mirror of https://github.com/mlaux/gb6.git
122 lines
2.6 KiB
C
122 lines
2.6 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "cpu.h"
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#include "types.h"
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void cpu_bind_mem_model(
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struct cpu *cpu,
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void *mem_model,
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u8 (*mem_read)(void *, u16),
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void (*mem_write)(void *, u16, u8)
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) {
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cpu->mem_model = mem_model;
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cpu->mem_read = mem_read;
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cpu->mem_write = mem_write;
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}
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static inline u16 read_af(struct cpu *cpu)
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{
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return cpu->a << 8 | cpu->f;
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}
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static inline u16 read_bc(struct cpu *cpu)
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{
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return cpu->b << 8 | cpu->c;
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}
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static inline u16 read_de(struct cpu *cpu)
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{
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return cpu->d << 8 | cpu->e;
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}
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static inline u16 read_hl(struct cpu *cpu)
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{
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return cpu->h << 8 | cpu->l;
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}
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static inline void write_af(struct cpu *cpu, int value)
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{
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cpu->a = value >> 8;
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cpu->f = value & 0xff;
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}
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static inline void write_bc(struct cpu *cpu, int value)
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{
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cpu->b = value >> 8;
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cpu->c = value & 0xff;
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}
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static inline void write_de(struct cpu *cpu, int value)
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{
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cpu->d = value >> 8;
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cpu->e = value & 0xff;
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}
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static inline void write_hl(struct cpu *cpu, int value)
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{
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cpu->h = value >> 8;
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cpu->l = value & 0xff;
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}
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void cpu_panic(struct cpu *cpu)
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{
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printf("a=%02x f=%02x b=%02x c=%02x\n", cpu->a, cpu->f, cpu->b, cpu->c);
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printf("d=%02x e=%02x h=%02x l=%02x\n", cpu->d, cpu->e, cpu->h, cpu->l);
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exit(0);
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}
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static inline u8 read8(struct cpu *cpu, u16 address)
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{
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return cpu->mem_read(cpu->mem_model, address);
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}
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static inline u16 read16(struct cpu *cpu, u16 address)
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{
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u8 low = read8(cpu, address);
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u8 high = read8(cpu, address + 1);
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return high << 8 | low;
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}
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static inline void write8(struct cpu *cpu, u16 address, u8 data)
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{
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cpu->mem_write(cpu->mem_model, address, data);
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}
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void cpu_step(struct cpu *cpu)
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{
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u8 opc = cpu->mem_read(cpu->mem_model, cpu->pc);
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switch (opc) {
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case 0: // NOP
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cpu->pc++;
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break;
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case 0x06: // LD B, d8
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cpu->b = read8(cpu, cpu->pc + 1);
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cpu->pc += 2;
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break;
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case 0x0e: // LD C, d8
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cpu->c = read8(cpu, cpu->pc + 1);
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cpu->pc += 2;
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break;
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case 0x21: // LD HL, d16
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write_hl(cpu, read16(cpu, cpu->pc + 1));
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cpu->pc += 3;
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break;
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case 0x32: // LD (HL-), A
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write8(cpu, read_hl(cpu), cpu->a);
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write_hl(cpu, read_hl(cpu) - 1);
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cpu->pc++;
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break;
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case 0xc3: // JP a16
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cpu->pc = read16(cpu, cpu->pc + 1);
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break;
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case 0xaf: // XOR A
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cpu->a = 0;
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cpu->pc++;
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break;
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default:
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printf("unknown opcode %02x\n", opc);
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cpu_panic(cpu);
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}
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}
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