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Merge pull request #486 from TomHarte/AppleIIEqualisation

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Ensures the Apple II retains horizontal sync for its entire display
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Thomas Harte 2018-06-24 11:27:57 -04:00 committed by GitHub
commit f72e260915
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1 changed files with 23 additions and 8 deletions
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31
Machines/AppleII/Video.hpp
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@ -82,17 +82,32 @@ template <class BusHandler> class Video: public VideoBase {
A frame is oriented around 65 cycles across, 262 lines down.
*/
const int first_sync_line = 220; // A complete guess. Information needed.
const int first_sync_column = 49; // Also a guess.
static const int first_sync_line = 220; // A complete guess. Information needed.
static const int first_sync_column = 49; // Also a guess.
static const int sync_length = 4; // One of the two likely candidates.
int int_cycles = cycles.as_int();
while(int_cycles) {
const int cycles_this_line = std::min(65 - column_, int_cycles);
const int ending_column = column_ + cycles_this_line;
if(row_ >= first_sync_line && row_ < first_sync_line + 3) {
crt_->output_sync(static_cast<unsigned int>(cycles_this_line) * 14);
// In effect apply an XOR to HSYNC and VSYNC flags in order to include equalising
// pulses (and hencce keep hsync approximately where it should be during vsync).
const int blank_start = std::max(first_sync_column - sync_length, column_);
const int blank_end = std::min(first_sync_column, ending_column);
if(blank_end > blank_start) {
if(blank_start > column_) {
crt_->output_sync(static_cast<unsigned int>(blank_start - column_) * 14);
}
crt_->output_blank(static_cast<unsigned int>(blank_end - blank_start) * 14);
if(blank_end < ending_column) {
crt_->output_sync(static_cast<unsigned int>(ending_column - blank_end) * 14);
}
} else {
crt_->output_sync(static_cast<unsigned int>(cycles_this_line) * 14);
}
} else {
const int ending_column = column_ + cycles_this_line;
const GraphicsMode line_mode = use_graphics_mode_ ? graphics_mode_ : GraphicsMode::Text;
// The first 40 columns are submitted to the CRT only upon completion;
@ -221,15 +236,15 @@ template <class BusHandler> class Video: public VideoBase {
}
const int sync_start = std::max(first_sync_column, column_);
const int sync_end = std::min(first_sync_column + 4, ending_column);
const int sync_end = std::min(first_sync_column + sync_length, ending_column);
if(sync_end > sync_start) {
crt_->output_sync(static_cast<unsigned int>(sync_end - sync_start) * 14);
}
int second_blank_start;
if(line_mode != GraphicsMode::Text && (!mixed_mode_ || row_ < 159 || row_ >= 192)) {
const int colour_burst_start = std::max(first_sync_column + 4, column_);
const int colour_burst_end = std::min(first_sync_column + 7, ending_column);
const int colour_burst_start = std::max(first_sync_column + sync_length + 1, column_);
const int colour_burst_end = std::min(first_sync_column + sync_length + 4, ending_column);
if(colour_burst_end > colour_burst_start) {
crt_->output_default_colour_burst(static_cast<unsigned int>(colour_burst_end - colour_burst_start) * 14);
}
@ -307,7 +322,7 @@ template <class BusHandler> class Video: public VideoBase {
static_cast<uint16_t>(((video_page_+1) * 0x400) + row_address);
}
const int flash_length = 8406;
static const int flash_length = 8406;
BusHandler &bus_handler_;
void output_data_to_column(int column) {
int length = column - pixel_pointer_column_;