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Ensured the line counter increments late on NTSC.

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This commit is contained in:
Thomas Harte 2016-06-27 22:12:55 -04:00
parent 24280844cb
commit de5d2f1113
2 changed files with 9 additions and 3 deletions
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9
Components/6560/6560.cpp
View File

@ -60,6 +60,7 @@ void MOS6560::set_output_mode(OutputMode output_mode)
chrominances = pal_chrominances;
display_type = Outputs::CRT::PAL50;
_timing.cycles_per_line = 71;
_timing.line_counter_increment_offset = 0;
_timing.lines_per_progressive_field = 312;
_timing.supports_interlacing = false;
break;
@ -68,6 +69,7 @@ void MOS6560::set_output_mode(OutputMode output_mode)
chrominances = ntsc_chrominances;
display_type = Outputs::CRT::NTSC60;
_timing.cycles_per_line = 65;
_timing.line_counter_increment_offset = 65 - 36; // TODO: 36 is from memory; need to look up.
_timing.lines_per_progressive_field = 261;
_timing.supports_interlacing = true;
break;
@ -147,11 +149,12 @@ void MOS6560::set_register(int address, uint8_t value)
uint8_t MOS6560::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 (uint8_t)(_vertical_counter << 7) | (_registers.direct_values[3] & 0x7f);
case 0x04: return (_vertical_counter >> 1) & 0xff;
case 0x03: return (uint8_t)(current_line << 7) | (_registers.direct_values[3] & 0x7f);
case 0x04: return (current_line >> 1) & 0xff;
}
}
@ -172,6 +175,7 @@ uint16_t MOS6560::get_address()
// keep track of internal time relative to this scanline
_horizontal_counter++;
_full_frame_counter++;
if(_horizontal_counter == _timing.cycles_per_line)
{
if(_horizontal_drawing_latch)
@ -197,6 +201,7 @@ uint16_t MOS6560::get_address()
if(_vertical_counter == (_registers.interlaced ? (_is_odd_frame ? 262 : 263) : _timing.lines_per_progressive_field))
{
_vertical_counter = 0;
_full_frame_counter = 0;
_is_odd_frame ^= true;
_current_row = 0;

3
Components/6560/6560.hpp
View File

@ -104,7 +104,7 @@ class MOS6560 {
unsigned int _cycles_in_state;
// counters that cover an entire field
int _horizontal_counter, _vertical_counter;
int _horizontal_counter, _vertical_counter, _full_frame_counter;
// latches dictating start and length of drawing
bool _vertical_drawing_latch, _horizontal_drawing_latch;
@ -129,6 +129,7 @@ class MOS6560 {
struct {
int cycles_per_line;
int line_counter_increment_offset;
int lines_per_progressive_field;
bool supports_interlacing;
} _timing;