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Make load and store use a packed union for safe alignment, rather than memcpy.

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Remove some pointless initialisation which is already done through memset
This commit is contained in:
Toby Jaffey 2025-12-18 12:01:50 +00:00
parent 17208a5112
commit d04811a3c5
2 changed files with 39 additions and 65 deletions
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69
uvm32/uvm32.c
View file

@ -45,7 +45,7 @@ SOFTWARE.
#ifndef UVM32_MEMCPY
#define UVM32_MEMCPY uvm32_memcpy
void *uvm32_memcpy(void *dst, const void *src, size_t len) {
static inline void *uvm32_memcpy(void *dst, const void *src, size_t len) {
uint8_t *d = (uint8_t *)dst;
const uint8_t *s = (const uint8_t *)src;
while(len--) {
@ -57,7 +57,7 @@ void *uvm32_memcpy(void *dst, const void *src, size_t len) {
#ifndef UVM32_MEMSET
#define UVM32_MEMSET uvm32_memset
void *uvm32_memset(void *buf, int c, size_t len) {
static inline void *uvm32_memset(void *buf, int c, size_t len) {
uint8_t *b = (uint8_t *)buf;
while(len--) {
*(b++) = c;
@ -101,11 +101,12 @@ static void setStatusErr(uvm32_state_t *vmst, uvm32_err_t err) {
void uvm32_init(uvm32_state_t *vmst) {
UVM32_MEMSET(vmst, 0x00, sizeof(uvm32_state_t));
vmst->_status = UVM32_STATUS_PAUSED;
vmst->_extramLen = 0;
vmst->_extram = (uint8_t *)NULL;
vmst->_extramDirty = false;
// handled by memset
// vmst->_status = UVM32_STATUS_PAUSED;
// vmst->_extramLen = 0;
// vmst->_extram = (uint8_t *)NULL;
// vmst->_extramDirty = false;
vmst->_core.pc = MINIRV32_RAM_IMAGE_OFFSET;
// https://projectf.io/posts/riscv-cheat-sheet/
@ -113,8 +114,9 @@ void uvm32_init(uvm32_state_t *vmst) {
// la sp, _sstack
// addi sp,sp,-16
vmst->_core.regs[2] = ((MINIRV32_RAM_IMAGE_OFFSET + UVM32_MEMORY_SIZE) & ~0xF) - 16; // 16 byte align stack
vmst->_core.regs[10] = 0x00; //hart ID
vmst->_core.regs[11] = 0;
// handled by memset
// vmst->_core.regs[10] = 0x00; //hart ID
//vmst->_core.regs[11] = 0;
vmst->_core.extraflags |= 3; // Machine-mode.
}
@ -411,6 +413,7 @@ uvm32_slice_t uvm32_arg_getslice_fixed(uvm32_state_t *vmst, uvm32_evt_t *evt, uv
static uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp) {
uvm32_state_t *vmst = (uvm32_state_t *)userdata;
addr -= UVM32_EXTRAM_BASE;
const uvm32_val_t *v = ((uvm32_val_t *)(&((uint8_t *)vmst->_extram)[addr]));
if (vmst->_extram != NULL) {
if (addr < vmst->_extramLen) {
@ -418,24 +421,23 @@ static uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t access
// Any other value will have caused UVM32_ERR_INTERNAL_CORE
switch(accessTyp) {
case 0:
return _uvm32_load1s(vmst->_extram, addr);
return v->i8;
break;
case 1:
return _uvm32_load2s(vmst->_extram, addr);
return v->i16;
break;
case 2:
return _uvm32_load4(vmst->_extram, addr);
return v->u32;
break;
case 5:
return _uvm32_load2(vmst->_extram, addr);
return v->u16;
break;
// have a default case to keep coverage check happy
// no other values are possible here
default: // fall through
case 4:
return _uvm32_load1(vmst->_extram, addr);
return v->u8;
break;
}
} else {
// Out of bounds
@ -448,19 +450,21 @@ static uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t access
static uint32_t _uvm32_extramStore(void *userdata, uint32_t addr, uint32_t val, uint32_t accessTyp) {
uvm32_state_t *vmst = (uvm32_state_t *)userdata;
addr -= UVM32_EXTRAM_BASE;
uvm32_val_t *v = ((uvm32_val_t *)(&((uint8_t *)vmst->_extram)[addr]));
if (vmst->_extram != NULL) {
if (addr < vmst->_extramLen) {
switch(accessTyp) {
case 1:
_uvm32_store2(vmst->_extram, addr, val);
v->u16 = val;
break;
case 2:
_uvm32_store4(vmst->_extram, addr, val);
v->u32 = val;
break;
// no other values are valid here and will be stopped above
default: // fall through
case 0:
_uvm32_store1(vmst->_extram, addr, val);
v->u8 = val;
break;
}
vmst->_extramDirty = true;
@ -488,35 +492,4 @@ uint32_t uvm32_getProgramCounter(const uvm32_state_t *vmst) {
return vmst->_core.pc;
}
// Access of memory bus in alignment safe way
static void _uvm32_store4(void *p, uint32_t off, uint32_t val) {
UVM32_MEMCPY((uint8_t *)p + off, &val, 4);
}
static void _uvm32_store2(void *p, uint32_t off, uint16_t val) {
UVM32_MEMCPY((uint8_t *)p + off, &val, 2);
}
static void _uvm32_store1(void *p, uint32_t off, uint8_t val) {
((uint8_t *)p)[off] = val;
}
static uint32_t _uvm32_load4(void *p, uint32_t off) {
uint32_t v;
UVM32_MEMCPY(&v, (uint8_t *)p + off, 4);
return v;
}
static uint16_t _uvm32_load2(void *p, uint32_t off) {
uint16_t v;
UVM32_MEMCPY(&v, (uint8_t *)p + off, 2);
return v;
}
static uint8_t _uvm32_load1(void *p, uint32_t off) {
return ((uint8_t *)p)[off];
}
static int16_t _uvm32_load2s(void *p, uint32_t off) {
int16_t v;
UVM32_MEMCPY(&v, (uint8_t *)p + off, 2);
return v;
}
static int8_t _uvm32_load1s(void *p, uint32_t off) {
return ((int8_t *)p)[off];
}

35
uvm32/uvm32.h
View file

@ -38,6 +38,15 @@ SOFTWARE.
// Include definitions for required syscalls
#include "uvm32_sys.h"
typedef union __attribute__((packed)) {
uint32_t u32;
uint16_t u16;
uint8_t u8;
int8_t i8;
int16_t i16;
int32_t i32;
} uvm32_val_t;
// Setup and hooks for mini-rv32ima emulator core
#define MINIRV32_DECORATE static
#define MINIRV32_RETURN_TRAP
@ -50,27 +59,19 @@ SOFTWARE.
#define MINIRV32_HANDLE_MEM_LOAD_CONTROL( addy, rval ) rval = _uvm32_extramLoad(userdata, addy, ( ir >> 12 ) & 0x7);
#define MINIRV32_HANDLE_MEM_STORE_CONTROL( addy, val ) if( _uvm32_extramStore(userdata, addy, val, ( ir >> 12 ) & 0x7) ) return val;
#define MINIRV32_CUSTOM_MEMORY_BUS
#define MINIRV32_STORE4( ofs, val ) _uvm32_store4(image, ofs, val)
#define MINIRV32_STORE2( ofs, val ) _uvm32_store2(image, ofs, val)
#define MINIRV32_STORE1( ofs, val ) _uvm32_store1(image, ofs, val)
#define MINIRV32_LOAD4( ofs ) _uvm32_load4(image, ofs)
#define MINIRV32_LOAD2( ofs ) _uvm32_load2(image, ofs)
#define MINIRV32_LOAD1( ofs ) _uvm32_load1(image, ofs)
#define MINIRV32_LOAD2_SIGNED( ofs ) _uvm32_load2s(image, ofs)
#define MINIRV32_LOAD1_SIGNED( ofs ) _uvm32_load1s(image, ofs)
#define MINIRV32_STORE4( ofs, val ) ((uvm32_val_t *)(&image[ofs]))->u32 = val
#define MINIRV32_STORE2( ofs, val ) ((uvm32_val_t *)(&image[ofs]))->u16 = val
#define MINIRV32_STORE1( ofs, val ) ((uvm32_val_t *)(&image[ofs]))->u8 = val
#define MINIRV32_LOAD4( ofs ) ((uvm32_val_t *)(&image[ofs]))->u32
#define MINIRV32_LOAD2( ofs ) ((uvm32_val_t *)(&image[ofs]))->u16
#define MINIRV32_LOAD1( ofs ) ((uvm32_val_t *)(&image[ofs]))->u8
#define MINIRV32_LOAD2_SIGNED( ofs ) ((uvm32_val_t *)(&image[ofs]))->i16
#define MINIRV32_LOAD1_SIGNED( ofs ) ((uvm32_val_t *)(&image[ofs]))->i8
#ifndef MINIRV32_IMPLEMENTATION
#define MINIRV32_STEPPROTO
#else
static uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp);
static uint32_t _uvm32_extramStore(void *userdata, uint32_t addr, uint32_t val, uint32_t accessTyp);
static void _uvm32_store4(void *p, uint32_t off, uint32_t val);
static void _uvm32_store2(void *p, uint32_t off, uint16_t val);
static void _uvm32_store1(void *p, uint32_t off, uint8_t val);
static uint32_t _uvm32_load4(void *p, uint32_t off);
static uint16_t _uvm32_load2(void *p, uint32_t off);
static uint8_t _uvm32_load1(void *p, uint32_t off);
static int16_t _uvm32_load2s(void *p, uint32_t off);
static int8_t _uvm32_load1s(void *p, uint32_t off);
#endif
#include "mini-rv32ima.h"
@ -127,7 +128,7 @@ typedef struct {
/*! Internal state of uvm32 */
typedef enum {
UVM32_STATUS_PAUSED,
UVM32_STATUS_PAUSED = 0,
UVM32_STATUS_RUNNING,
UVM32_STATUS_ERROR,
UVM32_STATUS_ENDED,