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Toggle vga 3DA value manually during text mode

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Fixes some infinite loops on some programs
This commit is contained in:
Ernest Wong 2018-01-14 19:10:04 +13:00 committed by Fabian
parent 1abb0895c8
commit 964691eaa5
1 changed files with 23 additions and 3 deletions
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26
src/vga.js
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@ -1954,10 +1954,25 @@ VGAScreen.prototype.port3DA_read = function()
{
dbg_log("3DA read - status 1 and clear attr index", LOG_VGA);
// status register, bit 3 set by update_vertical_retrace
var value = this.port_3DA_value;
this.port_3DA_value ^= 1;
this.port_3DA_value &= 1;
// Status register, bit 3 set by update_vertical_retrace
// during screen-fill-buffer
if(!this.graphical_mode)
{
// But screen-fill-buffer may not get triggered in text mode
// so toggle it manually here
if(this.port_3DA_value & 1)
{
this.port_3DA_value ^= 8;
}
this.port_3DA_value ^= 1;
}
else
{
this.port_3DA_value ^= 1;
this.port_3DA_value &= 1;
}
this.attribute_controller_index = -1;
return value;
};
@ -2329,12 +2344,17 @@ VGAScreen.prototype.screen_fill_buffer = function()
if(!this.graphical_mode)
{
// text mode
// Update anyway - programs waiting for signal before
// changing to graphical mode
this.update_vertical_retrace();
return;
}
if(!this.dest_buffer)
{
dbg_log("Cannot fill buffer: No destination buffer", LOG_VGA);
// Update anyway
this.update_vertical_retrace();
return;
}