| 1 | #include <linux/module.h>
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| 2 | #include <linux/bitops.h>
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| 3 | #include <asm/types.h>
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| 4 |
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| 5 | |
| 6 | * hweightN - returns the hamming weight of a N-bit word
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| 7 | * @x: the word to weigh
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| 8 | *
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| 9 | * The Hamming Weight of a number is the total number of bits set in it.
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| 10 |
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| 11 |
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| 12 | unsigned int __sw_hweight32(unsigned int w)
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| 13 | {
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| 14 | #ifdef ARCH_HAS_FAST_MULTIPLIER
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| 15 | w -= (w >> 1) & 0x55555555;
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| 16 | w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
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| 17 | w = (w + (w >> 4)) & 0x0f0f0f0f;
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| 18 | return (w * 0x01010101) >> 24;
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| 19 | #else
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| 20 | unsigned int res = w - ((w >> 1) & 0x55555555);
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| 21 | res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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| 22 | res = (res + (res >> 4)) & 0x0F0F0F0F;
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| 23 | res = res + (res >> 8);
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| 24 | return (res + (res >> 16)) & 0x000000FF;
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| 25 | #endif
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| 26 | }
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| 27 | EXPORT_SYMBOL(__sw_hweight32);
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| 28 |
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| 29 | unsigned int __sw_hweight16(unsigned int w)
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| 30 | {
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| 31 | unsigned int res = w - ((w >> 1) & 0x5555);
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| 32 | res = (res & 0x3333) + ((res >> 2) & 0x3333);
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| 33 | res = (res + (res >> 4)) & 0x0F0F;
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| 34 | return (res + (res >> 8)) & 0x00FF;
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| 35 | }
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| 36 | EXPORT_SYMBOL(__sw_hweight16);
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| 37 |
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| 38 | unsigned int __sw_hweight8(unsigned int w)
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| 39 | {
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| 40 | unsigned int res = w - ((w >> 1) & 0x55);
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| 41 | res = (res & 0x33) + ((res >> 2) & 0x33);
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| 42 | return (res + (res >> 4)) & 0x0F;
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| 43 | }
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| 44 | EXPORT_SYMBOL(__sw_hweight8);
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| 45 |
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| 46 | unsigned long __sw_hweight64(__u64 w)
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| 47 | {
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| 48 | #if BITS_PER_LONG == 32
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| 49 | return __sw_hweight32((unsigned int)(w >> 32)) +
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| 50 | __sw_hweight32((unsigned int)w);
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| 51 | #elif BITS_PER_LONG == 64
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| 52 | #ifdef ARCH_HAS_FAST_MULTIPLIER
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| 53 | w -= (w >> 1) & 0x5555555555555555ul;
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| 54 | w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
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| 55 | w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
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| 56 | return (w * 0x0101010101010101ul) >> 56;
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| 57 | #else
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| 58 | __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
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| 59 | res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
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| 60 | res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
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| 61 | res = res + (res >> 8);
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| 62 | res = res + (res >> 16);
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| 63 | return (res + (res >> 32)) & 0x00000000000000FFul;
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| 64 | #endif
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| 65 | #endif
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| 66 | }
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| 67 | EXPORT_SYMBOL(__sw_hweight64);
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