mirror of
https://github.com/TomHarte/CLK.git
synced 2024-12-27 01:31:42 +00:00
218 lines
6.5 KiB
C++
218 lines
6.5 KiB
C++
//
|
||
// Video.cpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 12/10/2016.
|
||
// Copyright © 2016 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#include "Video.hpp"
|
||
|
||
using namespace Oric;
|
||
|
||
namespace {
|
||
const unsigned int PAL50VSyncStartPosition = 256*64;
|
||
const unsigned int PAL60VSyncStartPosition = 234*64;
|
||
const unsigned int PAL50VSyncEndPosition = 259*64;
|
||
const unsigned int PAL60VSyncEndPosition = 238*64;
|
||
const unsigned int PAL50Period = 312*64;
|
||
const unsigned int PAL60Period = 262*64;
|
||
}
|
||
|
||
VideoOutput::VideoOutput(uint8_t *memory) :
|
||
ram_(memory),
|
||
frame_counter_(0), counter_(0),
|
||
is_graphics_mode_(false),
|
||
character_set_base_address_(0xb400),
|
||
phase_(0),
|
||
v_sync_start_position_(PAL50VSyncStartPosition), v_sync_end_position_(PAL50VSyncEndPosition),
|
||
counter_period_(PAL50Period), next_frame_is_sixty_hertz_(false),
|
||
crt_(new Outputs::CRT::CRT(64*6, 6, Outputs::CRT::DisplayType::PAL50, 1))
|
||
{
|
||
// TODO: this is a copy and paste from the Electron; factor out.
|
||
crt_->set_rgb_sampling_function(
|
||
"vec3 rgb_sample(usampler2D sampler, vec2 coordinate, vec2 icoordinate)"
|
||
"{"
|
||
"uint texValue = texture(sampler, coordinate).r;"
|
||
"texValue >>= 4 - (int(icoordinate.x * 8) & 4);"
|
||
"return vec3( uvec3(texValue) & uvec3(4u, 2u, 1u));"
|
||
"}");
|
||
|
||
crt_->set_output_device(Outputs::CRT::Television);
|
||
crt_->set_visible_area(crt_->get_rect_for_area(50, 224, 16 * 6, 40 * 6, 4.0f / 3.0f));
|
||
}
|
||
|
||
std::shared_ptr<Outputs::CRT::CRT> VideoOutput::get_crt()
|
||
{
|
||
return crt_;
|
||
}
|
||
|
||
void VideoOutput::run_for_cycles(int number_of_cycles)
|
||
{
|
||
// Vertical: 0–39: pixels; otherwise blank; 48–53 sync, 54–56 colour burst
|
||
// Horizontal: 0–223: pixels; otherwise blank; 256–259 sync
|
||
|
||
#define clamp(action) \
|
||
if(cycles_run_for <= number_of_cycles) { action; } else cycles_run_for = number_of_cycles;
|
||
|
||
while(number_of_cycles)
|
||
{
|
||
int h_counter = counter_ & 63;
|
||
int cycles_run_for = 0;
|
||
|
||
if(counter_ >= v_sync_start_position_ && counter_ < v_sync_end_position_)
|
||
{
|
||
// this is a sync line
|
||
cycles_run_for = v_sync_end_position_ - counter_;
|
||
clamp(crt_->output_sync((unsigned int)(v_sync_end_position_ - v_sync_start_position_) * 6));
|
||
}
|
||
else if(counter_ < 224*64 && h_counter < 40)
|
||
{
|
||
// this is a pixel line
|
||
if(!h_counter)
|
||
{
|
||
ink_ = 0xff;
|
||
paper_ = 0x00;
|
||
use_alternative_character_set_ = use_double_height_characters_ = blink_text_ = false;
|
||
set_character_set_base_address();
|
||
phase_ += 64;
|
||
pixel_target_ = crt_->allocate_write_area(120);
|
||
|
||
if(!counter_)
|
||
{
|
||
phase_ += 128; // TODO: incorporate all the lines that were missed
|
||
frame_counter_++;
|
||
|
||
v_sync_start_position_ = next_frame_is_sixty_hertz_ ? PAL60VSyncStartPosition : PAL50VSyncStartPosition;
|
||
v_sync_end_position_ = next_frame_is_sixty_hertz_ ? PAL60VSyncEndPosition : PAL50VSyncEndPosition;
|
||
counter_period_ = next_frame_is_sixty_hertz_ ? PAL60Period : PAL50Period;
|
||
}
|
||
}
|
||
|
||
cycles_run_for = std::min(40 - h_counter, number_of_cycles);
|
||
int columns = cycles_run_for;
|
||
int pixel_base_address = 0xa000 + (counter_ >> 6) * 40;
|
||
int character_base_address = 0xbb80 + (counter_ >> 9) * 40;
|
||
uint8_t blink_mask = (blink_text_ && (frame_counter_&32)) ? 0x00 : 0xff;
|
||
|
||
while(columns--)
|
||
{
|
||
uint8_t pixels, control_byte;
|
||
|
||
if(is_graphics_mode_ && counter_ < 200*64)
|
||
{
|
||
control_byte = pixels = ram_[pixel_base_address + h_counter];
|
||
}
|
||
else
|
||
{
|
||
int address = character_base_address + h_counter;
|
||
control_byte = ram_[address];
|
||
int line = use_double_height_characters_ ? ((counter_ >> 7) & 7) : ((counter_ >> 6) & 7);
|
||
pixels = ram_[character_set_base_address_ + (control_byte&127) * 8 + line];
|
||
}
|
||
|
||
uint8_t inverse_mask = (control_byte & 0x80) ? 0x77 : 0x00;
|
||
pixels &= blink_mask;
|
||
|
||
if(control_byte & 0x60)
|
||
{
|
||
if(pixel_target_)
|
||
{
|
||
uint8_t colours[2] = {
|
||
(uint8_t)(paper_ ^ inverse_mask),
|
||
(uint8_t)(ink_ ^ inverse_mask),
|
||
};
|
||
|
||
pixel_target_[0] = (colours[(pixels >> 4)&1] & 0x0f) | (colours[(pixels >> 5)&1] & 0xf0);
|
||
pixel_target_[1] = (colours[(pixels >> 2)&1] & 0x0f) | (colours[(pixels >> 3)&1] & 0xf0);
|
||
pixel_target_[2] = (colours[(pixels >> 0)&1] & 0x0f) | (colours[(pixels >> 1)&1] & 0xf0);
|
||
}
|
||
}
|
||
else
|
||
{
|
||
switch(control_byte & 0x1f)
|
||
{
|
||
case 0x00: ink_ = 0x00; break;
|
||
case 0x01: ink_ = 0x44; break;
|
||
case 0x02: ink_ = 0x22; break;
|
||
case 0x03: ink_ = 0x66; break;
|
||
case 0x04: ink_ = 0x11; break;
|
||
case 0x05: ink_ = 0x55; break;
|
||
case 0x06: ink_ = 0x33; break;
|
||
case 0x07: ink_ = 0x77; break;
|
||
|
||
case 0x08: case 0x09: case 0x0a: case 0x0b:
|
||
case 0x0c: case 0x0d: case 0x0e: case 0x0f:
|
||
use_alternative_character_set_ = (control_byte&1);
|
||
use_double_height_characters_ = (control_byte&2);
|
||
blink_text_ = (control_byte&4);
|
||
set_character_set_base_address();
|
||
break;
|
||
|
||
case 0x10: paper_ = 0x00; break;
|
||
case 0x11: paper_ = 0x44; break;
|
||
case 0x12: paper_ = 0x22; break;
|
||
case 0x13: paper_ = 0x66; break;
|
||
case 0x14: paper_ = 0x11; break;
|
||
case 0x15: paper_ = 0x55; break;
|
||
case 0x16: paper_ = 0x33; break;
|
||
case 0x17: paper_ = 0x77; break;
|
||
|
||
case 0x18: case 0x19: case 0x1a: case 0x1b:
|
||
case 0x1c: case 0x1d: case 0x1e: case 0x1f:
|
||
is_graphics_mode_ = (control_byte & 4);
|
||
next_frame_is_sixty_hertz_ = !(control_byte & 2);
|
||
break;
|
||
|
||
default: break;
|
||
}
|
||
if(pixel_target_) pixel_target_[0] = pixel_target_[1] = pixel_target_[2] = (uint8_t)(paper_ ^ inverse_mask);
|
||
}
|
||
if(pixel_target_) pixel_target_ += 3;
|
||
h_counter++;
|
||
}
|
||
|
||
if(h_counter == 40)
|
||
{
|
||
crt_->output_data(40 * 6, 2);
|
||
}
|
||
}
|
||
else
|
||
{
|
||
// this is a blank line (or the equivalent part of a pixel line)
|
||
if(h_counter < 48)
|
||
{
|
||
cycles_run_for = 48 - h_counter;
|
||
clamp(
|
||
int period = (counter_ < 224*64) ? 8 : 48;
|
||
crt_->output_blank((unsigned int)period * 6);
|
||
);
|
||
}
|
||
else if(h_counter < 54)
|
||
{
|
||
cycles_run_for = 54 - h_counter;
|
||
clamp(crt_->output_sync(6 * 6));
|
||
}
|
||
else if(h_counter < 56)
|
||
{
|
||
cycles_run_for = 56 - h_counter;
|
||
clamp(crt_->output_colour_burst(2 * 6, phase_, 128));
|
||
}
|
||
else
|
||
{
|
||
cycles_run_for = 64 - h_counter;
|
||
clamp(crt_->output_blank(8 * 6));
|
||
}
|
||
}
|
||
|
||
counter_ = (counter_ + cycles_run_for)%counter_period_;
|
||
number_of_cycles -= cycles_run_for;
|
||
}
|
||
}
|
||
|
||
void VideoOutput::set_character_set_base_address()
|
||
{
|
||
if(is_graphics_mode_) character_set_base_address_ = use_alternative_character_set_ ? 0x9c00 : 0x9800;
|
||
else character_set_base_address_ = use_alternative_character_set_ ? 0xb800 : 0xb400;
|
||
}
|