| Willy Tarreau | be384c6 | 2007-04-28 14:00:17 +0200 | [diff] [blame] | 1 | /* |
| 2 | * bitops.h : macros and functions for bit operations. |
| 3 | * (C) 2002 - Willy Tarreau - willy@ant-computing.com |
| 4 | * |
| 5 | */ |
| 6 | |
| 7 | #ifndef __BITOPS_H__ |
| 8 | #define __BITOPS_H__ |
| 9 | |
| 10 | /* how many bits are needed to code the size of an int (eg: 32bits -> 5) */ |
| 11 | #define LONGSHIFT 5 |
| 12 | #define LLONGSHIFT 6 |
| 13 | #define LONGBITS 32 |
| 14 | #define LLONGBITS 64 |
| 15 | |
| 16 | /* very fast FFS function : returns the position of the lowest 1 */ |
| 17 | #define __ffs_fast32(___a) ({ \ |
| 18 | register int ___x, ___bits = 32; \ |
| 19 | if (___a) { \ |
| 20 | ___x = (___a); \ |
| 21 | ___bits--; \ |
| 22 | if (___x & 0x0000ffff) { ___x &= 0x0000ffff; ___bits -= 16;} \ |
| 23 | if (___x & 0x00ff00ff) { ___x &= 0x00ff00ff; ___bits -= 8;} \ |
| 24 | if (___x & 0x0f0f0f0f) { ___x &= 0x0f0f0f0f; ___bits -= 4;} \ |
| 25 | if (___x & 0x33333333) { ___x &= 0x33333333; ___bits -= 2;} \ |
| 26 | if (___x & 0x55555555) { ___x &= 0x55555555; ___bits -= 1;} \ |
| 27 | }\ |
| 28 | ___bits; \ |
| 29 | }) |
| 30 | |
| 31 | /* very fast FLS function : returns the position of the highest 1 */ |
| 32 | #define __fls_fast32(___a) ({ \ |
| 33 | register int ___x, ___bits = 0; \ |
| 34 | if (___a) { \ |
| 35 | ___x = (___a); \ |
| 36 | if (___x & 0xffff0000) { ___x &= 0xffff0000; ___bits += 16;} \ |
| 37 | if (___x & 0xff00ff00) { ___x &= 0xff00ff00; ___bits += 8;} \ |
| 38 | if (___x & 0xf0f0f0f0) { ___x &= 0xf0f0f0f0; ___bits += 4;} \ |
| 39 | if (___x & 0xcccccccc) { ___x &= 0xcccccccc; ___bits += 2;} \ |
| 40 | if (___x & 0xaaaaaaaa) { ___x &= 0xaaaaaaaa; ___bits += 1;} \ |
| 41 | } else { \ |
| 42 | ___bits = 32; \ |
| 43 | } \ |
| 44 | ___bits; \ |
| 45 | }) |
| 46 | |
| 47 | /* very fast FFS function working on 64 bits */ |
| 48 | #define __ffs_fast64(___a) ({ \ |
| 49 | register int ___bits = 64; \ |
| 50 | register unsigned long ___x = ((___a) >> 32); \ |
| 51 | if ((___a) & 0xffffffffUL) { \ |
| 52 | ___x = (___a) & 0xffffffffUL; \ |
| 53 | ___bits -= 32; \ |
| 54 | } \ |
| 55 | if (___x) { \ |
| 56 | ___bits--; \ |
| 57 | if (___x & 0x0000ffff) { ___x &= 0x0000ffff; ___bits -= 16;} \ |
| 58 | if (___x & 0x00ff00ff) { ___x &= 0x00ff00ff; ___bits -= 8;} \ |
| 59 | if (___x & 0x0f0f0f0f) { ___x &= 0x0f0f0f0f; ___bits -= 4;} \ |
| 60 | if (___x & 0x33333333) { ___x &= 0x33333333; ___bits -= 2;} \ |
| 61 | if (___x & 0x55555555) { ___x &= 0x55555555; ___bits -= 1;} \ |
| 62 | }\ |
| 63 | ___bits; \ |
| 64 | }) |
| 65 | |
| 66 | |
| 67 | /* very fast FLS function working on 64 bits */ |
| 68 | #define __fls_fast64(___a) ({ \ |
| 69 | register int ___bits = 0; \ |
| 70 | register unsigned long ___x = (___a); \ |
| 71 | if (((unsigned long long)(___a)) >> 32) { \ |
| 72 | ___x = ((unsigned long long)(___a)) >> 32; \ |
| 73 | ___bits += 32; \ |
| 74 | } \ |
| 75 | if (___x) { \ |
| 76 | if (___x & 0xffff0000) { ___x &= 0xffff0000; ___bits += 16;} \ |
| 77 | if (___x & 0xff00ff00) { ___x &= 0xff00ff00; ___bits += 8;} \ |
| 78 | if (___x & 0xf0f0f0f0) { ___x &= 0xf0f0f0f0; ___bits += 4;} \ |
| 79 | if (___x & 0xcccccccc) { ___x &= 0xcccccccc; ___bits += 2;} \ |
| 80 | if (___x & 0xaaaaaaaa) { ___x &= 0xaaaaaaaa; ___bits += 1;} \ |
| 81 | } else { \ |
| 82 | ___bits += 32; \ |
| 83 | } \ |
| 84 | ___bits; \ |
| 85 | }) |
| 86 | |
| 87 | static int ffs_fast32(register unsigned long a) { |
| 88 | return __ffs_fast32(a); |
| 89 | } |
| 90 | |
| 91 | static int fls_fast32(unsigned long a) { |
| 92 | return __fls_fast32(a); |
| 93 | } |
| 94 | |
| 95 | static int ffs_fast64(unsigned long long a) { |
| 96 | return __ffs_fast64(a); |
| 97 | } |
| 98 | |
| 99 | static int fls_fast64(unsigned long long a) { |
| 100 | return __fls_fast64(a); |
| 101 | } |
| 102 | |
| 103 | #endif /* __BITOPS_H__ */ |