unsigned short stackPop16 (void){
unsigned short value = 0;
//reading is done this way to support correct timing
unsigned short temp1 = readMemory8(registers.SP);
unsigned short temp2 = readMemory8(registers.SP + 1) << 8;
value = temp1 | temp2;
registers.SP += 2;
return value;
}
/*
* Expected timing (fresh DMA):
* M = 0: write to $FF46 happens
* M = 1: nothing (OAM still accessible)
* M = 2: new DMA starts, OAM reads will return $FF
* Expected timing (restarted DMA):
* M = 0: write to $FF46 happens. Previous DMA is running (OAM *not* accessible)
* M = 1: previous DMA is running (OAM *not* accessible)
* M = 2: new DMA starts, OAM reads will return $FF
*/
void updateDMA (){
if (dmastate.start){
//directMemoryAccess(dmastate.address);
dmastate.running = TRUE;
dmastate.start = FALSE;
dmastate.timer = 0;
//dmastate.timer = 640;
}
if (dmastate.prepare){
dmastate.start = TRUE;
dmastate.prepare = FALSE;
}
if (dmastate.running){
gpu_reading = 1;
memory[0xFE00 + dmastate.timer] = readMemory8(dmastate.address + dmastate.timer);
gpu_reading = 0;
dmastate.timer += 1;
if (dmastate.timer > 160){
dmastate.running = FALSE;
dmastate.timer = 0;
}
}
}
unsigned long MemoryForCpu::read8_se(unsigned long addr)
{
unsigned char c;
if(port->read8(addr, &c))
return signExtend8(c);
if(ifont->read8(addr, &c))
return signExtend8(c);
if(rommmp->read8(addr, &c))
return signExtend8(c);
return signExtend8(readMemory8(addr));
}
unsigned char MemoryForCpu::read8_0e(unsigned long addr)
{
unsigned char c;
if(port->read8(addr, &c))
return c;
if(ifont->read8(addr, &c))
return c;
if(rommmp->read8(addr, &c))
return c;
return readMemory8(addr);
}
/**
* readMemory16 - read 2 bytes from memory
*
* @address the position to read from
*/
unsigned short readMemory16(unsigned short address)
{
return (readMemory8(address) | (readMemory8(address + 1) << 8));
}
