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周伯威 Po-Wei Chou 2016-05-05 17:18:28 -04:00
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@ -2461,7 +2461,9 @@ works in 4 operations and requires no subsquent verification. It simplifies
to
```c
#define haszero(v) (((v) - 0x01010101UL) & ~(v) & 0x80808080UL)```
#define haszero(v) (((v) - 0x01010101UL) & ~(v) & 0x80808080UL)
```
The subexpression (v - 0x01010101UL), evaluates to a high bit set in any
byte whenever the corresponding byte in v is zero or greater than 0x80.
The sub-expression ~v & 0x80808080UL