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Stack optimizations

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This commit is contained in:
Jeff Parsons 2015-02-01 12:48:04 -08:00 • committed by jeffpar
commit 13c50f7bd0
17 changed files with 3183 additions and 3129 deletions
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19
modules/pcjs/lib/x86op0f.js
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@ -132,7 +132,6 @@ var X86Op0F = {
this.regEDI = this.getShort(0x826);
this.regESI = this.getShort(0x828);
this.regEBP = this.getShort(0x82A);
this.regESP = this.getShort(0x82C);
this.regEBX = this.getShort(0x82E);
this.regEDX = this.getShort(0x830);
this.regECX = this.getShort(0x832);
@ -142,14 +141,24 @@ var X86Op0F = {
this.segSS.loadDesc6(0x842, this.getShort(0x820));
this.segDS.loadDesc6(0x848, this.getShort(0x81E));
this.setPS(this.getShort(0x818));
this.setIP(this.getShort(0x81A));
/*
* TODO: The bytes at 0x851 and 0x85D "should be zeroes", but do we rely on that, or do we load zeros ourselves?
* It's important to call setIP() and setSP() *after* the segCS and segSS loads, so that the CPU's
* linear IP and SP registers (regLIP and regLSP) will be updated properly. Ordinarily that would be
* taken care of by simply using the CPU's setCS() and setSS() functions, but those functions call the
* default descriptor load() functions, and obviously here we must use loadDesc6() instead.
*/
this.addrGDT = this.getShort(0x84E) | (this.getShort(0x850) << 16);
this.setIP(this.getShort(0x81A));
this.setSP(this.getShort(0x82C));
/*
* The bytes at 0x851 and 0x85D "should be zeroes", as per the "Undocumented iAPX 286 Test Instruction"
* document, but the LOADALL issued by RAMDRIVE in PC-DOS 7.0 contains 0xFF in both of those bytes, resulting
* in very large addrGDT and addrIDT values. Obviously, we can't have that, so we load only the low byte
* of the second word for both of those registers.
*/
this.addrGDT = this.getShort(0x84E) | (this.getByte(0x850) << 16);
this.addrGDTLimit = this.addrGDT + this.getShort(0x852);
this.segLDT.loadDesc6(0x854, this.getShort(0x81C));
this.addrIDT = this.getShort(0x85A) | (this.getShort(0x85C) << 16);
this.addrIDT = this.getShort(0x85A) | (this.getByte(0x85C) << 16);
this.addrIDTLimit = this.addrIDT + this.getShort(0x85E);
this.segTSS.loadDesc6(0x860, this.getShort(0x816));
this.nStepCycles -= 195;