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225 lines
7.9 KiB
C++
225 lines
7.9 KiB
C++
//
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// Video.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 12/10/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Video.hpp"
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using namespace Oric;
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namespace {
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const unsigned int PAL50VSyncStartPosition = 256*64;
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const unsigned int PAL60VSyncStartPosition = 234*64;
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const unsigned int PAL50VSyncEndPosition = 259*64;
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const unsigned int PAL60VSyncEndPosition = 238*64;
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const unsigned int PAL50Period = 312*64;
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const unsigned int PAL60Period = 262*64;
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}
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VideoOutput::VideoOutput(uint8_t *memory) :
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ram_(memory),
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crt_(new Outputs::CRT::CRT(64*6, 6, Outputs::CRT::DisplayType::PAL50, 2)),
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v_sync_start_position_(PAL50VSyncStartPosition), v_sync_end_position_(PAL50VSyncEndPosition),
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counter_period_(PAL50Period) {
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crt_->set_rgb_sampling_function(
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"vec3 rgb_sample(usampler2D sampler, vec2 coordinate)"
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"{"
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"uint texValue = texture(sampler, coordinate).r;"
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"return vec3( uvec3(texValue) & uvec3(4u, 2u, 1u));"
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"}");
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crt_->set_composite_sampling_function(
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"float composite_sample(usampler2D sampler, vec2 coordinate, float phase, float amplitude)"
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"{"
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"uint texValue = uint(dot(texture(sampler, coordinate).rg, uvec2(1, 256)));"
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"uint iPhase = uint((phase + 3.141592654 + 0.39269908175) * 2.0 / 3.141592654) & 3u;"
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"texValue = (texValue >> (4u*(3u - iPhase))) & 15u;"
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"return (float(texValue) - 4.0) / 20.0;"
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"}"
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);
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crt_->set_composite_function_type(Outputs::CRT::CRT::CompositeSourceType::DiscreteFourSamplesPerCycle, 0.0f);
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set_video_signal(Outputs::CRT::VideoSignal::Composite);
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crt_->set_visible_area(crt_->get_rect_for_area(54, 224, 16 * 6, 40 * 6, 4.0f / 3.0f));
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}
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void VideoOutput::set_video_signal(Outputs::CRT::VideoSignal video_signal) {
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video_signal_ = video_signal;
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crt_->set_video_signal(video_signal);
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}
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void VideoOutput::set_colour_rom(const std::vector<uint8_t> &rom) {
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for(std::size_t c = 0; c < 8; c++) {
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std::size_t index = (c << 2);
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uint16_t rom_value = static_cast<uint16_t>((static_cast<uint16_t>(rom[index]) << 8) | static_cast<uint16_t>(rom[index+1]));
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rom_value = (rom_value & 0xff00) | ((rom_value >> 4)&0x000f) | ((rom_value << 4)&0x00f0);
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colour_forms_[c] = rom_value;
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}
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// check for big endianness and byte swap if required
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uint16_t test_value = 0x0001;
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if(*reinterpret_cast<uint8_t *>(&test_value) != 0x01) {
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for(std::size_t c = 0; c < 8; c++) {
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colour_forms_[c] = static_cast<uint16_t>((colour_forms_[c] >> 8) | (colour_forms_[c] << 8));
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}
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}
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}
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Outputs::CRT::CRT *VideoOutput::get_crt() {
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return crt_.get();
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}
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void VideoOutput::run_for(const Cycles cycles) {
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// Vertical: 0-39: pixels; otherwise blank; 48-53 sync, 54-56 colour burst
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// Horizontal: 0-223: pixels; otherwise blank; 256-259 sync
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#define clamp(action) \
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if(cycles_run_for <= number_of_cycles) { action; } else cycles_run_for = number_of_cycles;
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int number_of_cycles = cycles.as_int();
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while(number_of_cycles) {
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int h_counter = counter_ & 63;
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int cycles_run_for = 0;
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if(counter_ >= v_sync_start_position_ && counter_ < v_sync_end_position_) {
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// this is a sync line
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cycles_run_for = v_sync_end_position_ - counter_;
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clamp(crt_->output_sync(static_cast<unsigned int>(v_sync_end_position_ - v_sync_start_position_) * 6));
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} else if(counter_ < 224*64 && h_counter < 40) {
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// this is a pixel line
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if(!h_counter) {
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ink_ = 0x7;
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paper_ = 0x0;
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use_alternative_character_set_ = use_double_height_characters_ = blink_text_ = false;
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set_character_set_base_address();
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pixel_target_ = reinterpret_cast<uint16_t *>(crt_->allocate_write_area(240));
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if(!counter_) {
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frame_counter_++;
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v_sync_start_position_ = next_frame_is_sixty_hertz_ ? PAL60VSyncStartPosition : PAL50VSyncStartPosition;
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v_sync_end_position_ = next_frame_is_sixty_hertz_ ? PAL60VSyncEndPosition : PAL50VSyncEndPosition;
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counter_period_ = next_frame_is_sixty_hertz_ ? PAL60Period : PAL50Period;
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}
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}
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cycles_run_for = std::min(40 - h_counter, number_of_cycles);
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int columns = cycles_run_for;
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int pixel_base_address = 0xa000 + (counter_ >> 6) * 40;
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int character_base_address = 0xbb80 + (counter_ >> 9) * 40;
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uint8_t blink_mask = (blink_text_ && (frame_counter_&32)) ? 0x00 : 0xff;
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while(columns--) {
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uint8_t pixels, control_byte;
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if(is_graphics_mode_ && counter_ < 200*64) {
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control_byte = pixels = ram_[pixel_base_address + h_counter];
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} else {
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int address = character_base_address + h_counter;
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control_byte = ram_[address];
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int line = use_double_height_characters_ ? ((counter_ >> 7) & 7) : ((counter_ >> 6) & 7);
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pixels = ram_[character_set_base_address_ + (control_byte&127) * 8 + line];
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}
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uint8_t inverse_mask = (control_byte & 0x80) ? 0x7 : 0x0;
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pixels &= blink_mask;
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if(control_byte & 0x60) {
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if(pixel_target_) {
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uint16_t colours[2];
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if(video_signal_ == Outputs::CRT::VideoSignal::RGB) {
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colours[0] = static_cast<uint8_t>(paper_ ^ inverse_mask);
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colours[1] = static_cast<uint8_t>(ink_ ^ inverse_mask);
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} else {
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colours[0] = colour_forms_[paper_ ^ inverse_mask];
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colours[1] = colour_forms_[ink_ ^ inverse_mask];
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}
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pixel_target_[0] = colours[(pixels >> 5)&1];
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pixel_target_[1] = colours[(pixels >> 4)&1];
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pixel_target_[2] = colours[(pixels >> 3)&1];
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pixel_target_[3] = colours[(pixels >> 2)&1];
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pixel_target_[4] = colours[(pixels >> 1)&1];
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pixel_target_[5] = colours[(pixels >> 0)&1];
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}
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} else {
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switch(control_byte & 0x1f) {
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case 0x00: ink_ = 0x0; break;
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case 0x01: ink_ = 0x4; break;
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case 0x02: ink_ = 0x2; break;
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case 0x03: ink_ = 0x6; break;
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case 0x04: ink_ = 0x1; break;
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case 0x05: ink_ = 0x5; break;
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case 0x06: ink_ = 0x3; break;
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case 0x07: ink_ = 0x7; break;
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case 0x08: case 0x09: case 0x0a: case 0x0b:
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case 0x0c: case 0x0d: case 0x0e: case 0x0f:
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use_alternative_character_set_ = (control_byte&1);
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use_double_height_characters_ = (control_byte&2);
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blink_text_ = (control_byte&4);
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set_character_set_base_address();
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break;
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case 0x10: paper_ = 0x0; break;
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case 0x11: paper_ = 0x4; break;
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case 0x12: paper_ = 0x2; break;
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case 0x13: paper_ = 0x6; break;
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case 0x14: paper_ = 0x1; break;
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case 0x15: paper_ = 0x5; break;
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case 0x16: paper_ = 0x3; break;
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case 0x17: paper_ = 0x7; break;
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case 0x18: case 0x19: case 0x1a: case 0x1b:
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case 0x1c: case 0x1d: case 0x1e: case 0x1f:
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is_graphics_mode_ = (control_byte & 4);
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next_frame_is_sixty_hertz_ = !(control_byte & 2);
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break;
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default: break;
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}
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if(pixel_target_) {
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pixel_target_[0] = pixel_target_[1] =
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pixel_target_[2] = pixel_target_[3] =
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pixel_target_[4] = pixel_target_[5] =
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(video_signal_ == Outputs::CRT::VideoSignal::RGB) ? paper_ ^ inverse_mask : colour_forms_[paper_ ^ inverse_mask];
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}
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}
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if(pixel_target_) pixel_target_ += 6;
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h_counter++;
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}
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if(h_counter == 40) {
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crt_->output_data(40 * 6);
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}
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} else {
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// this is a blank line (or the equivalent part of a pixel line)
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if(h_counter < 48) {
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cycles_run_for = 48 - h_counter;
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clamp(
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int period = (counter_ < 224*64) ? 8 : 48;
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crt_->output_blank(static_cast<unsigned int>(period) * 6);
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);
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} else if(h_counter < 54) {
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cycles_run_for = 54 - h_counter;
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clamp(crt_->output_sync(6 * 6));
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} else if(h_counter < 56) {
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cycles_run_for = 56 - h_counter;
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clamp(crt_->output_default_colour_burst(2 * 6));
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} else {
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cycles_run_for = 64 - h_counter;
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clamp(crt_->output_blank(8 * 6));
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}
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}
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counter_ = (counter_ + cycles_run_for)%counter_period_;
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number_of_cycles -= cycles_run_for;
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}
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}
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void VideoOutput::set_character_set_base_address() {
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if(is_graphics_mode_) character_set_base_address_ = use_alternative_character_set_ ? 0x9c00 : 0x9800;
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else character_set_base_address_ = use_alternative_character_set_ ? 0xb800 : 0xb400;
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}
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