LXR linux/tools/testing/selftests/bpf/progs/test

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (c) 2019 Facebook
   3#include <features.h>
   4
   5typedef unsigned int u32;
   6
   7static __always_inline u32 rol32(u32 word, unsigned int shift)
   8{
   9        return (word << shift) | (word >> ((-shift) & 31));
  10}
  11
  12#define __jhash_mix(a, b, c)                    \
  13{                                               \
  14        a -= c;  a ^= rol32(c, 4);  c += b;     \
  15        b -= a;  b ^= rol32(a, 6);  a += c;     \
  16        c -= b;  c ^= rol32(b, 8);  b += a;     \
  17        a -= c;  a ^= rol32(c, 16); c += b;     \
  18        b -= a;  b ^= rol32(a, 19); a += c;     \
  19        c -= b;  c ^= rol32(b, 4);  b += a;     \
  20}
  21
  22#define __jhash_final(a, b, c)                  \
  23{                                               \
  24        c ^= b; c -= rol32(b, 14);              \
  25        a ^= c; a -= rol32(c, 11);              \
  26        b ^= a; b -= rol32(a, 25);              \
  27        c ^= b; c -= rol32(b, 16);              \
  28        a ^= c; a -= rol32(c, 4);               \
  29        b ^= a; b -= rol32(a, 14);              \
  30        c ^= b; c -= rol32(b, 24);              \
  31}
  32
  33#define JHASH_INITVAL           0xdeadbeef
  34
  35static ATTR
  36u32 jhash(const void *key, u32 length, u32 initval)
  37{
  38        u32 a, b, c;
  39        const unsigned char *k = key;
  40
  41        a = b = c = JHASH_INITVAL + length + initval;
  42
  43        while (length > 12) {
  44                a += *(volatile u32 *)(k);
  45                b += *(volatile u32 *)(k + 4);
  46                c += *(volatile u32 *)(k + 8);
  47                __jhash_mix(a, b, c);
  48                length -= 12;
  49                k += 12;
  50        }
  51        switch (length) {
  52        case 12: c += (u32)k[11]<<24;
  53        case 11: c += (u32)k[10]<<16;
  54        case 10: c += (u32)k[9]<<8;
  55        case 9:  c += k[8];
  56        case 8:  b += (u32)k[7]<<24;
  57        case 7:  b += (u32)k[6]<<16;
  58        case 6:  b += (u32)k[5]<<8;
  59        case 5:  b += k[4];
  60        case 4:  a += (u32)k[3]<<24;
  61        case 3:  a += (u32)k[2]<<16;
  62        case 2:  a += (u32)k[1]<<8;
  63        case 1:  a += k[0];
  64                 c ^= a;
  65                 __jhash_final(a, b, c);
  66        case 0: /* Nothing left to add */
  67                break;
  68        }
  69
  70        return c;
  71}
  72