mirror of
https://github.com/TomHarte/CLK.git
synced 2025-10-31 05:16:08 +00:00
1370 lines
51 KiB
C++
1370 lines
51 KiB
C++
//
|
||
// 9918.cpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 25/11/2017.
|
||
// Copyright 2017 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#include "Components/9918/9918.hpp"
|
||
|
||
#include "Outputs/Log.hpp"
|
||
|
||
#include <cassert>
|
||
#include <cstring>
|
||
#include <cstdlib>
|
||
|
||
using namespace TI::TMS;
|
||
|
||
namespace {
|
||
|
||
// 342 internal cycles are 228/227.5ths of a line, so 341.25 cycles should be a whole
|
||
// line. Therefore multiply everything by four, but set line length to 1365 rather than 342*4 = 1368.
|
||
constexpr unsigned int CRTCyclesPerLine = 1365;
|
||
constexpr unsigned int CRTCyclesDivider = 4;
|
||
|
||
using Logger = Log::Logger<Log::Source::TMS9918>;
|
||
|
||
}
|
||
|
||
template <Personality personality>
|
||
Base<personality>::Base() :
|
||
crt_(CRTCyclesPerLine, CRTCyclesDivider, Outputs::Display::Type::NTSC60, Outputs::Display::InputDataType::Red8Green8Blue8) {
|
||
// Unimaginatively, this class just passes RGB through to the shader. Investigation is needed
|
||
// into whether there's a more natural form. It feels unlikely given the diversity of chips modelled.
|
||
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
// Cf. https://www.smspower.org/forums/8161-SMSDisplayTiming
|
||
|
||
// "For a line interrupt, /INT is pulled low 608 mclks into the appropriate scanline relative to pixel 0.
|
||
// This is 3 mclks before the rising edge of /HSYNC which starts the next scanline."
|
||
//
|
||
// i.e. it's 304 internal clocks after the end of the left border.
|
||
mode_timing_.line_interrupt_position = (LineLayout<personality>::EndOfLeftBorder + 304) % LineLayout<personality>::CyclesPerLine;
|
||
|
||
// For a frame interrupt, /INT is pulled low 607 mclks into scanline 192 (of scanlines 0 through 261) relative to pixel 0.
|
||
// This is 4 mclks before the rising edge of /HSYNC which starts the next scanline.
|
||
//
|
||
// i.e. it's 1/2 cycle before the line interrupt position, which I have rounded. Ugh.
|
||
mode_timing_.end_of_frame_interrupt_position.column = mode_timing_.line_interrupt_position - 1;
|
||
mode_timing_.end_of_frame_interrupt_position.row = 192 + (LineLayout<personality>::EndOfLeftBorder + 304) / LineLayout<personality>::CyclesPerLine;
|
||
}
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
// TODO: this is used for interrupt _prediction_ but won't handle text modes correctly, and indeed
|
||
// can't be just a single value where the programmer has changed into or out of text modes during the
|
||
// middle of a line, since screen mode is latched (so it'll be one value for that line, another from then onwards).a
|
||
mode_timing_.line_interrupt_position = LineLayout<personality>::EndOfPixels;
|
||
}
|
||
|
||
// Establish that output is delayed after reading by `output_lag` cycles,
|
||
// i.e. the fetch pointer is currently _ahead_ of the output pointer.
|
||
output_pointer_.row = output_pointer_.column = 0;
|
||
|
||
fetch_pointer_ = output_pointer_;
|
||
fetch_pointer_.column += output_lag;
|
||
|
||
fetch_line_buffer_ = line_buffers_.begin();
|
||
draw_line_buffer_ = line_buffers_.begin();
|
||
fetch_sprite_buffer_ = sprite_buffers_.begin();
|
||
}
|
||
|
||
template <Personality personality>
|
||
TMS9918<personality>::TMS9918() {
|
||
this->crt_.set_display_type(Outputs::Display::DisplayType::RGB);
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
this->crt_.set_fixed_framing(Outputs::Display::Rect(0.07f, 0.065f, 0.875f, 0.875f));
|
||
} else {
|
||
this->crt_.set_fixed_framing(Outputs::Display::Rect(0.07f, 0.0375f, 0.875f, 0.875f));
|
||
}
|
||
|
||
// The TMS remains in-phase with the NTSC colour clock; this is an empirical measurement
|
||
// intended to produce the correct relationship between the hard edges between pixels and
|
||
// the colour clock. It was eyeballed rather than derived from any knowledge of the TMS
|
||
// colour burst generator because I've yet to find any.
|
||
this->crt_.set_immediate_default_phase(0.85f);
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::set_tv_standard(const TVStandard standard) {
|
||
// TODO: the Yamaha is programmable on this at runtime.
|
||
this->tv_standard_ = standard;
|
||
switch(standard) {
|
||
case TVStandard::PAL:
|
||
this->mode_timing_.total_lines = 313;
|
||
this->mode_timing_.first_vsync_line = 253;
|
||
this->crt_.set_new_display_type(CRTCyclesPerLine, Outputs::Display::Type::PAL50);
|
||
break;
|
||
default:
|
||
this->mode_timing_.total_lines = 262;
|
||
this->mode_timing_.first_vsync_line = 227;
|
||
this->crt_.set_new_display_type(CRTCyclesPerLine, Outputs::Display::Type::NTSC60);
|
||
break;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::set_scan_target(Outputs::Display::ScanTarget *const scan_target) {
|
||
this->crt_.set_scan_target(scan_target);
|
||
}
|
||
|
||
template <Personality personality>
|
||
Outputs::Display::ScanStatus TMS9918<personality>::get_scaled_scan_status() const {
|
||
// The input was scaled by 3/4 to convert half cycles to internal ticks,
|
||
// so undo that and also allow for: (i) the multiply by 4 that it takes
|
||
// to reach the CRT; and (ii) the fact that the half-cycles value was scaled,
|
||
// and this should really reply in whole cycles.
|
||
return this->crt_.get_scaled_scan_status() * (4.0f / (3.0f * 8.0f));
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::set_display_type(const Outputs::Display::DisplayType display_type) {
|
||
this->crt_.set_display_type(display_type);
|
||
}
|
||
|
||
template <Personality personality>
|
||
Outputs::Display::DisplayType TMS9918<personality>::get_display_type() const {
|
||
return this->crt_.get_display_type();
|
||
}
|
||
|
||
void SpriteBuffer::reset_sprite_collection() {
|
||
sprites_stopped = false;
|
||
active_sprite_slot = 0;
|
||
|
||
for(int c = 0; c < 8; ++c) {
|
||
active_sprites[c].shift_position = 0;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::posit_sprite(const int sprite_number, const int sprite_position, const uint8_t screen_row) {
|
||
// Evaluation of visibility of sprite 0 is always the first step in
|
||
// populating a sprite buffer; so use it to uncork a new one.
|
||
if(!sprite_number) {
|
||
advance(fetch_sprite_buffer_);
|
||
fetched_sprites_ = &*fetch_sprite_buffer_;
|
||
fetch_sprite_buffer_->reset_sprite_collection();
|
||
fetch_sprite_buffer_->sprite_terminator = mode_timing_.sprite_terminator(fetch_line_buffer_->screen_mode);
|
||
|
||
if constexpr (SpriteBuffer::test_is_filling) {
|
||
fetch_sprite_buffer_->is_filling = true;
|
||
}
|
||
}
|
||
|
||
if(!(status_ & StatusSpriteOverflow)) {
|
||
status_ = uint8_t((status_ & ~0x1f) | (sprite_number & 0x1f));
|
||
}
|
||
if(fetch_sprite_buffer_->sprites_stopped) return;
|
||
|
||
// A sprite Y of 208 means "don't scan the list any further".
|
||
if(mode_timing_.allow_sprite_terminator && sprite_position == fetch_sprite_buffer_->sprite_terminator) {
|
||
fetch_sprite_buffer_->sprites_stopped = true;
|
||
return;
|
||
}
|
||
|
||
const auto sprite_row = uint8_t(screen_row - sprite_position);
|
||
if(sprite_row >= sprite_height_) return; // The less-than-zero case is dealt with by the cast to unsigned.
|
||
|
||
if(fetch_sprite_buffer_->active_sprite_slot == mode_timing_.maximum_visible_sprites) {
|
||
status_ |= StatusSpriteOverflow;
|
||
return;
|
||
}
|
||
|
||
auto &sprite = fetch_sprite_buffer_->active_sprites[fetch_sprite_buffer_->active_sprite_slot];
|
||
sprite.index = sprite_number;
|
||
sprite.row = sprite_row >> (sprites_magnified_ ? 1 : 0);
|
||
++fetch_sprite_buffer_->active_sprite_slot;
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::run_for(const HalfCycles cycles) {
|
||
// As specific as I've been able to get:
|
||
// Scanline time is always 228 cycles.
|
||
// PAL output is 313 lines total. NTSC output is 262 lines total.
|
||
// Interrupt is signalled upon entering the lower border.
|
||
|
||
// Convert 456 clocked half cycles per line to 342 internal cycles per line;
|
||
// the internal clock is 1.5 times the nominal 3.579545 Mhz that I've advertised
|
||
// for this part. So multiply by three quarters.
|
||
const int int_cycles = this->clock_converter_.to_internal(cycles.as<int>());
|
||
if(!int_cycles) return;
|
||
|
||
// There are two intertwined processes here, 'fetching' (i.e. writing to the
|
||
// line buffers with newly-fetched video contents) and 'output' (reading from
|
||
// the line buffers and generating video).
|
||
int fetch_cycles_pool = int_cycles;
|
||
int output_cycles_pool = int_cycles;
|
||
|
||
while(fetch_cycles_pool || output_cycles_pool) {
|
||
#ifndef NDEBUG
|
||
LineBufferPointer backup = this->output_pointer_;
|
||
#endif
|
||
|
||
if(fetch_cycles_pool) {
|
||
// Determine how much writing to do; at the absolute most go to the end of this line.
|
||
const int fetch_cycles = std::min(
|
||
LineLayout<personality>::CyclesPerLine - this->fetch_pointer_.column,
|
||
fetch_cycles_pool
|
||
);
|
||
const int end_column = this->fetch_pointer_.column + fetch_cycles;
|
||
|
||
// ... and to any pending Yamaha commands.
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
if(Storage<personality>::command_) {
|
||
Storage<personality>::minimum_command_column_ =
|
||
this->fetch_pointer_.column + Storage<personality>::command_->cycles;
|
||
Storage<personality>::command_->cycles -= fetch_cycles;
|
||
}
|
||
}
|
||
|
||
|
||
// ---------------------------------------
|
||
// Latch scrolling position, if necessary.
|
||
// ---------------------------------------
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
// TODO: where did this magic constant come from? https://www.smspower.org/forums/17970-RoadRashHow#111000 mentioned in passing
|
||
// that "the vertical scroll register is latched at the start of the active display" and this is two clocks before that, so it's
|
||
// not uncompelling. I can just no longer find my source.
|
||
static constexpr auto latch_time = LineLayout<personality>::EndOfLeftBorder - 2;
|
||
static_assert(latch_time > 0);
|
||
if(this->fetch_pointer_.column < latch_time && end_column >= latch_time) {
|
||
if(!this->fetch_pointer_.row) {
|
||
Storage<personality>::latched_vertical_scroll_ = Storage<personality>::vertical_scroll_;
|
||
|
||
if(Storage<personality>::mode4_enable_) {
|
||
this->mode_timing_.pixel_lines = 192;
|
||
if(this->mode2_enable_ && this->mode1_enable_) this->mode_timing_.pixel_lines = 224;
|
||
if(this->mode2_enable_ && this->mode3_enable_) this->mode_timing_.pixel_lines = 240;
|
||
|
||
this->mode_timing_.allow_sprite_terminator = this->mode_timing_.pixel_lines == 192;
|
||
this->mode_timing_.first_vsync_line = (this->mode_timing_.total_lines + this->mode_timing_.pixel_lines) >> 1;
|
||
|
||
this->mode_timing_.end_of_frame_interrupt_position.row = this->mode_timing_.pixel_lines + 1;
|
||
}
|
||
}
|
||
this->fetch_line_buffer_->latched_horizontal_scroll = Storage<personality>::horizontal_scroll_;
|
||
}
|
||
}
|
||
|
||
|
||
// ------------------------
|
||
// Perform memory accesses.
|
||
// ------------------------
|
||
#define fetch(function, clock, offset) { \
|
||
const int first_window = from_internal<personality, clock>(this->fetch_pointer_.column); \
|
||
const int final_window = from_internal<personality, clock>(end_column); \
|
||
if(first_window == final_window) break; \
|
||
const auto y = uint8_t( \
|
||
this->fetch_line_buffer_->vertical_state == VerticalState::Prefetch ? \
|
||
offset - 1 : (this->fetch_pointer_.row + offset)); \
|
||
if(final_window != clock_rate<personality, clock>()) { \
|
||
function<true>(y, first_window, final_window); \
|
||
} else { \
|
||
function<false>(y, first_window, final_window); \
|
||
} \
|
||
}
|
||
|
||
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
fetch(this->template fetch_yamaha, Clock::Internal, Storage<personality>::vertical_offset_);
|
||
} else {
|
||
switch(this->fetch_line_buffer_->fetch_mode) {
|
||
case FetchMode::Text: fetch(this->template fetch_tms_text, Clock::TMSMemoryWindow, 0); break;
|
||
case FetchMode::Character: fetch(this->template fetch_tms_character, Clock::TMSMemoryWindow, 0); break;
|
||
case FetchMode::SMS: fetch(this->template fetch_sms, Clock::TMSMemoryWindow, 0); break;
|
||
case FetchMode::Refresh: fetch(this->template fetch_tms_refresh, Clock::TMSMemoryWindow, 0); break;
|
||
|
||
default: break;
|
||
}
|
||
}
|
||
|
||
#undef fetch
|
||
|
||
|
||
// -------------------------------
|
||
// Check for interrupt conditions.
|
||
// -------------------------------
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
// The Sega VDP offers a decrementing counter for triggering line interrupts;
|
||
// it is reloaded either when it overflows or upon every non-pixel line after the first.
|
||
// It is otherwise decremented.
|
||
if(
|
||
this->fetch_pointer_.column < this->mode_timing_.line_interrupt_position &&
|
||
end_column >= this->mode_timing_.line_interrupt_position
|
||
) {
|
||
if(this->fetch_pointer_.row >= 0 && this->fetch_pointer_.row <= this->mode_timing_.pixel_lines) {
|
||
if(!this->line_interrupt_counter_) {
|
||
this->line_interrupt_pending_ = true;
|
||
this->line_interrupt_counter_ = this->line_interrupt_target_;
|
||
} else {
|
||
--this->line_interrupt_counter_;
|
||
}
|
||
} else {
|
||
this->line_interrupt_counter_ = this->line_interrupt_target_;
|
||
}
|
||
}
|
||
}
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
// The Yamaha VDPs allow the user to specify which line an interrupt should occur on,
|
||
// which is relative to the current vertical base. Such an interrupt will occur immediately
|
||
// after pixels have ended.
|
||
if(
|
||
this->vertical_active_ &&
|
||
this->fetch_pointer_.column < Storage<personality>::mode_description_.end_cycle &&
|
||
end_column >= Storage<personality>::mode_description_.end_cycle &&
|
||
this->fetch_pointer_.row == ((this->line_interrupt_target_ - Storage<personality>::vertical_offset_) & 0xff)
|
||
) {
|
||
this->line_interrupt_pending_ = true;
|
||
Storage<personality>::line_matches_ = true;
|
||
}
|
||
|
||
if(
|
||
this->fetch_pointer_.column < Storage<personality>::mode_description_.start_cycle &&
|
||
end_column >= Storage<personality>::mode_description_.start_cycle
|
||
) {
|
||
Storage<personality>::line_matches_ = false;
|
||
}
|
||
}
|
||
|
||
if(
|
||
this->fetch_pointer_.row == this->mode_timing_.end_of_frame_interrupt_position.row &&
|
||
this->fetch_pointer_.column < this->mode_timing_.end_of_frame_interrupt_position.column &&
|
||
end_column >= this->mode_timing_.end_of_frame_interrupt_position.column
|
||
) {
|
||
this->status_ |= StatusInterrupt;
|
||
}
|
||
|
||
|
||
|
||
// -------------
|
||
// Advance time.
|
||
// -------------
|
||
this->fetch_pointer_.column = end_column;
|
||
fetch_cycles_pool -= fetch_cycles;
|
||
|
||
// Check for end of line.
|
||
if(this->fetch_pointer_.column == LineLayout<personality>::CyclesPerLine) {
|
||
this->fetch_pointer_.column = 0;
|
||
this->fetch_pointer_.row = (this->fetch_pointer_.row + 1) % this->mode_timing_.total_lines;
|
||
|
||
this->vertical_active_ |= !this->fetch_pointer_.row;
|
||
this->vertical_active_ &= this->fetch_pointer_.row != this->mode_timing_.pixel_lines;
|
||
|
||
// Yamaha: handle blinking.
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
if(!this->fetch_pointer_.row && Storage<personality>::blink_periods_) {
|
||
--Storage<personality>::blink_counter_;
|
||
while(!Storage<personality>::blink_counter_) {
|
||
Storage<personality>::in_blink_ ^= 1;
|
||
Storage<personality>::blink_counter_ = (Storage<personality>::blink_periods_ >> (Storage<personality>::in_blink_ << 2)) & 0xf;
|
||
}
|
||
}
|
||
}
|
||
|
||
// Progress towards any delayed events.
|
||
this->minimum_access_column_ =
|
||
std::max(
|
||
0,
|
||
this->minimum_access_column_ - LineLayout<personality>::CyclesPerLine
|
||
);
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
Storage<personality>::minimum_command_column_ =
|
||
std::max(
|
||
0,
|
||
Storage<personality>::minimum_command_column_ - LineLayout<personality>::CyclesPerLine
|
||
);
|
||
}
|
||
|
||
this->advance(this->fetch_line_buffer_);
|
||
if(this->fetched_sprites_ && this->fetched_sprites_->active_sprite_slot) {
|
||
this->fetch_line_buffer_->sprites = this->fetched_sprites_;
|
||
this->fetched_sprites_ = nullptr;
|
||
} else {
|
||
this->fetch_line_buffer_->sprites = nullptr;
|
||
}
|
||
|
||
// Establish the current screen output mode, which will be captured as a
|
||
// line mode momentarily.
|
||
this->screen_mode_ = this->template current_screen_mode<true>();
|
||
this->underlying_mode_ = this->template current_screen_mode<false>();
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
auto &desc = Storage<personality>::mode_description_;
|
||
desc.pixels_per_byte = pixels_per_byte(this->underlying_mode_);
|
||
desc.width = width(this->underlying_mode_);
|
||
desc.rotate_address = interleaves_banks(this->underlying_mode_);
|
||
if(is_text(this->underlying_mode_)) {
|
||
desc.start_cycle = LineLayout<personality>::TextModeEndOfLeftBorder;
|
||
desc.end_cycle = LineLayout<personality>::TextModeEndOfPixels;
|
||
} else {
|
||
desc.start_cycle = LineLayout<personality>::EndOfLeftBorder;
|
||
desc.end_cycle = LineLayout<personality>::EndOfPixels;
|
||
}
|
||
}
|
||
|
||
// Based on the output mode, pick a line mode.
|
||
this->fetch_line_buffer_->first_pixel_output_column = LineLayout<personality>::EndOfLeftBorder;
|
||
this->fetch_line_buffer_->next_border_column = LineLayout<personality>::EndOfPixels;
|
||
this->fetch_line_buffer_->pixel_count = 256;
|
||
this->fetch_line_buffer_->screen_mode = this->screen_mode_;
|
||
this->mode_timing_.maximum_visible_sprites = 4;
|
||
switch(this->screen_mode_) {
|
||
case ScreenMode::Text:
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
} else {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Text;
|
||
}
|
||
this->fetch_line_buffer_->first_pixel_output_column = LineLayout<personality>::TextModeEndOfLeftBorder;
|
||
this->fetch_line_buffer_->next_border_column = LineLayout<personality>::TextModeEndOfPixels;
|
||
this->fetch_line_buffer_->pixel_count = 240;
|
||
break;
|
||
case ScreenMode::YamahaText80:
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
this->fetch_line_buffer_->first_pixel_output_column = LineLayout<personality>::TextModeEndOfLeftBorder;
|
||
this->fetch_line_buffer_->next_border_column = LineLayout<personality>::TextModeEndOfPixels;
|
||
this->fetch_line_buffer_->pixel_count = 480;
|
||
break;
|
||
|
||
case ScreenMode::SMSMode4:
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::SMS;
|
||
this->mode_timing_.maximum_visible_sprites = 8;
|
||
break;
|
||
|
||
case ScreenMode::YamahaGraphics3:
|
||
case ScreenMode::YamahaGraphics4:
|
||
case ScreenMode::YamahaGraphics7:
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
this->mode_timing_.maximum_visible_sprites = 8;
|
||
break;
|
||
case ScreenMode::YamahaGraphics5:
|
||
case ScreenMode::YamahaGraphics6:
|
||
this->fetch_line_buffer_->pixel_count = 512;
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
this->mode_timing_.maximum_visible_sprites = 8;
|
||
break;
|
||
default:
|
||
// This covers both MultiColour and Graphics modes.
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
} else {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Character;
|
||
}
|
||
break;
|
||
}
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
this->fetch_line_buffer_->first_pixel_output_column += Storage<personality>::adjustment_[0];
|
||
this->fetch_line_buffer_->next_border_column += Storage<personality>::adjustment_[0];
|
||
}
|
||
|
||
this->fetch_line_buffer_->vertical_state =
|
||
this->screen_mode_ == ScreenMode::Blank ?
|
||
VerticalState::Blank :
|
||
this->vertical_state();
|
||
const bool is_refresh = this->fetch_line_buffer_->vertical_state == VerticalState::Blank;
|
||
|
||
Storage<personality>::begin_line(this->screen_mode_, is_refresh);
|
||
|
||
if(is_refresh) {
|
||
// The Yamaha handles refresh lines via its own microprogram; other VDPs
|
||
// can fall back on the regular refresh mechanic.
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Yamaha;
|
||
} else {
|
||
this->fetch_line_buffer_->fetch_mode = FetchMode::Refresh;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
|
||
#ifndef NDEBUG
|
||
assert(backup.row == this->output_pointer_.row && backup.column == this->output_pointer_.column);
|
||
backup = this->fetch_pointer_;
|
||
#endif
|
||
|
||
|
||
if(output_cycles_pool) {
|
||
// Determine how much time has passed in the remainder of this line, and proceed.
|
||
const int target_output_cycles = std::min(
|
||
LineLayout<personality>::CyclesPerLine - this->output_pointer_.column,
|
||
output_cycles_pool
|
||
);
|
||
int output_cycles_performed = 0;
|
||
uint32_t next_cram_value = 0;
|
||
|
||
while(output_cycles_performed < target_output_cycles) {
|
||
int output_cycles = target_output_cycles - output_cycles_performed;
|
||
if(!output_cycles) continue;
|
||
|
||
// Grab the next CRAM dot value and schedule a break in output if applicable.
|
||
const uint32_t cram_value = next_cram_value;
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
next_cram_value = 0;
|
||
|
||
if(!this->upcoming_cram_dots_.empty() && this->upcoming_cram_dots_.front().location.row == this->output_pointer_.row) {
|
||
int time_until_dot = this->upcoming_cram_dots_.front().location.column - this->output_pointer_.column;
|
||
|
||
if(time_until_dot < output_cycles) {
|
||
output_cycles = time_until_dot;
|
||
next_cram_value = this->upcoming_cram_dots_.front().value;
|
||
this->upcoming_cram_dots_.erase(this->upcoming_cram_dots_.begin());
|
||
}
|
||
}
|
||
}
|
||
|
||
output_cycles_performed += output_cycles;
|
||
|
||
const int end_column = this->output_pointer_.column + output_cycles;
|
||
|
||
|
||
// --------------------
|
||
// Output video stream.
|
||
// --------------------
|
||
|
||
#define crt_convert(action, time) this->crt_.action(from_internal<personality, Clock::CRT>(time))
|
||
#define output_sync(x) crt_convert(output_sync, x)
|
||
#define output_blank(x) crt_convert(output_blank, x)
|
||
#define output_default_colour_burst(x) crt_convert(output_default_colour_burst, x)
|
||
|
||
#define intersect(left, right, code) { \
|
||
const int start = std::max(this->output_pointer_.column, left); \
|
||
const int end = std::min(end_column, right); \
|
||
if(end > start) {\
|
||
code;\
|
||
}\
|
||
}
|
||
|
||
#define border(left, right) intersect(left, right, this->output_border(end - start, cram_value))
|
||
|
||
const auto left_blank = [&]() {
|
||
// Blanking region: output the entire sequence when the cursor
|
||
// crosses the start-of-border point.
|
||
if(
|
||
this->output_pointer_.column < LineLayout<personality>::EndOfLeftErase &&
|
||
end_column >= LineLayout<personality>::EndOfLeftErase
|
||
) {
|
||
output_sync(LineLayout<personality>::EndOfSync);
|
||
output_blank(LineLayout<personality>::StartOfColourBurst - LineLayout<personality>::EndOfSync);
|
||
output_default_colour_burst(LineLayout<personality>::EndOfColourBurst - LineLayout<personality>::StartOfColourBurst);
|
||
output_blank(LineLayout<personality>::EndOfLeftErase - LineLayout<personality>::EndOfColourBurst);
|
||
}
|
||
};
|
||
|
||
const auto right_blank = [&]() {
|
||
if(end_column == LineLayout<personality>::CyclesPerLine) {
|
||
output_blank(LineLayout<personality>::CyclesPerLine - LineLayout<personality>::EndOfRightBorder);
|
||
}
|
||
};
|
||
|
||
if(this->draw_line_buffer_->vertical_state != VerticalState::Pixels) {
|
||
if(
|
||
this->output_pointer_.row >= this->mode_timing_.first_vsync_line &&
|
||
this->output_pointer_.row < this->mode_timing_.first_vsync_line + 4
|
||
) {
|
||
// Vertical sync.
|
||
// TODO: the Yamaha and Mega Drive both support interlaced video.
|
||
if(end_column == LineLayout<personality>::CyclesPerLine) {
|
||
output_sync(LineLayout<personality>::CyclesPerLine);
|
||
}
|
||
} else {
|
||
left_blank();
|
||
border(LineLayout<personality>::EndOfLeftErase, LineLayout<personality>::EndOfRightBorder);
|
||
right_blank();
|
||
}
|
||
} else {
|
||
left_blank();
|
||
|
||
// Left border.
|
||
border(LineLayout<personality>::EndOfLeftErase, this->draw_line_buffer_->first_pixel_output_column);
|
||
|
||
#define draw(function, clock) { \
|
||
const int relative_start = from_internal<personality, clock>(start - this->draw_line_buffer_->first_pixel_output_column); \
|
||
const int relative_end = from_internal<personality, clock>(end - this->draw_line_buffer_->first_pixel_output_column); \
|
||
if(relative_start == relative_end) break; \
|
||
this->function; }
|
||
|
||
// Pixel region.
|
||
intersect(
|
||
this->draw_line_buffer_->first_pixel_output_column,
|
||
this->draw_line_buffer_->next_border_column,
|
||
if(!this->asked_for_write_area_) {
|
||
this->asked_for_write_area_ = true;
|
||
|
||
this->pixel_origin_ = this->pixel_target_ = reinterpret_cast<uint32_t *>(
|
||
this->crt_.begin_data(size_t(this->draw_line_buffer_->pixel_count))
|
||
);
|
||
}
|
||
|
||
if(this->pixel_target_) {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
draw(draw_yamaha(0, relative_start, relative_end), Clock::Internal); // TODO: what is the correct 'y'?
|
||
} else {
|
||
switch(this->draw_line_buffer_->fetch_mode) {
|
||
case FetchMode::SMS: draw(draw_sms(relative_start, relative_end, cram_value), Clock::TMSPixel); break;
|
||
case FetchMode::Character: draw(draw_tms_character(relative_start, relative_end), Clock::TMSPixel); break;
|
||
case FetchMode::Text: draw(template draw_tms_text<false>(relative_start, relative_end), Clock::TMSPixel); break;
|
||
|
||
default: break; /* Dealt with elsewhere. */
|
||
}
|
||
}
|
||
}
|
||
|
||
if(end == this->draw_line_buffer_->next_border_column) {
|
||
const int length = this->draw_line_buffer_->next_border_column - this->draw_line_buffer_->first_pixel_output_column;
|
||
this->crt_.output_data(from_internal<personality, Clock::CRT>(length), size_t(this->draw_line_buffer_->pixel_count));
|
||
this->pixel_origin_ = this->pixel_target_ = nullptr;
|
||
this->asked_for_write_area_ = false;
|
||
}
|
||
);
|
||
|
||
#undef draw
|
||
|
||
// Right border.
|
||
border(this->draw_line_buffer_->next_border_column, LineLayout<personality>::EndOfRightBorder);
|
||
|
||
right_blank();
|
||
}
|
||
|
||
#undef border
|
||
#undef intersect
|
||
|
||
#undef crt_convert
|
||
#undef output_sync
|
||
#undef output_blank
|
||
#undef output_default_colour_burst
|
||
|
||
|
||
|
||
// -------------
|
||
// Advance time.
|
||
// -------------
|
||
this->output_pointer_.column = end_column;
|
||
if(end_column == LineLayout<personality>::CyclesPerLine) {
|
||
// Advance line buffer.
|
||
this->advance(this->draw_line_buffer_);
|
||
}
|
||
}
|
||
|
||
output_cycles_pool -= target_output_cycles;
|
||
if(this->output_pointer_.column == LineLayout<personality>::CyclesPerLine) {
|
||
this->output_pointer_.column = 0;
|
||
this->output_pointer_.row = (this->output_pointer_.row + 1) % this->mode_timing_.total_lines;
|
||
}
|
||
}
|
||
|
||
assert(backup.row == this->fetch_pointer_.row && backup.column == this->fetch_pointer_.column);
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::output_border(int cycles, [[maybe_unused]] const uint32_t cram_dot) {
|
||
cycles = from_internal<personality, Clock::CRT>(cycles);
|
||
|
||
uint32_t border_colour;
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
border_colour = Storage<personality>::colour_ram_[16 + background_colour_];
|
||
|
||
if(cram_dot) {
|
||
// Four CRT cycles is one pixel width, so this doesn't need clock conversion.
|
||
// TODO: on the Mega Drive it may be only 3 colour cycles, depending on mode.
|
||
crt_.output_level<uint32_t>(4, border_colour | cram_dot);
|
||
cycles -= 4;
|
||
}
|
||
} else {
|
||
border_colour = palette()[background_colour_];
|
||
}
|
||
|
||
if(!cycles) {
|
||
return;
|
||
}
|
||
|
||
crt_.output_level<uint32_t>(cycles, border_colour);
|
||
}
|
||
|
||
// MARK: - External interface.
|
||
|
||
template <Personality personality>
|
||
int Base<personality>::masked_address(const int address) const {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
return address & 3;
|
||
} else {
|
||
return address & 1;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::write_vram(const uint8_t value) {
|
||
write_phase_ = false;
|
||
|
||
// Enqueue the write to occur at the next available slot.
|
||
read_ahead_buffer_ = value;
|
||
queued_access_ = MemoryAccess::Write;
|
||
minimum_access_column_ = fetch_pointer_.column + LineLayout<personality>::VRAMAccessDelay;
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::commit_register(int reg, const uint8_t value) {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
reg &= 0x3f;
|
||
} else if constexpr (is_sega_vdp(personality)) {
|
||
if(reg & 0x40) {
|
||
Storage<personality>::cram_is_selected_ = true;
|
||
return;
|
||
}
|
||
reg &= 0xf;
|
||
} else {
|
||
reg &= 0x7;
|
||
}
|
||
|
||
//
|
||
// Generic TMS functionality.
|
||
//
|
||
switch(reg) {
|
||
case 0:
|
||
mode2_enable_ = value & 0x02;
|
||
break;
|
||
|
||
case 1:
|
||
blank_display_ = !(value & 0x40);
|
||
generate_interrupts_ = value & 0x20;
|
||
mode1_enable_ = value & 0x10;
|
||
mode3_enable_ = value & 0x08;
|
||
sprites_16x16_ = value & 0x02;
|
||
sprites_magnified_ = value & 0x01;
|
||
|
||
sprite_height_ = 8;
|
||
if(sprites_16x16_) sprite_height_ <<= 1;
|
||
if(sprites_magnified_) sprite_height_ <<= 1;
|
||
break;
|
||
|
||
case 2: install_field<10>(pattern_name_address_, value); break;
|
||
case 3: install_field<6>(colour_table_address_, value); break;
|
||
case 4: install_field<11>(pattern_generator_table_address_, value); break;
|
||
case 5: install_field<7>(sprite_attribute_table_address_, value); break;
|
||
case 6: install_field<11>(sprite_generator_table_address_, value); break;
|
||
|
||
case 7:
|
||
text_colour_ = value >> 4;
|
||
background_colour_ = value & 0xf;
|
||
break;
|
||
|
||
default: break;
|
||
}
|
||
|
||
//
|
||
// Sega extensions.
|
||
//
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
switch(reg) {
|
||
default: break;
|
||
|
||
case 0:
|
||
Storage<personality>::vertical_scroll_lock_ = value & 0x80;
|
||
Storage<personality>::horizontal_scroll_lock_ = value & 0x40;
|
||
Storage<personality>::hide_left_column_ = value & 0x20;
|
||
enable_line_interrupts_ = value & 0x10;
|
||
Storage<personality>::shift_sprites_8px_left_ = value & 0x08;
|
||
Storage<personality>::mode4_enable_ = value & 0x04;
|
||
break;
|
||
|
||
case 2:
|
||
Storage<personality>::pattern_name_address_ =
|
||
pattern_name_address_ | ((personality == TMS::SMSVDP) ? 0x000 : 0x400);
|
||
break;
|
||
|
||
case 5:
|
||
Storage<personality>::sprite_attribute_table_address_ =
|
||
sprite_attribute_table_address_ | ((personality == TMS::SMSVDP) ? 0x00 : 0x80);
|
||
break;
|
||
|
||
case 6:
|
||
Storage<personality>::sprite_generator_table_address_ =
|
||
sprite_generator_table_address_ | ((personality == TMS::SMSVDP) ? 0x0000 : 0x1800);
|
||
break;
|
||
|
||
case 8:
|
||
Storage<personality>::horizontal_scroll_ = value;
|
||
break;
|
||
|
||
case 9:
|
||
Storage<personality>::vertical_scroll_ = value;
|
||
break;
|
||
|
||
case 10:
|
||
line_interrupt_target_ = value;
|
||
break;
|
||
}
|
||
}
|
||
|
||
//
|
||
// Yamaha extensions.
|
||
//
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
switch(reg) {
|
||
default: break;
|
||
|
||
case 0:
|
||
Storage<personality>::mode_ = uint8_t(
|
||
(Storage<personality>::mode_ & 3) |
|
||
((value & 0xe) << 1)
|
||
);
|
||
enable_line_interrupts_ = value & 0x10;
|
||
|
||
// b1–b3: M3–M5
|
||
// b4: enable horizontal retrace interrupt
|
||
// b5: enable light pen interrupts
|
||
// b6: set colour bus to input or output mode
|
||
break;
|
||
|
||
case 1:
|
||
Storage<personality>::mode_ = uint8_t(
|
||
(Storage<personality>::mode_ & 0x1c) |
|
||
((value & 0x10) >> 4) |
|
||
((value & 0x08) >> 2)
|
||
);
|
||
break;
|
||
|
||
case 7:
|
||
Storage<personality>::background_palette_[0] = Storage<personality>::palette_[background_colour_];
|
||
break;
|
||
|
||
case 8:
|
||
Storage<personality>::solid_background_ = value & 0x20;
|
||
Storage<personality>::sprites_enabled_ = !(value & 0x02);
|
||
if(value & 0x01) {
|
||
Logger::error().append("TODO: Yamaha greyscale");
|
||
}
|
||
// b7: "1 = input on colour bus, enable mouse; 1 = output on colour bus, disable mouse" [documentation clearly in error]
|
||
// b6: 1 = enable light pen
|
||
// b5: sets the colour of code 0 to the colour of the palette (???)
|
||
// b4: 1 = colour bus in input mode; 0 = colour bus in output mode
|
||
// b3: 1 = VRAM is 64kx1 or 64kx4; 0 = 16kx1 or 16kx4; affects refresh.
|
||
// b1: 1 = disable sprites (and release sprite access slots)
|
||
// b0: 1 = output in grayscale
|
||
break;
|
||
|
||
case 9:
|
||
mode_timing_.pixel_lines = (value & 0x80) ? 212 : 192;
|
||
mode_timing_.end_of_frame_interrupt_position.row = mode_timing_.pixel_lines+1;
|
||
// TODO: on the Yamaha, at least, tie this interrupt overtly to vertical state.
|
||
|
||
if(value & 0x08) {
|
||
Logger::error().append("TODO: Yamaha interlace mode");
|
||
}
|
||
|
||
// b7: 1 = 212 lines of pixels; 0 = 192
|
||
// b5 & b4: select simultaneous mode (seems to relate to line length and in-phase colour?)
|
||
// b3: 1 = interlace on
|
||
// b2: 1 = display two graphic screens interchangeably by even/odd field
|
||
// b1: 1 = PAL mode; 0 = NTSC mode
|
||
// b0: 1 = [dot clock] DLCLK is input; 0 = DLCLK is output
|
||
break;
|
||
|
||
// b0–b2: A14–A16 of the colour table.
|
||
case 10: install_field<14>(colour_table_address_, value); break;
|
||
|
||
// b0–b1: A15–A16 of the sprite table.
|
||
case 11: install_field<15>(sprite_attribute_table_address_, value); break;
|
||
|
||
case 12:
|
||
Storage<personality>::blink_text_colour_ = value >> 4;
|
||
Storage<personality>::blink_background_colour_ = value & 0xf;
|
||
// as per register 7, but in blink mode.
|
||
break;
|
||
|
||
case 13:
|
||
Storage<personality>::blink_periods_ = value;
|
||
if(!value) {
|
||
Storage<personality>::in_blink_ = 0;
|
||
}
|
||
|
||
// b0–b3: display time for odd page;
|
||
// b4–b7: display time for even page.
|
||
break;
|
||
|
||
case 14: install_field<14>(ram_pointer_, value); break;
|
||
|
||
case 15:
|
||
Storage<personality>::selected_status_ = value & 0xf;
|
||
break;
|
||
|
||
case 16:
|
||
Storage<personality>::palette_entry_ = value;
|
||
// b0–b3: palette entry for writing on port 2; autoincrements upon every write.
|
||
break;
|
||
|
||
case 17:
|
||
Storage<personality>::increment_indirect_register_ = !(value & 0x80);
|
||
Storage<personality>::indirect_register_ = value & 0x3f;
|
||
break;
|
||
|
||
case 18:
|
||
Storage<personality>::adjustment_[0] = (8 - ((value & 15) ^ 8)) * 4;
|
||
Storage<personality>::adjustment_[1] = 8 - ((value >> 4) ^ 8);
|
||
// b0-b3: horizontal adjustment
|
||
// b4-b7: vertical adjustment
|
||
break;
|
||
|
||
case 19:
|
||
line_interrupt_target_ = value;
|
||
// b0–b7: line to match for interrupts (if eabled)
|
||
break;
|
||
|
||
case 20:
|
||
case 21:
|
||
case 22:
|
||
// Logger::error().append("TODO: Yamaha colour burst selection; %02x", value);
|
||
// Documentation is "fill with 0s for no colour burst; magic pattern for colour burst"
|
||
break;
|
||
|
||
case 23:
|
||
Storage<personality>::vertical_offset_ = value;
|
||
break;
|
||
|
||
case 32: Storage<personality>::command_context_.source.template set<0, false>(value); break;
|
||
case 33: Storage<personality>::command_context_.source.template set<0, true>(value); break;
|
||
case 34: Storage<personality>::command_context_.source.template set<1, false>(value); break;
|
||
case 35: Storage<personality>::command_context_.source.template set<1, true>(value); break;
|
||
|
||
case 36: Storage<personality>::command_context_.destination.template set<0, false>(value); break;
|
||
case 37: Storage<personality>::command_context_.destination.template set<0, true>(value); break;
|
||
case 38: Storage<personality>::command_context_.destination.template set<1, false>(value); break;
|
||
case 39: Storage<personality>::command_context_.destination.template set<1, true>(value); break;
|
||
|
||
case 40: Storage<personality>::command_context_.size.template set<0, false>(value); break;
|
||
case 41: Storage<personality>::command_context_.size.template set<0, true>(value); break;
|
||
case 42: Storage<personality>::command_context_.size.template set<1, false>(value); break;
|
||
case 43: Storage<personality>::command_context_.size.template set<1, true>(value); break;
|
||
|
||
case 44:
|
||
Storage<personality>::command_context_.colour.set(value);
|
||
|
||
// Check whether a command was blocked on this.
|
||
if(
|
||
Storage<personality>::command_ &&
|
||
Storage<personality>::command_->access == Command::AccessType::WaitForColourReceipt
|
||
) {
|
||
Storage<personality>::command_->advance();
|
||
Storage<personality>::update_command_step(fetch_pointer_.column);
|
||
}
|
||
break;
|
||
|
||
case 45:
|
||
Storage<personality>::command_context_.arguments = value;
|
||
// b6: MXC, i.e. destination for INed/OUTed video data; 0 = video RAM; 1 = expansion RAM.
|
||
// b5: MXD, destination for command engine.
|
||
// b4: MXS, source for command engine.
|
||
// b3: DIY
|
||
// b2: DIX
|
||
// b1: EQ
|
||
// b0: MAJ
|
||
break;
|
||
|
||
case 46:
|
||
// b0–b3: LO0–LO3 (i.e. operation to apply if this is a logical command)
|
||
// b4–b7: CM0-CM3 (i.e. command to perform)
|
||
|
||
// If a command is already ongoing and this is not a stop, ignore it.
|
||
if(Storage<personality>::command_ && (value >> 4) != 0b0000) {
|
||
break;
|
||
}
|
||
|
||
#define Begin(x) Storage<personality>::command_ = std::make_unique<Commands::x>(Storage<personality>::command_context_, Storage<personality>::mode_description_);
|
||
using MoveType = Commands::MoveType;
|
||
switch(value >> 4) {
|
||
// All codes not listed below are invalid; treat them as STOP.
|
||
default:
|
||
case 0b0000: Storage<personality>::command_ = nullptr; break; // STOP.
|
||
|
||
case 0b0100: Begin(Point<true>); break; // POINT [read a pixel colour].
|
||
case 0b0101: Begin(Point<false>); break; // PSET [plot a pixel].
|
||
case 0b0110: break; // TODO: srch. [search horizontally for a colour]
|
||
case 0b0111: Begin(Line); break; // LINE [draw a Bresenham line].
|
||
|
||
case 0b1000: Begin(Fill<true>); break; // LMMV [logical move, VDP to VRAM, i.e. solid-colour fill].
|
||
case 0b1001: Begin(Move<MoveType::Logical>); break; // LMMM [logical move, VRAM to VRAM].
|
||
case 0b1010: break; // TODO: lmcm. [logical move, VRAM to CPU]
|
||
case 0b1011: Begin(MoveFromCPU<true>); break; // LMMC [logical move, CPU to VRAM].
|
||
|
||
case 0b1100: Begin(Fill<false>); break; // HMMV [high-speed move, VDP to VRAM, i.e. single-byte fill].
|
||
case 0b1101: Begin(Move<MoveType::HighSpeed>); break; // HMMM [high-speed move, VRAM to VRAM].
|
||
case 0b1110: Begin(Move<MoveType::YOnly>); break; // YMMM [high-speed move, y only, VRAM to VRAM].
|
||
case 0b1111: Begin(MoveFromCPU<false>); break; // HMMC [high-speed move, CPU to VRAM].
|
||
}
|
||
#undef Begin
|
||
|
||
Storage<personality>::command_context_.pixel_operation = CommandContext::LogicalOperation(value & 7);
|
||
Storage<personality>::command_context_.test_source = value & 8;
|
||
|
||
// Kill the command immediately if it's done in zero operations
|
||
// (e.g. a line of length 0).
|
||
if(!Storage<personality>::command_ && (value >> 4)) {
|
||
Logger::error().append("TODO: Yamaha command %02x", value);
|
||
}
|
||
|
||
// Seed timing information if a command was found.
|
||
Storage<personality>::update_command_step(fetch_pointer_.column);
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::write_register(const uint8_t value) {
|
||
// 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;
|
||
|
||
// The initial write should half update the access pointer, other than
|
||
// on the Yamaha.
|
||
if constexpr (!is_yamaha_vdp(personality)) {
|
||
install_field<0>(ram_pointer_, value);
|
||
}
|
||
return;
|
||
}
|
||
|
||
// The RAM pointer is always set on a second write, regardless of
|
||
// whether the caller is intending to enqueue a VDP operation.
|
||
// If this isn't a Yamaha VDP then the RAM address is updated
|
||
// regardless of whether this turns out to be a register access.
|
||
//
|
||
// The top two bits are used to determine the type of write; only
|
||
// the lower six are actual address.
|
||
if constexpr (!is_yamaha_vdp(personality)) {
|
||
install_field<8, 6>(ram_pointer_, value);
|
||
}
|
||
|
||
write_phase_ = false;
|
||
if(value & 0x80) {
|
||
commit_register(value, low_write_);
|
||
} else {
|
||
// This is an access via the RAM pointer; if this is a Yamaha VDP then update
|
||
// the low 14-bits of the RAM pointer now.
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
install_field<0>(ram_pointer_, low_write_);
|
||
install_field<8, 6>(ram_pointer_, value);
|
||
}
|
||
|
||
if(!(value & 0x40)) {
|
||
// A read request is enqueued upon setting the address; conversely a write
|
||
// won't be enqueued unless and until some actual data is supplied.
|
||
queued_access_ = MemoryAccess::Read;
|
||
minimum_access_column_ = fetch_pointer_.column + LineLayout<personality>::VRAMAccessDelay;
|
||
}
|
||
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
Storage<personality>::cram_is_selected_ = false;
|
||
}
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::write_palette(const uint8_t value) {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
if(!Storage<personality>::palette_write_phase_) {
|
||
Storage<personality>::new_colour_ = value;
|
||
Storage<personality>::palette_write_phase_ = true;
|
||
return;
|
||
}
|
||
|
||
Storage<personality>::palette_write_phase_ = false;
|
||
|
||
const uint8_t r = ((Storage<personality>::new_colour_ >> 4) & 7) * 255 / 7;
|
||
const uint8_t g = (value & 7) * 255 / 7;
|
||
const uint8_t b = (Storage<personality>::new_colour_ & 7) * 255 / 7;
|
||
|
||
Storage<personality>::palette_[Storage<personality>::palette_entry_ & 0xf] = palette_pack(r, g, b);
|
||
Storage<personality>::background_palette_[Storage<personality>::palette_entry_ & 0xf] = palette_pack(r, g, b);
|
||
Storage<personality>::background_palette_[0] = Storage<personality>::palette_[background_colour_];
|
||
|
||
++Storage<personality>::palette_entry_;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void Base<personality>::write_register_indirect([[maybe_unused]] const uint8_t value) {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
// Register 17 cannot be written to indirectly.
|
||
if(Storage<personality>::indirect_register_ != 17) {
|
||
commit_register(Storage<personality>::indirect_register_, value);
|
||
}
|
||
Storage<personality>::indirect_register_ += Storage<personality>::increment_indirect_register_;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::write(int address, uint8_t value) {
|
||
switch(this->masked_address(address)) {
|
||
default: break;
|
||
case 0: this->write_vram(value); break;
|
||
case 1: this->write_register(value); break;
|
||
case 2: this->write_palette(value); break;
|
||
case 3: this->write_register_indirect(value); break;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
uint8_t Base<personality>::read_vram() {
|
||
// Take whatever is currently in the read-ahead buffer and
|
||
// enqueue a further read to occur at the next available slot.
|
||
const uint8_t result = read_ahead_buffer_;
|
||
queued_access_ = MemoryAccess::Read;
|
||
return result;
|
||
}
|
||
|
||
template <Personality personality>
|
||
uint8_t Base<personality>::read_register() {
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
switch(Storage<personality>::selected_status_) {
|
||
default:
|
||
case 0: break;
|
||
|
||
case 1: {
|
||
// b7 = light pen; set when light is detected, reset on read;
|
||
// or: mouse button 2 currently down.
|
||
// b6 = light pen button or mouse button 1.
|
||
// b5–b1 = VDP identification (0 = 9938; 2 = 9958)
|
||
// b0 = set when the VDP reaches the line provided in the line interrupt register.
|
||
// Reset upon read.
|
||
const uint8_t result =
|
||
(personality == Personality::V9938 ? 0x0 : 0x4) |
|
||
((line_interrupt_pending_ && enable_line_interrupts_) ? 0x01 : 0x00);
|
||
|
||
line_interrupt_pending_ = false;
|
||
return result;
|
||
} break;
|
||
|
||
case 2: {
|
||
// b7 = transfer ready flag (i.e. VDP ready for next transfer)
|
||
// b6 = 1 during vblank
|
||
// b5 = 1 during hblank
|
||
// b4 = set if colour detected during search command
|
||
// b1 = display field odd/even
|
||
// b0 = command ongoing
|
||
const uint8_t transfer_ready =
|
||
(queued_access_ == MemoryAccess::None ? 0x80 : 0x00) &
|
||
((
|
||
!Storage<personality>::command_ ||
|
||
!Storage<personality>::command_->is_cpu_transfer ||
|
||
Storage<personality>::command_->access == Command::AccessType::WaitForColourReceipt
|
||
) ? 0x80 : 0x00);
|
||
|
||
return
|
||
transfer_ready |
|
||
(vertical_state() != VerticalState::Pixels ? 0x40 : 0x00) |
|
||
(is_horizontal_blank() ? 0x20 : 0x00) |
|
||
(Storage<personality>::command_ ? 0x01 : 0x00);
|
||
|
||
} break;
|
||
|
||
case 3: return uint8_t(Storage<personality>::collision_location_[0]);
|
||
case 4: return uint8_t((Storage<personality>::collision_location_[0] >> 8) | 0xfe);
|
||
case 5: return uint8_t(Storage<personality>::collision_location_[1]);
|
||
case 6: return uint8_t((Storage<personality>::collision_location_[1] >> 8) | 0xfc);
|
||
|
||
case 7: return Storage<personality>::colour_status_;
|
||
|
||
case 8: return uint8_t(Storage<personality>::colour_location_);
|
||
case 9: return uint8_t((Storage<personality>::colour_location_ >> 8) | 0xfe);
|
||
}
|
||
}
|
||
|
||
// Gets the status register.
|
||
const uint8_t result = status_;
|
||
status_ &= ~(StatusInterrupt | StatusSpriteOverflow | StatusSpriteCollision);
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
line_interrupt_pending_ = false;
|
||
}
|
||
return result;
|
||
}
|
||
|
||
template <Personality personality>
|
||
uint8_t TMS9918<personality>::read(const int address) {
|
||
const int target = this->masked_address(address);
|
||
|
||
if(target < 2) {
|
||
this->write_phase_ = false;
|
||
}
|
||
|
||
switch(target) {
|
||
default: return 0xff;
|
||
case 0: return this->read_vram();
|
||
case 1: return this->read_register();
|
||
}
|
||
}
|
||
|
||
// MARK: - Ephemeral state.
|
||
|
||
template <Personality personality>
|
||
int Base<personality>::fetch_line() const {
|
||
// This is the proper Master System value; TODO: what's correct for Yamaha, etc?
|
||
static constexpr int row_change_position = 31;
|
||
|
||
return
|
||
(this->fetch_pointer_.column < row_change_position)
|
||
? (this->fetch_pointer_.row + this->mode_timing_.total_lines - 1) % this->mode_timing_.total_lines
|
||
: this->fetch_pointer_.row;
|
||
}
|
||
|
||
template <Personality personality>
|
||
VerticalState Base<personality>::vertical_state() const {
|
||
if(vertical_active_) {
|
||
return VerticalState::Pixels;
|
||
} else if(fetch_pointer_.row == mode_timing_.total_lines - 1) {
|
||
return VerticalState::Prefetch;
|
||
} else {
|
||
return VerticalState::Blank;
|
||
}
|
||
}
|
||
|
||
template <Personality personality>
|
||
bool Base<personality>::is_horizontal_blank() const {
|
||
return fetch_pointer_.column < LineLayout<personality>::EndOfLeftErase || fetch_pointer_.column >= LineLayout<personality>::EndOfRightBorder;
|
||
}
|
||
|
||
template <Personality personality>
|
||
uint8_t TMS9918<personality>::get_current_line() const {
|
||
int source_row = this->fetch_line();
|
||
|
||
if(this->tv_standard_ == TVStandard::NTSC) {
|
||
if(this->mode_timing_.pixel_lines == 240) {
|
||
// NTSC 256x240: 00-FF, 00-06
|
||
} else if(this->mode_timing_.pixel_lines == 224) {
|
||
// NTSC 256x224: 00-EA, E5-FF
|
||
if(source_row >= 0xeb) source_row -= 6;
|
||
} else {
|
||
// NTSC 256x192: 00-DA, D5-FF
|
||
if(source_row >= 0xdb) source_row -= 6;
|
||
}
|
||
} else {
|
||
if(this->mode_timing_.pixel_lines == 240) {
|
||
// PAL 256x240: 00-FF, 00-0A, D2-FF
|
||
if(source_row >= 267) source_row -= 0x39;
|
||
} else if(this->mode_timing_.pixel_lines == 224) {
|
||
// PAL 256x224: 00-FF, 00-02, CA-FF
|
||
if(source_row >= 259) source_row -= 0x39;
|
||
} else {
|
||
// PAL 256x192: 00-F2, BA-FF
|
||
if(source_row >= 0xf3) source_row -= 0x39;
|
||
}
|
||
}
|
||
|
||
return uint8_t(source_row);
|
||
}
|
||
template <Personality personality>
|
||
HalfCycles TMS9918<personality>::next_sequence_point() const {
|
||
if(!this->generate_interrupts_ && !this->enable_line_interrupts_) return HalfCycles::max();
|
||
if(get_interrupt_line()) return HalfCycles::max();
|
||
|
||
// Calculate the amount of time until the next end-of-frame interrupt.
|
||
const int frame_length = LineLayout<personality>::CyclesPerLine * this->mode_timing_.total_lines;
|
||
int time_until_frame_interrupt =
|
||
(
|
||
((this->mode_timing_.end_of_frame_interrupt_position.row * LineLayout<personality>::CyclesPerLine) + this->mode_timing_.end_of_frame_interrupt_position.column + frame_length) -
|
||
((this->fetch_pointer_.row * LineLayout<personality>::CyclesPerLine) + this->fetch_pointer_.column)
|
||
) % frame_length;
|
||
if(!time_until_frame_interrupt) time_until_frame_interrupt = frame_length;
|
||
|
||
if(!this->enable_line_interrupts_) {
|
||
return this->clock_converter_.half_cycles_before_internal_cycles(time_until_frame_interrupt);
|
||
}
|
||
|
||
// Calculate when the next line interrupt will occur.
|
||
int next_line_interrupt_row = -1;
|
||
|
||
int cycles_to_next_interrupt_threshold = this->mode_timing_.line_interrupt_position - this->fetch_pointer_.column;
|
||
int line_of_next_interrupt_threshold = this->fetch_pointer_.row;
|
||
if(cycles_to_next_interrupt_threshold <= 0) {
|
||
cycles_to_next_interrupt_threshold += LineLayout<personality>::CyclesPerLine;
|
||
++line_of_next_interrupt_threshold;
|
||
}
|
||
|
||
if constexpr (is_sega_vdp(personality)) {
|
||
// If there is still time for a line interrupt this frame, that'll be it;
|
||
// otherwise it'll be on the next frame, supposing there's ever time for
|
||
// it at all.
|
||
if(line_of_next_interrupt_threshold + this->line_interrupt_counter_ <= this->mode_timing_.pixel_lines) {
|
||
next_line_interrupt_row = line_of_next_interrupt_threshold + this->line_interrupt_counter_;
|
||
} else {
|
||
if(this->line_interrupt_target_ <= this->mode_timing_.pixel_lines)
|
||
next_line_interrupt_row = this->mode_timing_.total_lines + this->line_interrupt_target_;
|
||
}
|
||
}
|
||
|
||
if constexpr (is_yamaha_vdp(personality)) {
|
||
next_line_interrupt_row = (this->line_interrupt_target_ - Storage<personality>::vertical_offset_) & 0xff;
|
||
}
|
||
|
||
// If there's actually no interrupt upcoming, despite being enabled, either return
|
||
// the frame end interrupt or no interrupt pending as appropriate.
|
||
if(next_line_interrupt_row == -1) {
|
||
return this->generate_interrupts_ ?
|
||
this->clock_converter_.half_cycles_before_internal_cycles(time_until_frame_interrupt) :
|
||
HalfCycles::max();
|
||
}
|
||
|
||
// Figure out the number of internal cycles until the next line interrupt, which is the amount
|
||
// of time to the next tick over and then next_line_interrupt_row - row_ lines further.
|
||
const int lines_until_interrupt = (next_line_interrupt_row - line_of_next_interrupt_threshold + this->mode_timing_.total_lines) % this->mode_timing_.total_lines;
|
||
const int local_cycles_until_line_interrupt = cycles_to_next_interrupt_threshold + lines_until_interrupt * LineLayout<personality>::CyclesPerLine;
|
||
if(!this->generate_interrupts_) return this->clock_converter_.half_cycles_before_internal_cycles(local_cycles_until_line_interrupt);
|
||
|
||
// Return whichever interrupt is closer.
|
||
return this->clock_converter_.half_cycles_before_internal_cycles(std::min(local_cycles_until_line_interrupt, time_until_frame_interrupt));
|
||
}
|
||
|
||
template <Personality personality>
|
||
HalfCycles TMS9918<personality>::get_time_until_line(int line) {
|
||
if(line < 0) line += this->mode_timing_.total_lines;
|
||
|
||
int cycles_to_next_interrupt_threshold = this->mode_timing_.line_interrupt_position - this->fetch_pointer_.column;
|
||
int line_of_next_interrupt_threshold = this->fetch_pointer_.row;
|
||
if(cycles_to_next_interrupt_threshold <= 0) {
|
||
cycles_to_next_interrupt_threshold += LineLayout<personality>::CyclesPerLine;
|
||
++line_of_next_interrupt_threshold;
|
||
}
|
||
|
||
if(line_of_next_interrupt_threshold > line) {
|
||
line += this->mode_timing_.total_lines;
|
||
}
|
||
|
||
return this->clock_converter_.half_cycles_before_internal_cycles(cycles_to_next_interrupt_threshold + (line - line_of_next_interrupt_threshold)*LineLayout<personality>::CyclesPerLine);
|
||
}
|
||
|
||
template <Personality personality>
|
||
bool TMS9918<personality>::get_interrupt_line() const {
|
||
return
|
||
((this->status_ & StatusInterrupt) && this->generate_interrupts_) ||
|
||
(this->enable_line_interrupts_ && this->line_interrupt_pending_);
|
||
}
|
||
|
||
// TODO: [potentially] remove Master System timing assumptions in latch and get_latched below, if any other VDP uses these calls.
|
||
template <Personality personality>uint8_t TMS9918<personality>::get_latched_horizontal_counter() const {
|
||
// Translate from internal numbering to the public numbering,
|
||
// which counts the 256 pixels as items 0–255, starts
|
||
// counting at -48, and returns only the top 8 bits of the number.
|
||
int public_counter = this->latched_column_ - LineLayout<personality>::EndOfLeftBorder;
|
||
if(public_counter < -46) public_counter += LineLayout<personality>::CyclesPerLine;
|
||
return uint8_t(public_counter >> 1);
|
||
}
|
||
|
||
template <Personality personality>
|
||
void TMS9918<personality>::latch_horizontal_counter() {
|
||
this->latched_column_ = this->fetch_pointer_.column;
|
||
}
|
||
|
||
template class TI::TMS::TMS9918<Personality::TMS9918A>;
|
||
template class TI::TMS::TMS9918<Personality::V9938>;
|
||
//template class TI::TMS::TMS9918<Personality::V9958>;
|
||
template class TI::TMS::TMS9918<Personality::SMSVDP>;
|
||
template class TI::TMS::TMS9918<Personality::SMS2VDP>;
|
||
//template class TI::TMS::TMS9918<Personality::GGVDP>;
|
||
//template class TI::TMS::TMS9918<Personality::MDVDP>;
|