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Merge pull request #631 from TomHarte/MacPageFlipping

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Removes the video and audio base address latches.
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Thomas Harte 2019-07-27 22:25:12 -04:00 committed by GitHub
commit cd49b3c89b
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2 changed files with 8 additions and 4 deletions
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1
Machines/Apple/Macintosh/Macintosh.cpp
View File

@ -405,6 +405,7 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
}
void set_use_alternate_buffers(bool use_alternate_screen_buffer, bool use_alternate_audio_buffer) {
update_video();
video_.set_use_alternate_buffers(use_alternate_screen_buffer, use_alternate_audio_buffer);
}

11
Machines/Apple/Macintosh/Video.cpp
View File

@ -49,6 +49,9 @@ void Video::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
}
void Video::run_for(HalfCycles duration) {
// Determine the current video and audio bases. These values don't appear to be latched, they apply immediately.
const size_t video_base = (use_alternate_screen_buffer_ ? (0xffff2700 >> 1) : (0xffffa700 >> 1)) & ram_mask_;
const size_t audio_base = (use_alternate_audio_buffer_ ? (0xffffa100 >> 1) : (0xfffffd00 >> 1)) & ram_mask_;
// The number of HalfCycles is literally the number of pixel clocks to move through,
// since pixel output occurs at twice the processor clock. So divide by 16 to get
@ -85,7 +88,7 @@ void Video::run_for(HalfCycles duration) {
if(pixel_buffer_) {
for(int c = first_word; c < final_pixel_word; ++c) {
uint16_t pixels = ram_[video_address_] ^ 0xffff;
uint16_t pixels = ram_[video_base + video_address_] ^ 0xffff;
++video_address_;
pixel_buffer_[15] = pixels & 0x01;
@ -135,7 +138,7 @@ void Video::run_for(HalfCycles duration) {
// Audio and disk fetches occur "just before video data".
if(final_word == 44) {
const uint16_t audio_word = ram_[audio_address_];
const uint16_t audio_word = ram_[audio_address_ + audio_base];
++audio_address_;
audio_.audio.post_sample(audio_word >> 8);
drive_speed_accumulator_.post_sample(audio_word & 0xff);
@ -149,13 +152,13 @@ void Video::run_for(HalfCycles duration) {
/*
Video: $1A700 and the alternate buffer starts at $12700; for a 512K Macintosh, add $60000 to these numbers.
*/
video_address_ = (use_alternate_screen_buffer_ ? (0xffff2700 >> 1) : (0xffffa700 >> 1)) & ram_mask_;
video_address_ = 0;
/*
"The main sound buffer is at $1FD00 in a 128K Macintosh, and the alternate buffer is at $1A100;
for a 512K Macintosh, add $60000 to these values."
*/
audio_address_ = (use_alternate_audio_buffer_ ? (0xffffa100 >> 1) : (0xfffffd00 >> 1)) & ram_mask_;
audio_address_ = 0;
}
}
}