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Adds a first attempt at CRAM dot output. With a TODO.

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This commit is contained in:
Thomas Harte 2018-10-26 19:26:46 -04:00
parent 916710353a
commit 521d603902
2 changed files with 116 additions and 88 deletions
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58
Components/9918/9918.cpp
View File

@ -93,7 +93,6 @@ TMS9918::TMS9918(Personality p):
"}");
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
@ -321,16 +320,31 @@ void TMS9918::run_for(const HalfCycles cycles) {
if(read_cycles_pool) {
// Determine how much time has passed in the remainder of this line, and proceed.
const int read_cycles = std::min(342 - read_pointer_.column, read_cycles_pool);
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];
// TODO: actually perform these dots, at least in part by further subdividing
// the period to run for.
upcoming_cram_dots_.clear();
// --------------------
// Output video stream.
// --------------------
@ -344,7 +358,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
}\
}
#define border(left, right) intersect(left, right, output_border(end - start))
#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) {
@ -401,7 +415,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
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, 0); break;
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;
@ -432,8 +446,9 @@ void TMS9918::run_for(const HalfCycles cycles) {
// Advance time.
// -------------
read_pointer_.column = end_column;
read_cycles_pool -= read_cycles;
}
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;
@ -444,16 +459,25 @@ void TMS9918::run_for(const HalfCycles cycles) {
}
}
void Base::output_border(int cycles) {
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_->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_];
*pixel_target = border_colour | cram_dot;
crt_->output_level(4);
cycles -= 4;
}
if(cycles) {
uint32_t *const pixel_target = reinterpret_cast<uint32_t *>(crt_->allocate_write_area(1));
*pixel_target = border_colour;
crt_->output_level(static_cast<unsigned int>(cycles));
}
crt_->output_level(static_cast<unsigned int>(cycles) * 4);
}
void TMS9918::set_register(int address, uint8_t value) {

10
Components/9918/Implementation/9918Base.hpp
View File

@ -127,7 +127,7 @@ class Base {
// A helper function to output the current border colour for
// the number of cycles supplied.
void output_border(int cycles);
void output_border(int cycles, uint32_t cram_dot);
// A struct to contain timing information for the current mode.
struct {
@ -343,9 +343,13 @@ class Base {
// Schedule a CRAM dot.
upcoming_cram_dots_.emplace_back();
CRAMDot &dot = upcoming_cram_dots_.back();
dot.location.row = write_pointer_.row;
dot.location.column = access_column;
dot.location.row = write_pointer_.row + (access_column / 342);
dot.location.column = access_column % 342;
dot.value = master_system_.colour_ram[ram_pointer_ & 0x1f];
// TODO: the location should actually be slightly in the past, as
// output trails memory reading; expose the length of that gap
// somewhere that makes it visible to here and adjust.
} else {
ram_[ram_pointer_ & 16383] = read_ahead_buffer_;
}