73 lines
2.0 KiB
C
73 lines
2.0 KiB
C
#include "fe.h"
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#include "pstdint.h"
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static uint64_t load_3(const unsigned char *in)
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{
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uint64_t result;
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result = (uint64_t) in[0];
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result |= ((uint64_t) in[1]) << 8;
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result |= ((uint64_t) in[2]) << 16;
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return result;
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}
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static uint64_t load_4(const unsigned char *in)
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{
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uint64_t result;
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result = (uint64_t) in[0];
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result |= ((uint64_t) in[1]) << 8;
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result |= ((uint64_t) in[2]) << 16;
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result |= ((uint64_t) in[3]) << 24;
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return result;
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}
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/*
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Ignores top bit of h.
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*/
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void fe_frombytes(fe h, const unsigned char *s)
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{
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int64_t h0 = load_4(s);
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int64_t h1 = load_3(s + 4) << 6;
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int64_t h2 = load_3(s + 7) << 5;
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int64_t h3 = load_3(s + 10) << 3;
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int64_t h4 = load_3(s + 13) << 2;
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int64_t h5 = load_4(s + 16);
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int64_t h6 = load_3(s + 20) << 7;
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int64_t h7 = load_3(s + 23) << 5;
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int64_t h8 = load_3(s + 26) << 4;
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int64_t h9 = (load_3(s + 29) & 8388607) << 2;
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int64_t carry0;
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int64_t carry1;
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int64_t carry2;
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int64_t carry3;
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int64_t carry4;
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int64_t carry5;
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int64_t carry6;
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int64_t carry7;
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int64_t carry8;
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int64_t carry9;
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carry9 = (h9 + (int64_t) (1<<24)) >> 25; h0 += carry9 * 19; h9 -= carry9 << 25;
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carry1 = (h1 + (int64_t) (1<<24)) >> 25; h2 += carry1; h1 -= carry1 << 25;
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carry3 = (h3 + (int64_t) (1<<24)) >> 25; h4 += carry3; h3 -= carry3 << 25;
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carry5 = (h5 + (int64_t) (1<<24)) >> 25; h6 += carry5; h5 -= carry5 << 25;
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carry7 = (h7 + (int64_t) (1<<24)) >> 25; h8 += carry7; h7 -= carry7 << 25;
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carry0 = (h0 + (int64_t) (1<<25)) >> 26; h1 += carry0; h0 -= carry0 << 26;
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carry2 = (h2 + (int64_t) (1<<25)) >> 26; h3 += carry2; h2 -= carry2 << 26;
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carry4 = (h4 + (int64_t) (1<<25)) >> 26; h5 += carry4; h4 -= carry4 << 26;
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carry6 = (h6 + (int64_t) (1<<25)) >> 26; h7 += carry6; h6 -= carry6 << 26;
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carry8 = (h8 + (int64_t) (1<<25)) >> 26; h9 += carry8; h8 -= carry8 << 26;
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h[0] = (int32_t) h0;
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h[1] = (int32_t) h1;
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h[2] = (int32_t) h2;
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h[3] = (int32_t) h3;
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h[4] = (int32_t) h4;
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h[5] = (int32_t) h5;
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h[6] = (int32_t) h6;
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h[7] = (int32_t) h7;
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h[8] = (int32_t) h8;
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h[9] = (int32_t) h9;
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}
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