cpu高效編程技術(shù)-在線瀏覽
2024-12-02 21:49本頁(yè)面
【正文】 … } 16 The Blocking Technique 17 The Blocking Technique // Increasing memory usage improves pression ratio // Reduced memory usage can improve speed, due to cache effect // Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache define MEMORY_USAGE 14 define HASH_LOG (MEMORY_USAGE2) define HASHTABLESIZE (1 HASH_LOG) struct refTables { HTYPE hashTable[HASHTABLESIZE]。 18 memchr magic_bits = ((unsigned long int) 0x7efefefe 32) | 0xfefefeff。 charmask |= charmask 16。 /* Instead of the traditional loop which tests each character, we will test a longword at a time. The tricky part is testing if *any of the four* bytes in the longword in question are zero. */ while (n = sizeof (longword)) { longword = *longword_ptr++ ^ charmask。
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