE_ABSOLUTE_X),
INS(0xbd, "LDA", 4, true, op_lda, ADDR_MODE_ABSOLUTE_X),
INS(0xbe, "LDX", 4, true, op_ldx, ADDR_MODE_ABSOLUTE_Y),
INE(0xbf),
INS(0xc0, "CPY", 2, false, op_cpy, ADDR_MODE_IMMEDIATE),
INS(0xc1, "CMP", 6, false, op_cmp, ADDR_MODE_INDIRECT_X),
INE(0xc2),
INE(0xc3),
INS(0xc4, "CPY", 3, false, op_cpy, ADDR_MODE_ZERO_PAGE),
INS(0xc5, "CMP", 3, false, op_cmp, ADDR_MODE_ZERO_PAGE),
INS(0xc6, "DEC", 5, false, op_dec, ADDR_MODE_ZERO_PAGE),
INE(0xc7),
INS(0xc8, "INY", 2, false, op_iny, ADDR_MODE_IMPLIED),
INS(0xc9, "CMP", 2, false, op_cmp, ADDR_MODE_IMMEDIATE),
INS(0xca, "DEX", 2, false, op_dex, ADDR_MODE_IMPLIED),
INE(0xcb),
INS(0xcc, "CPY", 4, false, op_cpy, ADDR_MODE_ABSOLUTE),
INS(0xcd, "CMP", 4, false, op_cmp, ADDR_MODE_ABSOLUTE),
INS(0xce, "DEC", 6, false, op_dec, ADDR_MODE_ABSOLUTE),
INE(0xcf),
INS(0xd0, "BNE", 2, true, op_bne, ADDR_MODE_RELATIVE),
INS(0xd1, "CMP", 5, true, op_cmp, ADDR_MODE_INDIRECT_Y),
INE(0xd2),
INE(0xd3),
INE(0xd4),
INS(0xd5, "CMP", 4, false, op_cmp, ADDR_MODE_ZERO_PAGE_X),
INS(0xd6, "DEC", 6, false, op_dec, ADDR_MODE_ZERO_PAGE_X),
INE(0xd7),
INS(0xd8, "CLD", 2, false, op_cld, ADDR_MODE_IMPLIED),
INS(0xd9, "CMP", 4, true, op_cmp, ADDR_MODE_ABSOLUTE_Y),
INE(0xda),
INE(0xdb),
INE(0xdc),
INS(0xdd, "CMP", 4, true, op_cmp, ADDR_MODE_ABSOLUTE_X),
INS(0xde, "DEC", 7, false, op_dec, ADDR_MODE_ABSOLUTE_X),
INE(0xdf),
INS(0xe0, "CPX", 2, false, op_cpx, ADDR_MODE_IMMEDIATE),
INS(0xe1, "SBC", 6, false, op_sbc, ADDR_MODE_INDIRECT_X),
INE(0xe2),
INE(0xe3),
INS(0xe4, "CPX", 3, false, op_cpx, ADDR_MODE_ZERO_PAGE),
INS(0xe5, "SBC", 3, false, op_sbc, ADDR_MODE_ZERO_PAGE),
INS(0xe6, "INC", 5, false, op_inc, ADDR_MODE_ZERO_PAGE),
INE(0xe7),
INS(0xe8, "INX", 2, false, op_inx, ADDR_MODE_IMPLIED),
INS(0xe9, "SBC", 2, false, op_sbc, ADDR_MODE_IMMEDIATE),
INS(0xea, "NOP", 2, false, op_nop, ADDR_MODE_IMPLIED),
INE(0xeb),
INS(0xec, "CPX", 4, false, op_cpx, ADDR_MODE_ABSOLUTE),
INS(0xed, "SBC", 4, false, op_sbc, ADDR_MODE_ABSOLUTE),
INS(0xee, "INC", 6, false, op_inc, ADDR_MODE_ABSOLUTE),
INE(0xef),
INS(0xf0, "BEQ", 2, true, op_beq, ADDR_MODE_RELATIVE),
INS(0xf1, "SBC", 5, true, op_sbc, ADDR_MODE_INDIRECT_Y),
INE(0xf2),
INE(0xf3),
INE(0xf4),
INS(0xf5, "SBC", 4, false, op_sbc, ADDR_MODE_ZERO_PAGE_X),
INS(0xf6, "INC", 6, false, op_inc, ADDR_MODE_ZERO_PAGE_X),
INE(0xf7),
INS(0xf8, "SED", 2, false, op_sed, ADDR_MODE_IMPLIED),
INS(0xf9, "SBC", 4, true, op_sbc, ADDR_MODE_ABSOLUTE_Y),
INE(0xfa),
INE(0xfb),
INE(0xfc),
INS(0xfd, "SBC", 4, true, op_sbc, ADDR_MODE_ABSOLUTE_X),
INS(0xfe, "INC", 7, false, op_inc, ADDR_MODE_ABSOLUTE_X),
INE(0xff),
};
#undef INE
#undef INS
instruction_t* instruction_get(uint8_t opc) {
return &instructions[opc];
}
uint8_t instruction_get_size(addr_mode_t mode) {
switch (mode) {
case ADDR_MODE_NONE: return 0;
case ADDR_MODE_ABSOLUTE: return 3;
case ADDR_MODE_ABSOLUTE_X: return 3;
case ADDR_MODE_ABSOLUTE_Y: return 3;
case ADDR_MODE_ACCUMULATOR: return 1;
case ADDR_MODE_IMMEDIATE: return 2;
case ADDR_MODE_IMPLIED: return 1;
case ADDR_MODE_IMPLIED_BRK: return 2;
case ADDR_MODE_INDIRECT: return 3;
case ADDR_MODE_INDIRECT_X: return 2;
case ADDR_MODE_INDIRECT_Y: return 2;
case ADDR_MODE_RELATIVE: return 2;
case ADDR_MODE_ZERO_PAGE: return 2;
case ADDR_MODE_ZERO_PAGE_X: return 2;
case ADDR_MODE_ZERO_PAGE_Y: return 2;
default: return 0;
}
}
static int op_adc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t old_acc = cpu->acc;
uint8_t val = cpu_read8(cpu, addr);
int res = cpu->acc + val + (uint8_t)cpu->flag_carry;
cpu->acc = (uint8_t)res;
cpu->flag_carry = res > 0xff;
cpu->flag_overflow = !((old_acc ^ val) & 0x80) && ((old_acc ^ cpu->acc) & 0x80);
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_and(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->acc = cpu->acc & val;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_asl(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
if (mode == ADDR_MODE_ACCUMULATOR) {
cpu->flag_carry = AGNES_GET_BIT(cpu->acc, 7);
cpu->acc = cpu->acc << 1;
cpu_update_zn_flags(cpu, cpu->acc);
} else {
uint8_t val = cpu_read8(cpu, addr);
cpu->flag_carry = AGNES_GET_BIT(val, 7);
val = val << 1;
cpu_write8(cpu, addr, val);
cpu_update_zn_flags(cpu, val);
}
return 0;
}
static int op_bcc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return !cpu->flag_carry ? take_branch(cpu, addr) : 0;
}
static int op_bcs(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return cpu->flag_carry ? take_branch(cpu, addr) : 0;
}
static int op_beq(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return cpu->flag_zero ? take_branch(cpu, addr) : 0;
}
static int op_bit(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
uint8_t res = cpu->acc & val;
cpu->flag_zero = res == 0;
cpu->flag_overflow = AGNES_GET_BIT(val, 6);
cpu->flag_negative = AGNES_GET_BIT(val, 7);
return 0;
}
static int op_bmi(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return cpu->flag_negative ? take_branch(cpu, addr) : 0;
}
static int op_bne(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return !cpu->flag_zero ? take_branch(cpu, addr) : 0;
}
static int op_bpl(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return !cpu->flag_negative ? take_branch(cpu, addr) : 0;
}
static int op_brk(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_stack_push16(cpu, cpu->pc);
uint8_t flags = cpu_get_flags(cpu);
cpu_stack_push8(cpu, flags | 0x30);
cpu->pc = cpu_read16(cpu, 0xfffe);
cpu->flag_dis_interrupt = true;
return 0;
}
static int op_bvc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return !cpu->flag_overflow ? take_branch(cpu, addr) : 0;
}
static int op_bvs(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return cpu->flag_overflow ? take_branch(cpu, addr) : 0;
}
static int op_clc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_carry = false;
return 0;
}
static int op_cld(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_decimal = false;
return 0;
}
static int op_cli(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_dis_interrupt = false;
return 0;
}
static int op_clv(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_overflow = false;
return 0;
}
static int op_cmp(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu_update_zn_flags(cpu, cpu->acc - val);
cpu->flag_carry = cpu->acc >= val;
return 0;
}
static int op_cpx(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu_update_zn_flags(cpu, cpu->x - val);
cpu->flag_carry = cpu->x >= val;
return 0;
}
static int op_cpy(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu_update_zn_flags(cpu, cpu->y - val);
cpu->flag_carry = cpu->y >= val;
return 0;
}
static int op_dec(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu_write8(cpu, addr, val - 1);
cpu_update_zn_flags(cpu, val - 1);
return 0;
}
static int op_dex(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->x--;
cpu_update_zn_flags(cpu, cpu->x);
return 0;
}
static int op_dey(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->y--;
cpu_update_zn_flags(cpu, cpu->y);
return 0;
}
static int op_eor(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->acc = cpu->acc ^ val;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_inc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu_write8(cpu, addr, val + 1);
cpu_update_zn_flags(cpu, val + 1);
return 0;
}
static int op_inx(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->x++;
cpu_update_zn_flags(cpu, cpu->x);
return 0;
}
static int op_iny(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->y++;
cpu_update_zn_flags(cpu, cpu->y);
return 0;
}
static int op_jmp(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->pc = addr;
return 0;
}
static int op_jsr(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_stack_push16(cpu, cpu->pc - 1);
cpu->pc = addr;
return 0;
}
static int op_lda(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->acc = val;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_ldx(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->x = val;
cpu_update_zn_flags(cpu, cpu->x);
return 0;
}
static int op_ldy(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->y = val;
cpu_update_zn_flags(cpu, cpu->y);
return 0;
}
static int op_lsr(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
if (mode == ADDR_MODE_ACCUMULATOR) {
cpu->flag_carry = AGNES_GET_BIT(cpu->acc, 0);
cpu->acc = cpu->acc >> 1;
cpu_update_zn_flags(cpu, cpu->acc);
} else {
uint8_t val = cpu_read8(cpu, addr);
cpu->flag_carry = AGNES_GET_BIT(val, 0);
val = val >> 1;
cpu_write8(cpu, addr, val);
cpu_update_zn_flags(cpu, val);
}
return 0;
}
static int op_nop(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
return 0;
}
static int op_ora(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
cpu->acc = cpu->acc | val;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_pha(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_stack_push8(cpu, cpu->acc);
return 0;
}
static int op_php(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t flags = cpu_get_flags(cpu);
cpu_stack_push8(cpu, flags | 0x30);
return 0;
}
static int op_pla(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->acc = cpu_stack_pop8(cpu);
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_plp(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t flags = cpu_stack_pop8(cpu);
cpu_restore_flags(cpu, flags);
return 0;
}
static int op_rol(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t old_carry = cpu->flag_carry;
if (mode == ADDR_MODE_ACCUMULATOR) {
cpu->flag_carry = AGNES_GET_BIT(cpu->acc, 7);
cpu->acc = (cpu->acc << 1) | old_carry;
cpu_update_zn_flags(cpu, cpu->acc);
} else {
uint8_t val = cpu_read8(cpu, addr);
cpu->flag_carry = AGNES_GET_BIT(val, 7);
val = (val << 1) | old_carry;
cpu_write8(cpu, addr, val);
cpu_update_zn_flags(cpu, val);
}
return 0;
}
static int op_ror(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t old_carry = cpu->flag_carry;
if (mode == ADDR_MODE_ACCUMULATOR) {
cpu->flag_carry = AGNES_GET_BIT(cpu->acc, 0);
cpu->acc = (cpu->acc >> 1) | (old_carry << 7);
cpu_update_zn_flags(cpu, cpu->acc);
} else {
uint8_t val = cpu_read8(cpu, addr);
cpu->flag_carry = AGNES_GET_BIT(val, 0);
val = (val >> 1) | (old_carry << 7);
cpu_write8(cpu, addr, val);
cpu_update_zn_flags(cpu, val);
}
return 0;
}
static int op_rti(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t flags = cpu_stack_pop8(cpu);
cpu_restore_flags(cpu, flags);
cpu->pc = cpu_stack_pop16(cpu);
return 0;
}
static int op_rts(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->pc = cpu_stack_pop16(cpu) + 1;
return 0;
}
static int op_sbc(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
uint8_t val = cpu_read8(cpu, addr);
uint8_t old_acc = cpu->acc;
int res = cpu->acc - val - (cpu->flag_carry ? 0 : 1);
cpu->acc = (uint8_t)res;
cpu_update_zn_flags(cpu, cpu->acc);
cpu->flag_carry = res >= 0;
cpu->flag_overflow = ((old_acc ^ val) & 0x80) && ((old_acc ^ cpu->acc) & 0x80);
return 0;
}
static int op_sec(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_carry = true;
return 0;
}
static int op_sed(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_decimal = true;
return 0;
}
static int op_sei(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->flag_dis_interrupt = true;
return 0;
}
static int op_sta(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_write8(cpu, addr, cpu->acc);
return 0;
}
static int op_stx(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_write8(cpu, addr, cpu->x);
return 0;
}
static int op_sty(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu_write8(cpu, addr, cpu->y);
return 0;
}
static int op_tax(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->x = cpu->acc;
cpu_update_zn_flags(cpu, cpu->x);
return 0;
}
static int op_tay(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->y = cpu->acc;
cpu_update_zn_flags(cpu, cpu->y);
return 0;
}
static int op_tsx(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->x = cpu->sp;
cpu_update_zn_flags(cpu, cpu->x);
return 0;
}
static int op_txa(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->acc = cpu->x;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int op_txs(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->sp = cpu->x;
return 0;
}
static int op_tya(cpu_t *cpu, uint16_t addr, addr_mode_t mode) {
cpu->acc = cpu->y;
cpu_update_zn_flags(cpu, cpu->acc);
return 0;
}
static int take_branch(cpu_t *cpu, uint16_t addr) {
bool page_crossed = (cpu->pc & 0xff00) != (addr & 0xff00);
cpu->pc = addr;
return page_crossed ? 2 : 1;
}
//FILE_END
//FILE_START:mapper.c
#ifndef AGNES_AMALGAMATED
#include "mapper0.h"
#include "agnes_types.h"
#include "mapper0.h"
#include "mapper1.h"
#include "mapper2.h"
#include "mapper4.h"
#endif
bool mapper_init(agnes_t *agnes) {
switch (agnes->gamepack.mapper) {
case 0: mapper0_init(&agnes->mapper.m0, agnes); return true;
case 1: mapper1_init(&agnes->mapper.m1, agnes); return true;
case 2: mapper2_init(&agnes->mapper.m2, agnes); return true;
case 4: mapper4_init(&agnes->mapper.m4, agnes); return true;
default: return false;
}
}
uint8_t mapper_read(agnes_t *agnes, uint16_t addr) {
switch (agnes->gamepack.mapper) {
case 0: return mapper0_read(&agnes->mapper.m0, addr);
case 1: return mapper1_read(&agnes->mapper.m1, addr);
case 2: return mapper2_read(&agnes->mapper.m2, addr);
case 4: return mapper4_read(&agnes->mapper.m4, addr);
default: return 0;
}
}
void mapper_write(agnes_t *agnes, uint16_t addr, uint8_t val) {
switch (agnes->gamepack.mapper) {
case 0: mapper0_write(&agnes->mapper.m0, addr, val); break;
case 1: mapper1_write(&agnes->mapper.m1, addr, val); break;
case 2: mapper2_write(&agnes->mapper.m2, addr, val); break;
case 4: mapper4_write(&agnes->mapper.m4, addr, val); break;
}
}
void mapper_pa12_rising_edge(agnes_t *agnes) {
switch (agnes->gamepack.mapper) {
case 4: mapper4_pa12_rising_edge(&agnes->mapper.m4); break;
}
}
//FILE_END
//FILE_START:mapper0.c
#ifndef AGNES_AMALGAMATED
#include "mapper0.h"
#include "agnes_types.h"
#endif
void mapper0_init(mapper0_t *mapper, agnes_t *agnes) {
mapper->agnes = agnes;
mapper->prg_bank_offsets[0] = 0;
mapper->prg_bank_offsets[1] = agnes->gamepack.prg_rom_banks_count > 1 ? (16 * 1024) : 0;
mapper->use_chr_ram = agnes->gamepack.chr_rom_banks_count == 0;
}
uint8_t mapper0_read(mapper0_t *mapper, uint16_t addr) {
uint8_t res = 0;
if (addr < 0x2000) {
if (mapper->use_chr_ram) {
res = mapper->chr_ram[addr];
} else {
res = mapper->agnes->gamepack.data[mapper->agnes->gamepack.chr_rom_offset + addr];
}
} else if (addr >= 0x8000) {
int bank = addr >> 14 & 0x1;
unsigned bank_offset = mapper->prg_bank_offsets[bank];
unsigned addr_offset = addr & 0x3fff;
unsigned offset = mapper->agnes->gamepack.prg_rom_offset + bank_offset + addr_offset;
res = mapper->agnes->gamepack.data[offset];
}
return res;
}
void mapper0_write(mapper0_t *mapper, uint16_t addr, uint8_t val) {
if (mapper->use_chr_ram && addr < 0x2000) {
mapper->chr_ram[addr] = val;
}
}
//FILE_END
//FILE_START:mapper1.c
#ifndef AGNES_AMALGAMATED
#include "mapper1.h"
#include "agnes_types.h"
#endif
static void mapper1_write_control(mapper1_t *mapper, uint8_t val);
static void mapper1_set_offsets(mapper1_t *mapper);
void mapper1_init(mapper1_t *mapper, agnes_t *agnes) {
mapper->agnes = agnes;
mapper->shift = 0;
mapper->shift_count = 0;
mapper->control = 0;
mapper->prg_mode = 3;
mapper->chr_mode = 0;
mapper->chr_banks[0] = 0;
mapper->chr_banks[1] = 0;
mapper->prg_bank = 0;
mapper->use_chr_ram = agnes->gamepack.chr_rom_banks_count == 0;
mapper1_set_offsets(mapper);
}
uint8_t mapper1_read(mapper1_t *mapper, uint16_t addr) {
uint8_t res = 0;
if (addr < 0x2000) {
if (mapper->use_chr_ram) {
res = mapper->chr_ram[addr];
} else {
unsigned bank = (addr >> 12) & 0x1;
unsigned bank_offset = mapper->chr_bank_offsets[bank];
unsigned addr_offset = addr & 0xfff;
unsigned offset = mapper->agnes->gamepack.chr_rom_offset + bank_offset + addr_offset;
res = mapper->agnes->gamepack.data[offset];
}
} else if (addr >= 0x6000 && addr < 0x8000) {
res = mapper->prg_ram[addr - 0x6000];
} else if (addr >= 0x8000) {
int bank = (addr >> 14) & 0x1;
unsigned bank_offset = mapper->prg_bank_offsets[bank];
unsigned addr_offset = addr & 0x3fff;
unsigned offset = mapper->agnes->gamepack.prg_rom_offset + bank_offset + addr_offset;
res = mapper->agnes->gamepack.data[offset];
}
return res;
}
void mapper1_write(mapper1_t *mapper, uint16_t addr, uint8_t val) {
if (addr < 0x2000) {
if (mapper->use_chr_ram) {
mapper->chr_ram[addr] = val;
}
} else if (addr >= 0x6000 && addr < 0x8000) {
mapper->prg_ram[addr - 0x6000] = val;
} else if (addr >= 0x8000) {
if (AGNES_GET_BIT(val, 7)) {
mapper->shift = 0;
mapper->shift_count = 0;
mapper1_write_control(mapper, mapper->control | 0x0c);
mapper1_set_offsets(mapper);
} else {
mapper->shift >>= 1;
mapper->shift = mapper->shift | ((val & 0x1) << 4);
mapper->shift_count++;
if (mapper->shift_count == 5) {
uint8_t shift_val = mapper->shift & 0x1f;
mapper->shift = 0;
mapper->shift_count = 0;
uint8_t reg = (addr >> 13) & 0x3; // bits 13 and 14 select register
switch (reg) {
case 0: mapper1_write_control(mapper, shift_val); break;
case 1: mapper->chr_banks[0] = shift_val; break;
case 2: mapper->chr_banks[1] = shift_val; break;
case 3: mapper->prg_bank = shift_val & 0xf; break;
}
mapper1_set_offsets(mapper);
}
}
}
}
static void mapper1_write_control(mapper1_t *mapper, uint8_t val) {
mapper->control = val;
switch (val & 0x3) {
case 0: mapper->agnes->mirroring_mode = MIRRORING_MODE_SINGLE_LOWER; break;
case 1: mapper->agnes->mirroring_mode = MIRRORING_MODE_SINGLE_UPPER; break;
case 2: mapper->agnes->mirroring_mode = MIRRORING_MODE_VERTICAL; break;
case 3: mapper->agnes->mirroring_mode = MIRRORING_MODE_HORIZONTAL; break;
}
mapper->prg_mode = (val >> 2) & 0x3;
mapper->chr_mode = (val >> 4) & 0x1;
}
static void mapper1_set_offsets(mapper1_t *mapper) {
switch (mapper->chr_mode) {
case 0: {
mapper->chr_bank_offsets[0] = (mapper->chr_banks[0] & 0xfe) * (8 * 1024);
mapper->chr_bank_offsets[1] = (mapper->chr_banks[0] & 0xfe) * (8 * 1024) + (4 * 1024);
break;
}
case 1: {
mapper->chr_bank_offsets[0] = mapper->chr_banks[0] * (4 * 1024);
mapper->chr_bank_offsets[1] = mapper->chr_banks[1] * (4 * 1024);
break;
}
}
switch (mapper->prg_mode) {
case 0: case 1: {
mapper->prg_bank_offsets[0] = (mapper->prg_bank & 0xe) * (32 * 1024);
mapper->prg_bank_offsets[1] = (mapper->prg_bank & 0xe) * (32 * 1024) + (16 * 1024);
break;
}
case 2: {
mapper->prg_bank_offsets[0] = 0;
mapper->prg_bank_offsets[1] = mapper->prg_bank * (16 * 1024);
break;
}
case 3: {
mapper->prg_bank_offsets[0] = mapper->prg_bank * (16 * 1024);
mapper->prg_bank_offsets[1] = (mapper->agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024);
break;
}
}
}
//FILE_END
//FILE_START:mapper2.c
#ifndef AGNES_AMALGAMATED
#include "mapper2.h"
#include "agnes_types.h"
#endif
void mapper2_init(mapper2_t *mapper, agnes_t *agnes) {
mapper->agnes = agnes;
mapper->prg_bank_offsets[0] = 0;
mapper->prg_bank_offsets[1] = (agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024);
}
uint8_t mapper2_read(mapper2_t *mapper, uint16_t addr) {
uint8_t res = 0;
if (addr < 0x2000) {
res = mapper->chr_ram[addr];
} else if (addr >= 0x8000) {
int bank = (addr >> 14) & 0x1;
unsigned bank_offset = mapper->prg_bank_offsets[bank];
unsigned addr_offset = addr & 0x3fff;
unsigned offset = mapper->agnes->gamepack.prg_rom_offset + bank_offset + addr_offset;
res = mapper->agnes->gamepack.data[offset];
}
return res;
}
void mapper2_write(mapper2_t *mapper, uint16_t addr, uint8_t val) {
if (addr < 0x2000) {
mapper->chr_ram[addr] = val;
} else if (addr >= 0x8000) {
int bank = val % (mapper->agnes->gamepack.prg_rom_banks_count);
mapper->prg_bank_offsets[0] = bank * (16 * 1024);
}
}
//FILE_END
//FILE_START:mapper4.c
#ifndef AGNES_AMALGAMATED
#include "mapper4.h"
#include "agnes_types.h"
#include "cpu.h"
#endif
static void mapper4_write_register(mapper4_t *mapper, uint16_t addr, uint8_t val);
static void mapper4_set_offsets(mapper4_t *mapper);
void mapper4_init(mapper4_t *mapper, agnes_t *agnes) {
mapper->agnes = agnes;
mapper->prg_mode = 0;
mapper->chr_mode = 0;
mapper->irq_enabled = false;
mapper->reg_ix = 0;
mapper->regs[0] = 0;
mapper->regs[1] = 2;
mapper->regs[2] = 4;
mapper->regs[3] = 5;
mapper->regs[4] = 6;
mapper->regs[5] = 7;
mapper->regs[6] = 0;
mapper->regs[7] = 1;
mapper->counter = 0;
mapper->counter_reload = 0;
mapper->use_chr_ram = agnes->gamepack.chr_rom_banks_count == 0;
mapper4_set_offsets(mapper);
}
void mapper4_pa12_rising_edge(mapper4_t *mapper) {
if (mapper->counter == 0) {
mapper->counter = mapper->counter_reload;
} else {
mapper->counter--;
if (mapper->counter == 0 && mapper->irq_enabled) {
cpu_trigger_irq(&mapper->agnes->cpu);
}
}
}
uint8_t mapper4_read(mapper4_t *mapper, uint16_t addr) {
uint8_t res = 0;
if (addr < 0x2000) {
int bank = (addr >> 10) & 0x7;
unsigned bank_offset = mapper->chr_bank_offsets[bank];
unsigned addr_offset = addr & 0x3ff;
unsigned offset = bank_offset + addr_offset;
if (mapper->use_chr_ram) {
offset = offset & ((8 * 1024) - 1);
res = mapper->chr_ram[offset];
} else {
unsigned chr_rom_size = (mapper->agnes->gamepack.chr_rom_banks_count * 8 * 1024);
offset = offset % chr_rom_size;
res = mapper->agnes->gamepack.data[mapper->agnes->gamepack.chr_rom_offset + offset];
}
} else if (addr >= 0x6000 && addr < 0x8000) {
return mapper->prg_ram[addr - 0x6000];
} else if (addr >= 0x8000) {
int bank = (addr >> 13) & 0x3;
unsigned bank_offset = mapper->prg_bank_offsets[bank];
unsigned addr_offset = addr & 0x1fff;
unsigned offset = mapper->agnes->gamepack.prg_rom_offset + bank_offset + addr_offset;
res = mapper->agnes->gamepack.data[offset];
}
return res;
}
void mapper4_write(mapper4_t *mapper, uint16_t addr, uint8_t val) {
if (addr < 0x2000 && mapper->use_chr_ram) {
int bank = (addr >> 10) & 0x7;
unsigned bank_offset = mapper->chr_bank_offsets[bank];
unsigned addr_offset = addr & 0x3ff;
unsigned full_offset = (bank_offset + addr_offset) & ((8 * 1024) - 1);
mapper->chr_ram[full_offset] = val;
} else if (addr >= 0x6000 && addr < 0x8000) {
mapper->prg_ram[addr - 0x6000] = val;
} else if (addr >= 0x8000) {
mapper4_write_register(mapper, addr, val);
}
}
static void mapper4_write_register(mapper4_t *mapper, uint16_t addr, uint8_t val) {
bool addr_odd = addr & 0x1;
bool addr_even = !addr_odd;
if (addr <= 0x9ffe && addr_even) { // Bank select ($8000-$9FFE, even)
mapper->reg_ix = val & 0x7;
mapper->prg_mode = (val >> 6) & 0x1;
mapper->chr_mode = (val >> 7) & 0x1;
mapper4_set_offsets(mapper);
} else if (addr <= 0x9fff && addr_odd) { // Bank data ($8001-$9FFF, odd)
mapper->regs[mapper->reg_ix] = val;
mapper4_set_offsets(mapper);
} else if (addr <= 0xbffe && addr_even) { // Mirroring ($A000-$BFFE, even)
if (mapper->agnes->mirroring_mode != MIRRORING_MODE_FOUR_SCREEN) {
mapper->agnes->mirroring_mode = (val & 0x1) ? MIRRORING_MODE_HORIZONTAL : MIRRORING_MODE_VERTICAL;
}
} else if (addr <= 0xbfff && addr_odd) { // PRG RAM protect ($A001-$BFFF, odd)
// probably not required (according to https://wiki.nesdev.com/w/index.php/MMC3)
} else if (addr <= 0xdffe && addr_even) { // IRQ latch ($C000-$DFFE, even)
mapper->counter_reload = val;
} else if (addr <= 0xdfff && addr_odd) { // IRQ reload ($C001-$DFFF, odd)
mapper->counter = 0;
} else if (addr <= 0xfffe && addr_even) { // IRQ disable ($E000-$FFFE, even)
mapper->irq_enabled = false;
} else if (addr <= 0xffff && addr_odd) { // IRQ enable ($E001-$FFFF, odd)
mapper->irq_enabled = true;
}
}
static void mapper4_set_offsets(mapper4_t *mapper) {
switch (mapper->chr_mode) {
case 0: { // R0_1, R0_2, R1_1, R1_2, R2, R3, R4, R5
mapper->chr_bank_offsets[0] = (mapper->regs[0] & 0xfe) * 1024;
mapper->chr_bank_offsets[1] = (mapper->regs[0] & 0xfe) * 1024 + 1024;
mapper->chr_bank_offsets[2] = (mapper->regs[1] & 0xfe) * 1024;
mapper->chr_bank_offsets[3] = (mapper->regs[1] & 0xfe) * 1024 + 1024;
mapper->chr_bank_offsets[4] = mapper->regs[2] * 1024;
mapper->chr_bank_offsets[5] = mapper->regs[3] * 1024;
mapper->chr_bank_offsets[6] = mapper->regs[4] * 1024;
mapper->chr_bank_offsets[7] = mapper->regs[5] * 1024;
break;
}
case 1: { // R2, R3, R4, R5, R0_1, R0_2, R1_1, R1_2
mapper->chr_bank_offsets[0] = mapper->regs[2] * 1024;
mapper->chr_bank_offsets[1] = mapper->regs[3] * 1024;
mapper->chr_bank_offsets[2] = mapper->regs[4] * 1024;
mapper->chr_bank_offsets[3] = mapper->regs[5] * 1024;
mapper->chr_bank_offsets[4] = (mapper->regs[0] & 0xfe) * 1024;
mapper->chr_bank_offsets[5] = (mapper->regs[0] & 0xfe) * 1024 + 1024;
mapper->chr_bank_offsets[6] = (mapper->regs[1] & 0xfe) * 1024;
mapper->chr_bank_offsets[7] = (mapper->regs[1] & 0xfe) * 1024 + 1024;
break;
}
}
switch (mapper->prg_mode) {
case 0: { // R6, R7, -2, -1
mapper->prg_bank_offsets[0] = mapper->regs[6] * (8 * 1024);
mapper->prg_bank_offsets[1] = mapper->regs[7] * (8 * 1024);
mapper->prg_bank_offsets[2] = (mapper->agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024);
mapper->prg_bank_offsets[3] = (mapper->agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024) + (8 * 1024);
break;
}
case 1: { // -2, R7, R6, -1
mapper->prg_bank_offsets[0] = (mapper->agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024);
mapper->prg_bank_offsets[1] = mapper->regs[7] * (8 * 1024);
mapper->prg_bank_offsets[2] = mapper->regs[6] * (8 * 1024);
mapper->prg_bank_offsets[3] = (mapper->agnes->gamepack.prg_rom_banks_count - 1) * (16 * 1024) + (8 * 1024);
break;
}
}
}
//FILE_END
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