rvemu

commit 0cc9916509027b5af4690f39d4c1ba10f9b49d5e
parent a7e5dc83d3e11fd14bca2d5641d415ee1faba162
Author: Michail Konstantinos Dimopoulos <mk@mcdim.xyz>
Date:   Sat,  5 Sep 2026 18:13:46 +0300

Fixed load/store signedness and cast-order bugs

Diffstat:
M
exec.c
 | 
13
++++++-------
M
main.c
 | 
8
++++----

2 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/exec.c b/exec.c
@@ -234,10 +234,9 @@ static void exec_itype_loads(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	case 0x4:
 		x = (uint32_t)(uint8_t)mem[addr];
 		break;
-		
 	case 0x5:
-		int16_t uhalf = (int16_t)mem[addr] | ((int16_t)mem[addr+1] << 8);
-		x = (uint32_t)(int32_t)uhalf;
+		uint16_t uhalf = (uint16_t)mem[addr] | ((uint16_t)mem[addr+1] << 8);
+		x = (uint32_t)uhalf;
 		break;
 	default:
 		raise_trap(cpu, TRAP_ILLEGAL_INSTRUCTION, inst);
@@ -269,7 +268,7 @@ static void exec_stype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 
 		if (addr % 2 == 0) {
 			mem[addr] = (uint8_t)cpu->x[s.rs2];
-			mem[addr+1] = (uint8_t)cpu->x[s.rs2] >> 8;
+			mem[addr+1] = (uint8_t)(cpu->x[s.rs2] >> 8);
 		}
 		break;
 	case 0x2:
@@ -279,9 +278,9 @@ static void exec_stype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 		}
 		if (addr % 4 == 0) {
 			mem[addr] =   (uint8_t)cpu->x[s.rs2];
-			mem[addr+1] = (uint8_t)cpu->x[s.rs2] >> 8;
-			mem[addr+2] = (uint8_t)cpu->x[s.rs2] >> 16;
-			mem[addr+3] = (uint8_t)cpu->x[s.rs2] >> 24;
+			mem[addr+1] = (uint8_t)(cpu->x[s.rs2] >> 8);
+			mem[addr+2] = (uint8_t)(cpu->x[s.rs2] >> 16);
+			mem[addr+3] = (uint8_t)(cpu->x[s.rs2] >> 24);
 		}
 		break;
 	default:
diff --git a/main.c b/main.c
@@ -19,12 +19,14 @@ load_program(uint8_t *mem)
 {
 	/* program */
 	uint32_t arr[] = {
+/*
 	0xfff00093,  // addi  x1, x0, -1
 	0xfff04113,  // xori  x2, x0, -1
 	0xfff06193,  // ori   x3, x0, -1
 	0xfff17213,  // andi  x4, x2, -1
 	0xfff02293,  // slti  x5, x0, -1
 	0xfff03313   // sltiu x6, x0, -1
+*/
 /*
 	0xfff00093,	// li      ra,-1
 	0xfff04113,	// not     sp,zero
@@ -42,7 +44,6 @@ load_program(uint8_t *mem)
       0xff750513,  // addi x10, x10, -9
       0x00100073   // ebreak
 */
-/*
 0x10000593,	//li      a1,256
 0xfff00513,	//li      a0,-1
 0x00a58023,	//sb      a0,0(a1)
@@ -62,7 +63,6 @@ load_program(uint8_t *mem)
 0x0085a503,	//lw      a0,8(a1)
 0x00000593,	//li      a1,0
 0x00100073	//ebreak
-*/
 /*
       0x00200093,  // addi x1, x0, 2
       0x00000113,  // addi x2, x0, 0
@@ -146,12 +146,12 @@ debugger(cpu_state_t *cpu, uint8_t *mem)
 		   strncmp(line, "registers", 9) == 0) {
 		printf("Registers:\n");
 		for (int i=0; i<32; i++) {
-			printf("0x%x: 0x%x\n", i, cpu->x[i]);
+			printf("x%d: 0x%x\n", i, cpu->x[i]);
 		}
 	} else if (strncmp(line, "m", 1) == 0 ||
 		   strncmp(line, "memory", 6) == 0) {
 		printf("Memory:\n");
-		for (uint32_t i=0; i<128; i+=4) {
+		for (uint32_t i=0; i<0x110; i+=4) {
 			if (cpu->pc == i) {
 				printf("-> ");
 			} else {