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104 lines
3.0 KiB
C
104 lines
3.0 KiB
C
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/*
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* bitops.h : macros and functions for bit operations.
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* (C) 2002 - Willy Tarreau - willy@ant-computing.com
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*
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*/
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#ifndef __BITOPS_H__
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#define __BITOPS_H__
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/* how many bits are needed to code the size of an int (eg: 32bits -> 5) */
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#define LONGSHIFT 5
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#define LLONGSHIFT 6
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#define LONGBITS 32
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#define LLONGBITS 64
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/* very fast FFS function : returns the position of the lowest 1 */
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#define __ffs_fast32(___a) ({ \
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register int ___x, ___bits = 32; \
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if (___a) { \
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___x = (___a); \
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___bits--; \
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if (___x & 0x0000ffff) { ___x &= 0x0000ffff; ___bits -= 16;} \
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if (___x & 0x00ff00ff) { ___x &= 0x00ff00ff; ___bits -= 8;} \
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if (___x & 0x0f0f0f0f) { ___x &= 0x0f0f0f0f; ___bits -= 4;} \
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if (___x & 0x33333333) { ___x &= 0x33333333; ___bits -= 2;} \
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if (___x & 0x55555555) { ___x &= 0x55555555; ___bits -= 1;} \
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}\
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___bits; \
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})
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/* very fast FLS function : returns the position of the highest 1 */
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#define __fls_fast32(___a) ({ \
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register int ___x, ___bits = 0; \
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if (___a) { \
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___x = (___a); \
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if (___x & 0xffff0000) { ___x &= 0xffff0000; ___bits += 16;} \
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if (___x & 0xff00ff00) { ___x &= 0xff00ff00; ___bits += 8;} \
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if (___x & 0xf0f0f0f0) { ___x &= 0xf0f0f0f0; ___bits += 4;} \
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if (___x & 0xcccccccc) { ___x &= 0xcccccccc; ___bits += 2;} \
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if (___x & 0xaaaaaaaa) { ___x &= 0xaaaaaaaa; ___bits += 1;} \
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} else { \
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___bits = 32; \
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} \
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___bits; \
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})
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/* very fast FFS function working on 64 bits */
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#define __ffs_fast64(___a) ({ \
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register int ___bits = 64; \
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register unsigned long ___x = ((___a) >> 32); \
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if ((___a) & 0xffffffffUL) { \
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___x = (___a) & 0xffffffffUL; \
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___bits -= 32; \
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} \
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if (___x) { \
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___bits--; \
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if (___x & 0x0000ffff) { ___x &= 0x0000ffff; ___bits -= 16;} \
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if (___x & 0x00ff00ff) { ___x &= 0x00ff00ff; ___bits -= 8;} \
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if (___x & 0x0f0f0f0f) { ___x &= 0x0f0f0f0f; ___bits -= 4;} \
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if (___x & 0x33333333) { ___x &= 0x33333333; ___bits -= 2;} \
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if (___x & 0x55555555) { ___x &= 0x55555555; ___bits -= 1;} \
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}\
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___bits; \
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})
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/* very fast FLS function working on 64 bits */
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#define __fls_fast64(___a) ({ \
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register int ___bits = 0; \
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register unsigned long ___x = (___a); \
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if (((unsigned long long)(___a)) >> 32) { \
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___x = ((unsigned long long)(___a)) >> 32; \
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___bits += 32; \
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} \
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if (___x) { \
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if (___x & 0xffff0000) { ___x &= 0xffff0000; ___bits += 16;} \
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if (___x & 0xff00ff00) { ___x &= 0xff00ff00; ___bits += 8;} \
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if (___x & 0xf0f0f0f0) { ___x &= 0xf0f0f0f0; ___bits += 4;} \
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if (___x & 0xcccccccc) { ___x &= 0xcccccccc; ___bits += 2;} \
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if (___x & 0xaaaaaaaa) { ___x &= 0xaaaaaaaa; ___bits += 1;} \
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} else { \
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___bits += 32; \
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} \
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___bits; \
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})
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static int ffs_fast32(register unsigned long a) {
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return __ffs_fast32(a);
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}
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static int fls_fast32(unsigned long a) {
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return __fls_fast32(a);
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}
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static int ffs_fast64(unsigned long long a) {
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return __ffs_fast64(a);
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}
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static int fls_fast64(unsigned long long a) {
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return __fls_fast64(a);
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}
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#endif /* __BITOPS_H__ */
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