refactor: improve CESU-8 encoding coding style#28
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mention-bot commented Aug 4, 2017
@fengmk2, thanks for your PR! By analyzing the history of the files in this pull request, we identified @gxcsoccer, @dead-horse and @pmq20 to be potential reviewers. |
| // 0x800: 2048 | ||
| this._bytes[index++]=(0xc0+((ch>>6)&0x1f))>>>32; | ||
| this._bytes[index++]=(0x80+(ch&0x3f))>>>32; | ||
| // this._bytes[index++] = (0xc0 + ((ch >> 6) & 0x1f)) >>> 32; |
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看上去 (0xc0 + ((ch >> 6) & 0x1f)) 和 (0x80 + (ch & 0x3f)) 的运算符都是正数，所以不会加出负数，因此去掉 >>> 32 是逻辑一致的。
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看上去 (0xc0 + ((ch >> 6) & 0x1f)) 和 (0x80 + (ch & 0x3f)) 的运算符都是正数，所以不会加出负数，因此去掉 >>> 32 是逻辑一致的。
| // 0x800: 2048 | ||
| this._bytes[index++]=(0xc0+((ch>>6)&0x1f))>>>32; | ||
| this._bytes[index++]=(0x80+(ch&0x3f))>>>32; | ||
| // this._bytes[index++] = (0xc0 + ((ch >> 6) & 0x1f)) >>> 32; |
There was a problem hiding this comment.
看上去 (0xc0 + ((ch >> 6) & 0x1f)) 和 (0x80 + (ch & 0x3f)) 的运算符都是正数，所以不会加出负数，因此去掉 >>> 32 是逻辑一致的。
pmq20 commented Aug 4, 2017
然而还要看是否有溢出的情况，我看看 |
pmq20 commented Aug 4, 2017
ch 的最大值是 65536，因此(0xc0 + ((ch >> 6) & 0x1f)) 和 (0x80 + (ch & 0x3f)) 的最大值分别是 192 和 128，不会超出 4294967296 因此不需要 |
BTW: js CESU-8 encoding is faster then Buffer UTF-8 encoding ``` putRawStringSmallLessThan0x80*10000: 672.642ms putRawStringSmallLessThan0x800*10000: 592.960ms putRawStringSmallBiggerThan0x800*10000: 861.010ms putUTF8RawStringSmallLessThan0x80*10000: 841.638ms putUTF8RawStringSmallLessThan0x800*10000: 958.383ms putUTF8RawStringSmallBiggerThan0x800*10000: 1793.470ms ```
fengmk2force-pushed the better-performance branch from 0911c1b to 7fa2f4cCompare
BTW: js CESU-8 encoding is faster then Buffer UTF-8 encoding