mirror of
https://github.com/MaskRay/ccls.git
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166 lines
5.5 KiB
C++
166 lines
5.5 KiB
C++
/*
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SipHash reference C implementation
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Copyright (c) 2012-2016 Jean-Philippe Aumasson
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<jeanphilippe.aumasson@gmail.com>
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Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
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To the extent possible under law, the author(s) have dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide. This software is distributed without any warranty.
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You should have received a copy of the CC0 Public Domain Dedication along
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with
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this software. If not, see
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<http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include <assert.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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/* default: SipHash-2-4 */
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#define cROUNDS 2
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#define dROUNDS 4
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#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
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#define U32TO8_LE(p, v) \
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(p)[0] = (uint8_t)((v)); \
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(p)[1] = (uint8_t)((v) >> 8); \
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(p)[2] = (uint8_t)((v) >> 16); \
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(p)[3] = (uint8_t)((v) >> 24);
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#define U64TO8_LE(p, v) \
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U32TO8_LE((p), (uint32_t)((v))); \
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U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
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#define U8TO64_LE(p) \
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(((uint64_t)((p)[0])) | ((uint64_t)((p)[1]) << 8) | \
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((uint64_t)((p)[2]) << 16) | ((uint64_t)((p)[3]) << 24) | \
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((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40) | \
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((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
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#define SIPROUND \
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do { \
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v0 += v1; \
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v1 = ROTL(v1, 13); \
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v1 ^= v0; \
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v0 = ROTL(v0, 32); \
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v2 += v3; \
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v3 = ROTL(v3, 16); \
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v3 ^= v2; \
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v0 += v3; \
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v3 = ROTL(v3, 21); \
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v3 ^= v0; \
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v2 += v1; \
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v1 = ROTL(v1, 17); \
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v1 ^= v2; \
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v2 = ROTL(v2, 32); \
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} while (0)
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#ifdef DEBUG
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#define TRACE \
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do { \
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printf("(%3d) v0 %08x %08x\n", (int)inlen, (uint32_t)(v0 >> 32), \
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(uint32_t)v0); \
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printf("(%3d) v1 %08x %08x\n", (int)inlen, (uint32_t)(v1 >> 32), \
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(uint32_t)v1); \
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printf("(%3d) v2 %08x %08x\n", (int)inlen, (uint32_t)(v2 >> 32), \
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(uint32_t)v2); \
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printf("(%3d) v3 %08x %08x\n", (int)inlen, (uint32_t)(v3 >> 32), \
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(uint32_t)v3); \
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} while (0)
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#else
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#define TRACE
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#endif
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int siphash(const uint8_t *in, const size_t inlen, const uint8_t *k,
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uint8_t *out, const size_t outlen) {
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assert((outlen == 8) || (outlen == 16));
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uint64_t v0 = 0x736f6d6570736575ULL;
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uint64_t v1 = 0x646f72616e646f6dULL;
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uint64_t v2 = 0x6c7967656e657261ULL;
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uint64_t v3 = 0x7465646279746573ULL;
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uint64_t k0 = U8TO64_LE(k);
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uint64_t k1 = U8TO64_LE(k + 8);
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uint64_t m;
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int i;
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const uint8_t *end = in + inlen - (inlen % sizeof(uint64_t));
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const int left = inlen & 7;
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uint64_t b = ((uint64_t)inlen) << 56;
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v3 ^= k1;
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v2 ^= k0;
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v1 ^= k1;
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v0 ^= k0;
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if (outlen == 16)
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v1 ^= 0xee;
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for (; in != end; in += 8) {
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m = U8TO64_LE(in);
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v3 ^= m;
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TRACE;
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for (i = 0; i < cROUNDS; ++i)
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SIPROUND;
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v0 ^= m;
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}
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switch (left) {
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case 7:
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b |= ((uint64_t)in[6]) << 48;
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case 6:
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b |= ((uint64_t)in[5]) << 40;
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case 5:
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b |= ((uint64_t)in[4]) << 32;
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case 4:
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b |= ((uint64_t)in[3]) << 24;
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case 3:
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b |= ((uint64_t)in[2]) << 16;
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case 2:
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b |= ((uint64_t)in[1]) << 8;
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case 1:
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b |= ((uint64_t)in[0]);
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break;
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case 0:
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break;
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}
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v3 ^= b;
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TRACE;
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for (i = 0; i < cROUNDS; ++i)
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SIPROUND;
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v0 ^= b;
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if (outlen == 16)
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v2 ^= 0xee;
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else
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v2 ^= 0xff;
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TRACE;
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for (i = 0; i < dROUNDS; ++i)
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SIPROUND;
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b = v0 ^ v1 ^ v2 ^ v3;
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U64TO8_LE(out, b);
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if (outlen == 8)
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return 0;
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v1 ^= 0xdd;
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TRACE;
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for (i = 0; i < dROUNDS; ++i)
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SIPROUND;
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b = v0 ^ v1 ^ v2 ^ v3;
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U64TO8_LE(out + 8, b);
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return 0;
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}
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