111 lines
2.6 KiB
C
111 lines
2.6 KiB
C
// vim:fileencoding=utf-8:foldmethod=marker
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#include "murmur3.h"
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#include "hasher.h"
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#include "../../../common/aliases/aliases.h"
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#include "../../../common/assert/assert.h"
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#include "../../../common/misc/misc_utils.h"
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wp_intern inline void validateMur3HasherData(const WpMur3HasherData *io);
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wp_intern inline u64 fmix64(u64 k);
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WpU128Hash wpX64Mur3Hasher128(WpU8Stream *bytes, void *hasher_io) {
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WpMur3HasherData *io = (WpMur3HasherData *)hasher_io;
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validateMur3HasherData(io);
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const i32 nblocks = (bytes->count * bytes->item_size) / 16;
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u64 h1 = io->seed;
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u64 h2 = io->seed;
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const u64 c1 = wpU64Const(0x87c37b91114253d5);
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const u64 c2 = wpU64Const(0x4cf5ad432745937f);
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//----------
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// body
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for(int i = 0; i < nblocks; ++i) {
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u64 k1 = *((u64 *)wpStreamConsumeCount(u8, bytes, sizeof(u64)));
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u64 k2 = *((u64 *)wpStreamConsumeCount(u8, bytes, sizeof(u64)));
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k1 *= c1;
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k1 = wpMiscUtilsRotl64(k1, 31);
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k1 *= c2;
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h1 ^= k1;
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h1 = wpMiscUtilsRotl64(h1, 27);
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h1 += h2;
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h1 = h1 * 5 +0x52dce729;
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k2 *= c2;
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k2 = wpMiscUtilsRotl64(k2, 33);
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k2 *= c1;
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h2 ^= k2;
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h2 = wpMiscUtilsRotl64(h2, 31);
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h2 += h1;
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h2 = h2*5+0x38495ab5;
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}
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//----------
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// tail
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const u8 *tail = wpStreamConsumeCount(u8, bytes, bytes->count - bytes->position);
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u64 k1 = 0;
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u64 k2 = 0;
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u64 len = bytes->count * bytes->item_size;
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switch(len & 15) {
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case 15: k2 ^= ((u64)tail[14]) << 48;
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case 14: k2 ^= ((u64)tail[13]) << 40;
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case 13: k2 ^= ((u64)tail[12]) << 32;
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case 12: k2 ^= ((u64)tail[11]) << 24;
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case 11: k2 ^= ((u64)tail[10]) << 16;
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case 10: k2 ^= ((u64)tail[ 9]) << 8;
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case 9: k2 ^= ((u64)tail[ 8]) << 0;
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k2 *= c2; k2 = wpMiscUtilsRotl64(k2,33); k2 *= c1; h2 ^= k2;
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case 8: k1 ^= ((u64)tail[ 7]) << 56;
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case 7: k1 ^= ((u64)tail[ 6]) << 48;
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case 6: k1 ^= ((u64)tail[ 5]) << 40;
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case 5: k1 ^= ((u64)tail[ 4]) << 32;
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case 4: k1 ^= ((u64)tail[ 3]) << 24;
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case 3: k1 ^= ((u64)tail[ 2]) << 16;
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case 2: k1 ^= ((u64)tail[ 1]) << 8;
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case 1: k1 ^= ((u64)tail[ 0]) << 0;
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k1 *= c1; k1 = wpMiscUtilsRotl64(k1,31); k1 *= c2; h1 ^= k1;
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};
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//----------
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// finalization
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h1 ^= len; h2 ^= len;
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h1 += h2;
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h2 += h1;
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h1 = fmix64(h1);
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h2 = fmix64(h2);
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h1 += h2;
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h2 += h1;
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return (WpU128Hash){ .hash = { [0] = h1, [1] = h2 } };
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}
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wp_intern inline void validateMur3HasherData(const WpMur3HasherData *data) {
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wpRuntimeAssert(data->magic == WP_MUR3_HASHER_MAGIC, "Invalid Murmur3 hash data");
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}
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wp_intern inline u64 fmix64(u64 k) {
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k ^= k >> 33;
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k *= wpU64Const(0xff51afd7ed558ccd);
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k ^= k >> 33;
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k *= wpU64Const(0xc4ceb9fe1a85ec53);
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k ^= k >> 33;
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return k;
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}
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