diff --git a/src/long.js b/src/long.js index 5af2cb9..751632b 100644 --- a/src/long.js +++ b/src/long.js @@ -54,6 +54,7 @@ function Long(low, high, unsigned) { */ Long.prototype.__isLong__; +// 用来区分是否为自己定义的long型 Object.defineProperty(Long.prototype, "__isLong__", { value: true, enumerable: false, @@ -149,12 +150,13 @@ function fromNumber(value, unsigned) { if (value >= TWO_PWR_64_DBL) return MAX_UNSIGNED_VALUE; } else { - if (value <= -TWO_PWR_63_DBL) + if (value <= -TWO_PWR_63_DBL)// 2^63-1 return MIN_VALUE; - if (value + 1 >= TWO_PWR_63_DBL) + if (value + 1 >= TWO_PWR_63_DBL)//2^63 return MAX_VALUE; } if (value < 0) + //neg()函数推测为反转，即负值变正值 return fromNumber(-value, unsigned).neg(); return fromBits((value % TWO_PWR_32_DBL) | 0, (value / TWO_PWR_32_DBL) | 0, unsigned); } @@ -211,12 +213,12 @@ function fromString(str, unsigned, radix) { throw Error('empty string'); if (str === "NaN" || str === "Infinity" || str === "+Infinity" || str === "-Infinity") return ZERO; - if (typeof unsigned === 'number') { + if (typeof unsigned === 'number') { // For goog.math.long compatibility radix = unsigned, - unsigned = false; + unsigned = false; } else { - unsigned = !! unsigned; + unsigned = !!unsigned; } radix = radix || 10; if (radix < 2 || 36 < radix) @@ -226,6 +228,7 @@ function fromString(str, unsigned, radix) { if ((p = str.indexOf('-')) > 0) throw Error('interior hyphen'); else if (p === 0) { + // 转为正值处理 return fromString(str.substring(1), unsigned, radix).neg(); } @@ -233,6 +236,7 @@ function fromString(str, unsigned, radix) { // minimize the calls to the very expensive emulated div. var radixToPower = fromNumber(pow_dbl(radix, 8)); + // 从最高位分8位处理一次，如果长度超过8位，则先处理高位，然后将高位直接乘以进制的8次方，再处理低后8位，循环到最后8位为止 var result = ZERO; for (var i = 0; i < str.length; i += 8) { var size = Math.min(8, str.length - i), @@ -393,7 +397,7 @@ Long.NEG_ONE = NEG_ONE; * @type {!Long} * @inner */ -var MAX_VALUE = fromBits(0xFFFFFFFF|0, 0x7FFFFFFF|0, false); +var MAX_VALUE = fromBits(0xFFFFFFFF | 0, 0x7FFFFFFF | 0, false); /** * Maximum signed value. @@ -405,7 +409,7 @@ Long.MAX_VALUE = MAX_VALUE; * @type {!Long} * @inner */ -var MAX_UNSIGNED_VALUE = fromBits(0xFFFFFFFF|0, 0xFFFFFFFF|0, true); +var MAX_UNSIGNED_VALUE = fromBits(0xFFFFFFFF | 0, 0xFFFFFFFF | 0, true); /** * Maximum unsigned value. @@ -417,7 +421,7 @@ Long.MAX_UNSIGNED_VALUE = MAX_UNSIGNED_VALUE; * @type {!Long} * @inner */ -var MIN_VALUE = fromBits(0, 0x80000000|0, false); +var MIN_VALUE = fromBits(0, 0x80000000 | 0, false); /** * Minimum signed value. @@ -436,6 +440,7 @@ var LongPrototype = Long.prototype; * @returns {number} */ LongPrototype.toInt = function toInt() { + //负值>>>0会变为正值 return this.unsigned ? this.low >>> 0 : this.low; }; @@ -462,7 +467,8 @@ LongPrototype.toString = function toString(radix) { throw RangeError('radix'); if (this.isZero()) return '0'; - if (this.isNegative()) { // Unsigned Longs are never negative + //如果是负值,Unsigned型的Long值永远不会为负值 + if (this.isNegative()) { if (this.eq(MIN_VALUE)) { // We need to change the Long value before it can be negated, so we remove // the bottom-most digit in this base and then recurse to do the rest. @@ -474,6 +480,7 @@ LongPrototype.toString = function toString(radix) { return '-' + this.neg().toString(radix); } + //每次处理6位，处理方式与字符串转换过来是类似的，和数学中十进制转换为N进制方法相同——相除法 // Do several (6) digits each time through the loop, so as to // minimize the calls to the very expensive emulated div. var radixToPower = fromNumber(pow_dbl(radix, 6), this.unsigned), @@ -745,8 +752,7 @@ LongPrototype.add = function add(addend) { if (!isLong(addend)) addend = fromValue(addend); - // Divide each number into 4 chunks of 16 bits, and then sum the chunks. - + // 将每个数字分成4个16比特的块，然后将这些块加起来 var a48 = this.high >>> 16; var a32 = this.high & 0xFFFF; var a16 = this.low >>> 16; @@ -919,7 +925,7 @@ LongPrototype.divide = function divide(divisor) { return UONE; res = UZERO; } - + // Repeat the following until the remainder is less than other: find a // floating-point that approximates remainder / other *from below*, add this // into the result, and subtract it from the remainder. It is critical that @@ -936,8 +942,8 @@ LongPrototype.divide = function divide(divisor) { var log2 = Math.ceil(Math.log(approx) / Math.LN2), delta = (log2 <= 48) ? 1 : pow_dbl(2, log2 - 48), - // Decrease the approximation until it is smaller than the remainder. Note - // that if it is too large, the product overflows and is negative. + // Decrease the approximation until it is smaller than the remainder. Note + // that if it is too large, the product overflows and is negative. approxRes = fromNumber(approx), approxRem = approxRes.mul(divisor); while (approxRem.isNegative() || approxRem.gt(rem)) { @@ -1129,7 +1135,7 @@ LongPrototype.toUnsigned = function toUnsigned() { * @param {boolean=} le Whether little or big endian, defaults to big endian * @returns {!Array.} Byte representation */ -LongPrototype.toBytes = function(le) { +LongPrototype.toBytes = function (le) { return le ? this.toBytesLE() : this.toBytesBE(); } @@ -1137,16 +1143,16 @@ LongPrototype.toBytes = function(le) { * Converts this Long to its little endian byte representation. * @returns {!Array.} Little endian byte representation */ -LongPrototype.toBytesLE = function() { +LongPrototype.toBytesLE = function () { var hi = this.high, lo = this.low; return [ - lo & 0xff, - (lo >>> 8) & 0xff, + lo & 0xff, + (lo >>> 8) & 0xff, (lo >>> 16) & 0xff, (lo >>> 24) & 0xff, - hi & 0xff, - (hi >>> 8) & 0xff, + hi & 0xff, + (hi >>> 8) & 0xff, (hi >>> 16) & 0xff, (hi >>> 24) & 0xff ]; @@ -1156,17 +1162,17 @@ LongPrototype.toBytesLE = function() { * Converts this Long to its big endian byte representation. * @returns {!Array.} Big endian byte representation */ -LongPrototype.toBytesBE = function() { +LongPrototype.toBytesBE = function () { var hi = this.high, lo = this.low; return [ (hi >>> 24) & 0xff, (hi >>> 16) & 0xff, - (hi >>> 8) & 0xff, - hi & 0xff, + (hi >>> 8) & 0xff, + hi & 0xff, (lo >>> 24) & 0xff, (lo >>> 16) & 0xff, - (lo >>> 8) & 0xff, - lo & 0xff + (lo >>> 8) & 0xff, + lo & 0xff ]; }