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 "io.h"
  7
  8#include "gb/gb.h"
  9
 10void GBIOInit(struct GB* gb) {
 11	memset(gb->memory.io, 0, sizeof(gb->memory.io));
 12}
 13
 14void GBIOReset(struct GB* gb) {
 15	memset(gb->memory.io, 0, sizeof(gb->memory.io));
 16
 17	GBIOWrite(gb, 0x05, 0);
 18	GBIOWrite(gb, 0x06, 0);
 19	GBIOWrite(gb, 0x07, 0);
 20	GBIOWrite(gb, 0x10, 0x80);
 21	GBIOWrite(gb, 0x11, 0xBF);
 22	GBIOWrite(gb, 0x12, 0xF3);
 23	GBIOWrite(gb, 0x12, 0xF3);
 24	GBIOWrite(gb, 0x14, 0xBF);
 25	GBIOWrite(gb, 0x16, 0x3F);
 26	GBIOWrite(gb, 0x17, 0x00);
 27	GBIOWrite(gb, 0x19, 0xBF);
 28	GBIOWrite(gb, 0x1A, 0x7F);
 29	GBIOWrite(gb, 0x1B, 0xFF);
 30	GBIOWrite(gb, 0x1C, 0x9F);
 31	GBIOWrite(gb, 0x1E, 0xBF);
 32	GBIOWrite(gb, 0x20, 0xFF);
 33	GBIOWrite(gb, 0x21, 0x00);
 34	GBIOWrite(gb, 0x22, 0x00);
 35	GBIOWrite(gb, 0x23, 0xBF);
 36	GBIOWrite(gb, 0x24, 0x77);
 37	GBIOWrite(gb, 0x25, 0xF3);
 38	GBIOWrite(gb, 0x26, 0xF1);
 39	GBIOWrite(gb, 0x40, 0x91);
 40	GBIOWrite(gb, 0x42, 0x00);
 41	GBIOWrite(gb, 0x43, 0x00);
 42	GBIOWrite(gb, 0x45, 0x00);
 43	GBIOWrite(gb, 0x47, 0xFC);
 44	GBIOWrite(gb, 0x48, 0xFF);
 45	GBIOWrite(gb, 0x49, 0xFF);
 46	GBIOWrite(gb, 0x4A, 0x00);
 47	GBIOWrite(gb, 0x4B, 0x00);
 48	GBIOWrite(gb, 0xFF, 0x00);
 49}
 50
 51void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
 52	switch (address) {
 53	case REG_DIV:
 54		GBTimerDivReset(&gb->timer);
 55		return;
 56	case REG_TIMA:
 57		// ???
 58		return;
 59	case REG_TMA:
 60		// Handled transparently by the registers
 61		break;
 62	case REG_TAC:
 63		value = GBTimerUpdateTAC(&gb->timer, value);
 64		break;
 65	case REG_IF:
 66		gb->memory.io[REG_IF] = value | 0xE0;
 67		GBUpdateIRQs(gb);
 68		return;
 69	case REG_LCDC:
 70		// TODO: handle GBC differences
 71		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
 72		GBVideoWriteLCDC(&gb->video, value);
 73		break;
 74	case REG_DMA:
 75		GBMemoryDMA(gb, value << 8);
 76		break;
 77	case REG_SCY:
 78	case REG_SCX:
 79	case REG_WY:
 80	case REG_WX:
 81	case REG_BGP:
 82	case REG_OBP0:
 83	case REG_OBP1:
 84		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
 85		break;
 86	case REG_STAT:
 87		GBVideoWriteSTAT(&gb->video, value);
 88		break;
 89	case REG_IE:
 90		gb->memory.ie = value;
 91		GBUpdateIRQs(gb);
 92		return;
 93	default:
 94		// TODO: Log
 95		if (address >= GB_SIZE_IO) {
 96			return;
 97		}
 98		break;
 99	}
100	gb->memory.io[address] = value;
101}
102
103static uint8_t _readKeys(struct GB* gb) {
104	uint8_t keys = *gb->keySource;
105	switch (gb->memory.io[REG_JOYP] & 0x30) {
106	case 0x20:
107		keys >>= 4;
108		break;
109	case 0x10:
110		break;
111	default:
112		// ???
113		keys = 0;
114		break;
115	}
116	return 0xC0 | (gb->memory.io[REG_JOYP] | 0xF) ^ (keys & 0xF);
117}
118
119uint8_t GBIORead(struct GB* gb, unsigned address) {
120	switch (address) {
121	case REG_JOYP:
122		return _readKeys(gb);
123	case REG_IF:
124		break;
125	case REG_IE:
126		return gb->memory.ie;
127	case REG_DIV:
128	case REG_TIMA:
129	case REG_TMA:
130	case REG_TAC:
131	case REG_LY:
132		// Handled transparently by the registers
133		break;
134	default:
135		// TODO: Log
136		if (address >= GB_SIZE_IO) {
137			return 0;
138		}
139		break;
140	}
141	return gb->memory.io[address];
142}