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59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
/*
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This file is adapted from amd64-51/fe25519_invert.c:
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Loops of squares are replaced by nsquares for better performance.
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*/
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#include "fe51.h"
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#ifdef HAVE_AVX_ASM
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#define fe51_square(x, y) fe51_nsquare(x, y, 1)
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void
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fe51_invert(fe51 *r, const fe51 *x)
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{
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fe51 z2;
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fe51 z9;
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fe51 z11;
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fe51 z2_5_0;
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fe51 z2_10_0;
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fe51 z2_20_0;
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fe51 z2_50_0;
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fe51 z2_100_0;
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fe51 t;
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/* 2 */ fe51_square(&z2, x);
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/* 4 */ fe51_square(&t, &z2);
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/* 8 */ fe51_square(&t, &t);
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/* 9 */ fe51_mul(&z9, &t, x);
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/* 11 */ fe51_mul(&z11, &z9, &z2);
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/* 22 */ fe51_square(&t, &z11);
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/* 2^5 - 2^0 = 31 */ fe51_mul(&z2_5_0, &t, &z9);
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/* 2^10 - 2^5 */ fe51_nsquare(&t, &z2_5_0, 5);
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/* 2^10 - 2^0 */ fe51_mul(&z2_10_0, &t, &z2_5_0);
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/* 2^20 - 2^10 */ fe51_nsquare(&t, &z2_10_0, 10);
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/* 2^20 - 2^0 */ fe51_mul(&z2_20_0, &t, &z2_10_0);
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/* 2^40 - 2^20 */ fe51_nsquare(&t, &z2_20_0, 20);
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/* 2^40 - 2^0 */ fe51_mul(&t, &t, &z2_20_0);
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/* 2^50 - 2^10 */ fe51_nsquare(&t, &t, 10);
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/* 2^50 - 2^0 */ fe51_mul(&z2_50_0, &t, &z2_10_0);
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/* 2^100 - 2^50 */ fe51_nsquare(&t, &z2_50_0, 50);
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/* 2^100 - 2^0 */ fe51_mul(&z2_100_0, &t, &z2_50_0);
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/* 2^200 - 2^100 */ fe51_nsquare(&t, &z2_100_0, 100);
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/* 2^200 - 2^0 */ fe51_mul(&t, &t, &z2_100_0);
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/* 2^250 - 2^50 */ fe51_nsquare(&t, &t, 50);
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/* 2^250 - 2^0 */ fe51_mul(&t, &t, &z2_50_0);
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/* 2^255 - 2^5 */ fe51_nsquare(&t, &t, 5);
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/* 2^255 - 21 */ fe51_mul(r, &t, &z11);
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}
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#endif
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