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Update Master System horizontal counter.

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This commit is contained in:
Thomas Harte 2023-04-26 22:49:46 -04:00
parent b5d9586362
commit 6c0feeedb4
2 changed files with 5 additions and 6 deletions
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9
Components/9918/Implementation/9918.cpp
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@ -1322,15 +1322,12 @@ bool TMS9918<personality>::get_interrupt_line() const {
// 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, which puts pixel output
// in the final 256 pixels of 342, to the public numbering,
// 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_ - (342 - 256);
if(public_counter < -46) public_counter += 342;
int public_counter = this->latched_column_ - LineLayout<personality>::EndOfLeftBorder;
if(public_counter < -46) public_counter += Timing<personality>::CyclesPerLine;
return uint8_t(public_counter >> 1);
// TODO: above is no longer correct.
}
template <Personality personality>

2
Components/9918/Implementation/9918Base.hpp
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@ -172,6 +172,8 @@ template <Personality personality> struct Base: public Storage<personality> {
// Set the position, in cycles, of the two interrupts,
// within a line.
//
// TODO: redetermine where this number came from.
struct {
int column = 313;
int row = 192;