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As an experiment, performed some very basic moving of playfield composition outside of the pixel loop.

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This commit is contained in:
Thomas Harte 2015-08-13 21:32:22 +01:00
parent 033655835a
commit 17bbe27c9a
2 changed files with 47 additions and 31 deletions
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75
Machines/Atari2600.cpp
View File

@ -62,11 +62,9 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
// get the playfield pixel and hence a proposed colour
const int x = offset >> 2;
const int mirrored = (x / 20) & (_playfieldControl&1);
const int index = mirrored ? x - 20 : 19 - (x%20);
const int byte = 2 - (index >> 3);
const int lowestBit = (byte&1)^1;
const int bit = (index & 7)^(lowestBit | (lowestBit << 1) | (lowestBit << 2));
uint8_t playfieldPixel = (_playfield[byte] >> bit)&1;
const int index = mirrored ? 39 - x : (x%20);
uint8_t playfieldPixel = _playfield[index];
uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? _playerColour[x / 20] : _playfieldColour;
// get player and missile proposed pixels
@ -123,25 +121,18 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
ballPixel = (ballIndex >= 0 && ballIndex < ballSize && (_ballGraphicsEnable&2)) ? 1 : 0;
// accumulate collisions
_collisions[0] |= ((missilePixels[0] & playerPixels[1]) << 7);
_collisions[0] |= ((missilePixels[0] & playerPixels[0]) << 6);
_collisions[1] |= ((missilePixels[1] & playerPixels[0]) << 7);
_collisions[1] |= ((missilePixels[1] & playerPixels[1]) << 6);
_collisions[0] |= ((missilePixels[0] & playerPixels[1]) << 7) | ((missilePixels[0] & playerPixels[0]) << 6);
_collisions[1] |= ((missilePixels[1] & playerPixels[0]) << 7) | ((missilePixels[1] & playerPixels[1]) << 6);
_collisions[2] |= ((playfieldPixel & playerPixels[0]) << 7);
_collisions[2] |= ((ballPixel & playerPixels[0]) << 6);
_collisions[3] |= ((playfieldPixel & playerPixels[1]) << 7);
_collisions[3] |= ((ballPixel & playerPixels[1]) << 6);
_collisions[2] |= ((playfieldPixel & playerPixels[0]) << 7) | ((ballPixel & playerPixels[0]) << 6);
_collisions[3] |= ((playfieldPixel & playerPixels[1]) << 7) | ((ballPixel & playerPixels[1]) << 6);
_collisions[4] |= ((playfieldPixel & missilePixels[0]) << 7);
_collisions[4] |= ((ballPixel & missilePixels[0]) << 6);
_collisions[5] |= ((playfieldPixel & missilePixels[1]) << 7);
_collisions[5] |= ((ballPixel & missilePixels[1]) << 6);
_collisions[4] |= ((playfieldPixel & missilePixels[0]) << 7) | ((ballPixel & missilePixels[0]) << 6);
_collisions[5] |= ((playfieldPixel & missilePixels[1]) << 7) | ((ballPixel & missilePixels[1]) << 6);
_collisions[6] |= ((playfieldPixel & ballPixel) << 7);
_collisions[7] |= ((playerPixels[0] & playerPixels[1]) << 7);
_collisions[7] |= ((missilePixels[0] & missilePixels[1]) << 6);
_collisions[7] |= ((playerPixels[0] & playerPixels[1]) << 7) | ((missilePixels[0] & missilePixels[1]) << 6);
// apply appropriate priority to pick a colour
playfieldPixel |= ballPixel;
@ -171,12 +162,12 @@ void Machine::output_pixels(int count)
// update hmove
if (!(_horizontalTimer&3)) {
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) {
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(_hMoveIsCounting) {
@ -200,16 +191,16 @@ void Machine::output_pixels(int count)
// 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 >= start_of_sync) state = OutputState::Blank;
else if (_horizontalTimer >= end_of_sync) state = OutputState::Sync;
else if (_horizontalTimer >= (_vBlankExtend ? 152 : 160)) state = OutputState::Blank;
else {
if (_horizontalTimer < (_vBlankExtend ? 152 : 160)) {
if(_vBlankEnabled) {
state = OutputState::Blank;
} else {
state = OutputState::Pixel;
}
}
else if (_horizontalTimer < end_of_sync) state = OutputState::Blank;
else if (_horizontalTimer < start_of_sync) state = OutputState::Sync;
else state = OutputState::Blank;
}
_lastOutputStateDuration++;
@ -373,9 +364,33 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
case 0x0a: _playfieldControl = *value; break;
case 0x0b:
case 0x0c: _playerReflection[decodedAddress - 0x0b] = *value; break;
case 0x0d:
_playfield[0] = ((*value) >> 4)&1;
_playfield[1] = ((*value) >> 5)&1;
_playfield[2] = ((*value) >> 6)&1;
_playfield[3] = (*value) >> 7;
break;
case 0x0e:
case 0x0f: _playfield[decodedAddress - 0x0d] = *value; break;
_playfield[4] = (*value) >> 7;
_playfield[5] = ((*value) >> 6)&1;
_playfield[6] = ((*value) >> 5)&1;
_playfield[7] = ((*value) >> 4)&1;
_playfield[8] = ((*value) >> 3)&1;
_playfield[9] = ((*value) >> 2)&1;
_playfield[10] = ((*value) >> 1)&1;
_playfield[11] = (*value)&1;
break;
case 0x0f:
_playfield[19] = (*value) >> 7;
_playfield[18] = ((*value) >> 6)&1;
_playfield[17] = ((*value) >> 5)&1;
_playfield[16] = ((*value) >> 4)&1;
_playfield[15] = ((*value) >> 3)&1;
_playfield[14] = ((*value) >> 2)&1;
_playfield[13] = ((*value) >> 1)&1;
_playfield[12] = (*value)&1;
break;
case 0x10: case 0x11: case 0x12: case 0x13:
case 0x14: _objectCounter[decodedAddress - 0x10] = 0; break;

3
Machines/Atari2600.hpp
View File

@ -41,9 +41,10 @@ class Machine: public CPU6502::Processor<Machine> {
uint8_t _piaTimerStatus;
// playfield registers
uint8_t _playfield[3], _playfieldControl;
uint8_t _playfieldControl;
uint8_t _playfieldColour;
uint8_t _backgroundColour;
uint8_t _playfield[40];
// player registers
uint8_t _playerColour[2];