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Added MACRO-10 work-arounds for numeric values with embedded binary shift counts

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Jeff 2017-03-16 12:45:19 -07:00 • committed by Jeff Parsons
commit ab0dccd866
12 changed files with 1565 additions and 1463 deletions
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30
modules/shared/lib/strlib.js
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@ -66,8 +66,8 @@ class Str {
* allowed; we remove them all before calling the built-in parseInt().
*
* More recently, we've added support for "^D", "^O", and "^B" prefixes to accommodate the base overrides
* that the PDP-10's MACRO-10 assembly language supports. If this support turns out to adversely affect
* other debuggers, then it will have to be "conditionalized".
* that the PDP-10's MACRO-10 assembly language supports (decimal, octal, and binary, respectively).
* If this support turns out to adversely affect other debuggers, then it will have to be "conditionalized".
*
* To summarize our non-standard alternatives: a 'y' suffix indicates binary, a '#' prefix indicates
* octal, a '$' prefix indicates hex, and a "0b" prefix indicates binary IF at least one comma is present.
@ -149,13 +149,37 @@ class Str {
if (chSuffix == null) s = s.substr(0, s.length - 1);
}
}
var v;
/*
* This adds support for the MACRO-10 binary shifting (Bn) suffix, which must be stripped from the
* number before parsing, and then applied to the value after parsing. If n is omitted, 35 is assumed,
* which is a net shift of zero. If n < 35, then a left shift of (35 - n) is required; if n > 35, then
* a right shift of -(35 - n) is required.
*/
var v, shift = 0;
var match = s.match(/(-?[0-9]+)B([0-9]*)/);
if (match) {
s = match[1];
shift = 35 - ((match[2] || 35) & 0xff);
}
if (Str.isValidInt(s, base) && !isNaN(v = parseInt(s, base))) {
/*
* With the need to support larger (eg, 36-bit) integers, truncating to 32 bits is no longer helpful.
*
* value = v|0;
*/
if (shift) {
/*
* Since binary shifting is a logical operation, and since shifting by division only works properly
* with positive numbers, we must convert a negative value to a positive value, by computing the two's
* complement.
*/
if (v < 0) v += Math.pow(2, 36);
if (shift > 0) {
v *= Math.pow(2, shift);
} else {
v = Math.trunc(v / Math.pow(2, -shift));
}
}
value = v;
}
}