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Added LSH and LSHC (albeit untested)

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Jeff 2017-03-03 17:44:27 -08:00 • committed by Jeff Parsons
commit a08c8c30bf
3 changed files with 308 additions and 239 deletions
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75
modules/pdp10/lib/cpuops.js
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@ -1380,7 +1380,13 @@ PDP10.opROT = function(op, acc)
};
/**
* opLSH(0o242000)
* opLSH(0o242000): Logical Shift
*
* From the DEC PDP-10 System Reference Manual (May 1968), p. 2-25:
*
* Shift AC the number of places specified by E. If E is positive, shift left bringing 0s into bit 35;
* data shifted out of bit 0 is lost. If E is negative, shift right bringing 0s into bit 0; data shifted
* out of bit 35 is lost.
*
* @this {CPUStatePDP10}
* @param {number} op
@ -1388,7 +1394,27 @@ PDP10.opROT = function(op, acc)
*/
PDP10.opLSH = function(op, acc)
{
this.opUndefined(op);
/*
* Convert the unsigned 18-bit value in regEA to a signed 8-bit value.
*/
var s = (this.regEA << 14) >> 24;
if (s) {
var w = this.readWord(acc);
if (s > 0) {
if (s >= 36) {
w = 0;
} else {
w = (w * Math.pow(2, s)) % PDP10.WORD_LIMIT;
}
} else {
if (s <= -36) {
w = 0;
} else {
w = Math.trunc(w / Math.pow(2, -s));
}
}
this.writeWord(acc, w);
}
};
/**
@ -1428,7 +1454,14 @@ PDP10.opROTC = function(op, acc)
};
/**
* opLSHC(0o246000)
* opLSHC(0o246000): Logical Shift Combined
*
* From the DEC PDP-10 System Reference Manual (May 1968), p. 2-25:
*
* Concatenate accumulators A and A+1 with A on the left, and shift the 72-bit combination the number
* of places specified by E. If E is positive, shift left bringing 0s into bit 71 (bit 35 of AC A + 1);
* bit 36 is shifted into bit 35; data shifted out of bit 0 is lost. If E is negative, shift right
* bringing 0s into bit 0; bit 35 is shifted into bit 36; data shifted out of bit 71 is lost.
*
* @this {CPUStatePDP10}
* @param {number} op
@ -1436,7 +1469,41 @@ PDP10.opROTC = function(op, acc)
*/
PDP10.opLSHC = function(op, acc)
{
this.opUndefined(op);
/*
* Convert the unsigned 18-bit value in regEA to a signed 8-bit value.
*/
var s = (this.regEA << 14) >> 24;
if (s) {
var wLeft = this.readWord(acc);
var wRight = this.readWord((acc + 1) & 0o17);
if (s > 0) {
if (s >= 36) {
wRight = 0;
if (s >= 72) {
wLeft = 0;
} else {
wLeft = (wRight * Math.pow(2, s - 36)) % PDP10.WORD_LIMIT;
}
} else {
wLeft = ((wLeft * Math.pow(2, s)) % PDP10.WORD_LIMIT) + Math.trunc(wRight / Math.pow(2, 36 - s));
wRight = (wRight * Math.pow(2, s)) % PDP10.WORD_LIMIT;
}
} else {
if (s <= -36) {
wLeft = 0;
if (s <= -72) {
wRight = 0;
} else {
wRight = Math.trunc(wLeft / Math.pow(2, -s - 36));
}
} else {
wRight = Math.trunc(wRight / Math.pow(2, -s)) + ((wLeft * Math.pow(2, 36 + s)) % PDP10.WORD_LIMIT);
wLeft = Math.trunc(wLeft / Math.pow(2, -s));
}
}
this.writeWord(acc, wLeft);
this.writeWord((acc + 1) & 0o17, wRight);
}
};
/**