rvemu

commit d0c2de1bcca990a4caf8c6e4a29a4ae1ed5d3f78
parent 4446e4fbe7569a37b01c06a28e26ef64c45c6e8c
Author: Michail Konstantinos Dimopoulos <mk@mcdim.xyz>
Date:   Tue, 17 Mar 2026 01:06:02 +0200

R-type done

Diffstat:
M
main.c
 | 
110
++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------

1 file changed, 72 insertions(+), 38 deletions(-)
diff --git a/main.c b/main.c
@@ -40,7 +40,7 @@ R-TYPE INSTRUCTION DECODING
 +------------+--------+--------+--------+---------+--------+
 opcode	 0x33	 0110011 
 */
-void exec_op(cpu_state_t *cpu, uint32_t inst) {
+void exec_rtype(cpu_state_t *cpu, uint32_t inst) {
 	printf("TYPE R\n");
 	rtype_t r;
 	r.rd = (inst >> 7) & 31;
@@ -49,7 +49,7 @@ void exec_op(cpu_state_t *cpu, uint32_t inst) {
 	r.rs2 = (inst >> 20) & 31;
 	r.funct7 = (inst >> 25) & 127;
 
-	/* print */
+	/**print**/
 	printf("f7      rs2   rs1   f3  rd    opcode\n");
 	print_binless(r.funct7, 7);
 	printf(" ");
@@ -61,56 +61,79 @@ void exec_op(cpu_state_t *cpu, uint32_t inst) {
 	printf(" ");
 	print_binless(r.rd, 5);
 	printf("\n");
+	/*********/
 
-	/* */
-
+	uint32_t x;
+	uint32_t shamt;
 	switch(r.funct3) {
 	case 0x0:
-		printf("HI\n\n");
 		switch(r.funct7) {
 		case 0x00:
 			printf("ADD\n");
-			printf("rs1:%d\nrs2:%d\nrd:%d\n",cpu->x[r.rs1],cpu->x[r.rs2],cpu->x[r.rd]);
-				
-			int x = cpu->x[r.rs1]+cpu->x[r.rs2];
-
-			printf("%d\n", x);
-
-			if (r.rd != 0) {
-				cpu->x[r.rd] = x;
-			}
-
-			printf("rd:%d\n", cpu->x[r.rd]);
-
+			x = cpu->x[r.rs1]+cpu->x[r.rs2];
 			break;
 		case 0x20:
 			printf("SUB\n");
-			printf("rs1:%d\nrs2:%d\nrd:%d\n",cpu->x[r.rs1],cpu->x[r.rs2],cpu->x[r.rd]);
-
 			x = cpu->x[r.rs1]-cpu->x[r.rs2];
-
-			if (r.rd != 0) {
-				cpu->x[r.rd] = x;
-			}
-
-			printf("rd:%d\n", cpu->x[r.rd]);
 			break;
+		default:
+			fprintf(stderr, "Illegal funct7\n");
+			return;
 		}
 		break;
+	case 0x1:
+		printf("Shift logical left\n");
+		shamt = cpu->x[r.rs2] & 31;
+		x = cpu->x[r.rs1] << shamt;
+		break;
+	case 0x2:
+		printf("Set less than\n");
+		x = ((int32_t)cpu->x[r.rs1] < (int32_t)cpu->x[r.rs2]) ? 1 : 0;
+		break;
+	case 0x3:
+		printf("Set less than U\n");
+		x = (cpu->x[r.rs1] < cpu->x[r.rs2]) ? 1 : 0;
+		break;
 	case 0x4:
 		printf("XOR\n");
+		x = cpu->x[r.rs1]^cpu->x[r.rs2];
+		break;
+	case 0x5:
+		switch(r.funct7) {
+		case 0x00:
+			printf("Shift logical right\n");
+			shamt = cpu->x[r.rs2] & 31;
+			x = cpu->x[r.rs1] >> shamt;
+			break;
+		case 0x20:
+			printf("Shift arithm right\n");
+			shamt = cpu->x[r.rs2] & 31;
+			x = (uint32_t)((int32_t)cpu->x[r.rs1] >> shamt);
+			break;
+		default:
+			fprintf(stderr, "Illegal funct7\n");
+			return;
+		}
 		break;
 	case 0x6:
 		printf("OR\n");
+		x = cpu->x[r.rs1]|cpu->x[r.rs2];
 		break;
 	case 0x7:
 		printf("AND\n");
-		printf("rs1:%d\nrs2:%d\nrd:%d",cpu->x[r.rs1],cpu->x[r.rs2],cpu->x[r.rd]);
-		
-		int x = r.rs1&r.rs2;
-		printf("%d\n", x);
+		x = cpu->x[r.rs1]&cpu->x[r.rs2];
 		break;
+	default:
+		fprintf(stderr, "Illegal funct3\n");
+		return;
 	}
+
+	printf("rs1:%u  rs2:%u  rd:%u\n",cpu->x[r.rs1],cpu->x[r.rs2],cpu->x[r.rd]);
+	if (r.rd != 0) {
+		cpu->x[r.rd] = x;
+	}
+
+	printf("rd:%u\n", cpu->x[r.rd]);
 }
 
 int main() {
@@ -118,8 +141,8 @@ int main() {
 	/* function pointer dispatch */
 	typedef void (*exec_fn)(cpu_state_t *, uint32_t inst);
 	static exec_fn opcode_table[128];
-	opcode_table[0x33] = exec_op;
-	/*opcode_table[0x13] = exec_op_imm;
+	opcode_table[0x33] = exec_rtype;
+	/*opcode_table[0x13] = exec_rtype_imm;
 	opcode_table[0x03] = exec_load;
 	opcode_table[0x23] = exec_store;
 	opcode_table[0x63] = exec_branch;
@@ -132,26 +155,37 @@ int main() {
 	uint32_t inst = 0x01F00033;
 
 	//	f7      rs2   rs1   f3  rd    opcode
-	//	0000000 00001 00010 000 00000 0110011
-	inst = 0x00110033;
+	//	0000000 00001 00010 000 00011 0110011
+	inst = 0x00110033; /* failed add because rd=0 */
+
+	//	f7      rs2   rs1   f3  rd    opcode
+	//	0000000 00001 00010 000 00011 0110011
+	inst = 0x001101B3; /* successful add */
 
 	//	f7      rs2   rs1   f3  rd    opcode
 	//	0100000 00001 00010 000 00011 0110011
-	//inst = 0x401101B3;
+	inst = 0x401101B3; /* successful sub */
+
+	//	f7      rs2   rs1   f3  rd    opcode
+	//	0000000 00001 00010 011 00011 0110011
+	inst = 0x1131B3; /* SLT */
+
+	//	f7      rs2   rs1   f3  rd    opcode
+	//	0000000 00001 00010 100 00011 0110011
+	//inst = 0x1141B3; /* XOR */
 
 	print_bin32(inst);
 	printf("\n");
 
 	/* decode instruction */
 	uint16_t opcode = inst & 127;
-	printf("opcode:");
-	printf("\n");
-	print_bin16(opcode);
+	printf("opcode: ");
+	print_binless(opcode,7);
 	printf("\n");
 
 	exec_fn fn = opcode_table[opcode];
 	cpu_state_t cpu;
-	cpu.x[1] = 5;
+	cpu.x[1] = 51;
 	cpu.x[2] = 14;