mirror of
https://github.com/TomHarte/CLK.git
synced 2024-07-09 21:29:53 +00:00
d97a073d1b
They all just as the CRT, as all are currently based on the CRT. Which doesn't currently know the total clock rate it would need to in order properly to scale the answer to the question. Further thought coming.
1041 lines
34 KiB
C++
1041 lines
34 KiB
C++
//
|
|
// 9918.cpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 25/11/2017.
|
|
// Copyright 2017 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#include "9918.hpp"
|
|
|
|
#include <cassert>
|
|
#include <cstring>
|
|
#include <cstdlib>
|
|
#include "../../Outputs/Log.hpp"
|
|
|
|
using namespace TI::TMS;
|
|
|
|
namespace {
|
|
|
|
constexpr uint8_t StatusInterrupt = 0x80;
|
|
constexpr uint8_t StatusSpriteOverflow = 0x40;
|
|
|
|
constexpr int StatusSpriteCollisionShift = 5;
|
|
constexpr uint8_t StatusSpriteCollision = 0x20;
|
|
|
|
// 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;
|
|
|
|
struct ReverseTable {
|
|
std::uint8_t map[256];
|
|
|
|
ReverseTable() {
|
|
for(int c = 0; c < 256; ++c) {
|
|
map[c] = static_cast<uint8_t>(
|
|
((c & 0x80) >> 7) |
|
|
((c & 0x40) >> 5) |
|
|
((c & 0x20) >> 3) |
|
|
((c & 0x10) >> 1) |
|
|
((c & 0x08) << 1) |
|
|
((c & 0x04) << 3) |
|
|
((c & 0x02) << 5) |
|
|
((c & 0x01) << 7)
|
|
);
|
|
}
|
|
}
|
|
} reverse_table;
|
|
|
|
}
|
|
|
|
Base::Base(Personality p) :
|
|
personality_(p),
|
|
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.
|
|
|
|
switch(p) {
|
|
case TI::TMS::TMS9918A:
|
|
case TI::TMS::SMSVDP:
|
|
case TI::TMS::SMS2VDP:
|
|
case TI::TMS::GGVDP:
|
|
ram_.resize(16 * 1024);
|
|
break;
|
|
case TI::TMS::V9938:
|
|
ram_.resize(128 * 1024);
|
|
break;
|
|
case TI::TMS::V9958:
|
|
ram_.resize(192 * 1024);
|
|
break;
|
|
}
|
|
|
|
if(is_sega_vdp(personality_)) {
|
|
mode_timing_.line_interrupt_position = 64;
|
|
|
|
mode_timing_.end_of_frame_interrupt_position.column = 63;
|
|
mode_timing_.end_of_frame_interrupt_position.row = 193;
|
|
}
|
|
|
|
// Establish that output is delayed after reading by `output_lag` cycles; start
|
|
// at a random position.
|
|
read_pointer_.row = rand() % 262;
|
|
read_pointer_.column = rand() % (342 - output_lag);
|
|
write_pointer_.row = read_pointer_.row;
|
|
write_pointer_.column = read_pointer_.column + output_lag;
|
|
}
|
|
|
|
TMS9918::TMS9918(Personality p):
|
|
Base(p) {
|
|
crt_.set_display_type(Outputs::Display::DisplayType::RGB);
|
|
crt_.set_visible_area(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.
|
|
crt_.set_immediate_default_phase(0.85f);
|
|
}
|
|
|
|
void TMS9918::set_tv_standard(TVStandard standard) {
|
|
tv_standard_ = standard;
|
|
switch(standard) {
|
|
case TVStandard::PAL:
|
|
mode_timing_.total_lines = 313;
|
|
mode_timing_.first_vsync_line = 253;
|
|
crt_.set_new_display_type(CRTCyclesPerLine, Outputs::Display::Type::PAL50);
|
|
break;
|
|
default:
|
|
mode_timing_.total_lines = 262;
|
|
mode_timing_.first_vsync_line = 227;
|
|
crt_.set_new_display_type(CRTCyclesPerLine, Outputs::Display::Type::NTSC60);
|
|
break;
|
|
}
|
|
}
|
|
|
|
void TMS9918::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
|
|
crt_.set_scan_target(scan_target);
|
|
}
|
|
|
|
Outputs::Display::ScanStatus TMS9918::get_scan_status() const {
|
|
return crt_.get_scan_status();
|
|
}
|
|
|
|
void TMS9918::set_display_type(Outputs::Display::DisplayType display_type) {
|
|
crt_.set_display_type(display_type);
|
|
}
|
|
|
|
void Base::LineBuffer::reset_sprite_collection() {
|
|
sprites_stopped = false;
|
|
active_sprite_slot = 0;
|
|
|
|
for(int c = 0; c < 8; ++c) {
|
|
active_sprites[c].shift_position = 0;
|
|
}
|
|
}
|
|
|
|
void Base::posit_sprite(LineBuffer &buffer, int sprite_number, int sprite_position, int screen_row) {
|
|
if(!(status_ & StatusSpriteOverflow)) {
|
|
status_ = static_cast<uint8_t>((status_ & ~0x1f) | (sprite_number & 0x1f));
|
|
}
|
|
if(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 == mode_timing_.sprite_terminator) {
|
|
buffer.sprites_stopped = true;
|
|
return;
|
|
}
|
|
|
|
const int sprite_row = (((screen_row + 1) % mode_timing_.total_lines) - ((sprite_position + 1) & 255)) & 255;
|
|
if(sprite_row < 0 || sprite_row >= sprite_height_) return;
|
|
|
|
if(buffer.active_sprite_slot == mode_timing_.maximum_visible_sprites) {
|
|
status_ |= StatusSpriteOverflow;
|
|
return;
|
|
}
|
|
|
|
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[buffer.active_sprite_slot];
|
|
sprite.index = sprite_number;
|
|
sprite.row = sprite_row >> (sprites_magnified_ ? 1 : 0);
|
|
++buffer.active_sprite_slot;
|
|
}
|
|
|
|
void TMS9918::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.
|
|
int int_cycles = int(cycles.as_integral() * 3) + cycles_error_;
|
|
cycles_error_ = int_cycles & 3;
|
|
int_cycles >>= 2;
|
|
if(!int_cycles) return;
|
|
|
|
// There are two intertwined processes here, 'writing' (which means writing to the
|
|
// line buffers, i.e. it's everything to do with collecting a line) and 'reading'
|
|
// (which means reading from the line buffers and generating video).
|
|
int write_cycles_pool = int_cycles;
|
|
int read_cycles_pool = int_cycles;
|
|
|
|
while(write_cycles_pool || read_cycles_pool) {
|
|
LineBufferPointer backup = read_pointer_;
|
|
|
|
if(write_cycles_pool) {
|
|
// Determine how much writing to do.
|
|
const int write_cycles = std::min(342 - write_pointer_.column, write_cycles_pool);
|
|
const int end_column = write_pointer_.column + write_cycles;
|
|
LineBuffer &line_buffer = line_buffers_[write_pointer_.row];
|
|
|
|
// Determine what this does to any enqueued VRAM access.
|
|
minimum_access_column_ = write_pointer_.column + cycles_until_access_;
|
|
cycles_until_access_ -= write_cycles;
|
|
|
|
|
|
// ---------------------------------------
|
|
// Latch scrolling position, if necessary.
|
|
// ---------------------------------------
|
|
if(is_sega_vdp(personality_)) {
|
|
if(write_pointer_.column < 61 && end_column >= 61) {
|
|
if(!write_pointer_.row) {
|
|
master_system_.latched_vertical_scroll = master_system_.vertical_scroll;
|
|
|
|
if(master_system_.mode4_enable) {
|
|
mode_timing_.pixel_lines = 192;
|
|
if(mode2_enable_ && mode1_enable_) mode_timing_.pixel_lines = 224;
|
|
if(mode2_enable_ && mode3_enable_) mode_timing_.pixel_lines = 240;
|
|
|
|
mode_timing_.allow_sprite_terminator = mode_timing_.pixel_lines == 192;
|
|
mode_timing_.first_vsync_line = (mode_timing_.total_lines + mode_timing_.pixel_lines) >> 1;
|
|
|
|
mode_timing_.end_of_frame_interrupt_position.row = mode_timing_.pixel_lines + 1;
|
|
}
|
|
}
|
|
line_buffer.latched_horizontal_scroll = master_system_.horizontal_scroll;
|
|
}
|
|
}
|
|
|
|
|
|
|
|
// ------------------------
|
|
// Perform memory accesses.
|
|
// ------------------------
|
|
#define fetch(function) \
|
|
if(final_window != 171) { \
|
|
function<true>(first_window, final_window);\
|
|
} else {\
|
|
function<false>(first_window, final_window);\
|
|
}
|
|
|
|
// column_ and end_column are in 342-per-line cycles;
|
|
// adjust them to a count of windows.
|
|
const int first_window = write_pointer_.column >> 1;
|
|
const int final_window = end_column >> 1;
|
|
if(first_window != final_window) {
|
|
switch(line_buffer.line_mode) {
|
|
case LineMode::Text: fetch(fetch_tms_text); break;
|
|
case LineMode::Character: fetch(fetch_tms_character); break;
|
|
case LineMode::SMS: fetch(fetch_sms); break;
|
|
case LineMode::Refresh: fetch(fetch_tms_refresh); break;
|
|
}
|
|
}
|
|
|
|
#undef fetch
|
|
|
|
|
|
|
|
// -------------------------------
|
|
// Check for interrupt conditions.
|
|
// -------------------------------
|
|
if(write_pointer_.column < mode_timing_.line_interrupt_position && end_column >= mode_timing_.line_interrupt_position) {
|
|
// 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(is_sega_vdp(personality_)) {
|
|
if(write_pointer_.row >= 0 && write_pointer_.row <= mode_timing_.pixel_lines) {
|
|
--line_interrupt_counter;
|
|
if(line_interrupt_counter == 0xff) {
|
|
line_interrupt_pending_ = true;
|
|
line_interrupt_counter = line_interrupt_target;
|
|
}
|
|
} else {
|
|
line_interrupt_counter = line_interrupt_target;
|
|
}
|
|
}
|
|
|
|
// TODO: the V9938 provides line interrupts from direct specification of the target line.
|
|
// So life is easy.
|
|
}
|
|
|
|
if(
|
|
write_pointer_.row == mode_timing_.end_of_frame_interrupt_position.row &&
|
|
write_pointer_.column < mode_timing_.end_of_frame_interrupt_position.column &&
|
|
end_column >= mode_timing_.end_of_frame_interrupt_position.column
|
|
) {
|
|
status_ |= StatusInterrupt;
|
|
}
|
|
|
|
|
|
|
|
// -------------
|
|
// Advance time.
|
|
// -------------
|
|
write_pointer_.column = end_column;
|
|
write_cycles_pool -= write_cycles;
|
|
|
|
if(write_pointer_.column == 342) {
|
|
write_pointer_.column = 0;
|
|
write_pointer_.row = (write_pointer_.row + 1) % mode_timing_.total_lines;
|
|
LineBuffer &next_line_buffer = line_buffers_[write_pointer_.row];
|
|
|
|
// Establish the output mode for the next line.
|
|
set_current_screen_mode();
|
|
|
|
// Based on the output mode, pick a line mode.
|
|
next_line_buffer.first_pixel_output_column = 86;
|
|
next_line_buffer.next_border_column = 342;
|
|
mode_timing_.maximum_visible_sprites = 4;
|
|
switch(screen_mode_) {
|
|
case ScreenMode::Text:
|
|
next_line_buffer.line_mode = LineMode::Text;
|
|
next_line_buffer.first_pixel_output_column = 94;
|
|
next_line_buffer.next_border_column = 334;
|
|
break;
|
|
case ScreenMode::SMSMode4:
|
|
next_line_buffer.line_mode = LineMode::SMS;
|
|
mode_timing_.maximum_visible_sprites = 8;
|
|
break;
|
|
default:
|
|
next_line_buffer.line_mode = LineMode::Character;
|
|
break;
|
|
}
|
|
|
|
if(
|
|
(screen_mode_ == ScreenMode::Blank) ||
|
|
(write_pointer_.row >= mode_timing_.pixel_lines && write_pointer_.row != mode_timing_.total_lines-1))
|
|
next_line_buffer.line_mode = LineMode::Refresh;
|
|
}
|
|
}
|
|
|
|
|
|
assert(backup.row == read_pointer_.row && backup.column == read_pointer_.column);
|
|
backup = write_pointer_;
|
|
|
|
|
|
if(read_cycles_pool) {
|
|
// Determine how much time has passed in the remainder of this line, and proceed.
|
|
const int target_read_cycles = std::min(342 - read_pointer_.column, read_cycles_pool);
|
|
int read_cycles_performed = 0;
|
|
uint32_t next_cram_value = 0;
|
|
|
|
while(read_cycles_performed < target_read_cycles) {
|
|
const uint32_t cram_value = next_cram_value;
|
|
next_cram_value = 0;
|
|
int read_cycles = target_read_cycles - read_cycles_performed;
|
|
if(!upcoming_cram_dots_.empty() && upcoming_cram_dots_.front().location.row == read_pointer_.row) {
|
|
int time_until_dot = upcoming_cram_dots_.front().location.column - read_pointer_.column;
|
|
|
|
if(time_until_dot < read_cycles) {
|
|
read_cycles = time_until_dot;
|
|
next_cram_value = upcoming_cram_dots_.front().value;
|
|
upcoming_cram_dots_.erase(upcoming_cram_dots_.begin());
|
|
}
|
|
}
|
|
|
|
if(!read_cycles) continue;
|
|
read_cycles_performed += read_cycles;
|
|
|
|
const int end_column = read_pointer_.column + read_cycles;
|
|
LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
|
|
|
|
|
|
// --------------------
|
|
// Output video stream.
|
|
// --------------------
|
|
|
|
#define intersect(left, right, code) { \
|
|
const int start = std::max(read_pointer_.column, left); \
|
|
const int end = std::min(end_column, right); \
|
|
if(end > start) {\
|
|
code;\
|
|
}\
|
|
}
|
|
|
|
#define border(left, right) intersect(left, right, output_border(end - start, cram_value))
|
|
|
|
if(line_buffer.line_mode == LineMode::Refresh || read_pointer_.row > mode_timing_.pixel_lines) {
|
|
if(read_pointer_.row >= mode_timing_.first_vsync_line && read_pointer_.row < mode_timing_.first_vsync_line+4) {
|
|
// Vertical sync.
|
|
if(end_column == 342) {
|
|
crt_.output_sync(342 * 4);
|
|
}
|
|
} else {
|
|
// Right border.
|
|
border(0, 15);
|
|
|
|
// Blanking region; total length is 58 cycles,
|
|
// and 58+15 = 73. So output the lot when the
|
|
// cursor passes 73.
|
|
if(read_pointer_.column < 73 && end_column >= 73) {
|
|
crt_.output_blank(8*4);
|
|
crt_.output_sync(26*4);
|
|
crt_.output_blank(2*4);
|
|
crt_.output_default_colour_burst(14*4);
|
|
crt_.output_blank(8*4);
|
|
}
|
|
|
|
// Border colour for the rest of the line.
|
|
border(73, 342);
|
|
}
|
|
} else {
|
|
// Right border.
|
|
border(0, 15);
|
|
|
|
// Blanking region.
|
|
if(read_pointer_.column < 73 && end_column >= 73) {
|
|
crt_.output_blank(8*4);
|
|
crt_.output_sync(26*4);
|
|
crt_.output_blank(2*4);
|
|
crt_.output_default_colour_burst(14*4);
|
|
crt_.output_blank(8*4);
|
|
}
|
|
|
|
// Left border.
|
|
border(73, line_buffer.first_pixel_output_column);
|
|
|
|
// Pixel region.
|
|
intersect(
|
|
line_buffer.first_pixel_output_column,
|
|
line_buffer.next_border_column,
|
|
if(!asked_for_write_area_) {
|
|
asked_for_write_area_ = true;
|
|
pixel_origin_ = pixel_target_ = reinterpret_cast<uint32_t *>(
|
|
crt_.begin_data(size_t(line_buffer.next_border_column - line_buffer.first_pixel_output_column))
|
|
);
|
|
}
|
|
|
|
if(pixel_target_) {
|
|
const int relative_start = start - line_buffer.first_pixel_output_column;
|
|
const int relative_end = end - line_buffer.first_pixel_output_column;
|
|
switch(line_buffer.line_mode) {
|
|
case LineMode::SMS: draw_sms(relative_start, relative_end, cram_value); break;
|
|
case LineMode::Character: draw_tms_character(relative_start, relative_end); break;
|
|
case LineMode::Text: draw_tms_text(relative_start, relative_end); break;
|
|
|
|
case LineMode::Refresh: break; /* Dealt with elsewhere. */
|
|
}
|
|
}
|
|
|
|
if(end == line_buffer.next_border_column) {
|
|
const int length = line_buffer.next_border_column - line_buffer.first_pixel_output_column;
|
|
crt_.output_data(length * 4, size_t(length));
|
|
pixel_origin_ = pixel_target_ = nullptr;
|
|
asked_for_write_area_ = false;
|
|
}
|
|
);
|
|
|
|
// Additional right border, if called for.
|
|
if(line_buffer.next_border_column != 342) {
|
|
border(line_buffer.next_border_column, 342);
|
|
}
|
|
}
|
|
|
|
#undef border
|
|
#undef intersect
|
|
|
|
|
|
|
|
// -------------
|
|
// Advance time.
|
|
// -------------
|
|
read_pointer_.column = end_column;
|
|
}
|
|
|
|
read_cycles_pool -= target_read_cycles;
|
|
if(read_pointer_.column == 342) {
|
|
read_pointer_.column = 0;
|
|
read_pointer_.row = (read_pointer_.row + 1) % mode_timing_.total_lines;
|
|
}
|
|
}
|
|
|
|
assert(backup.row == write_pointer_.row && backup.column == write_pointer_.column);
|
|
}
|
|
}
|
|
|
|
void Base::output_border(int cycles, uint32_t cram_dot) {
|
|
cycles *= 4;
|
|
uint32_t border_colour =
|
|
is_sega_vdp(personality_) ?
|
|
master_system_.colour_ram[16 + background_colour_] :
|
|
palette[background_colour_];
|
|
|
|
if(cram_dot) {
|
|
uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_.begin_data(1));
|
|
if(pixel_target) {
|
|
*pixel_target = border_colour | cram_dot;
|
|
}
|
|
crt_.output_level(4);
|
|
cycles -= 4;
|
|
}
|
|
|
|
if(cycles) {
|
|
// If the border colour is 0, that can be communicated
|
|
// more efficiently as an explicit blank.
|
|
if(border_colour) {
|
|
uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_.begin_data(1));
|
|
if(pixel_target) {
|
|
*pixel_target = border_colour;
|
|
}
|
|
crt_.output_level(cycles);
|
|
} else {
|
|
crt_.output_blank(cycles);
|
|
}
|
|
}
|
|
}
|
|
|
|
void TMS9918::write(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;
|
|
|
|
// Enqueue the write to occur at the next available slot.
|
|
read_ahead_buffer_ = value;
|
|
queued_access_ = MemoryAccess::Write;
|
|
cycles_until_access_ = vram_access_delay();
|
|
|
|
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;
|
|
|
|
// The initial write should half update the access pointer.
|
|
ram_pointer_ = (ram_pointer_ & 0xff00) | low_write_;
|
|
return;
|
|
}
|
|
|
|
// The RAM pointer is always set on a second write, regardless of
|
|
// whether the caller is intending to enqueue a VDP operation.
|
|
ram_pointer_ = (ram_pointer_ & 0x00ff) | static_cast<uint16_t>(value << 8);
|
|
|
|
write_phase_ = false;
|
|
if(value & 0x80) {
|
|
if(is_sega_vdp(personality_)) {
|
|
if(value & 0x40) {
|
|
master_system_.cram_is_selected = true;
|
|
return;
|
|
}
|
|
value &= 0xf;
|
|
} else {
|
|
value &= 0x7;
|
|
}
|
|
|
|
// This is a write to a register.
|
|
switch(value) {
|
|
case 0:
|
|
if(is_sega_vdp(personality_)) {
|
|
master_system_.vertical_scroll_lock = !!(low_write_ & 0x80);
|
|
master_system_.horizontal_scroll_lock = !!(low_write_ & 0x40);
|
|
master_system_.hide_left_column = !!(low_write_ & 0x20);
|
|
enable_line_interrupts_ = !!(low_write_ & 0x10);
|
|
master_system_.shift_sprites_8px_left = !!(low_write_ & 0x08);
|
|
master_system_.mode4_enable = !!(low_write_ & 0x04);
|
|
}
|
|
mode2_enable_ = !!(low_write_ & 0x02);
|
|
break;
|
|
|
|
case 1:
|
|
blank_display_ = !(low_write_ & 0x40);
|
|
generate_interrupts_ = !!(low_write_ & 0x20);
|
|
mode1_enable_ = !!(low_write_ & 0x10);
|
|
mode3_enable_ = !!(low_write_ & 0x08);
|
|
sprites_16x16_ = !!(low_write_ & 0x02);
|
|
sprites_magnified_ = !!(low_write_ & 0x01);
|
|
|
|
sprite_height_ = 8;
|
|
if(sprites_16x16_) sprite_height_ <<= 1;
|
|
if(sprites_magnified_) sprite_height_ <<= 1;
|
|
break;
|
|
|
|
case 2:
|
|
pattern_name_address_ = size_t((low_write_ & 0xf) << 10) | 0x3ff;
|
|
master_system_.pattern_name_address = pattern_name_address_ | ((personality_ == TMS::SMSVDP) ? 0x000 : 0x400);
|
|
break;
|
|
|
|
case 3:
|
|
colour_table_address_ = size_t(low_write_ << 6) | 0x3f;
|
|
break;
|
|
|
|
case 4:
|
|
pattern_generator_table_address_ = size_t((low_write_ & 0x07) << 11) | 0x7ff;
|
|
break;
|
|
|
|
case 5:
|
|
sprite_attribute_table_address_ = size_t((low_write_ & 0x7f) << 7) | 0x7f;
|
|
master_system_.sprite_attribute_table_address = sprite_attribute_table_address_ | ((personality_ == TMS::SMSVDP) ? 0x00 : 0x80);
|
|
break;
|
|
|
|
case 6:
|
|
sprite_generator_table_address_ = size_t((low_write_ & 0x07) << 11) | 0x7ff;
|
|
master_system_.sprite_generator_table_address = sprite_generator_table_address_ | ((personality_ == TMS::SMSVDP) ? 0x0000 : 0x1800);
|
|
break;
|
|
|
|
case 7:
|
|
text_colour_ = low_write_ >> 4;
|
|
background_colour_ = low_write_ & 0xf;
|
|
break;
|
|
|
|
case 8:
|
|
if(is_sega_vdp(personality_)) {
|
|
master_system_.horizontal_scroll = low_write_;
|
|
}
|
|
break;
|
|
|
|
case 9:
|
|
if(is_sega_vdp(personality_)) {
|
|
master_system_.vertical_scroll = low_write_;
|
|
}
|
|
break;
|
|
|
|
case 10:
|
|
if(is_sega_vdp(personality_)) {
|
|
line_interrupt_target = low_write_;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
LOG("Unknown TMS write: " << int(low_write_) << " to " << int(value));
|
|
break;
|
|
}
|
|
} else {
|
|
// This is an access via the RAM pointer.
|
|
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;
|
|
cycles_until_access_ = vram_access_delay();
|
|
}
|
|
master_system_.cram_is_selected = false;
|
|
}
|
|
}
|
|
|
|
uint8_t TMS9918::get_current_line() {
|
|
// Determine the row to return.
|
|
constexpr int row_change_position = 63; // This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
|
|
int source_row =
|
|
(write_pointer_.column < row_change_position)
|
|
? (write_pointer_.row + mode_timing_.total_lines - 1)%mode_timing_.total_lines
|
|
: write_pointer_.row;
|
|
|
|
if(tv_standard_ == TVStandard::NTSC) {
|
|
if(mode_timing_.pixel_lines == 240) {
|
|
// NTSC 256x240: 00-FF, 00-06
|
|
} else if(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(mode_timing_.pixel_lines == 240) {
|
|
// PAL 256x240: 00-FF, 00-0A, D2-FF
|
|
if(source_row >= 267) source_row -= 0x39;
|
|
} else if(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 static_cast<uint8_t>(source_row);
|
|
}
|
|
|
|
uint8_t TMS9918::get_latched_horizontal_counter() {
|
|
// Translate from internal numbering, which puts pixel output
|
|
// in the final 256 pixels of 342, to the public numbering,
|
|
// which makes the 256 pixels the first 256 spots, but starts
|
|
// counting at -48, and returns only the top 8 bits of the number.
|
|
int public_counter = latched_column_ - 86;
|
|
if(public_counter < -46) public_counter += 342;
|
|
return uint8_t(public_counter >> 1);
|
|
}
|
|
|
|
void TMS9918::latch_horizontal_counter() {
|
|
latched_column_ = write_pointer_.column;
|
|
}
|
|
|
|
uint8_t TMS9918::read(int address) {
|
|
write_phase_ = false;
|
|
|
|
// Reads from address 0 read video RAM, via the read-ahead buffer.
|
|
if(!(address & 1)) {
|
|
// Enqueue the write to occur at the next available slot.
|
|
uint8_t result = read_ahead_buffer_;
|
|
queued_access_ = MemoryAccess::Read;
|
|
return result;
|
|
}
|
|
|
|
// Reads from address 1 get the status register.
|
|
uint8_t result = status_;
|
|
status_ &= ~(StatusInterrupt | StatusSpriteOverflow | StatusSpriteCollision);
|
|
line_interrupt_pending_ = false;
|
|
return result;
|
|
}
|
|
|
|
HalfCycles Base::half_cycles_before_internal_cycles(int internal_cycles) {
|
|
return HalfCycles(((internal_cycles << 2) + (2 - cycles_error_)) / 3);
|
|
}
|
|
|
|
HalfCycles TMS9918::get_time_until_interrupt() {
|
|
if(!generate_interrupts_ && !enable_line_interrupts_) return HalfCycles(-1);
|
|
if(get_interrupt_line()) return HalfCycles(0);
|
|
|
|
// Calculate the amount of time until the next end-of-frame interrupt.
|
|
const int frame_length = 342 * mode_timing_.total_lines;
|
|
int time_until_frame_interrupt =
|
|
(
|
|
((mode_timing_.end_of_frame_interrupt_position.row * 342) + mode_timing_.end_of_frame_interrupt_position.column + frame_length) -
|
|
((write_pointer_.row * 342) + write_pointer_.column)
|
|
) % frame_length;
|
|
if(!time_until_frame_interrupt) time_until_frame_interrupt = frame_length;
|
|
|
|
if(!enable_line_interrupts_) return 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 = mode_timing_.line_interrupt_position - write_pointer_.column;
|
|
int line_of_next_interrupt_threshold = write_pointer_.row;
|
|
if(cycles_to_next_interrupt_threshold <= 0) {
|
|
cycles_to_next_interrupt_threshold += 342;
|
|
++line_of_next_interrupt_threshold;
|
|
}
|
|
|
|
if(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 + line_interrupt_counter <= mode_timing_.pixel_lines) {
|
|
next_line_interrupt_row = line_of_next_interrupt_threshold + line_interrupt_counter;
|
|
} else {
|
|
if(line_interrupt_target <= mode_timing_.pixel_lines)
|
|
next_line_interrupt_row = mode_timing_.total_lines + line_interrupt_target;
|
|
}
|
|
}
|
|
|
|
// 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 generate_interrupts_ ?
|
|
half_cycles_before_internal_cycles(time_until_frame_interrupt) :
|
|
HalfCycles(-1);
|
|
}
|
|
|
|
// 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 local_cycles_until_line_interrupt = cycles_to_next_interrupt_threshold + (next_line_interrupt_row - line_of_next_interrupt_threshold) * 342;
|
|
if(!generate_interrupts_) return half_cycles_before_internal_cycles(local_cycles_until_line_interrupt);
|
|
|
|
// Return whichever interrupt is closer.
|
|
return half_cycles_before_internal_cycles(std::min(local_cycles_until_line_interrupt, time_until_frame_interrupt));
|
|
}
|
|
|
|
HalfCycles TMS9918::get_time_until_line(int line) {
|
|
if(line < 0) line += mode_timing_.total_lines;
|
|
|
|
int cycles_to_next_interrupt_threshold = mode_timing_.line_interrupt_position - write_pointer_.column;
|
|
int line_of_next_interrupt_threshold = write_pointer_.row;
|
|
if(cycles_to_next_interrupt_threshold <= 0) {
|
|
cycles_to_next_interrupt_threshold += 342;
|
|
++line_of_next_interrupt_threshold;
|
|
}
|
|
|
|
if(line_of_next_interrupt_threshold > line) {
|
|
line += mode_timing_.total_lines;
|
|
}
|
|
|
|
return half_cycles_before_internal_cycles(cycles_to_next_interrupt_threshold + (line - line_of_next_interrupt_threshold)*342);
|
|
}
|
|
|
|
bool TMS9918::get_interrupt_line() {
|
|
return ((status_ & StatusInterrupt) && generate_interrupts_) || (enable_line_interrupts_ && line_interrupt_pending_);
|
|
}
|
|
|
|
// MARK: -
|
|
|
|
void Base::draw_tms_character(int start, int end) {
|
|
LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
|
|
|
|
// Paint the background tiles.
|
|
const int pixels_left = end - start;
|
|
if(screen_mode_ == ScreenMode::MultiColour) {
|
|
for(int c = start; c < end; ++c) {
|
|
pixel_target_[c] = palette[
|
|
(line_buffer.patterns[c >> 3][0] >> (((c & 4)^4))) & 15
|
|
];
|
|
}
|
|
} else {
|
|
const int shift = start & 7;
|
|
int byte_column = start >> 3;
|
|
|
|
int length = std::min(pixels_left, 8 - shift);
|
|
|
|
int pattern = reverse_table.map[line_buffer.patterns[byte_column][0]] >> shift;
|
|
uint8_t colour = line_buffer.patterns[byte_column][1];
|
|
uint32_t colours[2] = {
|
|
palette[(colour & 15) ? (colour & 15) : background_colour_],
|
|
palette[(colour >> 4) ? (colour >> 4) : background_colour_]
|
|
};
|
|
|
|
int background_pixels_left = pixels_left;
|
|
while(true) {
|
|
background_pixels_left -= length;
|
|
for(int c = 0; c < length; ++c) {
|
|
pixel_target_[c] = colours[pattern&0x01];
|
|
pattern >>= 1;
|
|
}
|
|
pixel_target_ += length;
|
|
|
|
if(!background_pixels_left) break;
|
|
length = std::min(8, background_pixels_left);
|
|
byte_column++;
|
|
|
|
pattern = reverse_table.map[line_buffer.patterns[byte_column][0]];
|
|
colour = line_buffer.patterns[byte_column][1];
|
|
colours[0] = palette[(colour & 15) ? (colour & 15) : background_colour_];
|
|
colours[1] = palette[(colour >> 4) ? (colour >> 4) : background_colour_];
|
|
}
|
|
}
|
|
|
|
// Paint sprites and check for collisions, but only if at least one sprite is active
|
|
// on this line.
|
|
if(line_buffer.active_sprite_slot) {
|
|
const int shift_advance = sprites_magnified_ ? 1 : 2;
|
|
// If this is the start of the line clip any part of any sprites that is off to the left.
|
|
if(!start) {
|
|
for(int index = 0; index < line_buffer.active_sprite_slot; ++index) {
|
|
LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
|
|
if(sprite.x < 0) sprite.shift_position -= shift_advance * sprite.x;
|
|
}
|
|
}
|
|
|
|
int sprite_buffer[256];
|
|
int sprite_collision = 0;
|
|
memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
|
|
|
|
constexpr uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
|
|
constexpr int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
|
|
|
|
// Draw all sprites into the sprite buffer.
|
|
const int shifter_target = sprites_16x16_ ? 32 : 16;
|
|
for(int index = line_buffer.active_sprite_slot - 1; index >= 0; --index) {
|
|
LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
|
|
if(sprite.shift_position < shifter_target) {
|
|
const int pixel_start = std::max(start, sprite.x);
|
|
for(int c = pixel_start; c < end && sprite.shift_position < shifter_target; ++c) {
|
|
const int shift = (sprite.shift_position >> 1) ^ 7;
|
|
int sprite_colour = (sprite.image[shift >> 3] >> (shift & 7)) & 1;
|
|
|
|
// A colision is detected regardless of sprite colour ...
|
|
sprite_collision |= sprite_buffer[c] & sprite_colour;
|
|
sprite_buffer[c] |= sprite_colour;
|
|
|
|
// ... but a sprite with the transparent colour won't actually be visible.
|
|
sprite_colour &= colour_masks[sprite.image[2]&15];
|
|
pixel_origin_[c] =
|
|
(pixel_origin_[c] & sprite_colour_selection_masks[sprite_colour^1]) |
|
|
(palette[sprite.image[2]&15] & sprite_colour_selection_masks[sprite_colour]);
|
|
|
|
sprite.shift_position += shift_advance;
|
|
}
|
|
}
|
|
}
|
|
|
|
status_ |= sprite_collision << StatusSpriteCollisionShift;
|
|
}
|
|
}
|
|
|
|
void Base::draw_tms_text(int start, int end) {
|
|
LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
|
|
const uint32_t colours[2] = { palette[background_colour_], palette[text_colour_] };
|
|
|
|
const int shift = start % 6;
|
|
int byte_column = start / 6;
|
|
int pattern = reverse_table.map[line_buffer.patterns[byte_column][0]] >> shift;
|
|
int pixels_left = end - start;
|
|
int length = std::min(pixels_left, 6 - shift);
|
|
while(true) {
|
|
pixels_left -= length;
|
|
for(int c = 0; c < length; ++c) {
|
|
pixel_target_[c] = colours[pattern&0x01];
|
|
pattern >>= 1;
|
|
}
|
|
pixel_target_ += length;
|
|
|
|
if(!pixels_left) break;
|
|
length = std::min(6, pixels_left);
|
|
byte_column++;
|
|
pattern = reverse_table.map[line_buffer.patterns[byte_column][0]];
|
|
}
|
|
}
|
|
|
|
void Base::draw_sms(int start, int end, uint32_t cram_dot) {
|
|
LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
|
|
int colour_buffer[256];
|
|
|
|
/*
|
|
Add extra border for any pixels that fall before the fine scroll.
|
|
*/
|
|
int tile_start = start, tile_end = end;
|
|
int tile_offset = start;
|
|
if(read_pointer_.row >= 16 || !master_system_.horizontal_scroll_lock) {
|
|
for(int c = start; c < (line_buffer.latched_horizontal_scroll & 7); ++c) {
|
|
colour_buffer[c] = 16 + background_colour_;
|
|
++tile_offset;
|
|
}
|
|
|
|
// Remove the border area from that to which tiles will be drawn.
|
|
tile_start = std::max(start - (line_buffer.latched_horizontal_scroll & 7), 0);
|
|
tile_end = std::max(end - (line_buffer.latched_horizontal_scroll & 7), 0);
|
|
}
|
|
|
|
|
|
uint32_t pattern;
|
|
uint8_t *const pattern_index = reinterpret_cast<uint8_t *>(&pattern);
|
|
|
|
/*
|
|
Add background tiles; these will fill the colour_buffer with values in which
|
|
the low five bits are a palette index, and bit six is set if this tile has
|
|
priority over sprites.
|
|
*/
|
|
if(tile_start < end) {
|
|
const int shift = tile_start & 7;
|
|
int byte_column = tile_start >> 3;
|
|
int pixels_left = tile_end - tile_start;
|
|
int length = std::min(pixels_left, 8 - shift);
|
|
|
|
pattern = *reinterpret_cast<const uint32_t *>(line_buffer.patterns[byte_column]);
|
|
if(line_buffer.names[byte_column].flags&2)
|
|
pattern >>= shift;
|
|
else
|
|
pattern <<= shift;
|
|
|
|
while(true) {
|
|
const int palette_offset = (line_buffer.names[byte_column].flags&0x18) << 1;
|
|
if(line_buffer.names[byte_column].flags&2) {
|
|
for(int c = 0; c < length; ++c) {
|
|
colour_buffer[tile_offset] =
|
|
((pattern_index[3] & 0x01) << 3) |
|
|
((pattern_index[2] & 0x01) << 2) |
|
|
((pattern_index[1] & 0x01) << 1) |
|
|
((pattern_index[0] & 0x01) << 0) |
|
|
palette_offset;
|
|
++tile_offset;
|
|
pattern >>= 1;
|
|
}
|
|
} else {
|
|
for(int c = 0; c < length; ++c) {
|
|
colour_buffer[tile_offset] =
|
|
((pattern_index[3] & 0x80) >> 4) |
|
|
((pattern_index[2] & 0x80) >> 5) |
|
|
((pattern_index[1] & 0x80) >> 6) |
|
|
((pattern_index[0] & 0x80) >> 7) |
|
|
palette_offset;
|
|
++tile_offset;
|
|
pattern <<= 1;
|
|
}
|
|
}
|
|
|
|
pixels_left -= length;
|
|
if(!pixels_left) break;
|
|
|
|
length = std::min(8, pixels_left);
|
|
byte_column++;
|
|
pattern = *reinterpret_cast<const uint32_t *>(line_buffer.patterns[byte_column]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
Apply sprites (if any).
|
|
*/
|
|
if(line_buffer.active_sprite_slot) {
|
|
const int shift_advance = sprites_magnified_ ? 1 : 2;
|
|
|
|
// If this is the start of the line clip any part of any sprites that is off to the left.
|
|
if(!start) {
|
|
for(int index = 0; index < line_buffer.active_sprite_slot; ++index) {
|
|
LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
|
|
if(sprite.x < 0) sprite.shift_position -= shift_advance * sprite.x;
|
|
}
|
|
}
|
|
|
|
int sprite_buffer[256];
|
|
int sprite_collision = 0;
|
|
memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
|
|
|
|
// Draw all sprites into the sprite buffer.
|
|
for(int index = line_buffer.active_sprite_slot - 1; index >= 0; --index) {
|
|
LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
|
|
if(sprite.shift_position < 16) {
|
|
const int pixel_start = std::max(start, sprite.x);
|
|
|
|
// TODO: it feels like the work below should be simplifiable;
|
|
// the double shift in particular, and hopefully the variable shift.
|
|
for(int c = pixel_start; c < end && sprite.shift_position < 16; ++c) {
|
|
const int shift = (sprite.shift_position >> 1);
|
|
const int sprite_colour =
|
|
(((sprite.image[3] << shift) & 0x80) >> 4) |
|
|
(((sprite.image[2] << shift) & 0x80) >> 5) |
|
|
(((sprite.image[1] << shift) & 0x80) >> 6) |
|
|
(((sprite.image[0] << shift) & 0x80) >> 7);
|
|
|
|
if(sprite_colour) {
|
|
sprite_collision |= sprite_buffer[c];
|
|
sprite_buffer[c] = sprite_colour | 0x10;
|
|
}
|
|
|
|
sprite.shift_position += shift_advance;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Draw the sprite buffer onto the colour buffer, wherever the tile map doesn't have
|
|
// priority (or is transparent).
|
|
for(int c = start; c < end; ++c) {
|
|
if(
|
|
sprite_buffer[c] &&
|
|
(!(colour_buffer[c]&0x20) || !(colour_buffer[c]&0xf))
|
|
) colour_buffer[c] = sprite_buffer[c];
|
|
}
|
|
|
|
if(sprite_collision)
|
|
status_ |= StatusSpriteCollision;
|
|
}
|
|
|
|
// Map from the 32-colour buffer to real output pixels, applying the specific CRAM dot if any.
|
|
pixel_target_[start] = master_system_.colour_ram[colour_buffer[start] & 0x1f] | cram_dot;
|
|
for(int c = start+1; c < end; ++c) {
|
|
pixel_target_[c] = master_system_.colour_ram[colour_buffer[c] & 0x1f];
|
|
}
|
|
|
|
// If the VDP is set to hide the left column and this is the final call that'll come
|
|
// this line, hide it.
|
|
if(end == 256) {
|
|
if(master_system_.hide_left_column) {
|
|
pixel_origin_[0] = pixel_origin_[1] = pixel_origin_[2] = pixel_origin_[3] =
|
|
pixel_origin_[4] = pixel_origin_[5] = pixel_origin_[6] = pixel_origin_[7] =
|
|
master_system_.colour_ram[16 + background_colour_];
|
|
}
|
|
}
|
|
}
|