psx emulator
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1.8 KiB

#include "insn.h"
#include <stddef.h>
#include <stdio.h>
#include "cpu.h"
#include "log.h"
#define TABLE_SIZE 0x34
#define BITS(x, start, len) (((x) >> (start)) & ((1 << (len)) - 1))
#define OP(insn) BITS(insn, 26, 6)
#define RS(insn) BITS(insn, 21, 5)
#define RT(insn) BITS(insn, 16, 5)
#define RD(insn) BITS(insn, 11, 5)
#define COMMENT(insn) BITS(insn, 6, 20)
#define IMM5(insn) BITS(insn, 6, 5)
#define OP2(insn) BITS(insn, 0, 6)
#define IMM(insn) BITS(insn, 0, 16)
static cpu_insn_handler primary_insn_handler[TABLE_SIZE];
static cpu_insn_handler secondary_insn_handler[TABLE_SIZE];
void insn_execute(cpu_t *cpu, uint32_t insn) {
const op_primary_t op = OP(insn);
if (op == SPECIAL) {
const op_secondary_t op2 = OP2(insn);
if (op2 > TABLE_SIZE || secondary_insn_handler[op2] == NULL) {
fatal("Unsupported instruction: insn=%08x, op=%02x, op2=%02x", insn,
op, op2);
}
secondary_insn_handler[op2](cpu, insn);
}
if (op > TABLE_SIZE || primary_insn_handler[op] == NULL) {
fatal("Unsupported instruction: insn=%08x, op=%02x", insn, op);
}
primary_insn_handler[op](cpu, insn);
}
void insn_lw(cpu_t *cpu, uint32_t insn) {
const uint8_t rt = RT(insn);
const uint8_t rs = RS(insn);
const uint16_t imm = IMM(insn);
debug("LW %s, [%s + %x]", REG_NAMES[rt], REG_NAMES[rs], imm);
cpu->regs[rt] = cpu_read32(cpu, cpu->regs[rs] + imm);
}
void insn_srl(cpu_t *cpu, uint32_t insn) {
const uint8_t rd = RT(insn);
const uint8_t rt = RT(insn);
const uint8_t imm5 = IMM5(insn);
debug("SRL %s, %s, %u", REG_NAMES[rd], REG_NAMES[rt], imm5);
cpu->regs[rd] = cpu->regs[rt] >> imm5;
}
static cpu_insn_handler primary_insn_handler[TABLE_SIZE] = {
[LW] = insn_lw,
};
static cpu_insn_handler secondary_insn_handler[TABLE_SIZE] = {
[SRL] = insn_srl,
};