gbemu/lib/cpu_proc.c

#include <cpu.h>
#include <emu.h>

//process CPU instructions...

static void proc_none(cpu_context *ctx) {
    printf("INVALID INSTRUCTION!\n");
    exit(-7);
}

static void proc_nop(cpu_context *ctx) {
    
}

void cpu_set_flags(cpu_context *ctx, u8 z, u8 n, u8 h, u8 c){
    if (z != -1){
        BIT_SET(ctx->regs.f, 7, z)
    }
    if (n != -1){
        BIT_SET(ctx->regs.f, 6, n)
    }
    if (h != -1){
        BIT_SET(ctx->regs.f, 5, h)
    }
    if (c != -1){
        BIT_SET(ctx->regs.f, 4, c)
    }
}

static void proc_xor(cpu_context *ctx) {
    ctx->regs.a ^= ctx->fetched_data & 0XFF;
    cpu_set_flags(ctx, ctx->regs.a == 0, 0, 0, 0);
}

static void proc_di(cpu_context *ctx) {
    ctx->int_master_enabled = false;
}

static void proc_ld(cpu_context *ctx) {
    //TODO
}

static bool check_condition(cpu_context *ctx) {
    bool z = CPU_FLAG_Z;
    bool c = CPU_FLAG_C;

    switch(ctx->cur_inst->cond) {
        case CT_NONE: return true;
        case CT_C: return c;
        case CT_NC: return !c;
        case CT_Z: return z;
        case CT_NZ: return !z;
    }

    return false;
}

static void proc_jp(cpu_context *ctx) {
    if (check_condition(ctx)) {
        ctx->regs.pc = ctx->fetched_data;
        emu_cycles(1);
    }
}

IN_PROC processors[] = {
    [IN_NONE] = proc_none,
    [IN_NOP] = proc_nop,
    [IN_LD] = proc_ld,
    [IN_JP] = proc_jp,
    [IN_DI] = proc_di,
    [IN_XOR] = proc_xor
};

IN_PROC inst_get_processor(in_type type) {
    return processors[type];
}