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/* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright 2006 Bob Jenkins
*
* Derived from public domain source, see
* <http://burtleburtle.net/bob/c/lookup3.c>:
*
* "lookup3.c, by Bob Jenkins, May 2006, Public Domain.
*
* These are functions for producing 32-bit hashes for hash table lookup...
* ...You can use this free for any purpose. It's in the public domain.
* It has no warranty."
*
* Copyright (c) 2014-2018 Solarflare Communications Inc.
* All rights reserved.
*/
#include "efx.h"
#include "efx_impl.h"
/* Hash initial value */
#define EFX_HASH_INITIAL_VALUE 0xdeadbeef
/*
* Rotate a 32-bit value left
*
* Allow platform to provide an intrinsic or optimised routine and
* fall-back to a simple shift based implementation.
*/
#if EFSYS_HAS_ROTL_DWORD
#define EFX_HASH_ROTATE(_value, _shift) \
EFSYS_ROTL_DWORD(_value, _shift)
#else
#define EFX_HASH_ROTATE(_value, _shift) \
(((_value) << (_shift)) | ((_value) >> (32 - (_shift))))
#endif
/* Mix three 32-bit values reversibly */
#define EFX_HASH_MIX(_a, _b, _c) \
do { \
_a -= _c; \
_a ^= EFX_HASH_ROTATE(_c, 4); \
_c += _b; \
_b -= _a; \
_b ^= EFX_HASH_ROTATE(_a, 6); \
_a += _c; \
_c -= _b; \
_c ^= EFX_HASH_ROTATE(_b, 8); \
_b += _a; \
_a -= _c; \
_a ^= EFX_HASH_ROTATE(_c, 16); \
_c += _b; \
_b -= _a; \
_b ^= EFX_HASH_ROTATE(_a, 19); \
_a += _c; \
_c -= _b; \
_c ^= EFX_HASH_ROTATE(_b, 4); \
_b += _a; \
_NOTE(CONSTANTCONDITION) \
} while (B_FALSE)
/* Final mixing of three 32-bit values into one (_c) */
#define EFX_HASH_FINALISE(_a, _b, _c) \
do { \
_c ^= _b; \
_c -= EFX_HASH_ROTATE(_b, 14); \
_a ^= _c; \
_a -= EFX_HASH_ROTATE(_c, 11); \
_b ^= _a; \
_b -= EFX_HASH_ROTATE(_a, 25); \
_c ^= _b; \
_c -= EFX_HASH_ROTATE(_b, 16); \
_a ^= _c; \
_a -= EFX_HASH_ROTATE(_c, 4); \
_b ^= _a; \
_b -= EFX_HASH_ROTATE(_a, 14); \
_c ^= _b; \
_c -= EFX_HASH_ROTATE(_b, 24); \
_NOTE(CONSTANTCONDITION) \
} while (B_FALSE)
/* Produce a 32-bit hash from 32-bit aligned input */
__checkReturn uint32_t
efx_hash_dwords(
__in_ecount(count) uint32_t const *input,
__in size_t count,
__in uint32_t init)
{
uint32_t a;
uint32_t b;
uint32_t c;
/* Set up the initial internal state */
a = b = c = EFX_HASH_INITIAL_VALUE +
(((uint32_t)count) * sizeof (uint32_t)) + init;
/* Handle all but the last three dwords of the input */
while (count > 3) {
a += input[0];
b += input[1];
c += input[2];
EFX_HASH_MIX(a, b, c);
count -= 3;
input += 3;
}
/* Handle the left-overs */
switch (count) {
case 3:
c += input[2];
/* Fall-through */
case 2:
b += input[1];
/* Fall-through */
case 1:
a += input[0];
EFX_HASH_FINALISE(a, b, c);
break;
case 0:
/* Should only get here if count parameter was zero */
break;
}
return (c);
}
#if EFSYS_IS_BIG_ENDIAN
/* Produce a 32-bit hash from arbitrarily aligned input */
__checkReturn uint32_t
efx_hash_bytes(
__in_ecount(length) uint8_t const *input,
__in size_t length,
__in uint32_t init)
{
uint32_t a;
uint32_t b;
uint32_t c;
/* Set up the initial internal state */
a = b = c = EFX_HASH_INITIAL_VALUE + (uint32_t)length + init;
/* Handle all but the last twelve bytes of the input */
while (length > 12) {
a += ((uint32_t)input[0]) << 24;
a += ((uint32_t)input[1]) << 16;
a += ((uint32_t)input[2]) << 8;
a += ((uint32_t)input[3]);
b += ((uint32_t)input[4]) << 24;
b += ((uint32_t)input[5]) << 16;
b += ((uint32_t)input[6]) << 8;
b += ((uint32_t)input[7]);
c += ((uint32_t)input[8]) << 24;
c += ((uint32_t)input[9]) << 16;
c += ((uint32_t)input[10]) << 8;
c += ((uint32_t)input[11]);
EFX_HASH_MIX(a, b, c);
length -= 12;
input += 12;
}
/* Handle the left-overs */
switch (length) {
case 12:
c += ((uint32_t)input[11]);
/* Fall-through */
case 11:
c += ((uint32_t)input[10]) << 8;
/* Fall-through */
case 10:
c += ((uint32_t)input[9]) << 16;
/* Fall-through */
case 9:
c += ((uint32_t)input[8]) << 24;
/* Fall-through */
case 8:
b += ((uint32_t)input[7]);
/* Fall-through */
case 7:
b += ((uint32_t)input[6]) << 8;
/* Fall-through */
case 6:
b += ((uint32_t)input[5]) << 16;
/* Fall-through */
case 5:
b += ((uint32_t)input[4]) << 24;
/* Fall-through */
case 4:
a += ((uint32_t)input[3]);
/* Fall-through */
case 3:
a += ((uint32_t)input[2]) << 8;
/* Fall-through */
case 2:
a += ((uint32_t)input[1]) << 16;
/* Fall-through */
case 1:
a += ((uint32_t)input[0]) << 24;
EFX_HASH_FINALISE(a, b, c);
break;
case 0:
/* Should only get here if length parameter was zero */
break;
}
return (c);
}
#elif EFSYS_IS_LITTLE_ENDIAN
/* Produce a 32-bit hash from arbitrarily aligned input */
__checkReturn uint32_t
efx_hash_bytes(
__in_ecount(length) uint8_t const *input,
__in size_t length,
__in uint32_t init)
{
uint32_t a;
uint32_t b;
uint32_t c;
/* Set up the initial internal state */
a = b = c = EFX_HASH_INITIAL_VALUE + (uint32_t)length + init;
/* Handle all but the last twelve bytes of the input */
while (length > 12) {
a += ((uint32_t)input[0]);
a += ((uint32_t)input[1]) << 8;
a += ((uint32_t)input[2]) << 16;
a += ((uint32_t)input[3]) << 24;
b += ((uint32_t)input[4]);
b += ((uint32_t)input[5]) << 8;
b += ((uint32_t)input[6]) << 16;
b += ((uint32_t)input[7]) << 24;
c += ((uint32_t)input[8]);
c += ((uint32_t)input[9]) << 8;
c += ((uint32_t)input[10]) << 16;
c += ((uint32_t)input[11]) << 24;
EFX_HASH_MIX(a, b, c);
length -= 12;
input += 12;
}
/* Handle the left-overs */
switch (length) {
case 12:
c += ((uint32_t)input[11]) << 24;
/* Fall-through */
case 11:
c += ((uint32_t)input[10]) << 16;
/* Fall-through */
case 10:
c += ((uint32_t)input[9]) << 8;
/* Fall-through */
case 9:
c += ((uint32_t)input[8]);
/* Fall-through */
case 8:
b += ((uint32_t)input[7]) << 24;
/* Fall-through */
case 7:
b += ((uint32_t)input[6]) << 16;
/* Fall-through */
case 6:
b += ((uint32_t)input[5]) << 8;
/* Fall-through */
case 5:
b += ((uint32_t)input[4]);
/* Fall-through */
case 4:
a += ((uint32_t)input[3]) << 24;
/* Fall-through */
case 3:
a += ((uint32_t)input[2]) << 16;
/* Fall-through */
case 2:
a += ((uint32_t)input[1]) << 8;
/* Fall-through */
case 1:
a += ((uint32_t)input[0]);
EFX_HASH_FINALISE(a, b, c);
break;
case 0:
/* Should only get here if length parameter was zero */
break;
}
return (c);
}
#else
#error "Neither of EFSYS_IS_{BIG,LITTLE}_ENDIAN is set"
#endif
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