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Tiny little speed improvement. Every little helps.

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This commit is contained in:
Thomas Harte 2015-08-13 21:50:24 +01:00
parent 17bbe27c9a
commit 92c7d56cc3
1 changed files with 10 additions and 6 deletions
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16
Machines/Atari2600.cpp
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@ -150,6 +150,10 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
pixel[3] = alphaValues[(outputColour >> 1)&7];
}
// in imputing the knowledge that all we're dealing with is the rollover from 159 to 0,
// this is faster than the straightforward +1)%160 per profiling
#define increment_object_counter(c) _objectCounter[c] = (_objectCounter[c]+1)&~((158-_objectCounter[c]) >> 8)
void Machine::output_pixels(int count)
{
const int32_t start_of_sync = 214;
@ -166,7 +170,7 @@ void Machine::output_pixels(int count)
const uint8_t counterValue = _hMoveCounter ^ 0x7;
for(int c = 0; c < 5; c++) {
if (counterValue == (_objectMotion[c] >> 4)) _hMoveFlags &= ~(1 << c);
if (_hMoveFlags&(1 << c)) _objectCounter[c] = (_objectCounter[c]+1)%160;
if (_hMoveFlags&(1 << c)) increment_object_counter(c);
}
}
@ -217,7 +221,6 @@ void Machine::output_pixels(int count)
if(state == OutputState::Pixel)
{
// printf("%d %d\n", _objectCounter[0], _objectCounter[1]);
_vBlankExtend = false;
_crt->allocate_write_area(160);
_outputBuffer = _crt->get_write_target_for_buffer(0);
@ -232,8 +235,11 @@ void Machine::output_pixels(int count)
get_output_pixel(&_outputBuffer[_lastOutputStateDuration * 4], 159 - _horizontalTimer);
// increment all graphics counters
for(int c = 0; c < 5; c++)
_objectCounter[c] = (_objectCounter[c]+1)%160;
increment_object_counter(0);
increment_object_counter(1);
increment_object_counter(2);
increment_object_counter(3);
increment_object_counter(4);
}
// assumption here: signed shifts right; otherwise it's just
@ -450,7 +456,6 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
break;
}
}
// printf("Uncaught TIA %04x\n", address);
}
// check for a PIA access
@ -490,7 +495,6 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
case 0x07: _writtenPiaTimerShift = _piaTimerShift = 10; _piaTimerValue = *value << 10; _piaTimerStatus &= ~0xc0; break;
}
}
// printf("Uncaught PIA %04x\n", address);
}
if(isReadOperation(operation)) {