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Verify CRTC OFFSET register is consistent with mode

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This commit is contained in:
Jeff Parsons 2015-06-14 21:44:51 -07:00
commit f1680ca1f9
1 changed files with 9 additions and 14 deletions
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23
modules/pcjs/lib/video.js
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@ -4015,14 +4015,14 @@ Video.prototype.setDimensions = function()
this.nRows = this.nDefaultRows;
this.nCellsPerWord = Video.aModeParms[Video.MODE.MDA_80X25][2];
var cbPadding = 0;
this.cbPadding = 0;
var modeParms = Video.aModeParms[this.nMode];
if (modeParms) {
this.nCols = modeParms[0];
this.nRows = modeParms[1];
this.nCellsPerWord = modeParms[2];
cbPadding = modeParms[3] || 0;
this.cbPadding = modeParms[3] || 0;
this.nFont = modeParms[4]; // this will be undefined for graphics modes
if (this.nMonitorType == ChipSet.MONITOR.EGACOLOR || this.nMonitorType == ChipSet.MONITOR.VGACOLOR) {
@ -4060,8 +4060,8 @@ Video.prototype.setDimensions = function()
this.nCells = (this.nCols * this.nRows)|0;
this.nCellCache = (this.nCells / this.nCellsPerWord)|0;
this.cbScreen = ((this.nCellCache << 1) + cbPadding)|0;
this.cbSplit = (cbPadding? ((this.cbScreen + cbPadding) >> 1) : 0);
this.cbScreen = ((this.nCellCache << 1) + this.cbPadding)|0;
this.cbSplit = (this.cbPadding? ((this.cbScreen + this.cbPadding) >> 1) : 0);
if (this.nMode >= Video.MODE.EGA_320X200) this.nCellCache <<= 1;
/*
@ -4683,22 +4683,17 @@ Video.prototype.updateScreen = function(fForce)
addrScreen += offScreen;
var cbScreen = this.cbScreen;
// if (this.nCard >= Video.CARD.EGA) {
if (this.nCard >= Video.CARD.EGA && this.cardActive.regCRTData[Card.CRTC.EGA.OFFSET]) {
/*
* Pre-EGA, the extent of visible screen memory (cbScreen) was derived from nCols * nRows,
* but since then, the logical width of screen memory can differ from the visible width (nCols).
* We now calculate the logical width, and the compute a new cbScreen in much the same way the
* original cbScreen was computed (but without any CGA-related padding considerations).
*
* Other variables that are affected include:
*
* this.nCells = (this.nCols * this.nRows)|0;
* this.nCellCache = (this.nCells / this.nCellsPerWord)|0;
*/
// var nCols = this.cardActive.regCRTData[Card.CRTC.EGA.OFFSET] << 1;
// cbScreen = ((nCols * this.nRows) / this.nCellsPerWord) << 1;
// this.assert(cbScreen === this.cbScreen);
// }
var nCols = this.cardActive.regCRTData[Card.CRTC.EGA.OFFSET] << (this.nFont? 1 : 4);
cbScreen = ((((nCols * this.nRows) / this.nCellsPerWord) << 1) + this.cbPadding)|0;
this.assert(cbScreen === this.cbScreen);
}
if (addrScreen + cbScreen > addrScreenLimit) {
cbScreen = addrScreenLimit - addrScreen;