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Define a generic ge_select() in additino to ge_select_base()

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This commit is contained in:
Frank Denis 2017-10-19 23:11:52 +02:00
parent fc3a62a493
commit 8a1e08cc52
1 changed files with 21 additions and 17 deletions
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38
src/libsodium/crypto_core/curve25519/ref10/curve25519_ref10.c
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@ -1655,33 +1655,37 @@ ge_cmov(ge_precomp *t, const ge_precomp *u, unsigned char b)
fe_cmov(t->xy2d, u->xy2d, b);
}
/* base[i][j] = (j+1)*256^i*B */
static const ge_precomp base[32][8] = {
#include "base.h"
};
static void
ge_select_base(ge_precomp *t, int pos, signed char b)
ge_select(ge_precomp *t, const ge_precomp precomp[8], const signed char b)
{
ge_precomp minust;
unsigned char bnegative = negative(b);
unsigned char babs = b - (((-bnegative) & b) * ((signed char) 1 << 1));
ge_precomp minust;
const unsigned char bnegative = negative(b);
const unsigned char babs = b - (((-bnegative) & b) * ((signed char) 1 << 1));
ge_precomp_0(t);
ge_cmov(t, &base[pos][0], equal(babs, 1));
ge_cmov(t, &base[pos][1], equal(babs, 2));
ge_cmov(t, &base[pos][2], equal(babs, 3));
ge_cmov(t, &base[pos][3], equal(babs, 4));
ge_cmov(t, &base[pos][4], equal(babs, 5));
ge_cmov(t, &base[pos][5], equal(babs, 6));
ge_cmov(t, &base[pos][6], equal(babs, 7));
ge_cmov(t, &base[pos][7], equal(babs, 8));
ge_cmov(t, &precomp[0], equal(babs, 1));
ge_cmov(t, &precomp[1], equal(babs, 2));
ge_cmov(t, &precomp[2], equal(babs, 3));
ge_cmov(t, &precomp[3], equal(babs, 4));
ge_cmov(t, &precomp[4], equal(babs, 5));
ge_cmov(t, &precomp[5], equal(babs, 6));
ge_cmov(t, &precomp[6], equal(babs, 7));
ge_cmov(t, &precomp[7], equal(babs, 8));
fe_copy(minust.yplusx, t->yminusx);
fe_copy(minust.yminusx, t->yplusx);
fe_neg(minust.xy2d, t->xy2d);
ge_cmov(t, &minust, bnegative);
}
static void
ge_select_base(ge_precomp *t, const int pos, const signed char b)
{
static const ge_precomp base[32][8] = { /* base[i][j] = (j+1)*256^i*B */
#include "base.h"
};
return ge_select(t, base[pos], b);
}
/*
r = p - q
*/