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Getting ready to retire old 16-bit flags code

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Jeff Parsons 2015-03-16 14:39:03 -07:00 • committed by jeffpar
commit 72cf8d1f4d
12 changed files with 4078 additions and 3318 deletions
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50
modules/pcjs/lib/x86.js
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@ -241,11 +241,57 @@ var X86 = {
MASK: 0xfff8 // index of corresponding entry in GDT, LDT or IDT
},
RESULT: {
/*
* Flags were originally computed based on the following:
*
* CF: resultZeroCarry & resultSize
* PF: resultParitySign & 0xff
* AF: (resultParitySign ^ resultAuxOverflow) & 0x0010 (AUXOVF_AF)
* ZF: resultZeroCarry & (resultSize - 1)
* SF: resultParitySign & (resultSize >> 1)
* OF: (resultParitySign ^ resultAuxOverflow ^ (resultParitySign >> 1)) & (resultSize >> 1)
*
* I386 builds now rely on the following result variables:
*
* resultDst, resultSrc, resultArith, resultLogic, resultType, and resultFlags
*
* and the flags are computed as follows:
*
* CF: ((resultDst ^ ((resultDst ^ resultSrc) & (resultSrc ^ resultArith))) & resultType)
* PF: (resultLogic & 0xff)
* AF: ((resultArith ^ (resultDst ^ resultSrc)) & AUXOVF_AF)
* ZF: (resultLogic & ((resultType - 1) | resultType))
* SF: (resultLogic & resultType)
* OF: (((resultDst ^ resultArith) & (resultSrc ^ resultArith)) & resultType)
*
* Arithmetic operations should call:
*
* setArithResult(dst, src, value, type)
* eg:
* setArithResult(dst, src, dst+src, X86.RESULT.BYTE | X86.RESULT.ALL)
*
* The 4th parameter, type, indicates both the size of the result (BYTE, WORD or DWORD) and which of
* the flags should now be considered "cached" by the new result variables. If the previous resultType
* specifies any flags not contained in the new type parameter, then those flags must be immediately
* calculated and written to the appropriate bit(s) in resultFlags.
*/
BYTE: 0x80,
WORD: 0x8000,
DWORD: 0x80000000|0,
TYPE: 0x80008080|0,
CF: 0x01,
PF: 0x02,
AF: 0x04,
ZF: 0x08,
SF: 0x10,
OF: 0x20,
ALL: 0x3F,
LOGIC: 0x1A,
NOTCF: 0x3E,
SIZE_BYTE: 0x00100,
SIZE_WORD: 0x10000,
AUXOVF_AF: 0x00010,
AUXOVF_OF: 0x08080,
AUXOVF_CF: 0x10100
AUXOVF_OF: 0x08080
},
/*
* Bit values for opFlags, which are all reset to zero prior to each instruction