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Simplified flag management

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This commit is contained in:
Jeff Parsons 2016-04-21 15:41:58 -07:00
commit 425f565b11
7 changed files with 443 additions and 382 deletions
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26
modules/pc8080/lib/cpudef.js
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@ -71,25 +71,7 @@ var CPUDef = {
SF: 0x0080, // bit 7: Sign flag
ALL: 0x00D5, // CF, PF, AF, ZF, SF
MASK: 0x00FF, //
IF: 0x0200, // bit 9: Interrupt flag (for internal use only)
OF: 0x0800 // bit 11: Overflow flag (for internal use only)
},
RESULT: {
/*
* Flags are computed using the following internal registers:
*
* CF: resultZeroCarry & resultSize (ie, 0x100 or 0x10000)
* PF: resultParitySign & 0xff
* AF: (resultParitySign ^ resultAuxOverflow) & 0x0010
* ZF: resultZeroCarry & (resultSize - 1)
* SF: resultParitySign & (resultSize >> 1)
* OF: (resultParitySign ^ resultAuxOverflow ^ (resultParitySign >> 1)) & (resultSize >> 1)
*/
SIZE_BYTE: 0x00100, // mask for byte arithmetic instructions (after subtracting 1)
SIZE_WORD: 0x10000, // mask for word arithmetic instructions (after subtracting 1)
AUXOVF_AF: 0x00010,
AUXOVF_OF: 0x08080,
AUXOVF_CF: 0x10100
IF: 0x0200 // bit 9: Interrupt flag (for internal use only)
},
PARITY: [ // 256-byte array with a 1 wherever the number of set bits of the array index is EVEN
1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
@ -132,10 +114,6 @@ var CPUDef = {
ACI: 0xCE, // PS.ALL
CALL: 0xCD
// to be continued....
},
CYCLES: {
ACI: 7 // 2 cycles, 7 states
// to be continued....
}
};
@ -148,7 +126,7 @@ CPUDef.PS.DIRECT = (CPUDef.PS.IF);
* However, PS "arithmetic" flags are NOT stored in regPS; they are maintained across
* separate result registers, hence the "indirect" designation.
*/
CPUDef.PS.INDIRECT = (CPUDef.PS.CF | CPUDef.PS.PF | CPUDef.PS.AF | CPUDef.PS.ZF | CPUDef.PS.SF | CPUDef.PS.OF);
CPUDef.PS.INDIRECT = (CPUDef.PS.CF | CPUDef.PS.PF | CPUDef.PS.AF | CPUDef.PS.ZF | CPUDef.PS.SF);
/*
* These are the default "always set" PS bits for the 8080.