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Updated comments in readSrcWord()

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Jeff 2016-11-13 11:50:07 -08:00 • committed by Jeff Parsons
commit 85163fe823
1 changed files with 11 additions and 10 deletions
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21
modules/pdp11/lib/cpustate.js
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@ -2056,8 +2056,8 @@ CPUStatePDP11.prototype.writeWordToPrevSpace = function(opCode, accessFlags, dat
* *
* WARNING: If the SRC operand is a register, we return a negative register number rather than the * WARNING: If the SRC operand is a register, we return a negative register number rather than the
* register value, because the final value of the register must be resolved AFTER the DST operand has * register value, because the final value of the register must be resolved AFTER the DST operand has
* been decoded and any pre-decrement or post-increment operations have been performed. See readSrcWord() * been decoded and any pre-decrement or post-increment operations affecting the SRC register have
* for more details. * been completed. See readSrcWord() for more details.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
* @param {number} opCode * @param {number} opCode
@ -2082,7 +2082,8 @@ CPUStatePDP11.prototype.readSrcByte = function(opCode)
* *
* WARNING: If the SRC operand is a register, we return a negative register number rather than the * WARNING: If the SRC operand is a register, we return a negative register number rather than the
* register value, because the final value of the register must be resolved AFTER the DST operand has * register value, because the final value of the register must be resolved AFTER the DST operand has
* been decoded and any pre-decrement or post-increment operations have been performed. * been decoded and any pre-decrement or post-increment operations affecting the SRC register have
* been completed.
* *
* Here's an example from DEC's "TRAP TEST": * Here's an example from DEC's "TRAP TEST":
* *
@ -2092,12 +2093,12 @@ CPUStatePDP11.prototype.readSrcByte = function(opCode)
* 007214: 001401 BEQ 007220 * 007214: 001401 BEQ 007220
* 007216: 000000 HALT * 007216: 000000 HALT
* *
* If we returned the value of R0 immediately, then "MOV R0,(R0)+" would write 6340 to the memory location, * If this function returned the value of R0 for the SRC operand of "MOV R0,(R0)+", then the operation
* rather than 6342. * would write 6340 to the destination, rather than 6342.
* *
* Most callers don't need to worry about this, because if they pass the result from readSrcWord() directly * Most callers don't need to worry about this, because if they pass the result from readSrcWord() directly
* to writeDstWord() or updateDstWord(), those functions will take care of converting any negative register * to writeDstWord() or updateDstWord(), those functions will take care of converting any negative register
* number back into the proper register value. The exceptions are opcodes that don't modify the DST operand * number back into the current register value. The exceptions are opcodes that don't modify the DST operand
* (BIT, BITB, CMP, and CMPB); those opcode handlers must deal with negative register numbers themselves. * (BIT, BITB, CMP, and CMPB); those opcode handlers must deal with negative register numbers themselves.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
@ -2175,7 +2176,7 @@ CPUStatePDP11.prototype.readDstWord = function(opCode)
/** /**
* updateDstByte(opCode, data, fnOp) * updateDstByte(opCode, data, fnOp)
* *
* Used whenever the dst operand (as described by opCode) needs to be read before writing. * Used whenever the DST operand (as described by opCode) needs to be read before writing.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
* @param {number} opCode * @param {number} opCode
@ -2200,7 +2201,7 @@ CPUStatePDP11.prototype.updateDstByte = function(opCode, data, fnOp)
/** /**
* updateDstWord(opCode, data, fnOp) * updateDstWord(opCode, data, fnOp)
* *
* Used whenever the dst operand (as described by opCode) needs to be read before writing. * Used whenever the DST operand (as described by opCode) needs to be read before writing.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
* @param {number} opCode * @param {number} opCode
@ -2229,7 +2230,7 @@ CPUStatePDP11.prototype.updateDstWord = function(opCode, data, fnOp)
/** /**
* writeDstByte(opCode, data, writeFlags) * writeDstByte(opCode, data, writeFlags)
* *
* Used whenever the dst operand (as described by opCode) does NOT need to be read before writing. * Used whenever the DST operand (as described by opCode) does NOT need to be read before writing.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
* @param {number} opCode * @param {number} opCode
@ -2266,7 +2267,7 @@ CPUStatePDP11.prototype.writeDstByte = function(opCode, data, writeFlags)
/** /**
* writeDstWord(opCode, data) * writeDstWord(opCode, data)
* *
* Used whenever the dst operand (as described by opCode) does NOT need to be read before writing. * Used whenever the DST operand (as described by opCode) does NOT need to be read before writing.
* *
* @this {CPUStatePDP11} * @this {CPUStatePDP11}
* @param {number} opCode * @param {number} opCode