// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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// modification, are permitted provided that the following conditions are
// met:
//
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// notice, this list of conditions and the following disclaimer.
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// in the documentation and/or other materials provided with the
// distribution.
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//
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/**
* @fileoverview This file contains helper code used by jspb.utils to
* handle 64-bit integer conversion to/from strings.
*
* @author cfallin@google.com (Chris Fallin)
*
* TODO(haberman): move this to javascript/closure/math?
*/
goog.provide('jspb.arith.Int64');
goog.provide('jspb.arith.UInt64');
/**
* UInt64 implements some 64-bit arithmetic routines necessary for properly
* handling 64-bit integer fields. It implements lossless integer arithmetic on
* top of JavaScript's number type, which has only 53 bits of precision, by
* representing 64-bit integers as two 32-bit halves.
*
* @param {number} lo The low 32 bits.
* @param {number} hi The high 32 bits.
* @constructor
*/
jspb.arith.UInt64 = function(lo, hi) {
/**
* The low 32 bits.
* @public {number}
*/
this.lo = lo;
/**
* The high 32 bits.
* @public {number}
*/
this.hi = hi;
};
/**
* Compare two 64-bit numbers. Returns -1 if the first is
* less, +1 if the first is greater, or 0 if both are equal.
* @param {!jspb.arith.UInt64} other
* @return {number}
*/
jspb.arith.UInt64.prototype.cmp = function(other) {
if (this.hi < other.hi || (this.hi == other.hi && this.lo < other.lo)) {
return -1;
} else if (this.hi == other.hi && this.lo == other.lo) {
return 0;
} else {
return 1;
}
};
/**
* Right-shift this number by one bit.
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.rightShift = function() {
var hi = this.hi >>> 1;
var lo = (this.lo >>> 1) | ((this.hi & 1) << 31);
return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
};
/**
* Left-shift this number by one bit.
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.leftShift = function() {
var lo = this.lo << 1;
var hi = (this.hi << 1) | (this.lo >>> 31);
return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
};
/**
* Test the MSB.
* @return {boolean}
*/
jspb.arith.UInt64.prototype.msb = function() {
return !!(this.hi & 0x80000000);
};
/**
* Test the LSB.
* @return {boolean}
*/
jspb.arith.UInt64.prototype.lsb = function() {
return !!(this.lo & 1);
};
/**
* Test whether this number is zero.
* @return {boolean}
*/
jspb.arith.UInt64.prototype.zero = function() {
return this.lo == 0 && this.hi == 0;
};
/**
* Add two 64-bit numbers to produce a 64-bit number.
* @param {!jspb.arith.UInt64} other
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.add = function(other) {
var lo = ((this.lo + other.lo) & 0xffffffff) >>> 0;
var hi =
(((this.hi + other.hi) & 0xffffffff) >>> 0) +
(((this.lo + other.lo) >= 0x100000000) ? 1 : 0);
return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
};
/**
* Subtract two 64-bit numbers to produce a 64-bit number.
* @param {!jspb.arith.UInt64} other
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.sub = function(other) {
var lo = ((this.lo - other.lo) & 0xffffffff) >>> 0;
var hi =
(((this.hi - other.hi) & 0xffffffff) >>> 0) -
(((this.lo - other.lo) < 0) ? 1 : 0);
return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
};
/**
* Multiply two 32-bit numbers to produce a 64-bit number.
* @param {number} a The first integer: must be in [0, 2^32-1).
* @param {number} b The second integer: must be in [0, 2^32-1).
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.mul32x32 = function(a, b) {
// Directly multiplying two 32-bit numbers may produce up to 64 bits of
// precision, thus losing precision because of the 53-bit mantissa of
// JavaScript numbers. So we multiply with 16-bit digits (radix 65536)
// instead.
var aLow = (a & 0xffff);
var aHigh = (a >>> 16);
var bLow = (b & 0xffff);
var bHigh = (b >>> 16);
var productLow =
// 32-bit result, result bits 0-31, take all 32 bits
(aLow * bLow) +
// 32-bit result, result bits 16-47, take bottom 16 as our top 16
((aLow * bHigh) & 0xffff) * 0x10000 +
// 32-bit result, result bits 16-47, take bottom 16 as our top 16
((aHigh * bLow) & 0xffff) * 0x10000;
var productHigh =
// 32-bit result, result bits 32-63, take all 32 bits
(aHigh * bHigh) +
// 32-bit result, result bits 16-47, take top 16 as our bottom 16
((aLow * bHigh) >>> 16) +
// 32-bit result, result bits 16-47, take top 16 as our bottom 16
((aHigh * bLow) >>> 16);
// Carry. Note that we actually have up to *two* carries due to addition of
// three terms.
while (productLow >= 0x100000000) {
productLow -= 0x100000000;
productHigh += 1;
}
return new jspb.arith.UInt64(productLow >>> 0, productHigh >>> 0);
};
/**
* Multiply this number by a 32-bit number, producing a 96-bit number, then
* truncate the top 32 bits.
* @param {number} a The multiplier.
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.mul = function(a) {
// Produce two parts: at bits 0-63, and 32-95.
var lo = jspb.arith.UInt64.mul32x32(this.lo, a);
var hi = jspb.arith.UInt64.mul32x32(this.hi, a);
// Left-shift hi by 32 bits, truncating its top bits. The parts will then be
// aligned for addition.
hi.hi = hi.lo;
hi.lo = 0;
return lo.add(hi);
};
/**
* Divide a 64-bit number by a 32-bit number to produce a
* 64-bit quotient and a 32-bit remainder.
* @param {number} _divisor
* @return {Array.<jspb.arith.UInt64>} array of [quotient, remainder],
* unless divisor is 0, in which case an empty array is returned.
*/
jspb.arith.UInt64.prototype.div = function(_divisor) {
if (_divisor == 0) {
return [];
}
// We perform long division using a radix-2 algorithm, for simplicity (i.e.,
// one bit at a time). TODO: optimize to a radix-2^32 algorithm, taking care
// to get the variable shifts right.
var quotient = new jspb.arith.UInt64(0, 0);
var remainder = new jspb.arith.UInt64(this.lo, this.hi);
var divisor = new jspb.arith.UInt64(_divisor, 0);
var unit = new jspb.arith.UInt64(1, 0);
// Left-shift the divisor and unit until the high bit of divisor is set.
while (!divisor.msb()) {
divisor = divisor.leftShift();
unit = unit.leftShift();
}
// Perform long division one bit at a time.
while (!unit.zero()) {
// If divisor < remainder, add unit to quotient and subtract divisor from
// remainder.
if (divisor.cmp(remainder) <= 0) {
quotient = quotient.add(unit);
remainder = remainder.sub(divisor);
}
// Right-shift the divisor and unit.
divisor = divisor.rightShift();
unit = unit.rightShift();
}
return [quotient, remainder];
};
/**
* Convert a 64-bit number to a string.
* @return {string}
* @override
*/
jspb.arith.UInt64.prototype.toString = function() {
var result = '';
var num = this;
while (!num.zero()) {
var divResult = num.div(10);
var quotient = divResult[0], remainder = divResult[1];
result = remainder.lo + result;
num = quotient;
}
if (result == '') {
result = '0';
}
return result;
};
/**
* Parse a string into a 64-bit number. Returns `null` on a parse error.
* @param {string} s
* @return {?jspb.arith.UInt64}
*/
jspb.arith.UInt64.fromString = function(s) {
var result = new jspb.arith.UInt64(0, 0);
// optimization: reuse this instance for each digit.
var digit64 = new jspb.arith.UInt64(0, 0);
for (var i = 0; i < s.length; i++) {
if (s[i] < '0' || s[i] > '9') {
return null;
}
var digit = parseInt(s[i], 10);
digit64.lo = digit;
result = result.mul(10).add(digit64);
}
return result;
};
/**
* Make a copy of the uint64.
* @return {!jspb.arith.UInt64}
*/
jspb.arith.UInt64.prototype.clone = function() {
return new jspb.arith.UInt64(this.lo, this.hi);
};
/**
* Int64 is like UInt64, but modifies string conversions to interpret the stored
* 64-bit value as a twos-complement-signed integer. It does *not* support the
* full range of operations that UInt64 does: only add, subtract, and string
* conversions.
*
* N.B. that multiply and divide routines are *NOT* supported. They will throw
* exceptions. (They are not necessary to implement string conversions, which
* are the only operations we really need in jspb.)
*
* @param {number} lo The low 32 bits.
* @param {number} hi The high 32 bits.
* @constructor
*/
jspb.arith.Int64 = function(lo, hi) {
/**
* The low 32 bits.
* @public {number}
*/
this.lo = lo;
/**
* The high 32 bits.
* @public {number}
*/
this.hi = hi;
};
/**
* Add two 64-bit numbers to produce a 64-bit number.
* @param {!jspb.arith.Int64} other
* @return {!jspb.arith.Int64}
*/
jspb.arith.Int64.prototype.add = function(other) {
var lo = ((this.lo + other.lo) & 0xffffffff) >>> 0;
var hi =
(((this.hi + other.hi) & 0xffffffff) >>> 0) +
(((this.lo + other.lo) >= 0x100000000) ? 1 : 0);
return new jspb.arith.Int64(lo >>> 0, hi >>> 0);
};
/**
* Subtract two 64-bit numbers to produce a 64-bit number.
* @param {!jspb.arith.Int64} other
* @return {!jspb.arith.Int64}
*/
jspb.arith.Int64.prototype.sub = function(other) {
var lo = ((this.lo - other.lo) & 0xffffffff) >>> 0;
var hi =
(((this.hi - other.hi) & 0xffffffff) >>> 0) -
(((this.lo - other.lo) < 0) ? 1 : 0);
return new jspb.arith.Int64(lo >>> 0, hi >>> 0);
};
/**
* Make a copy of the int64.
* @return {!jspb.arith.Int64}
*/
jspb.arith.Int64.prototype.clone = function() {
return new jspb.arith.Int64(this.lo, this.hi);
};
/**
* Convert a 64-bit number to a string.
* @return {string}
* @override
*/
jspb.arith.Int64.prototype.toString = function() {
// If the number is negative, find its twos-complement inverse.
var sign = (this.hi & 0x80000000) != 0;
var num = new jspb.arith.UInt64(this.lo, this.hi);
if (sign) {
num = new jspb.arith.UInt64(0, 0).sub(num);
}
return (sign ? '-' : '') + num.toString();
};
/**
* Parse a string into a 64-bit number. Returns `null` on a parse error.
* @param {string} s
* @return {?jspb.arith.Int64}
*/
jspb.arith.Int64.fromString = function(s) {
var hasNegative = (s.length > 0 && s[0] == '-');
if (hasNegative) {
s = s.substring(1);
}
var num = jspb.arith.UInt64.fromString(s);
if (num === null) {
return null;
}
if (hasNegative) {
num = new jspb.arith.UInt64(0, 0).sub(num);
}
return new jspb.arith.Int64(num.lo, num.hi);
};