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Collapsed two methods into one, to avoid redundant pixel copying.

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This commit is contained in:
Thomas Harte 2015-07-27 22:12:13 -04:00
parent 828ae66a45
commit 164866d613
2 changed files with 40 additions and 39 deletions
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48
Machines/Atari2600.cpp
View File

@ -70,40 +70,30 @@ void Machine::output_pixels(int count)
{
while(count--)
{
OutputState state;
// logic: if in vsync, output that; otherwise if in vblank then output that;
// otherwise output a pixel
if(_vSyncEnabled) {
output_state(OutputState::Sync, nullptr);
state = OutputState::Sync;
} else {
// blank is decoded as 68 counts; sync and colour burst as 16 counts
// it'll be about 43 cycles from start of hsync to start of visible frame, so...
// guesses, until I can find information: 26 cycles blank, 16 sync, 40 blank, 160 pixels
if(_horizontalTimer > 214) output_state(OutputState::Blank, nullptr);
else if (_horizontalTimer > 188) output_state(OutputState::Sync, nullptr);
else if (_horizontalTimer >= 160) output_state(OutputState::Blank, nullptr);
if(_horizontalTimer > 214) state = OutputState::Blank;
else if (_horizontalTimer > 188) state = OutputState::Sync;
else if (_horizontalTimer >= 160) state = OutputState::Blank;
else {
if(_vBlankEnabled) {
output_state(OutputState::Blank, nullptr);
state = OutputState::Blank;
} else {
uint8_t outputPixel[4];
get_output_pixel(outputPixel, 159 - _horizontalTimer);
output_state(OutputState::Pixel, outputPixel);
state = OutputState::Pixel;
}
}
}
// assumption here: signed shifts right; otherwise it's just
// an attempt to avoid both the % operator and a conditional
_horizontalTimer--;
const int32_t sign_extension = _horizontalTimer >> 31;
_horizontalTimer = (_horizontalTimer&~sign_extension) | (sign_extension&227);
}
}
void Machine::output_state(OutputState state, uint8_t *pixel)
{
_lastOutputStateDuration++;
if(state != _lastOutputState)
{
@ -124,11 +114,13 @@ void Machine::output_state(OutputState state, uint8_t *pixel)
}
if(state == OutputState::Pixel && _outputBuffer)
{
_outputBuffer[(_lastOutputStateDuration * 4) + 0] = pixel[0];
_outputBuffer[(_lastOutputStateDuration * 4) + 1] = pixel[1];
_outputBuffer[(_lastOutputStateDuration * 4) + 2] = pixel[2];
_outputBuffer[(_lastOutputStateDuration * 4) + 3] = pixel[3];
get_output_pixel(&_outputBuffer[_lastOutputStateDuration * 4], 159 - _horizontalTimer);
// assumption here: signed shifts right; otherwise it's just
// an attempt to avoid both the % operator and a conditional
_horizontalTimer--;
const int32_t sign_extension = _horizontalTimer >> 31;
_horizontalTimer = (_horizontalTimer&~sign_extension) | (sign_extension&227);
}
}
@ -160,6 +152,16 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
// check for a TIA access
if (!(address&0x1080)) {
if(isReadOperation(operation)) {
switch(address & 0xf) {
case 0x00: *value = 0x3f; break;
case 0x01: *value = 0x3f; break;
case 0x02: *value = 0x3f; break;
case 0x03: *value = 0x3f; break;
case 0x04: *value = 0x3f; break;
case 0x05: *value = 0x3f; break;
case 0x06: *value = 0x7f; break;
case 0x07: *value = 0x3f; break;
}
} else {
switch(address & 0x3f) {
case 0: _vSyncEnabled = !!(*value & 0x02); break;

1
Machines/Atari2600.hpp
View File

@ -57,7 +57,6 @@ class Machine: public CPU6502::Processor<Machine> {
void output_pixels(int count);
void get_output_pixel(uint8_t *pixel, int offset);
void output_state(OutputState state, uint8_t *pixel);
Outputs::CRT *_crt;
// latched output state