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Attempted to reintroduce enough logic to handle [most of] line timing, such that WSYNC works. Initial objective is to get back to having a working background.

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This commit is contained in:
Thomas Harte 2017-01-29 13:47:36 -05:00
parent fba6baaa9c
commit 9c3597c7e3
2 changed files with 42 additions and 2 deletions
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40
Machines/Atari2600/TIA.cpp
View File

@ -9,8 +9,14 @@
#include "TIA.hpp"
using namespace Atari2600;
namespace {
const int cycles_per_line = 228;
const double NTSC_clock_rate = 1194720;
const double PAL_clock_rate = 1182298;
}
TIA::TIA()
TIA::TIA() :
horizontal_counter_(0)
{
/*
crt_.reset(new Outputs::CRT::CRT(228, 1, 263, Outputs::CRT::ColourSpace::YIQ, 228, 1, false, 1));
@ -64,6 +70,28 @@ TIA::~TIA()
void TIA::run_for_cycles(int number_of_cycles)
{
// if part way through a line, definitely perform a partial, at most up to the end of the line
if(horizontal_counter_)
{
int cycles = std::min(number_of_cycles, cycles_per_line - horizontal_counter_);
output_for_cycles(cycles);
horizontal_counter_ = (horizontal_counter_ + cycles) % cycles_per_line;
number_of_cycles -= cycles;
}
// output full lines for as long as possible
while(number_of_cycles > cycles_per_line)
{
output_line();
number_of_cycles -= cycles_per_line;
}
// partly start a new line if necessary
if(number_of_cycles)
{
output_for_cycles(number_of_cycles);
horizontal_counter_ = (horizontal_counter_ + number_of_cycles) % cycles_per_line;
}
}
void TIA::set_vsync(bool vsync)
@ -80,7 +108,7 @@ void TIA::reset_horizontal_counter()
int TIA::get_cycles_until_horizontal_blank(unsigned int from_offset)
{
return 10;
return cycles_per_line - (horizontal_counter_ + (int)from_offset) % cycles_per_line;
}
void TIA::set_background_colour(uint8_t colour)
@ -175,3 +203,11 @@ uint8_t TIA::get_collision_flags(int offset)
void TIA::clear_collision_flags()
{
}
void TIA::output_for_cycles(int number_of_cycles)
{
}
void TIA::output_line()
{
}

4
Machines/Atari2600/TIA.hpp
View File

@ -61,6 +61,10 @@ class TIA {
private:
std::shared_ptr<Outputs::CRT::CRT> crt_;
int horizontal_counter_;
void output_for_cycles(int number_of_cycles);
void output_line();
};
}