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Added a two-slot buffer of scans and a comon dispatch mechanism.

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This commit is contained in:
Thomas Harte 2016-01-23 17:44:34 -05:00
parent f4cd0aa38e
commit 20cab08f8f
2 changed files with 66 additions and 28 deletions
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75
Outputs/CRT.cpp
View File

@ -64,7 +64,16 @@ void CRT::set_new_timing(unsigned int cycles_per_line, unsigned int height_of_di
}
}
CRT::CRT(unsigned int cycles_per_line, unsigned int height_of_display, unsigned int number_of_buffers, ...)
CRT::CRT(unsigned int cycles_per_line, unsigned int height_of_display, unsigned int number_of_buffers, ...) :
_next_scan(0),
_frames_with_delegate(0),
_frame_read_pointer(0),
_horizontal_counter(0),
_sync_capacitor_charge_level(0),
_is_receiving_sync(false),
_is_in_hsync(false),
_is_in_vsync(false),
_rasterPosition({.x = 0, .y = 0})
{
set_new_timing(cycles_per_line, height_of_display);
@ -79,24 +88,10 @@ CRT::CRT(unsigned int cycles_per_line, unsigned int height_of_display, unsigned
_frame_builders[frame] = new CRTFrameBuilder(bufferWidth, bufferHeight, number_of_buffers, va);
va_end(va);
}
_frames_with_delegate = 0;
_frame_read_pointer = 0;
_current_frame_builder = _frame_builders[0];
// reset raster position
_rasterPosition.x = _rasterPosition.y = 0;
// reset flywheel sync
_expected_next_hsync = _cycles_per_line;
_horizontal_counter = 0;
// reset the vertical charge capacitor
_sync_capacitor_charge_level = 0;
// start off not in horizontal sync, not receiving a sync signal
_is_receiving_sync = false;
_is_in_hsync = false;
_is_in_vsync = false;
}
CRT::~CRT()
@ -349,35 +344,61 @@ void CRT::set_delegate(Delegate *delegate)
#pragma mark - stream feeding methods
void CRT::output_scan(Scan *scan)
{
bool this_is_sync = (scan->type == Type::Sync);
bool hsync_requested = !_is_receiving_sync && this_is_sync;
bool vsync_requested = _is_receiving_sync;
_is_receiving_sync = this_is_sync;
advance_cycles(scan->number_of_cycles, scan->source_divider, hsync_requested, vsync_requested, this_is_sync, scan->type);
_next_scan ^= 1;
}
/*
These all merely channel into advance_cycles, supplying appropriate arguments
*/
void CRT::output_sync(unsigned int number_of_cycles)
{
bool _hsync_requested = !_is_receiving_sync; // ensure this really is edge triggered; someone calling output_sync twice in succession shouldn't trigger it twice
_is_receiving_sync = true;
advance_cycles(number_of_cycles, 1, _hsync_requested, false, true, Type::Sync);
_scans[_next_scan].type = Type::Sync;
_scans[_next_scan].number_of_cycles = number_of_cycles;
output_scan(&_scans[_next_scan]);
}
void CRT::output_blank(unsigned int number_of_cycles)
{
bool _vsync_requested = _is_receiving_sync;
_is_receiving_sync = false;
advance_cycles(number_of_cycles, 1, false, _vsync_requested, false, Type::Blank);
_scans[_next_scan].type = Type::Blank;
_scans[_next_scan].number_of_cycles = number_of_cycles;
output_scan(&_scans[_next_scan]);
}
void CRT::output_level(unsigned int number_of_cycles)
{
bool _vsync_requested = _is_receiving_sync;
_is_receiving_sync = false;
advance_cycles(number_of_cycles, 1, false, _vsync_requested, false, Type::Level);
_scans[_next_scan].type = Type::Level;
_scans[_next_scan].number_of_cycles = number_of_cycles;
_scans[_next_scan].tex_x = _current_frame_builder ? _current_frame_builder->_write_x_position : 0;
_scans[_next_scan].tex_y = _current_frame_builder ? _current_frame_builder->_write_y_position : 0;
output_scan(&_scans[_next_scan]);
}
void CRT::output_colour_burst(unsigned int number_of_cycles, uint8_t phase, uint8_t magnitude)
{
_scans[_next_scan].type = Type::ColourBurst;
_scans[_next_scan].number_of_cycles = number_of_cycles;
_scans[_next_scan].phase = phase;
_scans[_next_scan].magnitude = magnitude;
output_scan(&_scans[_next_scan]);
}
void CRT::output_data(unsigned int number_of_cycles, unsigned int source_divider)
{
bool _vsync_requested = _is_receiving_sync;
_is_receiving_sync = false;
advance_cycles(number_of_cycles, source_divider, false, _vsync_requested, false, Type::Data);
_scans[_next_scan].type = Type::Data;
_scans[_next_scan].number_of_cycles = number_of_cycles;
_scans[_next_scan].tex_x = _current_frame_builder ? _current_frame_builder->_write_x_position : 0;
_scans[_next_scan].tex_y = _current_frame_builder ? _current_frame_builder->_write_y_position : 0;
_scans[_next_scan].source_divider = source_divider;
output_scan(&_scans[_next_scan]);
}
#pragma mark - Buffer supply

19
Outputs/CRT.hpp
View File

@ -144,7 +144,7 @@ class CRT {
// the outer entry point for dispatching output_sync, output_blank, output_level and output_data
enum Type {
Sync, Level, Data, Blank
Sync, Level, Data, Blank, ColourBurst
} type;
void advance_cycles(unsigned int number_of_cycles, unsigned int source_divider, bool hsync_requested, bool vsync_requested, bool vsync_charging, Type type);
@ -157,6 +157,23 @@ class CRT {
};
SyncEvent get_next_vertical_sync_event(bool vsync_is_requested, unsigned int cycles_to_run_for, unsigned int *cycles_advanced);
SyncEvent get_next_horizontal_sync_event(bool hsync_is_requested, unsigned int cycles_to_run_for, unsigned int *cycles_advanced);
// each call to output_* generates a scan. A two-slot queue for scans allows edge extensions.
struct Scan {
Type type;
unsigned int number_of_cycles;
union {
struct {
unsigned int source_divider;
uint16_t tex_x, tex_y;
};
struct {
uint8_t phase, magnitude;
};
};
} _scans[2];
int _next_scan;
void output_scan(Scan *scan);
};
}