1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2019 Facebook 3 4 typedef unsigned int u32; 5 6 static __attribute__((always_inline)) u32 rol32(u32 word, unsigned int shift) 7 { 8 return (word << shift) | (word >> ((-shift) & 31)); 9 } 10 11 #define __jhash_mix(a, b, c) \ 12 { \ 13 a -= c; a ^= rol32(c, 4); c += b; \ 14 b -= a; b ^= rol32(a, 6); a += c; \ 15 c -= b; c ^= rol32(b, 8); b += a; \ 16 a -= c; a ^= rol32(c, 16); c += b; \ 17 b -= a; b ^= rol32(a, 19); a += c; \ 18 c -= b; c ^= rol32(b, 4); b += a; \ 19 } 20 21 #define __jhash_final(a, b, c) \ 22 { \ 23 c ^= b; c -= rol32(b, 14); \ 24 a ^= c; a -= rol32(c, 11); \ 25 b ^= a; b -= rol32(a, 25); \ 26 c ^= b; c -= rol32(b, 16); \ 27 a ^= c; a -= rol32(c, 4); \ 28 b ^= a; b -= rol32(a, 14); \ 29 c ^= b; c -= rol32(b, 24); \ 30 } 31 32 #define JHASH_INITVAL 0xdeadbeef 33 34 static ATTR 35 u32 jhash(const void *key, u32 length, u32 initval) 36 { 37 u32 a, b, c; 38 const unsigned char *k = key; 39 40 a = b = c = JHASH_INITVAL + length + initval; 41 42 while (length > 12) { 43 a += *(volatile u32 *)(k); 44 b += *(volatile u32 *)(k + 4); 45 c += *(volatile u32 *)(k + 8); 46 __jhash_mix(a, b, c); 47 length -= 12; 48 k += 12; 49 } 50 switch (length) { 51 case 12: c += (u32)k[11]<<24; 52 case 11: c += (u32)k[10]<<16; 53 case 10: c += (u32)k[9]<<8; 54 case 9: c += k[8]; 55 case 8: b += (u32)k[7]<<24; 56 case 7: b += (u32)k[6]<<16; 57 case 6: b += (u32)k[5]<<8; 58 case 5: b += k[4]; 59 case 4: a += (u32)k[3]<<24; 60 case 3: a += (u32)k[2]<<16; 61 case 2: a += (u32)k[1]<<8; 62 case 1: a += k[0]; 63 c ^= a; 64 __jhash_final(a, b, c); 65 case 0: /* Nothing left to add */ 66 break; 67 } 68 69 return c; 70 } 71