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calls, jumps, and stack.

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This commit is contained in:
Samuel Walker 2025-01-30 22:54:33 -07:00
parent 022c24dd35
commit dd1c6d2e0e
Signed by: piwalker
GPG Key ID: 616B1928705EA4C9
7 changed files with 146 additions and 4 deletions
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2
include/cpu.h
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@ -51,3 +51,5 @@ void fetch_data();
u8 cpu_get_ie_register();
void cpu_set_ie_register(u8 ie);
cpu_registers *cpu_get_regs();

9
include/stack.h Normal file
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@ -0,0 +1,9 @@
#pragma once
#include <common.h>
void stack_push(u8 data);
void stack_push16(u16 data);
u8 stack_pop();
u16 stack_pop16();

1
lib/cpu_fetch.c
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@ -17,6 +17,7 @@ void fetch_data() {
return;
case AM_R_R:
ctx.fetched_data = cpu_read_reg(ctx.cur_inst->reg_2);
return;
case AM_R_D8:
ctx.fetched_data = bus_read(ctx.regs.pc);
emu_cycles(1);

72
lib/cpu_proc.c
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@ -1,6 +1,7 @@
#include <cpu.h>
#include <emu.h>
#include <bus.h>
#include <stack.h>
//process CPU instructions...
@ -28,6 +29,21 @@ static void proc_nop(cpu_context *ctx) {
}
static void proc_pop(cpu_context *ctx) {
u16 n = stack_pop16();
cpu_set_reg(ctx->cur_inst->reg_1, n);
emu_cycles(2);
if (ctx->cur_inst->reg_1 == RT_AF) {
cpu_set_reg(ctx->cur_inst->reg_1, n & 0xFFF0);
}
}
static void proc_push(cpu_context *ctx) {
stack_push16(cpu_read_reg(ctx->cur_inst->reg_1));
emu_cycles(2);
}
static void proc_ldh(cpu_context *ctx) {
if (!ctx->dest_is_mem) {
cpu_set_reg(ctx->cur_inst->reg_1, bus_read(0XFF00 | ctx->fetched_data));
@ -83,13 +99,56 @@ static bool check_condition(cpu_context *ctx) {
return false;
}
static void proc_jp(cpu_context *ctx) {
static void goto_addr(cpu_context *ctx, u16 addr, bool pushpc){
if (check_condition(ctx)) {
ctx->regs.pc = ctx->fetched_data;
if(pushpc) {
stack_push16(ctx->regs.pc);
emu_cycles(2);
}
ctx->regs.pc = addr;
emu_cycles(1);
}
}
static void proc_jp(cpu_context *ctx) {
goto_addr(ctx, ctx->fetched_data, false);
}
static void proc_call(cpu_context *ctx) {
goto_addr(ctx, ctx->fetched_data, true);
}
static void proc_rst(cpu_context *ctx) {
goto_addr(ctx, ctx->cur_inst->param, true);
}
static void proc_ret(cpu_context *ctx) {
if (ctx->cur_inst->cond != CT_NONE) {
emu_cycles(1);
}
if(check_condition(ctx)){
u16 lo = stack_pop();
emu_cycles(1);
u16 hi = stack_pop();
emu_cycles(1);
u16 n = (hi << 8) | lo;
ctx->regs.pc = n;
emu_cycles(1);
}
}
static void proc_reti(cpu_context *ctx) {
ctx->int_master_enabled = true;
proc_ret(ctx);
}
static void proc_jr(cpu_context *ctx) {
char rel = (char)(ctx->fetched_data & 0XFF);
u16 addr = ctx->regs.pc + rel;
goto_addr(ctx, addr, false);
}
IN_PROC processors[] = {
[IN_NONE] = proc_none,
[IN_NOP] = proc_nop,
@ -97,7 +156,14 @@ IN_PROC processors[] = {
[IN_JP] = proc_jp,
[IN_DI] = proc_di,
[IN_XOR] = proc_xor,
[IN_LDH] = proc_ldh
[IN_LDH] = proc_ldh,
[IN_POP] = proc_pop,
[IN_PUSH] = proc_push,
[IN_CALL] = proc_call,
[IN_JR] = proc_jr,
[IN_RET] = proc_ret,
[IN_RETI] = proc_reti,
[IN_RST] = proc_rst
};
IN_PROC inst_get_processor(in_type type) {

4
lib/cpu_util.c
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@ -49,3 +49,7 @@ void cpu_set_reg(reg_type rt, u16 val) {
case RT_NONE: break;
}
}
cpu_registers *cpu_get_regs() {
return &ctx.regs;
}

37
lib/instructions.c
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@ -16,20 +16,25 @@ instruction instructions[0x100] = {
[0x12] = {IN_LD, AM_MR_R, RT_DE, RT_A},
[0x15] = {IN_DEC, AM_R, RT_D},
[0x16] = {IN_LD, AM_R_D8, RT_D},
[0x18] = {IN_JR, AM_D8},
[0x1A] = {IN_LD, AM_R_MR, RT_A, RT_DE},
[0x1E] = {IN_LD, AM_R_D8, RT_E},
//0x2X
[0x20] = {IN_JR, AM_D8, RT_NONE, RT_NONE, CT_NZ},
[0x21] = {IN_LD, AM_R_D16, RT_HL},
[0x22] = {IN_LD, AM_HLI_R, RT_HL, RT_A},
[0x25] = {IN_DEC, AM_R, RT_H},
[0x26] = {IN_LD, AM_R_D8, RT_H},
[0x28] = {IN_JR, AM_D8, RT_NONE, RT_NONE, CT_Z},
[0x2A] = {IN_LD, AM_R_HLI, RT_A, RT_HL},
[0x2E] = {IN_LD, AM_R_D8, RT_L},
//0x3X
[0x30] = {IN_JR, AM_D8, RT_NONE, RT_NONE, CT_NC},
[0x31] = {IN_LD, AM_R_D16, RT_SP},
[0x32] = {IN_LD, AM_HLD_R, RT_HL, RT_A},
[0x35] = {IN_DEC, AM_MR, RT_HL},
[0x36] = {IN_LD, AM_MR_D8, RT_HL},
[0x38] = {IN_JR, AM_D8, RT_NONE, RT_NONE, CT_C},
[0x3A] = {IN_LD, AM_R_HLD, RT_A, RT_HL},
[0x3E] = {IN_LD, AM_R_D8, RT_A},
//0x4X
@ -106,17 +111,49 @@ instruction instructions[0x100] = {
[0xAF] = {IN_XOR, AM_R, RT_A},
//0xBX
//0xCX
[0xC0] = {IN_RET, AM_IMP, RT_NONE, RT_NONE, CT_NZ},
[0xC1] = {IN_POP, AM_IMP, RT_BC},
[0xC2] = {IN_JP, AM_D16, RT_NONE, RT_NONE, CT_NZ},
[0xC3] = {IN_JP, AM_D16},
[0xC4] = {IN_CALL, AM_D16, RT_NONE, RT_NONE, CT_NZ},
[0xC5] = {IN_PUSH, AM_IMP, RT_BC},
[0xC7] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x00},
[0xC8] = {IN_RET, AM_IMP, RT_NONE, RT_NONE, CT_Z},
[0xC9] = {IN_RET},
[0xCA] = {IN_JP, AM_D16, RT_NONE, RT_NONE, CT_Z},
[0xCC] = {IN_CALL, AM_D16, RT_NONE, RT_NONE, CT_Z},
[0xCD] = {IN_CALL, AM_D16},
[0xCF] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x08},
//0xDX
[0xD0] = {IN_RET, AM_IMP, RT_NONE, RT_NONE, CT_NC},
[0xD1] = {IN_POP, AM_IMP, RT_DE},
[0xD2] = {IN_JP, AM_D16, RT_NONE, RT_NONE, CT_NC},
[0xD4] = {IN_CALL, AM_D16, RT_NONE, RT_NONE, CT_NC},
[0xD5] = {IN_PUSH, AM_IMP, RT_DE},
[0xD7] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x10},
[0xD8] = {IN_RET, AM_IMP, RT_NONE, RT_NONE, CT_C},
[0xD9] = {IN_RETI},
[0xDA] = {IN_JP, AM_D16, RT_NONE, RT_NONE, CT_C},
[0xDC] = {IN_CALL, AM_D16, RT_NONE, RT_NONE, CT_C},
[0xDF] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x18},
//0xEX
[0xE0] = {IN_LDH, AM_A8_R, RT_NONE, RT_A},
[0xE1] = {IN_POP, AM_IMP, RT_HL},
[0xE2] = {IN_LD, AM_MR_R, RT_C, RT_A},
[0xE5] = {IN_PUSH, AM_IMP, RT_HL},
[0xE7] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x20},
[0xE9] = {IN_JP, AM_MR, RT_HL},
[0xEA] = {IN_LD, AM_A16_R, RT_NONE, RT_A},
[0xEF] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x28},
//0xFX
[0xF0] = {IN_LDH, AM_R_A8, RT_A},
[0xF1] = {IN_POP, AM_IMP, RT_AF},
[0xF2] = {IN_LD, AM_R_MR, RT_A, RT_C},
[0xF3] = {IN_DI},
[0xF5] = {IN_PUSH, AM_IMP, RT_AF},
[0xF7] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x30},
[0xFA] = {IN_LD, AM_R_A16, RT_A},
[0xFF] = {IN_RST, AM_IMP, RT_NONE, RT_NONE, CT_NONE, 0x38}
};
instruction *instruction_by_opcode(u8 opcode) {

23
lib/stack.c Normal file
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@ -0,0 +1,23 @@
#include <stack.h>
#include <cpu.h>
#include <bus.h>
void stack_push(u8 data){
cpu_get_regs()->sp--;
bus_write(cpu_get_regs()->sp, data);
}
void stack_push16(u16 data){
stack_push((data >> 8) & 0xFF);
stack_push(data & 0xFF);
}
u8 stack_pop(){
return bus_read(cpu_get_regs()->sp++);
}
u16 stack_pop16(){
u16 lo = stack_pop();
u16 hi = stack_pop();
return (hi << 8) || lo;
}