1/* Copyright (c) 2013-2016 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#include "gb.h"
  7
  8#include "gb/io.h"
  9
 10#include "util/crc32.h"
 11#include "util/memory.h"
 12#include "util/math.h"
 13#include "util/patch.h"
 14#include "util/vfs.h"
 15
 16const uint32_t DMG_LR35902_FREQUENCY = 0x400000;
 17const uint32_t CGB_LR35902_FREQUENCY = 0x800000;
 18const uint32_t SGB_LR35902_FREQUENCY = 0x418B1E;
 19
 20const uint32_t GB_COMPONENT_MAGIC = 0x400000;
 21
 22static void GBInit(struct LR35902Core* cpu, struct LR35902Component* component);
 23static void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh);
 24static void GBProcessEvents(struct LR35902Core* cpu);
 25static void GBSetInterrupts(struct LR35902Core* cpu, bool enable);
 26static void GBHitStub(struct LR35902Core* cpu);
 27
 28void GBCreate(struct GB* gb) {
 29	gb->d.id = GB_COMPONENT_MAGIC;
 30	gb->d.init = GBInit;
 31	gb->d.deinit = 0;
 32}
 33
 34static void GBInit(struct LR35902Core* cpu, struct LR35902Component* component) {
 35	struct GB* gb = (struct GB*) component;
 36	gb->cpu = cpu;
 37
 38	GBInterruptHandlerInit(&cpu->irqh);
 39	GBMemoryInit(gb);
 40	GBVideoInit(&gb->video);
 41
 42	gb->romVf = 0;
 43
 44	gb->pristineRom = 0;
 45	gb->pristineRomSize = 0;
 46	gb->yankedRomSize = 0;
 47}
 48
 49bool GBLoadROM(struct GB* gb, struct VFile* vf, struct VFile* sav, const char* fname) {
 50	GBUnloadROM(gb);
 51	gb->romVf = vf;
 52	gb->pristineRomSize = vf->size(vf);
 53	vf->seek(vf, 0, SEEK_SET);
 54#ifdef _3DS
 55	gb->pristineRom = 0;
 56	if (gb->pristineRomSize <= romBufferSize) {
 57		gb->pristineRom = romBuffer;
 58		vf->read(vf, romBuffer, gb->pristineRomSize);
 59	}
 60#else
 61	gb->pristineRom = vf->map(vf, gb->pristineRomSize, MAP_READ);
 62#endif
 63	if (!gb->pristineRom) {
 64		return false;
 65	}
 66	gb->yankedRomSize = 0;
 67	gb->memory.rom = gb->pristineRom;
 68	gb->activeFile = fname;
 69	gb->memory.romSize = gb->pristineRomSize;
 70	gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
 71	return true;
 72	// TODO: error check
 73}
 74
 75void GBUnloadROM(struct GB* gb) {
 76	// TODO: Share with GBAUnloadROM
 77	if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
 78		if (gb->yankedRomSize) {
 79			gb->yankedRomSize = 0;
 80		}
 81		mappedMemoryFree(gb->memory.rom, 0x400000);
 82	}
 83	gb->memory.rom = 0;
 84
 85	if (gb->romVf) {
 86#ifndef _3DS
 87		gb->romVf->unmap(gb->romVf, gb->pristineRom, gb->pristineRomSize);
 88#endif
 89		gb->pristineRom = 0;
 90		gb->romVf = 0;
 91	}
 92}
 93
 94void GBDestroy(struct GB* gb) {
 95	GBUnloadROM(gb);
 96
 97	GBMemoryDeinit(gb);
 98}
 99
100void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh) {
101	irqh->reset = GBReset;
102	irqh->processEvents = GBProcessEvents;
103	irqh->setInterrupts = GBSetInterrupts;
104	irqh->hitStub = GBHitStub;
105}
106
107void GBReset(struct LR35902Core* cpu) {
108	cpu->a = 1;
109	cpu->f.packed = 0xB0;
110	cpu->b = 0;
111	cpu->c = 0x13;
112	cpu->d = 0;
113	cpu->e = 0xD8;
114	cpu->h = 1;
115	cpu->l = 0x4D;
116	cpu->sp = 0xFFFE;
117	cpu->pc = 0x100;
118
119	struct GB* gb = (struct GB*) cpu->master;
120
121	if (gb->yankedRomSize) {
122		gb->memory.romSize = gb->yankedRomSize;
123		gb->yankedRomSize = 0;
124	}
125	GBMemoryReset(gb);
126
127	gb->video.p = gb;
128	GBVideoReset(&gb->video);
129}
130
131void GBUpdateIRQs(struct GB* gb) {
132	if (!gb->memory.ime) {
133		return;
134	}
135	int irqs = gb->memory.ie & gb->memory.io[REG_IF];
136	if (!irqs) {
137		return;
138	}
139	if (irqs & (1 << GB_IRQ_VBLANK)) {
140		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_VBLANK);
141		return;
142	}
143	if (irqs & (1 << GB_IRQ_LCDSTAT)) {
144		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_LCDSTAT);
145		return;
146	}
147	if (irqs & (1 << GB_IRQ_TIMER)) {
148		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_TIMER);
149		return;
150	}
151	if (irqs & (1 << GB_IRQ_SIO)) {
152		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_SIO);
153		return;
154	}
155	if (irqs & (1 << GB_IRQ_KEYPAD)) {
156		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_KEYPAD);
157	}
158}
159
160void GBProcessEvents(struct LR35902Core* cpu) {
161	struct GB* gb = (struct GB*) cpu->master;
162	int32_t cycles = cpu->nextEvent;
163	int32_t nextEvent = INT_MAX;
164	int32_t testEvent;
165
166	testEvent = GBVideoProcessEvents(&gb->video, cycles);
167	if (testEvent < nextEvent) {
168		nextEvent = testEvent;
169	}
170
171	cpu->cycles -= cycles;
172	cpu->nextEvent = nextEvent;
173}
174
175void GBSetInterrupts(struct LR35902Core* cpu, bool enable) {
176	struct GB* gb = (struct GB*) cpu->master;
177	gb->memory.ime = enable;
178	GBUpdateIRQs(gb);
179}
180
181void GBHitStub(struct LR35902Core* cpu) {
182	// TODO
183	//printf("Hit stub at address %04X\n", cpu->pc);
184}