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111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
//
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// CRTInputBufferBuilder.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 08/03/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "CRTInputBufferBuilder.hpp"
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#include "CRTOpenGL.hpp"
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#include <string.h>
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using namespace Outputs::CRT;
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CRTInputBufferBuilder::CRTInputBufferBuilder(size_t bytes_per_pixel) :
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_bytes_per_pixel(bytes_per_pixel),
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_next_write_x_position(0),
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_next_write_y_position(0),
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_image(new uint8_t[bytes_per_pixel * InputBufferBuilderWidth * InputBufferBuilderHeight])
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{}
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void CRTInputBufferBuilder::allocate_write_area(size_t required_length)
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{
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if(_next_write_y_position != InputBufferBuilderHeight)
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{
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_last_allocation_amount = required_length;
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if(_next_write_x_position + required_length + 2 > InputBufferBuilderWidth)
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{
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_next_write_x_position = 0;
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_next_write_y_position++;
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if(_next_write_y_position == InputBufferBuilderHeight)
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return;
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}
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_write_x_position = _next_write_x_position + 1;
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_write_y_position = _next_write_y_position;
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_write_target_pointer = (_write_y_position * InputBufferBuilderWidth) + _write_x_position;
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_next_write_x_position += required_length + 2;
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}
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}
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bool CRTInputBufferBuilder::is_full()
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{
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return (_next_write_y_position == InputBufferBuilderHeight);
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}
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void CRTInputBufferBuilder::reduce_previous_allocation_to(size_t actual_length)
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{
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if(_next_write_y_position == InputBufferBuilderHeight) return;
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uint8_t *const image_pointer = _image.get();
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// correct if the writing cursor was reset while a client was writing
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if(_next_write_x_position == 0 && _next_write_y_position == 0)
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{
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memmove(&image_pointer[_bytes_per_pixel], &image_pointer[_write_target_pointer * _bytes_per_pixel], actual_length * _bytes_per_pixel);
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_write_target_pointer = 1;
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_last_allocation_amount = actual_length;
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_next_write_x_position = (uint16_t)(actual_length + 2);
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_write_x_position = 1;
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_write_y_position = 0;
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}
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// book end the allocation with duplicates of the first and last pixel, to protect
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// against rounding errors when this run is drawn
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memcpy( &image_pointer[(_write_target_pointer - 1) * _bytes_per_pixel],
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&image_pointer[_write_target_pointer * _bytes_per_pixel],
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_bytes_per_pixel);
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memcpy( &image_pointer[(_write_target_pointer + actual_length) * _bytes_per_pixel],
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&image_pointer[(_write_target_pointer + actual_length - 1) * _bytes_per_pixel],
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_bytes_per_pixel);
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// return any allocated length that wasn't actually used to the available pool
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_next_write_x_position -= (_last_allocation_amount - actual_length);
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}
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uint8_t *CRTInputBufferBuilder::get_image_pointer()
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{
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return _image.get();
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}
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uint16_t CRTInputBufferBuilder::get_and_finalise_current_line()
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{
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uint16_t result = _write_y_position + (_next_write_x_position ? 1 : 0);
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_next_write_x_position = _next_write_y_position = 0;
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return result;
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}
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uint8_t *CRTInputBufferBuilder::get_write_target()
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{
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return (_next_write_y_position == InputBufferBuilderHeight) ? nullptr : &_image.get()[_write_target_pointer * _bytes_per_pixel];
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}
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uint16_t CRTInputBufferBuilder::get_last_write_x_position()
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{
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return _write_x_position;
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}
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uint16_t CRTInputBufferBuilder::get_last_write_y_position()
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{
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return _write_y_position;
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}
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size_t CRTInputBufferBuilder::get_bytes_per_pixel()
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{
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return _bytes_per_pixel;
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}
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