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 "sio.h"
 7
 8#include "gb/gb.h"
 9#include "gb/io.h"
10#include "gb/serialize.h"
11
12void _GBSIOProcessEvents(struct mTiming* timing, void* context, uint32_t cyclesLate);
13
14void GBSIOInit(struct GBSIO* sio) {
15	sio->pendingSB = 0xFF;
16	sio->event.context = sio;
17	sio->event.name = "GB SIO";
18	sio->event.callback = _GBSIOProcessEvents;
19	sio->event.priority = 0x30;
20}
21
22void GBSIOReset(struct GBSIO* sio) {
23	sio->nextEvent = INT_MAX;
24	sio->remainingBits = 0;
25}
26
27void GBSIODeinit(struct GBSIO* sio) {
28	UNUSED(sio);
29	// Nothing to do yet
30}
31
32void _GBSIOProcessEvents(struct mTiming* timing, void* context, uint32_t cyclesLate) {
33	UNUSED(cyclesLate);
34	struct GBSIO* sio = context;
35	--sio->remainingBits;
36	sio->p->memory.io[REG_SB] &= ~(8 >> sio->remainingBits);
37	sio->p->memory.io[REG_SB] |= sio->pendingSB & ~(8 >> sio->remainingBits);
38	if (!sio->remainingBits) {
39		sio->p->memory.io[REG_IF] |= (1 << GB_IRQ_SIO);
40		sio->p->memory.io[REG_SC] = GBRegisterSCClearEnable(sio->p->memory.io[REG_SC]);
41		GBUpdateIRQs(sio->p);
42	} else {
43		mTimingSchedule(timing, &sio->event, sio->period);
44	}
45}
46
47void GBSIOWriteSC(struct GBSIO* sio, uint8_t sc) {
48	sio->period = 0x1000; // TODO Shift Clock
49	if (GBRegisterSCIsEnable(sc)) {
50		if (GBRegisterSCIsShiftClock(sc)) {
51			mTimingSchedule(&sio->p->timing, &sio->event, sio->period);
52		}
53		sio->remainingBits = 8;
54	}
55}
56