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32 lines
1.0 KiB
C
32 lines
1.0 KiB
C
#include "byte.h"
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/* byte_diff returns negative, 0, or positive, depending on whether the
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* string one[0], one[1], ..., one[len-1] is lexicographically smaller
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* than, equal to, or greater than the string one[0], one[1], ...,
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* one[len-1]. When the strings are different, byte_diff does not read
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* bytes past the first difference. */
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int byte_diff(const void* a, size_t len, const void* b) {
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#if 0
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/* this gets miscompiled by gcc 4.3.2 on x86_64 */
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register const unsigned char* s=a;
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register const unsigned char* t=b;
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register const unsigned char* u=t+len;
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register int j;
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j=0;
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for (;;) {
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if (t==u) break; if ((j=((unsigned int)*s-*t))) break; ++s; ++t;
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if (t==u) break; if ((j=((unsigned int)*s-*t))) break; ++s; ++t;
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if (t==u) break; if ((j=((unsigned int)*s-*t))) break; ++s; ++t;
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if (t==u) break; if ((j=((unsigned int)*s-*t))) break; ++s; ++t;
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}
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return j;
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#else
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size_t i;
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for (i=0; i<len; ++i) {
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int r=((unsigned char*)a)[i] - ((unsigned char*)b)[i];
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if (r) return r;
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}
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return 0;
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#endif
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}
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