rvemu

commit 50e9877a99f750e157f402ab7cfefb35f06514a9
parent cae55a983faec0c7b20e685d5b6bb4fc3a58e88b
Author: Michail Konstantinos Dimopoulos <mk@mcdim.xyz>
Date:   Wed, 26 Aug 2026 19:35:29 +0300

Von Neumann: Instructions in memoryspace

Diffstat:
M
main.c
 | 
63
+++++++++++++++++++++++++++++++++++++++++++++++++--------------

1 file changed, 49 insertions(+), 14 deletions(-)
diff --git a/main.c b/main.c
@@ -177,6 +177,8 @@ void exec_itype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	}
 
 	printf("rd:%u\n", cpu->x[i.rd]);
+
+	cpu->pc += 4;
 }
 
 /*
@@ -281,6 +283,7 @@ void exec_rtype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	}
 
 	printf("rd:%u\n", cpu->x[r.rd]);
+	cpu->pc += 4;
 }
 
 /*
@@ -353,6 +356,7 @@ void exec_ltype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	if (i.rd != 0) {
 		cpu->x[i.rd] = x;
 	}
+	cpu->pc += 4;
 
 	printf("\nrd:%d\n", cpu->x[i.rd]);
 	printf("rd:%x\n", cpu->x[i.rd]);
@@ -432,6 +436,8 @@ void exec_stype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 		fprintf(stderr, "Illegal funct3\n");
 		return;
 	}
+
+	cpu->pc += 4;
 }
 
 /*
@@ -492,11 +498,49 @@ void exec_btype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 				return;
 			}
 			cpu->pc = target;
+		} else {
+			cpu->pc += 4;
 		}
 	}
 
 }
 
+void
+load_program(uint8_t *mem)
+{
+	/* PROGRAM */
+	uint32_t arr[] = {
+		0x500193, // addi x3, x0, 5
+		0x600093, // addi x1, x0, 6
+		0x118263, // beq x3, x1. +4
+		0x728263  // beq x5, x7, +4
+	};
+	size_t len = sizeof(arr) / sizeof(arr[0]);
+
+	int b = 0; /*byte*/
+	for (int i=0; i<len; i++) {
+		
+		mem[b+0] = (uint8_t)(arr[i] >> 0);
+		mem[b+1] = (uint8_t)(arr[i] >> 8);
+		mem[b+2] = (uint8_t)(arr[i] >> 16);
+		mem[b+3] = (uint8_t)(arr[i] >> 24);
+
+		b+=4;
+	}
+}
+
+static inline uint32_t
+make_instruction(uint8_t *mem, int index)
+{
+	uint32_t inst = 0;
+	inst |= (uint32_t)(mem[index+0]) << 0;
+	inst |= (uint32_t)(mem[index+1]) << 8;
+	inst |= (uint32_t)(mem[index+2]) << 16;
+	inst |= (uint32_t)(mem[index+3]) << 24;
+	return inst;
+
+}
+
 /* Function pointer dispatch */
 typedef void (*exec_fn)(cpu_state_t *, uint32_t inst, uint8_t *mem);
 
@@ -519,18 +563,10 @@ int main() {
 	cpu_state_t cpu = {0};
 
 	uint8_t mem[MEMSIZE] = {0};
-	
-	/* PROGRAM */
-	uint32_t arr[] = {
-		0x500193,
-		0x600093,
-		0x118263,
-		0x728263
-	};
-	size_t len = sizeof(arr) / sizeof(arr[0]);
 
+	load_program(mem);
+	
 	/* fetch & run */
-	size_t i = 0;
 	while (1) {
 
 		printf("\n>");
@@ -544,11 +580,11 @@ int main() {
 		    strncmp(line, "step", 4) == 0  ||
 		    strncmp(line, "n", 1) == 0 ||
 		    strncmp(line, "next", 4) == 0) {
-			if (i >= len) return 0;
+			//if (i >= len) return 0;
 
-			uint32_t inst = arr[i];
+			uint32_t inst = make_instruction(mem, cpu.pc);
 
-			printf("------------INST%d------\n", i);
+			printf("------------INST------\n");
 			print_bin32(inst);
 			printf("\n");
 
@@ -567,7 +603,6 @@ int main() {
 			}
 
 			fn(&cpu,inst,mem);
-			i++;
 
 		} else if (strncmp(line, "r", 1) == 0 ||
 			   strncmp(line, "registers", 9) == 0) {