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
 41	gb->video.p = gb;
 42	GBVideoInit(&gb->video);
 43
 44	gb->romVf = 0;
 45
 46	gb->pristineRom = 0;
 47	gb->pristineRomSize = 0;
 48	gb->yankedRomSize = 0;
 49}
 50
 51bool GBLoadROM(struct GB* gb, struct VFile* vf, struct VFile* sav, const char* fname) {
 52	GBUnloadROM(gb);
 53	gb->romVf = vf;
 54	gb->pristineRomSize = vf->size(vf);
 55	vf->seek(vf, 0, SEEK_SET);
 56#ifdef _3DS
 57	gb->pristineRom = 0;
 58	if (gb->pristineRomSize <= romBufferSize) {
 59		gb->pristineRom = romBuffer;
 60		vf->read(vf, romBuffer, gb->pristineRomSize);
 61	}
 62#else
 63	gb->pristineRom = vf->map(vf, gb->pristineRomSize, MAP_READ);
 64#endif
 65	if (!gb->pristineRom) {
 66		return false;
 67	}
 68	gb->yankedRomSize = 0;
 69	gb->memory.rom = gb->pristineRom;
 70	gb->activeFile = fname;
 71	gb->memory.romSize = gb->pristineRomSize;
 72	gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
 73	return true;
 74	// TODO: error check
 75}
 76
 77void GBUnloadROM(struct GB* gb) {
 78	// TODO: Share with GBAUnloadROM
 79	if (gb->memory.rom && gb->pristineRom != gb->memory.rom) {
 80		if (gb->yankedRomSize) {
 81			gb->yankedRomSize = 0;
 82		}
 83		mappedMemoryFree(gb->memory.rom, 0x400000);
 84	}
 85	gb->memory.rom = 0;
 86
 87	if (gb->romVf) {
 88#ifndef _3DS
 89		gb->romVf->unmap(gb->romVf, gb->pristineRom, gb->pristineRomSize);
 90#endif
 91		gb->pristineRom = 0;
 92		gb->romVf = 0;
 93	}
 94}
 95
 96void GBDestroy(struct GB* gb) {
 97	GBUnloadROM(gb);
 98
 99	GBMemoryDeinit(gb);
100}
101
102void GBInterruptHandlerInit(struct LR35902InterruptHandler* irqh) {
103	irqh->reset = GBReset;
104	irqh->processEvents = GBProcessEvents;
105	irqh->setInterrupts = GBSetInterrupts;
106	irqh->hitStub = GBHitStub;
107}
108
109void GBReset(struct LR35902Core* cpu) {
110	cpu->a = 1;
111	cpu->f.packed = 0xB0;
112	cpu->b = 0;
113	cpu->c = 0x13;
114	cpu->d = 0;
115	cpu->e = 0xD8;
116	cpu->h = 1;
117	cpu->l = 0x4D;
118	cpu->sp = 0xFFFE;
119	cpu->pc = 0x100;
120
121	struct GB* gb = (struct GB*) cpu->master;
122
123	if (gb->yankedRomSize) {
124		gb->memory.romSize = gb->yankedRomSize;
125		gb->yankedRomSize = 0;
126	}
127	GBMemoryReset(gb);
128	GBVideoReset(&gb->video);
129	GBIOReset(gb);
130}
131
132void GBUpdateIRQs(struct GB* gb) {
133	if (!gb->memory.ime) {
134		return;
135	}
136	int irqs = gb->memory.ie & gb->memory.io[REG_IF];
137	if (!irqs) {
138		return;
139	}
140	if (irqs & (1 << GB_IRQ_VBLANK)) {
141		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_VBLANK);
142		return;
143	}
144	if (irqs & (1 << GB_IRQ_LCDSTAT)) {
145		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_LCDSTAT);
146		return;
147	}
148	if (irqs & (1 << GB_IRQ_TIMER)) {
149		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_TIMER);
150		return;
151	}
152	if (irqs & (1 << GB_IRQ_SIO)) {
153		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_SIO);
154		return;
155	}
156	if (irqs & (1 << GB_IRQ_KEYPAD)) {
157		LR35902RaiseIRQ(gb->cpu, GB_VECTOR_KEYPAD);
158	}
159}
160
161void GBProcessEvents(struct LR35902Core* cpu) {
162	struct GB* gb = (struct GB*) cpu->master;
163	int32_t cycles = cpu->nextEvent;
164	int32_t nextEvent = INT_MAX;
165	int32_t testEvent;
166
167	testEvent = GBVideoProcessEvents(&gb->video, cycles);
168	if (testEvent < nextEvent) {
169		nextEvent = testEvent;
170	}
171
172	cpu->cycles -= cycles;
173	cpu->nextEvent = nextEvent;
174}
175
176void GBSetInterrupts(struct LR35902Core* cpu, bool enable) {
177	struct GB* gb = (struct GB*) cpu->master;
178	gb->memory.ime = enable;
179	GBUpdateIRQs(gb);
180}
181
182void GBHitStub(struct LR35902Core* cpu) {
183	// TODO
184	//printf("Hit stub at address %04X\n", cpu->pc);
185}
186
187bool GBIsROM(struct VFile* vf) {
188	vf->seek(vf, 0x104, SEEK_SET);
189	uint8_t header[4];
190	static const uint8_t knownHeader[4] = { 0xCE, 0xED, 0x66, 0x66};
191
192	if (vf->read(vf, &header, sizeof(header)) < (ssize_t) sizeof(header)) {
193		return false;
194	}
195	if (memcmp(header, knownHeader, sizeof(header))) {
196		return false;
197	}
198	return true;
199}