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Fixed handling of redundant address/data override prefixes

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This commit is contained in:
Jeff Parsons 2015-07-17 10:14:17 -07:00
commit b6e8eb8877
4 changed files with 68 additions and 19 deletions
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20
modules/pcjs/lib/debugger.js
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@ -3228,15 +3228,25 @@ if (DEBUGGER) {
var bOpcode = this.getByte(dbgAddr, 1);
/*
* Incorporate the following prefixes into the current instruction byte stream.
* TODO: Determine the actual effect of multiple OS (and/or multiple AS) prefixes.
* Incorporate OS and AS prefixes into the current instruction.
*
* And the verdict is in: redundant OS and AS prefixes must be ignored;
* see opOS() and opAS() for details. We limit the amount of redundancy
* to something reasonable (ie, 4).
*/
var cMax = 2; // let's make sure unfortunate memory contents don't screw us
var cMax = 4;
var fDataPrefix = false, fAddrPrefix = false;
while ((bOpcode == X86.OPCODE.OS || bOpcode == X86.OPCODE.AS) && cMax--) {
if (bOpcode == X86.OPCODE.OS) {
dbgAddr.fData32 = !dbgAddr.fData32;
if (!fDataPrefix) {
dbgAddr.fData32 = !dbgAddr.fData32;
fDataPrefix = true;
}
} else {
dbgAddr.fAddr32 = !dbgAddr.fAddr32;
if (!fAddrPrefix) {
dbgAddr.fAddr32 = !dbgAddr.fAddr32;
fAddrPrefix = true;
}
}
bOpcode = this.getByte(dbgAddr, 1);
}