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Ensures NTSC raster count rollover; previously it was positing a line '261' for half of '0'.

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Thomas Harte 2018-04-08 16:18:41 -04:00
parent 28947bb3c4
commit 1c5972f7b0
1 changed files with 9 additions and 4 deletions
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13
Components/6560/6560.hpp
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@ -198,7 +198,7 @@ template <class T> class MOS6560 {
horizontal_drawing_latch_ = false;
vertical_counter_ ++;
if(vertical_counter_ == (registers_.interlaced ? (is_odd_frame_ ? 262 : 263) : timing_.lines_per_progressive_field)) {
if(vertical_counter_ == lines_this_field()) {
vertical_counter_ = 0;
full_frame_counter_ = 0;
@ -414,11 +414,10 @@ template <class T> class MOS6560 {
*/
uint8_t get_register(int address) {
address &= 0xf;
int current_line = (full_frame_counter_ + timing_.line_counter_increment_offset) / timing_.cycles_per_line;
switch(address) {
default: return registers_.direct_values[address];
case 0x03: return static_cast<uint8_t>(current_line << 7) | (registers_.direct_values[3] & 0x7f);
case 0x04: return (current_line >> 1) & 0xff;
case 0x03: return static_cast<uint8_t>(raster_value() << 7) | (registers_.direct_values[3] & 0x7f);
case 0x04: return (raster_value() >> 1) & 0xff;
}
}
@ -454,6 +453,12 @@ template <class T> class MOS6560 {
// counters that cover an entire field
int horizontal_counter_ = 0, vertical_counter_ = 0, full_frame_counter_;
const int lines_this_field() {
return registers_.interlaced ? (is_odd_frame_ ? 262 : 263) : timing_.lines_per_progressive_field;
}
const int raster_value() {
return ((full_frame_counter_ + timing_.line_counter_increment_offset) / timing_.cycles_per_line) % lines_this_field();
}
// latches dictating start and length of drawing
bool vertical_drawing_latch_, horizontal_drawing_latch_;