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CLK/Components/9918/9918.cpp

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//
// 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>
using namespace TI::TMS;
namespace {
const uint8_t StatusInterrupt = 0x80;
const uint8_t StatusSpriteOverflow = 0x40;
const int StatusSpriteCollisionShift = 5;
const uint8_t StatusSpriteCollision = 0x20;
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),
// 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.
crt_(new Outputs::CRT::CRT(1365, 4, Outputs::CRT::DisplayType::NTSC60, 4)) {
switch(p) {
case TI::TMS::TMS9918A:
case TI::TMS::SMSVDP:
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 = 65;
mode_timing_.end_of_frame_interrupt_position.column = 63;
mode_timing_.end_of_frame_interrupt_position.row = 193;
}
}
TMS9918::TMS9918(Personality p):
Base(p) {
// Unimaginatively, this class just passes RGB through to the shader. Investigation is needed
// into whether there's a more natural form.
crt_->set_rgb_sampling_function(
"vec3 rgb_sample(usampler2D sampler, vec2 coordinate)"
"{"
"return texture(sampler, coordinate).rgb / vec3(255.0);"
"}");
crt_->set_video_signal(Outputs::CRT::VideoSignal::RGB);
crt_->set_visible_area(Outputs::CRT::Rect(0.055f, 0.025f, 0.9f, 0.9f));
crt_->set_input_gamma(2.8f);
// 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);
}
Outputs::CRT::CRT *TMS9918::get_crt() {
return crt_.get();
}
void Base::reset_sprite_collection() {
sprite_set_.sprites_stopped = false;
sprite_set_.fetched_sprite_slot = sprite_set_.active_sprite_slot;
sprite_set_.active_sprite_slot = 0;
for(int c = 0; c < sprite_set_.fetched_sprite_slot; ++c) {
sprite_set_.active_sprites[c].shift_position = 0;
}
}
void Base::posit_sprite(int sprite_number, int sprite_position, int screen_row) {
if(!(status_ & StatusSpriteOverflow)) {
status_ = static_cast<uint8_t>((status_ & ~0x1f) | (sprite_number & 0x1f));
}
if(sprite_set_.sprites_stopped)
return;
// const int sprite_position = ram_[sprite_attribute_table_address_ + static_cast<size_t>(sprite_number << 2)];
// A sprite Y of 208 means "don't scan the list any further".
if(mode_timing_.allow_sprite_terminator && sprite_position == 208) {
sprite_set_.sprites_stopped = true;
return;
}
const int sprite_row = (screen_row - sprite_position)&255;
if(sprite_row < 0 || sprite_row >= sprite_height_) return;
if(sprite_set_.active_sprite_slot == mode_timing_.maximum_visible_sprites) {
status_ |= StatusSpriteOverflow;
return;
}
SpriteSet::ActiveSprite &sprite = sprite_set_.active_sprites[sprite_set_.active_sprite_slot];
sprite.index = sprite_number;
sprite.row = sprite_row >> (sprites_magnified_ ? 1 : 0);
++sprite_set_.active_sprite_slot;
}
void Base::get_sprite_contents(int field, int cycles_left, int screen_row) {
/* int sprite_id = field / 6;
field %= 6;
while(true) {
const int cycles_in_sprite = std::min(cycles_left, 6 - field);
cycles_left -= cycles_in_sprite;
const int final_field = cycles_in_sprite + field;
assert(sprite_id < 4);
SpriteSet::ActiveSprite &sprite = sprite_sets_[active_sprite_set_].active_sprites[sprite_id];
if(field < 4) {
std::memcpy(
&sprite.info[field],
&ram_[sprite_attribute_table_address_ + static_cast<size_t>((sprite.index << 2) + field)],
static_cast<size_t>(std::min(4, final_field) - field));
}
field = std::min(4, final_field);
const int sprite_offset = sprite.info[2] & ~(sprites_16x16_ ? 3 : 0);
const size_t sprite_address = sprite_generator_table_address_ + static_cast<size_t>(sprite_offset << 3) + sprite.row; // TODO: recalclate sprite.row from screen_row (?)
while(field < final_field) {
sprite.image[field - 4] = ram_[sprite_address + static_cast<size_t>(((field - 4) << 4))];
field++;
}
if(!cycles_left) return;
field = 0;
sprite_id++;
}*/
}
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 = (cycles.as_int() * 3) + cycles_error_;
cycles_error_ = int_cycles & 3;
int_cycles >>= 2;
if(!int_cycles) return;
while(int_cycles) {
// Determine how much time has passed in the remainder of this line, and proceed.
const int cycles_left = std::min(342 - column_, int_cycles);
const int end_column = column_ + cycles_left;
// ---------------------------------------
// Latch scrolling position, if necessary.
// ---------------------------------------
if(column_ < 61 && end_column >= 61) {
if(!row_) {
master_system_.latched_vertical_scroll = master_system_.vertical_scroll;
}
master_system_.latched_horizontal_scroll = master_system_.horizontal_scroll;
}
// ------------------------
// Perform memory accesses.
// ------------------------
#define fetch(function) \
if(end_column < 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 = column_ >> 1;
const int final_window = end_column >> 1;
if(first_window != final_window) {
switch(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
// --------------------
// Output video stream.
// --------------------
#define intersect(left, right, code) \
{ \
const int start = std::max(column_, left); \
const int end = std::min(end_column, right); \
if(end > start) {\
code;\
}\
}
if(line_mode_ == LineMode::Refresh || row_ > mode_timing_.pixel_lines) {
if(row_ >= mode_timing_.first_vsync_line && row_ < mode_timing_.first_vsync_line+4) {
// Vertical sync.
if(end_column == 342) {
crt_->output_sync(342 * 4);
}
} else {
// Right border.
intersect(0, 15, output_border(end - start));
// Blanking region.
if(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);
}
// Most of line.
intersect(73, 342, output_border(end - start));
}
} else {
// Right border.
intersect(0, 15, output_border(end - start));
// Blanking region.
if(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.
intersect(73, mode_timing_.first_pixel_output_column, output_border(end - start));
// Pixel region.
intersect(
mode_timing_.first_pixel_output_column,
mode_timing_.next_border_column,
if(start == mode_timing_.first_pixel_output_column) {
pixel_origin_ = pixel_target_ = reinterpret_cast<uint32_t *>(
crt_->allocate_write_area(static_cast<unsigned int>(mode_timing_.next_border_column - mode_timing_.first_pixel_output_column) + 8) // TODO: the +8 is really for the SMS only; make it optional.
);
}
if(pixel_target_) {
const int relative_start = start - mode_timing_.first_pixel_output_column;
const int relative_end = end - mode_timing_.first_pixel_output_column;
switch(line_mode_) {
case LineMode::SMS: draw_sms(relative_start, relative_end); 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 == mode_timing_.next_border_column) {
const unsigned int length = static_cast<unsigned int>(mode_timing_.next_border_column - mode_timing_.first_pixel_output_column);
crt_->output_data(length * 4, length);
pixel_origin_ = pixel_target_ = nullptr;
}
);
// Additional right border, if called for.
if(mode_timing_.next_border_column != 342) {
intersect(mode_timing_.next_border_column, 342, output_border(end - start));
}
}
#undef intersect
// -----------------
// End video stream.
// -----------------
// -------------------------------
// Check for interrupt conditions.
// -------------------------------
if(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(row_ >= 0 && 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(
row_ == mode_timing_.end_of_frame_interrupt_position.row &&
column_ < mode_timing_.end_of_frame_interrupt_position.column &&
end_column >= mode_timing_.end_of_frame_interrupt_position.column
) {
status_ |= StatusInterrupt;
}
// -------------
// Advance time.
// -------------
column_ = end_column; // column_ is now the column that has been reached in this line.
int_cycles -= cycles_left; // Count down duration to run for.
// -----------------------------------
// Prepare for next line, potentially.
// -----------------------------------
if(column_ == 342) {
column_ = 0;
row_ = (row_ + 1) % mode_timing_.total_lines;
// Establish the output mode for the next line.
set_current_mode();
// Based on the output mode, pick a line mode.
mode_timing_.first_pixel_output_column = 86;
mode_timing_.next_border_column = 342;
mode_timing_.maximum_visible_sprites = 4;
switch(screen_mode_) {
case ScreenMode::Text:
line_mode_ = LineMode::Text;
mode_timing_.first_pixel_output_column = 94;
mode_timing_.next_border_column = 334;
break;
case ScreenMode::SMSMode4:
line_mode_ = LineMode::SMS;
mode_timing_.maximum_visible_sprites = 8;
break;
default:
line_mode_ = LineMode::Character;
break;
}
if((screen_mode_ == ScreenMode::Blank) || (row_ >= mode_timing_.pixel_lines && row_ != mode_timing_.total_lines-1)) line_mode_ = LineMode::Refresh;
}
}
}
void Base::output_border(int cycles) {
uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(1));
if(pixel_target) {
if(is_sega_vdp(personality_)) {
*pixel_target = master_system_.colour_ram[16 + background_colour_];
} else {
*pixel_target = palette[background_colour_];
}
}
crt_->output_level(static_cast<unsigned int>(cycles) * 4);
}
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;
// Enqueue the write to occur at the next available slot.
read_ahead_buffer_ = value;
queued_access_ = MemoryAccess::Write;
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) {
switch(personality_) {
default:
value &= 0x7;
break;
case TI::TMS::SMSVDP:
if(value & 0x40) {
master_system_.cram_is_selected = true;
return;
}
value &= 0xf;
break;
}
// 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;
break;
case 3:
colour_table_address_ = size_t(low_write_ << 6) | 0x1f;
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;
break;
case 6:
sprite_generator_table_address_ = size_t((low_write_ & 0x07) << 11) | 0x7ff;
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_;
// printf("Set to %d at %d, %d\n", low_write_, row_, column_);
}
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:
// printf("Unknown TMS write: %d to %d\n", low_write_, 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;
}
master_system_.cram_is_selected = false;
}
}
uint8_t TMS9918::get_current_line() {
// Determine the row to return.
static const int row_change_position = 62; // This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
int source_row = (column_ < row_change_position) ? (row_ + mode_timing_.total_lines - 1)%mode_timing_.total_lines : row_;
// This assumes NTSC 192-line. TODO: other modes.
if(source_row >= 0xdb) source_row -= 6;
// printf("Current row: %d -> %d\n", row_, source_row);
return static_cast<uint8_t>(source_row);
/*
TODO: Full proper sequence of current lines:
NTSC 256x192 00-DA, D5-FF
NTSC 256x224 00-EA, E5-FF
NTSC 256x240 00-FF, 00-06
PAL 256x192 00-F2, BA-FF
PAL 256x224 00-FF, 00-02, CA-FF
PAL 256x240 00-FF, 00-0A, D2-FF
*/
}
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_ = column_;
}
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)) {
// 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) - 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;
const int time_until_frame_interrupt =
(
((mode_timing_.end_of_frame_interrupt_position.row * 342) + mode_timing_.end_of_frame_interrupt_position.column + frame_length) -
((row_ * 342) + column_)
) % frame_length;
if(!enable_line_interrupts_) return half_cycles_before_internal_cycles(time_until_frame_interrupt);
// Calculate the row upon which the next line interrupt will occur;
int next_line_interrupt_row = -1;
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(row_+line_interrupt_counter <= mode_timing_.pixel_lines) {
next_line_interrupt_row = row_+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.
int local_cycles_until_next_tick = (mode_timing_.line_interrupt_position - column_ + 342) % 342;
if(!local_cycles_until_next_tick) local_cycles_until_next_tick += 342;
const int local_cycles_until_line_interrupt = local_cycles_until_next_tick + (next_line_interrupt_row - row_) * 342;
if(!generate_interrupts_) return half_cycles_before_internal_cycles(time_until_frame_interrupt);
// Return whichever interrupt is closer.
return half_cycles_before_internal_cycles(std::min(local_cycles_until_line_interrupt, time_until_frame_interrupt));
}
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) {
// if(!start) printf("\n");
// printf("%d to %d | ", start, end);
// for(int c = start; c < end; ++c) {
// pixel_target_[c] = static_cast<uint32_t>(c * 0x01010101);
// }
/*
// --------------
// Output pixels.
// --------------
case LineMode::Character: {
// If this is the start of the visible area, seed sprite shifter positions.
SpriteSet &sprite_set = sprite_sets_[active_sprite_set_ ^ 1];
if(output_column_ == first_pixel_column_) {
int c = sprite_set.active_sprite_slot;
while(c--) {
SpriteSet::ActiveSprite &sprite = sprite_set.active_sprites[c];
sprite.shift_position = -sprite.info[1];
if(sprite.info[3] & 0x80) {
sprite.shift_position += 32;
if(sprite.shift_position > 0 && !sprites_magnified_)
sprite.shift_position *= 2;
}
}
}
// Paint the background tiles.
const int pixels_left = pixels_end - output_column_;
if(current_mode_ == ScreenMode::MultiColour) {
int pixel_location = output_column_ - first_pixel_column_;
for(int c = 0; c < pixels_left; ++c) {
pixel_target_[c] = palette[
(pattern_buffer_[(pixel_location + c) >> 3] >> (((pixel_location + c) & 4)^4)) & 15
];
}
pixel_target_ += pixels_left;
} else {
const int shift = (output_column_ - first_pixel_column_) & 7;
int byte_column = (output_column_ - first_pixel_column_) >> 3;
int length = std::min(pixels_left, 8 - shift);
int pattern = reverse_table.map[pattern_buffer_[byte_column]] >> shift;
uint8_t colour = colour_buffer_[byte_column];
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[pattern_buffer_[byte_column]];
colour = colour_buffer_[byte_column];
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(sprite_set.active_sprite_slot) {
int sprite_pixels_left = pixels_left;
const int shift_advance = sprites_magnified_ ? 1 : 2;
static const uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
static const int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
while(sprite_pixels_left--) {
// sprite_colour is the colour that's going to reach the display after sprite logic has been
// applied; by default assume that nothing is going to be drawn.
uint32_t sprite_colour = pixel_base_[output_column_ - first_pixel_column_];
// The sprite_mask is used to keep track of whether two sprites have both sought to output
// a pixel at the same location, and to feed that into the status register's sprite
// collision bit.
int sprite_mask = 0;
int c = sprite_set.active_sprite_slot;
while(c--) {
SpriteSet::ActiveSprite &sprite = sprite_set.active_sprites[c];
if(sprite.shift_position < 0) {
sprite.shift_position++;
continue;
} else if(sprite.shift_position < 32) {
int mask = sprite.image[sprite.shift_position >> 4] << ((sprite.shift_position&15) >> 1);
mask = (mask >> 7) & 1;
// Ignore the right half of whatever was collected if sprites are not in 16x16 mode.
if(sprite.shift_position < (sprites_16x16_ ? 32 : 16)) {
// If any previous sprite has been painted in this column and this sprite
// has this pixel set, set the sprite collision status bit.
status_ |= (mask & sprite_mask) << StatusSpriteCollisionShift;
sprite_mask |= mask;
// Check that the sprite colour is not transparent
mask &= colour_masks[sprite.info[3]&15];
sprite_colour = (sprite_colour & sprite_colour_selection_masks[mask^1]) | (palette[sprite.info[3]&15] & sprite_colour_selection_masks[mask]);
}
sprite.shift_position += shift_advance;
}
}
// Output whichever sprite colour was on top.
pixel_base_[output_column_ - first_pixel_column_] = sprite_colour;
output_column_++;
}
}
output_column_ = pixels_end;
} break;
}
}*/
}
void Base::draw_tms_text(int start, int end) {
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[pattern_buffer_[byte_column]] >> 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[pattern_buffer_[byte_column]];
}
}
void Base::draw_sms(int start, int end) {
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(row_ >= 16 || !master_system_.horizontal_scroll_lock) {
for(int c = start; c < (master_system_.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 - (master_system_.latched_horizontal_scroll & 7), 0);
tile_end = std::max(end - (master_system_.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<uint32_t *>(master_system_.tile_graphics[byte_column]);
if(master_system_.names[byte_column].flags&2)
pattern >>= shift;
else
pattern <<= shift;
while(true) {
const int palette_offset = (master_system_.names[byte_column].flags&0x18) << 1;
if(master_system_.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<uint32_t *>(master_system_.tile_graphics[byte_column]);
}
}
/*
Apply sprites (if any).
*/
if(sprite_set_.fetched_sprite_slot) {
int sprite_buffer[256];
int sprite_collision = 0;
memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(int));
// Draw all sprites into the sprite buffer.
for(int index = sprite_set_.fetched_sprite_slot - 1; index >= 0; --index) {
SpriteSet::ActiveSprite &sprite = sprite_set_.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 += sprites_magnified_ ? 1 : 2;
}
}
}
// 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.
for(int c = start; 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_];
}
}
}
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