code / tomo

   1 // This file holds the internals for the SipHash implementation. For a few
   2 // cases, we want to include this for incrementally computing hashes.
   3 // Otherwise, it suffices to just use the siphash24() function from siphash.h
   4 
   5 #pragma once
   6 
   7 #include <stddef.h>
   8 #include <stdint.h>
   9 #include <string.h>
  10 
  11 #include "siphash.h"
  12 
  13 /* <MIT License>
  14  Copyright (c) 2013  Marek Majkowski <marek@popcount.org>
  15  Copyright (c) 2018  Samantha McVey <samantham@posteo.net>
  16  Copyright (c) 2024  Bruce Hill <bruce@bruce-hill.com>
  17 
  18  Permission is hereby granted, free of charge, to any person obtaining a copy
  19  of this software and associated documentation files (the "Software"), to deal
  20  in the Software without restriction, including without limitation the rights
  21  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  22  copies of the Software, and to permit persons to whom the Software is
  23  furnished to do so, subject to the following conditions:
  24 
  25  The above copyright notice and this permission notice shall be included in
  26  all copies or substantial portions of the Software.
  27 
  28  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  29  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  30  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  31  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  32  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  33  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  34  THE SOFTWARE.
  35  </MIT License>
  36 
  37  Original location:
  38         https://github.com/majek/csiphash/
  39 
  40  Original solution inspired by code from:
  41         Samuel Neves (supercop/crypto_auth/siphash24/little)
  42         djb (supercop/crypto_auth/siphash24/little2)
  43         Jean-Philippe Aumasson (https://131002.net/siphash/siphash24.c)
  44 
  45  Extensive modifications for MoarVM by Samantha McVey
  46 
  47  Further modifications for Tomo by Bruce Hill
  48 */
  49 struct siphash {
  50     uint64_t v0;
  51     uint64_t v1;
  52     uint64_t v2;
  53     uint64_t v3;
  54     uint64_t b;
  55 };
  56 typedef struct siphash siphash;
  57 #define ROTATE(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
  58 
  59 #define HALF_ROUND(a, b, c, d, s, t)                                                                                   \
  60     a += b;                                                                                                            \
  61     c += d;                                                                                                            \
  62     b = ROTATE(b, s) ^ a;                                                                                              \
  63     d = ROTATE(d, t) ^ c;                                                                                              \
  64     a = ROTATE(a, 32);
  65 
  66 #define DOUBLE_ROUND(v0, v1, v2, v3)                                                                                   \
  67     HALF_ROUND(v0, v1, v2, v3, 13, 16);                                                                                \
  68     HALF_ROUND(v2, v1, v0, v3, 17, 21);                                                                                \
  69     HALF_ROUND(v0, v1, v2, v3, 13, 16);                                                                                \
  70     HALF_ROUND(v2, v1, v0, v3, 17, 21);
  71 
  72 MACROLIKE void siphashinit(siphash *sh, size_t src_sz) {
  73     const uint64_t k0 = TOMO_HASH_KEY[0];
  74     const uint64_t k1 = TOMO_HASH_KEY[1];
  75     sh->b = (uint64_t)src_sz << 56;
  76     sh->v0 = k0 ^ 0x736f6d6570736575ULL;
  77     sh->v1 = k1 ^ 0x646f72616e646f6dULL;
  78     sh->v2 = k0 ^ 0x6c7967656e657261ULL;
  79     sh->v3 = k1 ^ 0x7465646279746573ULL;
  80 }
  81 MACROLIKE void siphashadd64bits(siphash *sh, const uint64_t in) {
  82     const uint64_t mi = in;
  83     sh->v3 ^= mi;
  84     DOUBLE_ROUND(sh->v0, sh->v1, sh->v2, sh->v3);
  85     sh->v0 ^= mi;
  86 }
  87 MACROLIKE uint64_t siphashfinish_last_part(siphash *sh, uint64_t t) {
  88     sh->b |= t;
  89     sh->v3 ^= sh->b;
  90     DOUBLE_ROUND(sh->v0, sh->v1, sh->v2, sh->v3);
  91     sh->v0 ^= sh->b;
  92     sh->v2 ^= 0xff;
  93     DOUBLE_ROUND(sh->v0, sh->v1, sh->v2, sh->v3);
  94     DOUBLE_ROUND(sh->v0, sh->v1, sh->v2, sh->v3);
  95     return (sh->v0 ^ sh->v1) ^ (sh->v2 ^ sh->v3);
  96 }
  97 /* This union helps us avoid doing weird things with pointers that can cause old
  98  * compilers like GCC 4 to generate bad code. In addition it is nicely more C
  99  * standards compliant to keep type punning to a minimum. */
 100 union SipHash64_union {
 101     uint64_t u64;
 102     uint32_t u32;
 103     uint8_t u8[8];
 104 };
 105 MACROLIKE uint64_t siphashfinish(siphash *sh, const uint8_t *src, size_t src_sz) {
 106     union SipHash64_union t = {0};
 107     switch (src_sz) {
 108     /* Falls through */
 109     case 7: t.u8[6] = src[6];
 110     /* Falls through */
 111     case 6: t.u8[5] = src[5];
 112     /* Falls through */
 113     case 5: t.u8[4] = src[4];
 114     /* Falls through */
 115     case 4: t.u8[3] = src[3];
 116     /* Falls through */
 117     case 3: t.u8[2] = src[2];
 118     /* Falls through */
 119     case 2: t.u8[1] = src[1];
 120     /* Falls through */
 121     case 1: t.u8[0] = src[0];
 122     default: break;
 123     }
 124     return siphashfinish_last_part(sh, t.u64);
 125 }