From 7a1656ab10ad865a270fed94ff3d76ac311e386b Mon Sep 17 00:00:00 2001
From: Toby Jaffey <toby@ringtailsoftware.co.uk>
Date: Thu, 11 Dec 2025 10:33:45 +0000
Subject: [PATCH] Handle 8, 16 and 32 bit accesses to extram.

---
 test/extram/rom/rom.c    | 25 +++++++++--
 test/extram/shared.h     |  6 +++
 test/extram/test/tests.c | 93 ++++++++++++++++++++++++++++++++++++++++
 uvm32/uvm32.c            | 43 +++++++++++++++++--
 uvm32/uvm32.h            |  8 ++--
 5 files changed, 163 insertions(+), 12 deletions(-)

diff --git a/test/extram/rom/rom.c b/test/extram/rom/rom.c
index bbd627f..9b8367e 100644
--- a/test/extram/rom/rom.c
+++ b/test/extram/rom/rom.c
@@ -13,19 +13,36 @@ void main(void) {
         } break;
         case TEST2: {
             uint32_t *p = (uint32_t *)UVM32_EXTRAM_BASE;
-            printdec(p[32]);   // past the end
+            printdec(p[32]);   // word read
         } break;
         case TEST3: {
             uint32_t *p = (uint32_t *)UVM32_EXTRAM_BASE;
-            p[32] = 1234;   // past the end
+            p[32] = 1234;   // past the end, out of bounds
         } break;
         case TEST4: {
             uint32_t *p = (uint32_t *)UVM32_EXTRAM_BASE;
-            p[0] = 1234; // good write
+            p[0] = 1234; // word write
             yield(0);
         } break;
+        case TEST5: {
+            uint8_t *p = (uint8_t *)UVM32_EXTRAM_BASE;
+            p[7] = 0xAB; // single byte write
+            yield(0);
+        } break;
+        case TEST6: {
+            uint8_t *p = (uint8_t *)UVM32_EXTRAM_BASE;
+            printdec(p[7]); // single byte read 
+        } break;
+        case TEST7: {
+            uint16_t *p = (uint16_t *)UVM32_EXTRAM_BASE;
+            p[7] = 0xABCD; // short write
+            yield(0);
+        } break;
+        case TEST8: {
+            uint16_t *p = (uint16_t *)UVM32_EXTRAM_BASE;
+            printdec(p[7]); // short read
+        } break;
 
     }
-
 }
 
diff --git a/test/extram/shared.h b/test/extram/shared.h
index 25f918c..f916cfe 100644
--- a/test/extram/shared.h
+++ b/test/extram/shared.h
@@ -6,5 +6,11 @@ enum {
     TEST2,
     TEST3,
     TEST4,
+    TEST5,
+    TEST6,
+    TEST7,
+    TEST8,
+    TEST9,
+    TEST10,
 };
 
diff --git a/test/extram/test/tests.c b/test/extram/test/tests.c
index d961f7c..a045d15 100644
--- a/test/extram/test/tests.c
+++ b/test/extram/test/tests.c
@@ -97,3 +97,96 @@ void test_extram_out_of_bounds_dirty_flag(void) {
     TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
 }
 
+void test_extram_byte_write(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST5);
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(true, uvm32_extramDirty(&vmst));
+
+    // check that byte 7 only of extram has changed
+    uint8_t *p = (uint8_t *)extram;
+    for (int i=0;i<sizeof(extram);i++) {
+        if (i == 7) {
+            TEST_ASSERT_EQUAL(0xAB, p[i]);
+        } else {
+            TEST_ASSERT_EQUAL(0x00, p[i]);
+        }
+    }
+}
+
+void test_extram_byte_read(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST6);
+
+    // set only byte 7 in extram
+    uint8_t *p = (uint8_t *)extram;
+    p[7] = 0xCD;
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+    // check for printdec of val
+    TEST_ASSERT_EQUAL(UVM32_EVT_SYSCALL, evt.typ);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINTDEC);
+    TEST_ASSERT_EQUAL(0xCD, uvm32_getval(&vmst, &evt, ARG0));
+}
+
+void test_extram_short_write(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST7);
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(true, uvm32_extramDirty(&vmst));
+
+    // check that short 7 only of extram has changed
+    uint16_t *p = (uint16_t *)extram;
+    for (int i=0;i<sizeof(extram);i++) {
+        if (i == 7) {
+            TEST_ASSERT_EQUAL(0xABCD, p[i]);
+        } else {
+            TEST_ASSERT_EQUAL(0x00, p[i]);
+        }
+    }
+}
+
+void test_extram_short_read(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST8);
+
+    // set only short 7 in extram
+    uint16_t *p = (uint16_t *)extram;
+    p[7] = 0xCDEF;
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+    // check for printdec of val
+    TEST_ASSERT_EQUAL(UVM32_EVT_SYSCALL, evt.typ);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINTDEC);
+    TEST_ASSERT_EQUAL(0xCDEF, uvm32_getval(&vmst, &evt, ARG0));
+}
+
+
diff --git a/uvm32/uvm32.c b/uvm32/uvm32.c
index a2439a4..7a9da97 100644
--- a/uvm32/uvm32.c
+++ b/uvm32/uvm32.c
@@ -326,12 +326,34 @@ uvm32_evt_syscall_buf_t uvm32_getbuf_fixed(uvm32_state_t *vmst, uvm32_evt_t *evt
     return scb;
 }
 
-uint32_t uvm32_extramLoad(void *userdata, uint32_t addr) {
+uint32_t uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp) {
+
     uvm32_state_t *vmst = (uvm32_state_t *)userdata;
     addr -= UVM32_EXTRAM_BASE;
+
     if (vmst->extram != UVM32_NULL) {
         if (addr < vmst->extramLen) {
-            return ((uint32_t *)vmst->extram)[addr / 4];
+            switch(accessTyp) {
+                case 0:
+                    return ((int8_t *)vmst->extram)[addr];
+                break;
+                case 1:
+                    return ((int16_t *)vmst->extram)[addr/2];
+                break;
+                case 2:
+                    return ((uint32_t *)vmst->extram)[addr / 4];
+                break;
+                case 4:
+                    return ((uint8_t *)vmst->extram)[addr];
+                break;
+                case 5:
+                    return ((uint16_t *)vmst->extram)[addr/2];
+                break;
+                default:
+                    setStatusErr(vmst, UVM32_ERR_MEM_RD);
+                    return 0;
+                break;
+            }
         } else {
             setStatusErr(vmst, UVM32_ERR_MEM_RD);
         }
@@ -339,12 +361,25 @@ uint32_t uvm32_extramLoad(void *userdata, uint32_t addr) {
     return 0;
 }
 
-uint32_t uvm32_extramStore(void *userdata, uint32_t addr, uint32_t val ) {
+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;
     if (vmst->extram != UVM32_NULL) {
         if (addr < vmst->extramLen) {
-            ((uint32_t *)vmst->extram)[addr / 4] = val;
+            switch(accessTyp) {
+                case 0:
+                    ((uint8_t *)vmst->extram)[addr] = val;
+                break;
+                case 1:
+                    ((uint16_t *)vmst->extram)[addr/2] = val;
+                break;
+                case 2:
+                    ((uint32_t *)vmst->extram)[addr/4] = val;
+                break;
+                default:
+                    setStatusErr(vmst, UVM32_ERR_MEM_WR);
+                break;
+            }
             vmst->extramDirty = true;
         } else {
             setStatusErr(vmst, UVM32_ERR_MEM_WR);
diff --git a/uvm32/uvm32.h b/uvm32/uvm32.h
index 3b63f46..f0e7a52 100644
--- a/uvm32/uvm32.h
+++ b/uvm32/uvm32.h
@@ -55,10 +55,10 @@ typedef struct {
 #define MINIRV32_DECORATE static
 #define MINI_RV32_RAM_SIZE UVM32_MEMORY_SIZE
 #define MINIRV32_POSTEXEC(pc, ir, retval) {if (retval > 0) return retval;}
-uint32_t uvm32_extramLoad(void *userdata, uint32_t addr);
-uint32_t uvm32_extramStore(void *userdata, uint32_t addr, uint32_t val);
-#define MINIRV32_HANDLE_MEM_LOAD_CONTROL( addy, rval ) rval = uvm32_extramLoad(userdata, addy);
-#define MINIRV32_HANDLE_MEM_STORE_CONTROL( addy, val ) if( uvm32_extramStore(userdata, addy, val) ) return val;
+uint32_t uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp);
+uint32_t uvm32_extramStore(void *userdata, uint32_t addr, uint32_t val, uint32_t accessTyp);
+#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;
 
 #ifndef MINIRV32_IMPLEMENTATION
 #define MINIRV32_STEPPROTO