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CLK/Outputs/CRT/Internals/CRTInputBufferBuilder.cpp

58 lines
1.7 KiB
C++

//
// CRTInputBufferBuilder.cpp
// Clock Signal
//
// Created by Thomas Harte on 08/03/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "CRTInputBufferBuilder.hpp"
#include "CRTOpenGL.hpp"
#include <string.h>
using namespace Outputs::CRT;
CRTInputBufferBuilder::CRTInputBufferBuilder(size_t bytes_per_pixel) :
bytes_per_pixel(bytes_per_pixel),
_next_write_x_position(0),
_next_write_y_position(0),
last_uploaded_line(0),
_wraparound_sync(glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0))
{}
CRTInputBufferBuilder::~CRTInputBufferBuilder()
{
glDeleteSync(_wraparound_sync);
}
void CRTInputBufferBuilder::allocate_write_area(size_t required_length)
{
_last_allocation_amount = required_length;
if(_next_write_x_position + required_length + 2 > InputBufferBuilderWidth)
{
move_to_new_line();
}
_write_x_position = _next_write_x_position + 1;
_write_y_position = _next_write_y_position;
_write_target_pointer = (_write_y_position * InputBufferBuilderWidth) + _write_x_position;
_next_write_x_position += required_length + 2;
}
void CRTInputBufferBuilder::reduce_previous_allocation_to(size_t actual_length, uint8_t *buffer)
{
// book end the allocation with duplicates of the first and last pixel, to protect
// against rounding errors when this run is drawn
memcpy( &buffer[(_write_target_pointer - 1) * bytes_per_pixel],
&buffer[_write_target_pointer * bytes_per_pixel],
bytes_per_pixel);
memcpy( &buffer[(_write_target_pointer + actual_length) * bytes_per_pixel],
&buffer[(_write_target_pointer + actual_length - 1) * bytes_per_pixel],
bytes_per_pixel);
// return any allocated length that wasn't actually used to the available pool
_next_write_x_position -= (_last_allocation_amount - actual_length);
}