41 lines
1.2 KiB
C
41 lines
1.2 KiB
C
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/* Copyright (c) 2014-2016 Cryptography Research, Inc.
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* Released under the MIT License. See LICENSE.txt for license information.
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*/
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#define GF_HEADROOM 2
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#define LIMB(x) (x##ull)&((1ull<<28)-1), (x##ull)>>28
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#define FIELD_LITERAL(a,b,c,d,e,f,g,h) \
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{{LIMB(a),LIMB(b),LIMB(c),LIMB(d),LIMB(e),LIMB(f),LIMB(g),LIMB(h)}}
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#define LIMB_PLACE_VALUE(i) 28
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void gf_add_RAW (gf out, const gf a, const gf b) {
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for (unsigned int i=0; i<sizeof(*out)/sizeof(out->limb[0]); i++) {
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out->limb[i] = a->limb[i] + b->limb[i];
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}
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}
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void gf_sub_RAW (gf out, const gf a, const gf b) {
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for (unsigned int i=0; i<sizeof(*out)/sizeof(out->limb[0]); i++) {
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out->limb[i] = a->limb[i] - b->limb[i];
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}
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}
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void gf_bias (gf a, int amt) {
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uint32_t co1 = ((1ull<<28)-1)*amt, co2 = co1-amt;
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for (unsigned int i=0; i<sizeof(*a)/sizeof(a->limb[0]); i++) {
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a->limb[i] += (i==sizeof(*a)/sizeof(a->limb[0])/2) ? co2 : co1;
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}
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}
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void gf_weak_reduce (gf a) {
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uint32_t mask = (1ull<<28) - 1;
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uint32_t tmp = a->limb[15] >> 28;
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a->limb[8] += tmp;
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for (unsigned int i=15; i>0; i--) {
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a->limb[i] = (a->limb[i] & mask) + (a->limb[i-1]>>28);
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}
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a->limb[0] = (a->limb[0] & mask) + tmp;
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}
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