mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-19 23:32:28 +00:00
555 lines
18 KiB
C++
555 lines
18 KiB
C++
//
|
||
// 9918.cpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 25/11/2017.
|
||
// Copyright © 2017 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#include "9918.hpp"
|
||
|
||
using namespace TI;
|
||
|
||
namespace {
|
||
|
||
const uint32_t palette_pack(uint8_t r, uint8_t g, uint8_t b) {
|
||
uint32_t result = 0;
|
||
uint8_t *result_ptr = reinterpret_cast<uint8_t *>(&result);
|
||
result_ptr[0] = r;
|
||
result_ptr[1] = g;
|
||
result_ptr[2] = b;
|
||
result_ptr[3] = 0;
|
||
return result;
|
||
}
|
||
|
||
const uint32_t palette[16] = {
|
||
palette_pack(0, 0, 0),
|
||
palette_pack(0, 0, 0),
|
||
palette_pack(90, 201, 81),
|
||
palette_pack(149, 231, 133),
|
||
|
||
palette_pack(113, 104, 183),
|
||
palette_pack(146, 132, 255),
|
||
palette_pack(200, 114, 89),
|
||
palette_pack(115, 222, 255),
|
||
|
||
palette_pack(238, 124, 90),
|
||
palette_pack(255, 166, 132),
|
||
palette_pack(219, 232, 92),
|
||
palette_pack(240, 247, 143),
|
||
|
||
palette_pack(78, 176, 63),
|
||
palette_pack(202, 118, 216),
|
||
palette_pack(233, 233, 233),
|
||
palette_pack(255, 255, 255)
|
||
};
|
||
|
||
}
|
||
|
||
TMS9918::TMS9918(Personality p) :
|
||
crt_(new Outputs::CRT::CRT(342, 1, Outputs::CRT::DisplayType::NTSC60, 4)) {
|
||
crt_->set_rgb_sampling_function(
|
||
"vec3 rgb_sample(usampler2D sampler, vec2 coordinate, vec2 icoordinate)"
|
||
"{"
|
||
"return texture(sampler, coordinate).rgb / vec3(255.0);"
|
||
"}");
|
||
crt_->set_output_device(Outputs::CRT::OutputDevice::Monitor);
|
||
crt_->set_visible_area(Outputs::CRT::Rect(0.055f, 0.025f, 0.9f, 0.9f));
|
||
}
|
||
|
||
std::shared_ptr<Outputs::CRT::CRT> TMS9918::get_crt() {
|
||
return crt_;
|
||
}
|
||
|
||
void TMS9918::run_for(const HalfCycles cycles) {
|
||
// As specific as I've been able to get:
|
||
// Scanline time is always 227.75 cycles.
|
||
// PAL output is 313 lines total. NTSC output is 262 lines total.
|
||
// Interrupt is signalled upon entering the lower border.
|
||
|
||
// Keep a count of cycles separate from internal counts to avoid
|
||
// potential errors mapping back and forth.
|
||
half_cycles_into_frame_ = (half_cycles_into_frame_ + cycles) % HalfCycles(frame_lines_ * 228 * 2);
|
||
|
||
// Convert to 342 cycles per line; the internal clock is 1.5 times the
|
||
// nominal 3.579545 Mhz that I've advertised for this part.
|
||
int int_cycles = (cycles.as_int() * 3) + cycles_error_;
|
||
cycles_error_ = int_cycles & 7;
|
||
int_cycles >>= 3;
|
||
if(!int_cycles) return;
|
||
|
||
//
|
||
// Break that down as:
|
||
// 26 cycles sync;
|
||
|
||
while(int_cycles) {
|
||
// Determine how much time has passed in the remainder of this line, and proceed.
|
||
int cycles_left = std::min(342 - column_, int_cycles);
|
||
column_ += cycles_left; // column_ is now the column that has been reached in this line.
|
||
int_cycles -= cycles_left; // Count down duration to run for.
|
||
|
||
|
||
|
||
// ------------------------------
|
||
// TODO: memory access slot here.
|
||
// ------------------------------
|
||
|
||
|
||
|
||
// ------------------------------
|
||
// Perform video memory accesses.
|
||
// ------------------------------
|
||
if(row_ < 192 && !blank_screen_) {
|
||
const int access_slot = column_ >> 1; // There are only 171 available memory accesses per line.
|
||
switch(line_mode_) {
|
||
case LineMode::Text:
|
||
access_pointer_ = std::min(30, access_slot);
|
||
if(access_pointer_ >= 30 && access_pointer_ < 150) {
|
||
const int row_base = pattern_name_address_ + (row_ >> 3) * 40;
|
||
const int start_column = (access_pointer_ - 30) / 3;
|
||
const int end = std::min(150, access_slot);
|
||
|
||
// Pattern names are collected every third window starting from window 30.
|
||
const int pattern_names_end = (end - 30) / 3;
|
||
std::memcpy(&pattern_names_[start_column], &ram_[row_base + start_column], static_cast<size_t>(pattern_names_end - start_column));
|
||
|
||
// Patterns are collected every third window starting from window 32.
|
||
const int pattern_buffer_end = (end - 32) / 3;
|
||
for(int column = start_column; column < pattern_buffer_end; ++column) {
|
||
pattern_buffer_[column] = ram_[pattern_generator_table_address_ + (pattern_names_[column] << 3) + (row_ & 7)];
|
||
}
|
||
}
|
||
break;
|
||
|
||
case LineMode::Character:
|
||
// Four access windows: no collection.
|
||
access_pointer_ = std::min(4, access_slot);
|
||
|
||
// Then ten access windows are filled with collection of sprite 3 and 4 details.
|
||
if(access_pointer_ >= 4 && access_pointer_ < 14) {
|
||
// TODO: this repeats the code below.
|
||
int end = std::min(14, access_slot);
|
||
while(access_pointer_ < end) {
|
||
const int offset = access_pointer_ - 2;
|
||
const int target = 2 + (offset / 6);
|
||
const int sprite = active_sprites_[target] & 31;
|
||
const int subcycle = offset % 6;
|
||
switch(subcycle) {
|
||
case 0: sprites_[target].y = ram_[sprite_attribute_table_address_ + (sprite << 2)]; break;
|
||
case 1: sprites_[target].x = ram_[sprite_attribute_table_address_ + (sprite << 2) + 1]; break;
|
||
case 2: sprites_[target].pattern_number = ram_[sprite_attribute_table_address_ + (sprite << 2) + 2]; break;
|
||
case 3: sprites_[target].colour = ram_[sprite_attribute_table_address_ + (sprite << 2) + 3]; break;
|
||
case 4:
|
||
case 5: {
|
||
const int sprite_offset = sprites_[target].pattern_number & ~(sprites_16x16_ ? 3 : 0);
|
||
const int sprite_row = (row_ - sprites_[target].y) & 15;
|
||
const int sprite_address =
|
||
sprite_generator_table_address_ + (sprite_offset << 3) + sprite_row + ((subcycle - 4) << 4);
|
||
sprites_[target].pattern[subcycle - 4] = ram_[sprite_address];
|
||
} break;
|
||
}
|
||
access_pointer_++;
|
||
}
|
||
}
|
||
|
||
// Four more access windows: no collection.
|
||
access_pointer_ = std::min(18, access_slot);
|
||
|
||
// Then eight access windows fetch the y position for the first eight sprites.
|
||
if(access_pointer_ >= 18 && access_pointer_ < 26) {
|
||
while(access_pointer_ < 26) {
|
||
const int sprite = access_pointer_ - 18;
|
||
sprite_locations_[sprite] = ram_[sprite_attribute_table_address_ + (sprite << 2)];
|
||
access_pointer_++;
|
||
}
|
||
}
|
||
|
||
// The next 128 access slots are video and sprite collection interleaved.
|
||
if(access_pointer_ >= 26 && access_pointer_ < 154) {
|
||
int end = std::min(154, access_slot);
|
||
|
||
int row_base = pattern_name_address_;
|
||
int pattern_base = pattern_generator_table_address_;
|
||
int colour_base = colour_table_address_;
|
||
if(screen_mode_ == 1) {
|
||
pattern_base &= 0x2000 | ((row_ & 0xc0) << 5);
|
||
colour_base &= 0x2000 | ((row_ & 0xc0) << 5);
|
||
}
|
||
row_base += (row_ << 2)&~31;
|
||
|
||
// Sprites 0–7: 18–25; then:
|
||
// 31, 35, 39 ... 47, 51, 55 ... 63, 67, 71 ... 79, 83, 87 ...
|
||
// 95, 99, 103 ... 111, 115, 119 ... 127, 131, 135 ... 143, 147, 151
|
||
//
|
||
// Relative to 31:
|
||
// 0, 4, 8, X, ...
|
||
|
||
// TODO: optimise this mess.
|
||
while(access_pointer_ < end) {
|
||
int character_column = ((access_pointer_ - 26) >> 2);
|
||
switch(access_pointer_&3) {
|
||
case 2:
|
||
pattern_names_[character_column] = ram_[row_base + character_column];
|
||
break;
|
||
case 3: {
|
||
const int slot = (access_pointer_ - 31) >> 2;
|
||
if((slot&3) == 3)
|
||
break;
|
||
const int sprite = slot - (slot >> 2) + 8;
|
||
sprite_locations_[sprite] = ram_[sprite_attribute_table_address_ + (sprite << 2)];
|
||
} break;
|
||
case 0:
|
||
if(screen_mode_ != 1) {
|
||
colour_buffer_[character_column] = ram_[colour_base + (pattern_names_[character_column] >> 3)];
|
||
} else {
|
||
colour_buffer_[character_column] = ram_[colour_base + (pattern_names_[character_column] << 3) + (row_ & 7)];
|
||
}
|
||
break;
|
||
case 1:
|
||
pattern_buffer_[character_column] = ram_[pattern_base + (pattern_names_[character_column] << 3) + (row_ & 7)];
|
||
break;
|
||
}
|
||
access_pointer_++;
|
||
}
|
||
|
||
if(access_pointer_ == 154) {
|
||
// Pick some sprites to display.
|
||
active_sprites_[0] = active_sprites_[1] = active_sprites_[2] = active_sprites_[3] = 0xff;
|
||
int slot = 0;
|
||
int last_visible = 0;
|
||
int sprite_height = 8;
|
||
if(sprites_16x16_) sprite_height <<= 1;
|
||
if(sprites_magnified_) sprite_height <<= 1;
|
||
for(int c = 0; c < 32; ++c) {
|
||
// A sprite Y of 208 means "don't scan the list any further".
|
||
if(sprite_locations_[c] == 208) break;
|
||
|
||
// Skip sprite if invisible anyway.
|
||
int offset = (row_ - sprite_locations_[c])&255;
|
||
if(offset < 0 || offset >= sprite_height) continue;
|
||
|
||
last_visible = c;
|
||
if(slot < 4) {
|
||
active_sprites_[slot] = c;
|
||
slot++;
|
||
} else {
|
||
// Set the fifth sprite bit and store the sprite if this is the first encountered.
|
||
if(!(status_ & 0x40)) {
|
||
status_ |= 0x40;
|
||
status_ = static_cast<uint8_t>((status_ & ~31) | c);
|
||
}
|
||
break;
|
||
}
|
||
}
|
||
|
||
if(!(status_ & 0x40)) {
|
||
status_ = static_cast<uint8_t>((status_ & ~31) | last_visible);
|
||
}
|
||
}
|
||
}
|
||
|
||
// Two access windows: no collection.
|
||
access_pointer_ = std::min(156, access_slot);
|
||
|
||
// Fourteen access windows: collect initial sprite information.
|
||
if(access_pointer_ >= 156 && access_pointer_ < 170) {
|
||
int end = std::min(170, access_slot);
|
||
while(access_pointer_ < end) {
|
||
const int target = (access_pointer_ - 156) / 6;
|
||
const int sprite = active_sprites_[target] & 31;
|
||
const int subcycle = access_pointer_ % 6;
|
||
switch(subcycle) {
|
||
case 0: sprites_[target].y = ram_[sprite_attribute_table_address_ + (sprite << 2)]; break;
|
||
case 1: sprites_[target].x = ram_[sprite_attribute_table_address_ + (sprite << 2) + 1]; break;
|
||
case 2: sprites_[target].pattern_number = ram_[sprite_attribute_table_address_ + (sprite << 2) + 2]; break;
|
||
case 3: sprites_[target].colour = ram_[sprite_attribute_table_address_ + (sprite << 2) + 3]; break;
|
||
case 4:
|
||
case 5: {
|
||
const int sprite_offset = sprites_[target].pattern_number & ~(sprites_16x16_ ? 3 : 0);
|
||
const int sprite_row = (row_ - sprites_[target].y) & 15;
|
||
const int sprite_address =
|
||
sprite_generator_table_address_ + (sprite_offset << 3) + sprite_row + ((subcycle - 4) << 4);
|
||
sprites_[target].pattern[subcycle - 4] = ram_[sprite_address];
|
||
} break;
|
||
}
|
||
access_pointer_++;
|
||
}
|
||
}
|
||
|
||
// There's a single unused access window here.
|
||
access_pointer_ = std::min(171, access_slot);
|
||
break;
|
||
}
|
||
}
|
||
// --------------------------
|
||
// End video memory accesses.
|
||
// --------------------------
|
||
|
||
|
||
|
||
// --------------------
|
||
// Output video stream.
|
||
// --------------------
|
||
if(row_ < 192 && !blank_screen_) {
|
||
// ----------------------
|
||
// Output horizontal sync
|
||
// ----------------------
|
||
if(!output_column_ && column_ >= 26) {
|
||
crt_->output_sync(static_cast<unsigned int>(26));
|
||
output_column_ = 26;
|
||
}
|
||
|
||
// --------------------------
|
||
// TODO: output colour burst.
|
||
// --------------------------
|
||
|
||
|
||
// -------------------
|
||
// Output left border.
|
||
// -------------------
|
||
if(output_column_ >= 26) {
|
||
int pixels_end = std::min(first_pixel_column_, column_);
|
||
if(output_column_ < pixels_end) {
|
||
output_border(pixels_end - output_column_);
|
||
output_column_ = pixels_end;
|
||
|
||
// Grab a pointer for drawing pixels to, if the moment has arrived.
|
||
if(pixels_end == first_pixel_column_) {
|
||
pixel_base_ = pixel_target_ = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(static_cast<unsigned int>(first_right_border_column_ - first_pixel_column_)));
|
||
}
|
||
}
|
||
}
|
||
|
||
// --------------
|
||
// Output pixels.
|
||
// --------------
|
||
if(output_column_ >= first_pixel_column_) {
|
||
int pixels_end = std::min(first_right_border_column_, column_);
|
||
|
||
if(output_column_ < pixels_end) {
|
||
switch(line_mode_) {
|
||
case LineMode::Text: {
|
||
const uint32_t colours[2] = { palette[background_colour_], palette[text_colour_] };
|
||
|
||
const int shift = (output_column_ - first_pixel_column_) % 6;
|
||
int byte_column = (output_column_ - first_pixel_column_) / 6;
|
||
int pattern = pattern_buffer_[byte_column] << shift;
|
||
int pixels_left = pixels_end - output_column_;
|
||
int length = std::min(pixels_left, 6 - shift);
|
||
while(true) {
|
||
pixels_left -= length;
|
||
while(length--) {
|
||
*pixel_target_ = colours[(pattern >> 7)&0x01];
|
||
pixel_target_++;
|
||
pattern <<= 1;
|
||
}
|
||
|
||
if(!pixels_left) break;
|
||
length = std::min(6, pixels_left);
|
||
byte_column++;
|
||
pattern = pattern_buffer_[byte_column];
|
||
}
|
||
output_column_ = pixels_end;
|
||
} break;
|
||
|
||
case LineMode::Character:
|
||
while(output_column_ < pixels_end) {
|
||
int base = (output_column_ - first_pixel_column_);
|
||
int address = base >> 3;
|
||
uint8_t colour = colour_buffer_[address];
|
||
uint8_t pattern = pattern_buffer_[address];
|
||
pattern >>= ((base&7)^7);
|
||
|
||
*pixel_target_ = (pattern&1) ? palette[colour >> 4] : palette[colour & 15];
|
||
pixel_target_ ++;
|
||
output_column_ ++;
|
||
}
|
||
break;
|
||
}
|
||
|
||
if(output_column_ == first_right_border_column_) {
|
||
// Just chuck the sprites on. Quick hack!
|
||
for(size_t c = 0; c < 4; ++c) {
|
||
if(active_sprites_[c^3] == 0xff) continue;
|
||
if(!(sprites_[c^3].colour&15)) continue;
|
||
for(int p = 0; p < (sprites_16x16_ ? 16 : 8); ++p) {
|
||
int x = sprites_[c^3].x + p;
|
||
if(sprites_[c^3].colour & 0x80) x -= 32;
|
||
if(x >= 0 && x < 256) {
|
||
if(((sprites_[c^3].pattern[p >> 3] << (p&7)) & 0x80)) pixel_base_[x] = palette[sprites_[c^3].colour & 15];
|
||
}
|
||
}
|
||
}
|
||
|
||
crt_->output_data(static_cast<unsigned int>(first_right_border_column_ - first_pixel_column_), 1);
|
||
pixel_target_ = nullptr;
|
||
}
|
||
}
|
||
}
|
||
|
||
// --------------------
|
||
// Output right border.
|
||
// --------------------
|
||
if(output_column_ >= first_right_border_column_) {
|
||
output_border(column_ - output_column_);
|
||
output_column_ = column_;
|
||
}
|
||
} else if(row_ >= first_vsync_line_ && row_ < first_vsync_line_+3) {
|
||
// Vertical sync.
|
||
if(column_ == 342) {
|
||
crt_->output_sync(static_cast<unsigned int>(342));
|
||
}
|
||
} else {
|
||
// Blank.
|
||
if(!output_column_ && column_ >= 26) {
|
||
crt_->output_sync(static_cast<unsigned int>(26));
|
||
output_column_ = 26;
|
||
}
|
||
if(output_column_ >= 26) {
|
||
output_border(column_ - output_column_);
|
||
output_column_ = column_;
|
||
}
|
||
}
|
||
// -----------------
|
||
// End video stream.
|
||
// -----------------
|
||
|
||
|
||
|
||
// -----------------------------------
|
||
// Prepare for next line, potentially.
|
||
// -----------------------------------
|
||
if(column_ == 342) {
|
||
access_pointer_ = column_ = output_column_ = 0;
|
||
row_ = (row_ + 1) % frame_lines_;
|
||
if(row_ == 192) status_ |= 0x80;
|
||
|
||
screen_mode_ = next_screen_mode_;
|
||
blank_screen_ = next_blank_screen_;
|
||
switch(screen_mode_) {
|
||
case 2:
|
||
line_mode_ = LineMode::Text;
|
||
first_pixel_column_ = 69;
|
||
first_right_border_column_ = 309;
|
||
break;
|
||
default:
|
||
line_mode_ = LineMode::Character;
|
||
first_pixel_column_ = 63;
|
||
first_right_border_column_ = 319;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
void TMS9918::output_border(int cycles) {
|
||
pixel_target_ = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(1));
|
||
if(pixel_target_) *pixel_target_ = palette[background_colour_];
|
||
crt_->output_level(static_cast<unsigned int>(cycles));
|
||
}
|
||
|
||
// TODO: as a temporary development measure, memory access below is magically instantaneous. Correct that.
|
||
|
||
void TMS9918::set_register(int address, uint8_t value) {
|
||
// Writes to address 0 are writes to the video RAM. Store
|
||
// the value and return.
|
||
if(!(address & 1)) {
|
||
write_phase_ = false;
|
||
read_ahead_buffer_ = value;
|
||
ram_[ram_pointer_ & 16383] = value;
|
||
ram_pointer_++;
|
||
return;
|
||
}
|
||
|
||
// Writes to address 1 are performed in pairs; if this is the
|
||
// low byte of a value, store it and wait for the high byte.
|
||
if(!write_phase_) {
|
||
low_write_ = value;
|
||
write_phase_ = true;
|
||
return;
|
||
}
|
||
|
||
write_phase_ = false;
|
||
if(value & 0x80) {
|
||
// This is a write to a register.
|
||
switch(value & 7) {
|
||
case 0:
|
||
next_screen_mode_ = (next_screen_mode_ & 6) | ((low_write_ & 2) >> 1);
|
||
// printf("NSM: %02x\n", next_screen_mode_);
|
||
break;
|
||
|
||
case 1:
|
||
next_blank_screen_ = !(low_write_ & 0x40);
|
||
generate_interrupts_ = !!(low_write_ & 0x20);
|
||
next_screen_mode_ = (next_screen_mode_ & 1) | ((low_write_ & 0x18) >> 3);
|
||
sprites_16x16_ = !!(low_write_ & 0x02);
|
||
sprites_magnified_ = !!(low_write_ & 0x01);
|
||
// printf("NSM: %02x\n", next_screen_mode_);
|
||
break;
|
||
|
||
case 2:
|
||
pattern_name_address_ = static_cast<uint16_t>((low_write_ & 0xf) << 10);
|
||
break;
|
||
|
||
case 3:
|
||
colour_table_address_ = static_cast<uint16_t>(low_write_ << 6);
|
||
break;
|
||
|
||
case 4:
|
||
pattern_generator_table_address_ = static_cast<uint16_t>((low_write_ & 0x07) << 11);
|
||
break;
|
||
|
||
case 5:
|
||
sprite_attribute_table_address_ = static_cast<uint16_t>((low_write_ & 0x7f) << 7);
|
||
break;
|
||
|
||
case 6:
|
||
sprite_generator_table_address_ = static_cast<uint16_t>((low_write_ & 0x07) << 11);
|
||
break;
|
||
|
||
case 7:
|
||
text_colour_ = low_write_ >> 4;
|
||
background_colour_ = low_write_ & 0xf;
|
||
break;
|
||
}
|
||
} else {
|
||
// This is a write to the RAM pointer.
|
||
ram_pointer_ = static_cast<uint16_t>(low_write_ | (value << 8));
|
||
if(!(value & 0x40)) {
|
||
// Officially a 'read' set, so perform lookahead.
|
||
read_ahead_buffer_ = ram_[ram_pointer_ & 16383];
|
||
ram_pointer_++;
|
||
}
|
||
}
|
||
}
|
||
|
||
uint8_t TMS9918::get_register(int address) {
|
||
write_phase_ = false;
|
||
|
||
// Reads from address 0 read video RAM, via the read-ahead buffer.
|
||
if(!(address & 1)) {
|
||
uint8_t result = read_ahead_buffer_;
|
||
read_ahead_buffer_ = ram_[ram_pointer_ & 16383];
|
||
ram_pointer_++;
|
||
return result;
|
||
}
|
||
|
||
// Reads from address 1 get the status register.
|
||
uint8_t result = status_;
|
||
status_ &= ~(0x80 | 0x40 | 0x20);
|
||
return result;
|
||
}
|
||
|
||
HalfCycles TMS9918::get_time_until_interrupt() {
|
||
if(!generate_interrupts_) return HalfCycles(-1);
|
||
if(get_interrupt_line()) return HalfCycles(0);
|
||
|
||
const int half_cycles_per_frame = frame_lines_ * 228 * 2;
|
||
int half_cycles_remaining = (192 * 228 * 2 + half_cycles_per_frame - half_cycles_into_frame_.as_int()) % half_cycles_per_frame;
|
||
return HalfCycles(half_cycles_remaining);
|
||
}
|
||
|
||
bool TMS9918::get_interrupt_line() {
|
||
return (status_ & 0x80) && generate_interrupts_;
|
||
}
|