From 2ca69051608f3cdbfa28e65de9ddd326a13cd000 Mon Sep 17 00:00:00 2001 From: Paul Loyd Date: Fri, 13 Dec 2013 01:16:08 +0400 Subject: [PATCH] buffer: optimize writeInt* methods Remove unnecessary encoding within writeInt* --- lib/buffer.js | 43 ------------------------------------------- 1 file changed, 43 deletions(-) diff --git a/lib/buffer.js b/lib/buffer.js index b433630..d2d8b52 100644 --- a/lib/buffer.js +++ b/lib/buffer.js @@ -678,50 +678,11 @@ Buffer.prototype.writeUInt32BE = function(value, offset, noAssert) { return writeUInt32(this, value, offset, true); }; - -/* - * We now move onto our friends in the signed number category. Unlike unsigned - * numbers, we're going to have to worry a bit more about how we put values into - * arrays. Since we are only worrying about signed 32-bit values, we're in - * slightly better shape. Unfortunately, we really can't do our favorite binary - * & in this system. It really seems to do the wrong thing. For example: - * - * > -32 & 0xff - * 224 - * - * What's happening above is really: 0xe0 & 0xff = 0xe0. However, the results of - * this aren't treated as a signed number. Ultimately a bad thing. - * - * What we're going to want to do is basically create the unsigned equivalent of - * our representation and pass that off to the wuint* functions. To do that - * we're going to do the following: - * - * - if the value is positive - * we can pass it directly off to the equivalent wuint - * - if the value is negative - * we do the following computation: - * mb + val + 1, where - * mb is the maximum unsigned value in that byte size - * val is the Javascript negative integer - * - * - * As a concrete value, take -128. In signed 16 bits this would be 0xff80. If - * you do out the computations: - * - * 0xffff - 128 + 1 - * 0xffff - 127 - * 0xff80 - * - * You can then encode this value as the signed version. This is really rather - * hacky, but it should work and get the job done which is our goal here. - */ - Buffer.prototype.writeInt8 = function(value, offset, noAssert) { value = +value; offset = offset >>> 0; if (!noAssert) checkInt(this, value, offset, 1, 0x7f, -0x80); - if (value < 0) value = 0xff + value + 1; this[offset] = value; return offset + 1; }; @@ -732,7 +693,6 @@ Buffer.prototype.writeInt16LE = function(value, offset, noAssert) { offset = offset >>> 0; if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000); - if (value < 0) value = 0xffff + value + 1; return writeUInt16(this, value, offset, false); }; @@ -742,7 +702,6 @@ Buffer.prototype.writeInt16BE = function(value, offset, noAssert) { offset = offset >>> 0; if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000); - if (value < 0) value = 0xffff + value + 1; return writeUInt16(this, value, offset, true); }; @@ -752,7 +711,6 @@ Buffer.prototype.writeInt32LE = function(value, offset, noAssert) { offset = offset >>> 0; if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000); - if (value < 0) value = 0xffffffff + value + 1; return writeUInt32(this, value, offset, false); }; @@ -762,6 +720,5 @@ Buffer.prototype.writeInt32BE = function(value, offset, noAssert) { offset = offset >>> 0; if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000); - if (value < 0) value = 0xffffffff + value + 1; return writeUInt32(this, value, offset, true); }; -- 2.7.4