From df4f845774a6534c3f01ae29a80697fc37b0285c Mon Sep 17 00:00:00 2001 From: Christopher Jeffrey Date: Wed, 6 Jul 2016 21:57:39 -0700 Subject: [PATCH] buffer: optimize hex_decode PR-URL: https://github.com/nodejs/node/pull/7602 Reviewed-By: Anna Henningsen --- benchmark/buffers/buffer-hex.js | 26 +++++++++++++++++ src/string_bytes.cc | 37 ++++++++++++++++--------- test/parallel/test-buffer-badhex.js | 43 +++++++++++++++++++++++++++++ 3 files changed, 93 insertions(+), 13 deletions(-) create mode 100644 benchmark/buffers/buffer-hex.js create mode 100644 test/parallel/test-buffer-badhex.js diff --git a/benchmark/buffers/buffer-hex.js b/benchmark/buffers/buffer-hex.js new file mode 100644 index 00000000000000..d05bb832b3068c --- /dev/null +++ b/benchmark/buffers/buffer-hex.js @@ -0,0 +1,26 @@ +'use strict'; + +const common = require('../common.js'); + +const bench = common.createBenchmark(main, { + len: [0, 1, 64, 1024], + n: [1e7] +}); + +function main(conf) { + const len = conf.len | 0; + const n = conf.n | 0; + const buf = Buffer.alloc(len); + + for (let i = 0; i < buf.length; i++) + buf[i] = i & 0xff; + + const hex = buf.toString('hex'); + + bench.start(); + + for (let i = 0; i < n; i += 1) + Buffer.from(hex, 'hex'); + + bench.end(n); +} diff --git a/src/string_bytes.cc b/src/string_bytes.cc index d1c6a573250b7e..8b993f57466f78 100644 --- a/src/string_bytes.cc +++ b/src/string_bytes.cc @@ -239,16 +239,27 @@ size_t base64_decode(char* const dst, const size_t dstlen, } -template -unsigned hex2bin(TypeName c) { - if (c >= '0' && c <= '9') - return c - '0'; - if (c >= 'A' && c <= 'F') - return 10 + (c - 'A'); - if (c >= 'a' && c <= 'f') - return 10 + (c - 'a'); - return static_cast(-1); -} +static const int8_t unhex_table[256] = + { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 + }; + +#define unhex(x) \ + static_cast(unhex_table[static_cast(x)]) template @@ -258,11 +269,11 @@ size_t hex_decode(char* buf, const size_t srcLen) { size_t i; for (i = 0; i < len && i * 2 + 1 < srcLen; ++i) { - unsigned a = hex2bin(src[i * 2 + 0]); - unsigned b = hex2bin(src[i * 2 + 1]); + unsigned a = unhex(src[i * 2 + 0]); + unsigned b = unhex(src[i * 2 + 1]); if (!~a || !~b) return i; - buf[i] = a * 16 + b; + buf[i] = (a << 4) | b; } return i; diff --git a/test/parallel/test-buffer-badhex.js b/test/parallel/test-buffer-badhex.js new file mode 100644 index 00000000000000..3611ba3a09cdae --- /dev/null +++ b/test/parallel/test-buffer-badhex.js @@ -0,0 +1,43 @@ +'use strict'; +require('../common'); +const assert = require('assert'); +const Buffer = require('buffer').Buffer; + +// Test hex strings and bad hex strings +{ + const buf1 = Buffer.alloc(4); + assert.strictEqual(buf1.length, 4); + assert.deepStrictEqual(buf1, new Buffer([0, 0, 0, 0])); + assert.strictEqual(buf1.write('abcdxx', 0, 'hex'), 2); + assert.deepStrictEqual(buf1, new Buffer([0xab, 0xcd, 0x00, 0x00])); + assert.strictEqual(buf1.toString('hex'), 'abcd0000'); + assert.strictEqual(buf1.write('abcdef01', 0, 'hex'), 4); + assert.deepStrictEqual(buf1, new Buffer([0xab, 0xcd, 0xef, 0x01])); + assert.strictEqual(buf1.toString('hex'), 'abcdef01'); + + const buf2 = Buffer.from(buf1.toString('hex'), 'hex'); + assert.strictEqual(buf1.toString('hex'), buf2.toString('hex')); + + const buf3 = Buffer.alloc(5); + assert.strictEqual(buf3.write('abcdxx', 1, 'hex'), 2); + assert.strictEqual(buf3.toString('hex'), '00abcd0000'); + + const buf4 = Buffer.alloc(4); + assert.deepStrictEqual(buf4, new Buffer([0, 0, 0, 0])); + assert.strictEqual(buf4.write('xxabcd', 0, 'hex'), 0); + assert.deepStrictEqual(buf4, new Buffer([0, 0, 0, 0])); + assert.strictEqual(buf4.write('xxab', 1, 'hex'), 0); + assert.deepStrictEqual(buf4, new Buffer([0, 0, 0, 0])); + assert.strictEqual(buf4.write('cdxxab', 0, 'hex'), 1); + assert.deepStrictEqual(buf4, new Buffer([0xcd, 0, 0, 0])); + + const buf5 = Buffer.alloc(256); + for (let i = 0; i < 256; i++) + buf5[i] = i; + + const hex = buf5.toString('hex'); + assert.deepStrictEqual(Buffer.from(hex, 'hex'), buf5); + + const badHex = hex.slice(0, 256) + 'xx' + hex.slice(256, 510); + assert.deepStrictEqual(Buffer.from(badHex, 'hex'), buf5.slice(0, 128)); +}