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Switches to bit unpacking on the GPU.

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This commit is contained in:
Thomas Harte 2018-04-07 22:17:47 -04:00
parent 506b4da6c3
commit 3821679efd
1 changed files with 12 additions and 15 deletions
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27
Machines/ZX8081/Video.cpp
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@ -13,12 +13,13 @@ 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.
// Set a composite sampling function that assumes 1bpp input.
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;"
"uint texValue = texture(sampler, coordinate).r;"
"texValue <<= int(icoordinate.x * 8) & 7;"
"return float(texValue & 128u);"
"}");
// Show only the centre 80% of the TV frame.
@ -45,10 +46,10 @@ void Video::flush(bool next_sync) {
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_);
unsigned int data_length = static_cast<unsigned int>(line_data_pointer_ - line_data_) * 8;
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);
crt_->output_data(output_length, 8);
line_data_pointer_ = line_data_ = nullptr;
cycles_since_update_ -= output_length;
} else return;
@ -79,25 +80,21 @@ void Video::output_byte(uint8_t byte) {
// Grab a buffer if one isn't already available.
if(!line_data_) {
line_data_pointer_ = line_data_ = crt_->allocate_write_area(320);
line_data_pointer_ = line_data_ = crt_->allocate_write_area(40);
}
// 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);
if(line_data_pointer_ - line_data_ == 40) {
crt_->output_data(40, 8);
cycles_since_update_ -= 320;
line_data_pointer_ = line_data_ = crt_->allocate_write_area(320);
line_data_pointer_ = line_data_ = crt_->allocate_write_area(40);
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;
line_data_pointer_[0] = byte;
line_data_pointer_ ++;
}
}