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CLK/Machines/ZX8081/Video.cpp
Thomas Harte ac80d10cd8 Separates the component parts of running an audio stream: task deferral, filtering and generation.
Walking towards improving opportunities for composition.
2017-12-17 21:26:06 -05:00

106 lines
3.0 KiB
C++

//
// Video.cpp
// Clock Signal
//
// Created by Thomas Harte on 06/06/2017.
// Copyright © 2017 Thomas Harte. All rights reserved.
//
#include "Video.hpp"
using namespace ZX8081;
Video::Video() :
crt_(new Outputs::CRT::CRT(207 * 2, 1, Outputs::CRT::DisplayType::PAL50, 1)) {
// Set a composite sampling function that assumes 8bpp input grayscale.
// TODO: lessen this to 1bpp.
crt_->set_composite_sampling_function(
"float composite_sample(usampler2D sampler, vec2 coordinate, vec2 icoordinate, float phase, float amplitude)"
"{"
"return float(texture(texID, coordinate).r) / 255.0;"
"}");
// Show only the centre 80% of the TV frame.
crt_->set_visible_area(Outputs::CRT::Rect(0.1f, 0.1f, 0.8f, 0.8f));
}
void Video::run_for(const HalfCycles half_cycles) {
// Just keep a running total of the amount of time that remains owed to the CRT.
cycles_since_update_ += static_cast<unsigned int>(half_cycles.as_int());
}
void Video::flush() {
flush(sync_);
}
void Video::flush(bool next_sync) {
if(sync_) {
// If in sync, that takes priority. Output the proper amount of sync.
crt_->output_sync(cycles_since_update_);
} else {
// If not presently in sync, then...
if(line_data_) {
// If there is output data queued, output it either if it's being interrupted by
// sync, or if we're past its end anyway. Otherwise let it be.
unsigned int data_length = static_cast<unsigned int>(line_data_pointer_ - line_data_);
if(data_length < cycles_since_update_ || next_sync) {
unsigned int output_length = std::min(data_length, cycles_since_update_);
crt_->output_data(output_length, 1);
line_data_pointer_ = line_data_ = nullptr;
cycles_since_update_ -= output_length;
} else return;
}
// Any pending pixels being dealt with, pad with the white level.
uint8_t *colour_pointer = static_cast<uint8_t *>(crt_->allocate_write_area(1));
if(colour_pointer) *colour_pointer = 0xff;
crt_->output_level(cycles_since_update_);
}
cycles_since_update_ = 0;
}
void Video::set_sync(bool sync) {
// Do nothing if sync hasn't changed.
if(sync_ == sync) return;
// Complete whatever was being drawn, and update sync.
flush(sync);
sync_ = sync;
}
void Video::output_byte(uint8_t byte) {
// Complete whatever was going on.
if(sync_) return;
flush();
// Grab a buffer if one isn't already available.
if(!line_data_) {
line_data_pointer_ = line_data_ = crt_->allocate_write_area(320);
}
// If a buffer was obtained, serialise the new pixels.
if(line_data_) {
// If the buffer is full, output it now and obtain a new one
if(line_data_pointer_ - line_data_ == 320) {
crt_->output_data(320, 1);
cycles_since_update_ -= 320;
line_data_pointer_ = line_data_ = crt_->allocate_write_area(320);
if(!line_data_) return;
}
uint8_t mask = 0x80;
for(int c = 0; c < 8; c++) {
line_data_pointer_[c] = (byte & mask) ? 0xff : 0x00;
mask >>= 1;
}
line_data_pointer_ += 8;
}
}
Outputs::CRT::CRT *Video::get_crt() {
return crt_.get();
}