14 #if BITS_PER_LONG == 32
16 #define hash_long(val, bits) hash_32(val, bits)  argument
18 #define hash_long(val, bits) hash_64(val, bits)  argument
21 #error Wordsize not 32 or 64
26  * high bits.  Since multiplication propagates changes to the most
27  * significant end only, it is essential that the high bits of the
31  * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
34  * ratio phi = (sqrt(5)-1)/2, or its negative, has particularly nice
37  * These are the negative, (1 - phi) = phi**2 = (3 - sqrt(5))/2,
51  * the arch-optimized versions with the generic.
55  * self-test will not false-positive.
65 static inline u32 hash_32(u32 val, unsigned int bits)  in hash_32()  argument
67 	/* High bits are more random, so use them. */  in hash_32()
68 	return __hash_32(val) >> (32 - bits);  in hash_32()
74 static __always_inline u32 hash_64_generic(u64 val, unsigned int bits)  in hash_64_generic()  argument
77 	/* 64x64-bit multiply is efficient on all 64-bit processors */  in hash_64_generic()
78 	return val * GOLDEN_RATIO_64 >> (64 - bits);  in hash_64_generic()
80 	/* Hash 64 bits using only 32x32-bit multiply. */  in hash_64_generic()
81 	return hash_32((u32)val ^ __hash_32(val >> 32), bits);  in hash_64_generic()
85 static inline u32 hash_ptr(const void *ptr, unsigned int bits)  in hash_ptr()  argument
87 	return hash_long((unsigned long)ptr, bits);  in hash_ptr()
96 	val ^= (val >> 32);  in hash32_ptr()