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This commit is contained in:
Antoni Piasecki
2026-02-28 19:27:17 +01:00
parent 9ee3b726a4
commit b7f27abaf4
2 changed files with 254 additions and 94 deletions
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8
build.sh
View File

@@ -1,13 +1,15 @@
#!/bin/bash
WARNINGS="-Wall -Wextra -Wpedantic -Wno-unused-variable -Wno-gnu-binary-literal"
echo "building mos6502..."
cc -Wall -Wextra -Wpedantic -std=c99 -o mos6502 mos6502.c
cc $WARNINGS -std=c99 -o mos6502 mos6502.c
if command -v pkg-config >/dev/null; then
RAYLIB_FLAGS=$(pkg-config --cflags --libs raylib 2>/dev/null)
if [ $? -eq 0 ]; then
echo "building chip8..."
cc -Wall -Wextra -Wpedantic -std=c99 -o chip8 chip8.c $RAYLIB_FLAGS
cc $WARNINGS -std=c99 -o chip8 chip8.c $RAYLIB_FLAGS
else
echo "raylib not found - skipping chip8..."
fi
@@ -15,7 +17,7 @@ if command -v pkg-config >/dev/null; then
LIBELF_FLAGS=$(pkg-config --cflags --libs libelf 2>/dev/null)
if [ $? -eq 0 ]; then
echo "building riscv64..."
cc -Wall -Wextra -Wpedantic -std=gnu11 -Wno-gnu-binary-literal -Wno-unused-variable -o riscv64 riscv64.c $LIBELF_FLAGS
cc $WARNINGS -std=gnu11 -o riscv64 riscv64.c $LIBELF_FLAGS
else
echo "libelf not found - skipping riscv64..."
fi

340
riscv64.c
View File

@@ -13,11 +13,49 @@
uint8_t rs1 = (ins >> 15) & 0b11111; \
int32_t imm = ((int32_t)ins) >> 20
#define PARSE_R_INS(ins) \
uint8_t rd = (ins >> 7) & 0b11111; \
uint8_t funct3 = (ins >> 12) & 0b111; \
uint8_t rs1 = (ins >> 15) & 0b11111; \
uint8_t rs2 = (ins >> 20) & 0b11111; \
int32_t funct7 = ((int32_t)ins) >> 25
#define PARSE_B_INS(ins) \
uint8_t funct3 = (ins >> 12) & 0b111; \
uint8_t rs1 = (ins >> 15) & 0b11111; \
uint8_t rs2 = (ins >> 20) & 0b11111; \
int32_t imm_12 = (ins >> 31) & 0b1; \
int32_t imm_10_5 = (ins >> 25) & 0b111111; \
int32_t imm_4_1 = (ins >> 8) & 0b1111; \
int32_t imm_11 = (ins >> 7) & 0b1; \
int32_t imm = \
(imm_12 << 12) | (imm_11 << 11) | (imm_10_5 << 5) | (imm_4_1 << 1); \
imm = (imm << 19) >> 19
#define PARSE_S_INS(ins) \
uint8_t funct3 = (ins >> 12) & 0b111; \
uint8_t rs1 = (ins >> 15) & 0b11111; \
uint8_t rs2 = (ins >> 20) & 0b11111; \
int32_t imm_11_5 = (ins >> 25) & 0b1111111; \
int32_t imm_4_0 = (ins >> 7) & 0b11111; \
int32_t imm = (imm_11_5 << 5) | imm_4_0; \
imm = (imm << 20) >> 20
#define PARSE_J_INS(ins) \
uint8_t rd = (ins >> 7) & 0b11111; \
int32_t imm_20 = (ins >> 31) & 0b1; \
int32_t imm_10_1 = (ins >> 21) & 0b1111111111; \
int32_t imm_11 = (ins >> 20) & 0b1; \
int32_t imm_19_12 = (ins >> 12) & 0b11111111; \
int32_t imm = \
(imm_20 << 20) | (imm_19_12 << 12) | (imm_11 << 11) | (imm_10_1 << 1); \
imm = (imm << 11) >> 11
#define PARSE_U_INS(ins) \
uint8_t rd = (ins >> 7) & 0b11111; \
int32_t imm = ((int32_t)ins) >> 20
int32_t imm = ins >> 12
static const char *REGS[32] = {
static const char *const REGS[32] = {
"zero", "ra", "sp", "gp", "tp", "t0", "t1", "t2", "fp", "s1", "a0",
"a1", "a2", "a3", "a4", "a5", "a6", "a7", "s2", "s3", "s4", "s5",
"s6", "s7", "s8", "s9", "s10", "s11", "t3", "t4", "t5", "t6"};
@@ -30,7 +68,7 @@ typedef struct {
typedef struct {
uint8_t *memory;
size_t pc;
uint64_t regs[32];
int64_t regs[32];
Section code_section;
} RISCV64;
@@ -75,7 +113,7 @@ RISCV64 riscv64_load(uint8_t *exe_bytes, size_t exe_size) {
};
}
void riscv64_dump(RISCV64 *r) {
void riscv64_dump(const RISCV64 *r) {
printf("REGS:");
for (size_t i = 0; i < 32; i++) {
printf(" %lu", r->regs[i]);
@@ -83,91 +121,121 @@ void riscv64_dump(RISCV64 *r) {
printf("\n");
}
void riscv64_disassemble(RISCV64 *r) {
r->pc = r->code_section.offset;
void riscv64_disassemble_one(const RISCV64 *r) {
uint32_t ins;
memcpy(&ins, r->memory + r->pc, 4);
while (r->pc < r->code_section.offset + r->code_section.size) {
uint32_t ins;
memcpy(&ins, r->memory + r->pc, 4);
uint16_t opcode = ins & 0b1111111;
uint16_t opcode = ins & 0b1111111;
// https://stackoverflow.com/questions/62939410/how-can-i-find-out-the-instruction-format-of-a-risc-v-instruction
switch (opcode) {
case 0b1100011: {
PARSE_B_INS(ins);
// https://stackoverflow.com/questions/62939410/how-can-i-find-out-the-instruction-format-of-a-risc-v-instruction
switch (opcode) {
case 0b1100011:
printf("B-type\n");
if (funct3 == 0b100) {
printf("blt %s, %s, %d\n", REGS[rs1], REGS[rs2], imm);
} else if (funct3 == 0b101) {
printf("bge %s, %s, %d\n", REGS[rs1], REGS[rs2], imm);
break;
case 0b0010011: {
PARSE_I_INS(ins);
switch (funct3) {
case 0b000:
printf("addi %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
break;
default:
fprintf(stderr, "I-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0000011:
printf("I-type 2\n");
break;
case 0b1100111:
printf("I-type 3\n");
break;
case 0b1110011: {
PARSE_I_INS(ins);
switch (funct3) {
case 0b000:
switch (imm) {
case 0:
printf("ecall\n");
break;
default:
fprintf(stderr, "I-type 4: funct3=000 unrecognized imm: %b\n", imm);
exit(1);
};
break;
default:
fprintf(stderr, "I-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b1101111:
printf("J-type\n");
break;
case 0b0110011:
printf("R-type 1\n");
break;
case 0b0101111:
printf("R-type 2\n");
break;
case 0b0111011:
printf("R-type 3\n");
break;
case 0b0100011:
printf("S-type\n");
break;
case 0b0110111:
printf("U-type 1\n");
break;
case 0b0010111: {
PARSE_U_INS(ins);
printf("auipc %s, %d\n", REGS[rd], imm);
}; break;
default:
fprintf(stderr, "Unrecognized opcode: %07b\n", opcode);
} else {
fprintf(stderr, "B-type: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0010011: {
PARSE_I_INS(ins);
r->pc += 4;
if (funct3 == 0b000) {
printf("addi %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else {
fprintf(stderr, "I-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0000011: {
PARSE_I_INS(ins);
if (funct3 == 0b000) {
printf("lb %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else {
fprintf(stderr, "I-type 2: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b1100111: {
PARSE_I_INS(ins);
printf("jalr %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
}; break;
case 0b1110011: {
PARSE_I_INS(ins);
if (funct3 == 0b000) {
if (imm == 0) {
printf("ecall\n");
} else {
fprintf(stderr, "I-type 4: funct3=000 unrecognized imm: %b\n", imm);
exit(1);
}
break;
} else {
fprintf(stderr, "I-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b1101111: {
PARSE_J_INS(ins);
printf("jal %s, %d\n", REGS[rd], imm);
}; break;
case 0b0110011: {
PARSE_R_INS(ins);
if (funct3 == 0b000) {
if (funct7 == 0) {
printf("add %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b000: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else {
fprintf(stderr, "R-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0101111:
fprintf(stderr, "R-type 2: unimplemented\n");
exit(1);
case 0b0111011:
fprintf(stderr, "R-type 3: unimplemented\n");
exit(1);
case 0b0100011: {
PARSE_S_INS(ins);
if (funct3 == 0b000) {
printf("sb %s, %d(%s)\n", REGS[rs2], imm, REGS[rs1]);
} else {
fprintf(stderr, "S-type: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0110111:
fprintf(stderr, "U-type 1: unimplemented\n");
exit(1);
break;
case 0b0010111: {
PARSE_U_INS(ins);
printf("auipc %s, %d\n", REGS[rd], imm);
}; break;
default:
fprintf(stderr, "Unrecognized opcode: %07b\n", opcode);
exit(1);
}
}
void riscv64_execute(RISCV64 *r) {
r->pc = r->code_section.offset;
r->regs[2] = (20 * 1024 * 1024) - 1; // set the stack pointer
while (r->pc < r->code_section.offset + r->code_section.size) {
r->regs[0] = 0; // clear the zero register
@@ -178,30 +246,81 @@ void riscv64_execute(RISCV64 *r) {
// https://stackoverflow.com/questions/62939410/how-can-i-find-out-the-instruction-format-of-a-risc-v-instruction
switch (opcode) {
case 0b1100011: {
PARSE_B_INS(ins);
if (funct3 == 0b101) { // bge
if (r->regs[rs1] >= r->regs[rs2]) {
r->pc += imm;
continue;
}
} else if (funct3 == 0b100) { // blt
if (r->regs[rs1] < r->regs[rs2]) {
r->pc += imm;
continue;
}
} else {
fprintf(stderr, "B-type: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0010011: {
PARSE_I_INS(ins);
switch (funct3) {
case 0b000:
if (funct3 == 0b000) { // addi
r->regs[rd] = r->regs[rs1] + imm;
break;
default:
} else {
fprintf(stderr, "I-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0000011: {
PARSE_I_INS(ins);
if (funct3 == 0b000) { // lb
r->regs[rd] = r->memory[r->regs[rs1] + imm];
} else {
fprintf(stderr, "I-type 2: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b1100111: { // jalr
PARSE_I_INS(ins);
uint32_t target = (r->regs[rs1] + imm) & ~1;
r->regs[rd] = r->pc + 4;
r->pc = target;
continue;
}; break;
case 0b1110011: {
PARSE_I_INS(ins);
switch (funct3) {
case 0b000:
switch (imm) {
case 0:
if (funct3 == 0b000) {
if (imm == 0) { // ecall
// https://jborza.com/post/2021-05-11-riscv-linux-syscalls/
switch (r->regs[17]) {
case 63: { // read
if (r->regs[10] != 0) {
fprintf(stderr, "read syscall implemented only for stdin.\n");
exit(1);
}
size_t start = r->regs[11];
size_t count = r->regs[12];
size_t bytes_read = 0;
for (size_t i = 0; i < count; i++) {
int c = getchar();
if (c == EOF)
break;
r->memory[start + i] = (uint8_t)c;
bytes_read++;
}
r->regs[10] = bytes_read;
}; break;
case 64: { // write
if (r->regs[10] != 1) {
fprintf(stderr, "write syscall is implemented only for stdout\n");
fprintf(stderr, "write syscall implemented only for stdout.\n");
exit(1);
}
@@ -213,7 +332,7 @@ void riscv64_execute(RISCV64 *r) {
}
}; break;
case 93: { // exit
printf("Program exited with code %lu.\n", r->regs[11]);
printf("Program exited with code %lu.\n", r->regs[10]);
return;
}; break;
default:
@@ -221,19 +340,52 @@ void riscv64_execute(RISCV64 *r) {
exit(1);
}
break;
default:
} else {
fprintf(stderr, "I-type 4: funct3=000 unrecognized imm: %b\n", imm);
exit(1);
};
break;
default:
} else {
fprintf(stderr, "I-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0010111: {
case 0b1101111: { // jal
PARSE_J_INS(ins);
r->regs[rd] = r->pc + 4;
r->pc += imm;
continue;
}; break;
case 0b0110011: {
PARSE_R_INS(ins);
if (funct3 == 0b000) {
if (funct7 == 0) { // add
r->regs[rd] = r->regs[rs1] + r->regs[rs2];
break;
} else {
fprintf(stderr, "R-type 1: funct3=0b000: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else {
fprintf(stderr, "R-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0100011: {
PARSE_S_INS(ins);
if (funct3 == 0b000) { // sb
size_t addr = r->regs[rs1] + imm;
r->memory[addr] = r->regs[rs2];
} else {
fprintf(stderr, "S-type: unrecognized funct3: %03b\n", funct3);
exit(1);
}
}; break;
case 0b0010111: { // auipc
PARSE_U_INS(ins);
r->regs[rd] = r->pc + (imm << 12);
r->regs[rd] = r->pc + (imm >> 12);
}; break;
default:
fprintf(stderr, "Unrecognized opcode: %07b\n", opcode);
@@ -272,6 +424,12 @@ int main(int argc, char *argv[]) {
fclose(file);
RISCV64 r = riscv64_load(exe_bytes, exe_size);
riscv64_disassemble(&r);
for (r.pc = r.code_section.offset;
r.pc < r.code_section.offset + r.code_section.size; r.pc += 4) {
riscv64_disassemble_one(&r);
}
printf("END DISASSEMBLY\n");
riscv64_execute(&r);
}