rvemu

commit e2aa4903fefda539540b4dc39619291196c02159
parent 01f7641b70f741df2279b57364a784bded02bb0b
Author: Michail Konstantinos Dimopoulos <mk@mcdim.xyz>
Date:   Wed,  2 Sep 2026 00:13:57 +0300

Added lui, auipc, fixed jal decoding

Diffstat:
M
decode.h
 | 
39
++++++++++++++++++++++++++++++++++-----
M
main.c
 | 
54
+++++++++++++++++++++++++++++++++++++++++++++++++-----

2 files changed, 83 insertions(+), 10 deletions(-)
diff --git a/decode.h b/decode.h
@@ -122,22 +122,51 @@ decode_btype(btype_t *b, uint32_t inst)
 J-TYPE INSTRUCTION FORMAT
 31                                    12 11      7 6      0
 +---------------------------------------+---------+--------+
-|             imm[31:12]                |   rd    | opcode |
+|        imm[20|10:1|11|19:12]          |   rd    | opcode |
 +---------------------------------------+---------+--------+
-opcode	 0x13	 0010011  immediates
+opcode	 0x6f   1101111  jal 
 */
 
 typedef struct {
 	uint8_t opcode;
-	uint8_t rd, rs1;
+	uint8_t rd;
 	uint32_t imm;
 } jtype_t;
 
 static inline void
 decode_jtype(jtype_t *j, uint32_t inst)
 {
-	j->rd =     (uint8_t)((inst >> 7) & 31);
-	j->imm =    (uint32_t)((inst >> 11) & 0xfffff);
+	j->rd =     (uint8_t)((inst >> 7) & 0x1f);
+
+	uint8_t imm_19_12 = (uint8_t)((inst >> 12) & 0xff);
+	uint8_t imm_11 = (uint8_t)((inst >> 20) & 1);
+	uint16_t imm_10_1 = (uint16_t)((inst >> 21) & 0x3ff);
+	uint8_t imm_20 = (uint8_t)((inst >> 31) & 1);
+
+	j->imm =    (uint32_t)(imm_19_12 | imm_11 | imm_10_1 | imm_20);
+}
+
+/*
+U-TYPE INSTRUCTION FORMAT
+31                                       11      7 6      0
++---------------------------------------+---------+--------+
+|             imm[31:12]                |   rd    | opcode |
++---------------------------------------+---------+--------+
+opcode	 0x37	 0110111	lui
+opcode	 0x17	 0010111	auipc 
+*/
+
+typedef struct {
+	uint8_t opcode;
+	uint8_t rd;
+	uint32_t imm;
+} utype_t;
+
+static inline void
+decode_utype(utype_t *u, uint32_t inst)
+{
+	u->rd =     (uint8_t)((inst >> 7) & 31);
+	u->imm =    (uint32_t)((inst >> 12) & 0xfffff);
 }
 
 #endif
diff --git a/main.c b/main.c
@@ -72,8 +72,7 @@ static void exec_itype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	printf("\n");
 	/*********/
 
-	uint32_t x;
-	uint32_t shamt;
+	uint32_t x; uint32_t shamt;
 	switch(i.funct3) {
 	case 0x0:
 		printf("ADDI\n");
@@ -495,7 +494,7 @@ static void exec_jtype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	x = cpu->pc + 4;
 	cpu->pc += j.imm;
 
-	printf("rs1:%u  imm:%u  rd:%u\n",cpu->x[j.rs1],j.imm,cpu->x[j.rd]);
+	printf("imm:%u  rd:%u\n",j.imm,cpu->x[j.rd]);
 	if (j.rd != 0) {
 		/* TODO: calculate & check addr */
 		cpu->x[j.rd] = x;
@@ -504,6 +503,48 @@ static void exec_jtype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	printf("rd:%u\n", cpu->x[j.rd]);
 }
 
+static void exec_utype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
+	(void)mem; /* suppressing unused parameters warning */
+	printf("TYPE U\n");
+	utype_t u;
+	decode_utype(&u, inst);
+
+	/**print**/
+	printf("imm                   rd    opcode\n");
+	print_binless(u.imm, 20);
+	printf(" ");
+	print_binless(u.rd, 5);
+	printf("\n");
+	/*********/
+
+	cpu->x[u.rd] = u.imm << 12;
+	cpu->pc += 4;
+
+	printf("rd:%u\n", cpu->x[u.rd]);
+	printf("rd:%x\n", cpu->x[u.rd]);
+}
+
+static void exec_utype_auipc(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
+	(void)mem; /* suppressing unused parameters warning */
+	printf("TYPE U\n");
+	utype_t u;
+	decode_utype(&u, inst);
+
+	/**print**/
+	printf("imm                   rd    opcode\n");
+	print_binless(u.imm, 20);
+	printf(" ");
+	print_binless(u.rd, 5);
+	printf("\n");
+	/*********/
+
+	cpu->x[u.rd] = cpu->pc + (u.imm << 12);
+	cpu->pc += 4;
+
+	printf("rd:%u\n", cpu->x[u.rd]);
+	printf("rd:%x\n", cpu->x[u.rd]);
+}
+
 static void
 load_program(uint8_t *mem)
 {
@@ -519,8 +560,9 @@ load_program(uint8_t *mem)
 	uint32_t arr[] = {
 		0x00500193,  // addi x3, x0, 5
 		0x00600093,  // addi x1, x0, 6
-		0x00118263,  // beq x3, x1. +4
-		0xfe728ae3 //   beq x5, x7, -12 -> addr 0
+		0xaaaaa3b7,  // lui x7, 0xaaaaa		-> rd:aaaaa000
+		//0xfe728ae3   // beq x5, x7, -12 	-> addr 0
+		0x1397	     // auipc x7 0x1 		-> rd 1008
 	};
 	size_t len = sizeof(arr) / sizeof(arr[0]);
 
@@ -563,6 +605,8 @@ init_opcode_table(void)
         opcode_table[0x23] = exec_stype;
         opcode_table[0x63] = exec_btype;
         opcode_table[0x6f] = exec_jtype;
+	opcode_table[0x37] = exec_utype;
+	opcode_table[0x17] = exec_utype_auipc;
 }
 /***/