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Did the absolute minimum necessary to get some sprites showing in some capacity.

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This commit is contained in:
Thomas Harte 2015-07-29 23:48:52 -04:00
parent 23df94d011
commit d1ae2caf91
2 changed files with 42 additions and 12 deletions
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53
Machines/Atari2600.cpp
View File

@ -39,6 +39,8 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
const int lowestBit = (byte&1)^1;
const int bit = (index & 7)^(lowestBit | (lowestBit << 1) | (lowestBit << 2));
// printf("%d -> %d -> %d -> %d/%d\n", offset, x, index, byte, bit);
uint8_t playFieldPixel = (_playfield[byte] >> bit)&1;
const uint8_t palette[16][3] =
@ -62,8 +64,19 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
uint8_t outputColour = playFieldPixel ? playfieldColour : _backgroundColour;
if(_horizontalTimer == _playerPosition[0]) outputColour = _player0Colour;
if(_horizontalTimer == _playerPosition[1]) outputColour = _player1Colour;
if(!playFieldPixel || !(_playfieldControl&0x04))
{
uint8_t playerOneBit = 0;
if(_horizontalTimer <= _playerPosition[0] && _horizontalTimer > _playerPosition[0] - 8) {
playerOneBit = _playerGraphics[0] >> ((_playerPosition[0] - _horizontalTimer) ^ ((_playerReflection[0]&0x8) ? 0 : 7));
if(playerOneBit&1) outputColour = _player0Colour;
}
if(_horizontalTimer <= _playerPosition[1] && _horizontalTimer > _playerPosition[1] - 8) {
playerOneBit = _playerGraphics[1] >> ((_playerPosition[1] - _horizontalTimer) ^ ((_playerReflection[1]&0x8) ? 0 : 7));
if(playerOneBit&1) outputColour = _player1Colour;
}
}
pixel[0] = palette[outputColour >> 4][0];
pixel[1] = palette[outputColour >> 4][1];
@ -158,14 +171,14 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
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;
case 0x00: returnValue &= 0x3f; break; // missile 0 / player collisions
case 0x01: returnValue &= 0x3f; break; // missile 1 / player collisions
case 0x02: returnValue &= 0x3f; break; // player 0 / playfield / ball collisions
case 0x03: returnValue &= 0x3f; break; // player 1 / playfield / ball collisions
case 0x04: returnValue &= 0x3f; break; // missile 0 / playfield / ball collisions
case 0x05: returnValue &= 0x3f; break; // missile 1 / playfield / ball collisions
case 0x06: returnValue &= 0x7f; break; // ball / playfield collisions
case 0x07: returnValue &= 0x3f; break; // player / player, missile / missile collisions
}
} else {
switch(address & 0x3f) {
@ -173,8 +186,8 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
case 0x01: _vBlankEnabled = !!(*value & 0x02); break;
case 0x02: {
cycle_count = _horizontalTimer / 3;
output_pixels(3 * cycle_count);
cycle_count += (_horizontalTimer / 3)+3;
output_pixels(_horizontalTimer+1);
} break;
case 0x03: _horizontalTimer = 227; break;
@ -204,6 +217,21 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
case 0x1d: _missileGraphicsEnable[0] = *value; break;
case 0x1e: _missileGraphicsEnable[1] = *value; break;
case 0x1f: _ballGraphicsEnable = *value; break;
case 0x20: _playerMotion[0] = *value; break;
case 0x21: _playerMotion[1] = *value; break;
case 0x22: _missileMotion[0] = *value; break;
case 0x23: _missileMotion[1] = *value; break;
case 0x24: _ballMotion = *value; break;
case 0x2a:
_playerPosition[0] += (int8_t)_playerMotion[0] >> 4;
_playerPosition[1] += (int8_t)_playerMotion[1] >> 4;
_missilePosition[0] += (int8_t)_missileMotion[0] >> 4;
_missilePosition[1] += (int8_t)_missileMotion[1] >> 4;
_ballPosition += (int8_t)_ballMotion >> 4;
break;
case 0x2b: _playerMotion[0] = _playerMotion[1] = _missileMotion[0] = _missileMotion[1] = _ballMotion = 0; break;
}
}
// printf("Uncaught TIA %04x\n", address);
@ -213,6 +241,7 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
if ((address&0x1280) == 0x280) {
if(isReadOperation(operation)) {
switch(address & 0xf) {
// case 0x00:
case 0x04: returnValue &= _piaTimerValue >> _piaTimerShift; break;
}
} else {

1
Machines/Atari2600.hpp
View File

@ -50,6 +50,7 @@ class Machine: public CPU6502::Processor<Machine> {
uint8_t _missileGraphicsEnable[2];
uint8_t _ballGraphicsEnable;
uint8_t _playerPosition[2], _missilePosition[2], _ballPosition;
uint8_t _playerMotion[2], _missileMotion[2], _ballMotion;
// graphics output
int32_t _horizontalTimer;