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 "lr35902.h"
  7
  8#include "isa-lr35902.h"
  9
 10void LR35902Init(struct LR35902Core* cpu) {
 11	cpu->master->init(cpu, cpu->master);
 12	size_t i;
 13	for (i = 0; i < cpu->numComponents; ++i) {
 14		if (cpu->components[i] && cpu->components[i]->init) {
 15			cpu->components[i]->init(cpu, cpu->components[i]);
 16		}
 17	}
 18}
 19
 20void LR35902Deinit(struct LR35902Core* cpu) {
 21	if (cpu->master->deinit) {
 22		cpu->master->deinit(cpu->master);
 23	}
 24	size_t i;
 25	for (i = 0; i < cpu->numComponents; ++i) {
 26		if (cpu->components[i] && cpu->components[i]->deinit) {
 27			cpu->components[i]->deinit(cpu->components[i]);
 28		}
 29	}
 30}
 31
 32void LR35902SetComponents(struct LR35902Core* cpu, struct mCPUComponent* master, int extra, struct mCPUComponent** extras) {
 33	cpu->master = master;
 34	cpu->numComponents = extra;
 35	cpu->components = extras;
 36}
 37
 38
 39void LR35902HotplugAttach(struct LR35902Core* cpu, size_t slot) {
 40	if (slot >= cpu->numComponents) {
 41		return;
 42	}
 43	cpu->components[slot]->init(cpu, cpu->components[slot]);
 44}
 45
 46void LR35902HotplugDetach(struct LR35902Core* cpu, size_t slot) {
 47	if (slot >= cpu->numComponents) {
 48		return;
 49	}
 50	cpu->components[slot]->deinit(cpu->components[slot]);
 51}
 52
 53void LR35902Reset(struct LR35902Core* cpu) {
 54	cpu->af = 0;
 55	cpu->bc = 0;
 56	cpu->de = 0;
 57	cpu->hl = 0;
 58
 59	cpu->sp = 0;
 60	cpu->pc = 0;
 61
 62	cpu->instruction = 0;
 63
 64	cpu->cycles = 0;
 65	cpu->nextEvent = 0;
 66	cpu->executionState = LR35902_CORE_FETCH;
 67	cpu->halted = 0;
 68
 69	cpu->irqPending = false;
 70	cpu->irqh.reset(cpu);
 71}
 72
 73void LR35902RaiseIRQ(struct LR35902Core* cpu, uint8_t vector) {
 74	cpu->irqPending = true;
 75	cpu->irqVector = vector;
 76}
 77
 78static void _LR35902InstructionIRQStall(struct LR35902Core* cpu) {
 79	cpu->executionState = LR35902_CORE_STALL;
 80}
 81
 82static void _LR35902InstructionIRQFinish(struct LR35902Core* cpu) {
 83	cpu->executionState = LR35902_CORE_OP2;
 84	cpu->instruction = _LR35902InstructionIRQStall;
 85}
 86
 87static void _LR35902InstructionIRQDelay(struct LR35902Core* cpu) {
 88	cpu->index = cpu->sp + 1;
 89	cpu->bus = cpu->pc >> 8;
 90	cpu->executionState = LR35902_CORE_MEMORY_STORE;
 91	cpu->instruction = _LR35902InstructionIRQFinish;
 92	cpu->pc = cpu->irqVector;
 93	cpu->memory.setActiveRegion(cpu, cpu->pc);
 94}
 95
 96static void _LR35902InstructionIRQ(struct LR35902Core* cpu) {
 97	cpu->sp -= 2; /* TODO: Atomic incrementing? */
 98	cpu->index = cpu->sp;
 99	cpu->bus = cpu->pc;
100	cpu->executionState = LR35902_CORE_MEMORY_STORE;
101	cpu->instruction = _LR35902InstructionIRQDelay;
102	cpu->irqh.setInterrupts(cpu, false);
103}
104
105static void _LR35902Step(struct LR35902Core* cpu) {
106	++cpu->cycles;
107	enum LR35902ExecutionState state = cpu->executionState;
108	++cpu->executionState;
109	cpu->executionState &= 3;
110	switch (state) {
111	case LR35902_CORE_FETCH:
112		if (cpu->irqPending) {
113			cpu->index = cpu->sp;
114			cpu->irqPending = false;
115			cpu->instruction = _LR35902InstructionIRQ;
116			break;
117		}
118		cpu->bus = cpu->memory.cpuLoad8(cpu, cpu->pc);
119		cpu->instruction = _lr35902InstructionTable[cpu->bus];
120		++cpu->pc;
121		break;
122	case LR35902_CORE_EXECUTE:
123		cpu->instruction(cpu);
124		break;
125	case LR35902_CORE_MEMORY_LOAD:
126		cpu->bus = cpu->memory.load8(cpu, cpu->index);
127		break;
128	case LR35902_CORE_MEMORY_STORE:
129		cpu->memory.store8(cpu, cpu->index, cpu->bus);
130		break;
131	case LR35902_CORE_READ_PC:
132		cpu->bus = cpu->memory.load8(cpu, cpu->pc);
133		++cpu->pc;
134		break;
135	case LR35902_CORE_STALL:
136		cpu->instruction = _lr35902InstructionTable[0]; // NOP
137		break;
138	default:
139		break;
140	}
141}
142
143void LR35902Tick(struct LR35902Core* cpu) {
144	_LR35902Step(cpu);
145	if (cpu->cycles >= cpu->nextEvent) {
146		cpu->irqh.processEvents(cpu);
147	}
148}
149
150void LR35902Run(struct LR35902Core* cpu) {
151	while (true) {
152		_LR35902Step(cpu);
153		if (cpu->cycles >= cpu->nextEvent) {
154			break;
155		} else if (cpu->executionState < LR35902_CORE_EXECUTE) {
156			// Silly hack: keep us from calling step if we know the next step is a no-op
157			++cpu->cycles;
158			++cpu->executionState;
159		}
160	}
161	cpu->irqh.processEvents(cpu);
162}