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dma.cpp
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dma.cpp
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#include "dma.h"
#include "gba.h"
#include <cstdint>
Dma::Dma(uint8_t num) {
_dmaNr = num;
_srcAddr = 0;
_dstAddr = 0;
_transfLen = 0;
_transfCounter = 0;
_reload_on_repeat = 0;
_fifoTransfer = false;
switch (_dmaNr) {
case 0:
_cnt = (dma_control_struct*)GBA::memory.get_io_reg(0xBA);
break;
case 1:
_cnt = (dma_control_struct*)GBA::memory.get_io_reg(0xc6);
break;
case 2:
_cnt = (dma_control_struct*)GBA::memory.get_io_reg(0xd2);
break;
case 3:
_cnt = (dma_control_struct*)GBA::memory.get_io_reg(0xdc);
break;
default:
throw "Invalid DMA channel specified";
break;
}
}
//reload some stuff on repeat
void Dma::load_on_repeat(void) {
if (!_reload_on_repeat)
return;
_fifoTransfer = false;
switch (_dmaNr) {
case 0: //DMA0
{
//read destination address
if (_cnt->dst_cnt == 3) { //increment + reload
_dstAddr = GBA::memory.read_32(0x40000B4);
_dstAddr &= 0x7FFFFFF; //internal memory only
}
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000B8);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
break;
}
case 1: //DMA1
{
//read destination address
if (_cnt->dst_cnt == 3) { //increment + reload
_dstAddr = GBA::memory.read_32(0x40000c0);
_dstAddr &= 0x7FFFFFF; //internal memory only
}
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000c4);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
_fifoTransfer = _cnt->repeat
&& (_dstAddr == 0x40000A0 || _dstAddr == 0x40000A4);
break;
}
case 2: //DMA2
{
//read destination address
if (_cnt->dst_cnt == 3) { //increment + reload
_dstAddr = GBA::memory.read_32(0x40000cc);
_dstAddr &= 0x7FFFFFF; //internal memory only
}
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000d0);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
_fifoTransfer = _cnt->repeat
&& (_dstAddr == 0x40000A0 || _dstAddr == 0x40000A4);
break;
}
case 3: //DMA3
{
//read destination address
if (_cnt->dst_cnt == 3) { //increment + reload
_dstAddr = GBA::memory.read_32(0x40000d8);
_dstAddr &= 0xFFFFFFF; //any memory
}
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000dc); //16 bit
if (_transfLen == 0) _transfLen = 0x10000;
_transfCounter = 0;
break;
}
}
}
void Dma::enable_dma(void) {
_fifoTransfer = false;
switch (_dmaNr) {
case 0: //DMA0
{
//read source address
_srcAddr = GBA::memory.read_32(0x40000B0);
_srcAddr &= 0x7FFFFFF; //internal memory only
//read destination address
_dstAddr = GBA::memory.read_32(0x40000B4);
_dstAddr &= 0x7FFFFFF; //internal memory only
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000B8);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
_reload_on_repeat = 0;
break;
}
case 1: //DMA1
{
//read source address
_srcAddr = GBA::memory.read_32(0x40000bc);
_srcAddr &= 0xFFFFFFF; //any memory
//read destination address
_dstAddr = GBA::memory.read_32(0x40000c0);
_dstAddr &= 0x7FFFFFF; //internal memory only
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000c4);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
_reload_on_repeat = 0;
//is FIFO transfer?
_fifoTransfer = _cnt->repeat
&& (_dstAddr == 0x40000A0 || _dstAddr == 0x40000A4);
break;
}
case 2: //DMA2
{
//read source address
_srcAddr = GBA::memory.read_32(0x40000c8);
_srcAddr &= 0xFFFFFFF; //any memory
//read destination address
_dstAddr = GBA::memory.read_32(0x40000cc);
_dstAddr &= 0x7FFFFFF; //internal memory only
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000d0);
_transfLen &= 0x3fff; //14 bit only
if (_transfLen == 0) _transfLen = 0x4000;
_transfCounter = 0;
_reload_on_repeat = 0;
//is FIFO transfer?
_fifoTransfer = _cnt->repeat
&& (_dstAddr == 0x40000A0 || _dstAddr == 0x40000A4);
break;
}
case 3: //DMA3
{
//read source address
_srcAddr = GBA::memory.read_32(0x40000d4);
_srcAddr &= 0xFFFFFFF; //any memory
//read destination address
_srcAddr = GBA::memory.read_32(0x40000d8);
_srcAddr &= 0xFFFFFFF; //any memory
//read transfer lenght
_transfLen = GBA::memory.read_16(0x40000dc); //16 bit
if (_transfLen == 0) _transfLen = 0x10000;
_transfCounter = 0;
_reload_on_repeat = 0;
break;
}
}
}
void Dma::trigger(Dma_Trigger trigger) {
if (!_cnt->enable)
return;
switch (_cnt->timing) {
case 0: //immidiately
full_run_dma();
break;
case 1: //vblank
if (trigger == Dma_Trigger::VBLANK) {
load_on_repeat();
full_run_dma();
}
break;
case 2: //hblank
if (trigger == Dma_Trigger::HBLANK) {
load_on_repeat();
full_run_dma();
}
break;
case 3: //special trigger
switch (_dmaNr) {
case 1: //DMA1 & DMA2 special triggers are FIFO
case 2:
if (trigger == Dma_Trigger::FIFO) {
load_on_repeat();
full_run_dma();
}
break;
case 3: //DMA3 special trigger is video capture
if (trigger == Dma_Trigger::VIDEO_CAPTURE) {
load_on_repeat();
full_run_dma();
}
break;
}
break;
}
}
void Dma::disable() {
_reload_on_repeat = false;
_fifoTransfer = false;
_cnt->enable = 0;
}
void Dma::full_run_dma(void) {
int8_t inc_transform[4] = {1, -1, 0, 1};
if (_fifoTransfer) { //fifo transfer. destination address is fixed
int32_t src_inc_mod = inc_transform[_cnt->src_cnt];
for (_transfCounter = 0; _transfCounter < 4; _transfCounter++) {
uint32_t read_val = GBA::memory.read_32(_srcAddr);
GBA::memory.write_32(_dstAddr, read_val);
_srcAddr += src_inc_mod * 4;
}
}else if (_cnt->type == 0){
//16 bit transfer
int32_t src_inc_mod = inc_transform[_cnt->src_cnt];
int32_t dst_inc_mod = inc_transform[_cnt->dst_cnt];
for (_transfCounter = 0; _transfCounter < _transfLen; _transfCounter++) {
uint16_t read_val = GBA::memory.read_16(_srcAddr);
GBA::memory.write_16(_dstAddr, read_val);
_srcAddr += 2 * src_inc_mod;
_dstAddr += 2 * dst_inc_mod;
}
}
else {
//32 bit transfer
for (_transfCounter = 0; _transfCounter < _transfLen; _transfCounter++) {
int32_t src_inc_mod = inc_transform[_cnt->src_cnt];
int32_t dst_inc_mod = inc_transform[_cnt->dst_cnt];
for (_transfCounter = 0; _transfCounter < _transfLen; _transfCounter++) {
uint32_t read_val = GBA::memory.read_32(_srcAddr);
GBA::memory.write_32(_dstAddr, read_val);
_srcAddr += 4 * src_inc_mod;
_dstAddr += 4 * dst_inc_mod;
}
}
}
_transfCounter = 0;
if (!_cnt->repeat) { //no repeat
_cnt->enable = 0;
}
if (_cnt->irq) //irq upon end of word count
GBA::irq.setDMAFlag(_dmaNr);
_reload_on_repeat = _cnt->repeat;
}