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crypto: Add generic 64-bit carry-less multiply routine
Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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3 changed files with 51 additions and 0 deletions
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@ -92,3 +92,20 @@ uint64_t clmul_32(uint32_t n, uint32_t m32)
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}
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return r;
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}
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Int128 clmul_64_gen(uint64_t n, uint64_t m)
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{
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uint64_t rl = 0, rh = 0;
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/* Bit 0 can only influence the low 64-bit result. */
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if (n & 1) {
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rl = m;
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}
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for (int i = 1; i < 64; ++i) {
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uint64_t mask = -((n >> i) & 1);
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rl ^= (m << i) & mask;
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rh ^= (m >> (64 - i)) & mask;
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}
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return int128_make128(rl, rh);
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}
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