101 lines
2.8 KiB
C
101 lines
2.8 KiB
C
#include "gf2x_arith.h"
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#include <assert.h>
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#include <string.h> // memset(...)
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/* allows the second operand to be shorter than the first */
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/* the result should be as large as the first operand*/
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static inline void gf2x_add_asymm(const size_t nr, DIGIT Res[],
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const size_t na, const DIGIT A[],
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const size_t nb, const DIGIT B[]) {
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assert(nr >= na && na >= nb);
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size_t i;
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size_t delta = na - nb;
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for (i = 0; i < delta; i++) {
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Res[i] = A[i];
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}
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for (i = 0; i < nb; i++) {
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Res[i + delta] = A[i + delta] ^ B[i];
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}
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}
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/* PRE: MAX ALLOWED ROTATION AMOUNT : DIGIT_SIZE_b */
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void PQCLEAN_LEDAKEMLT32_CLEAN_right_bit_shift_n(size_t length, DIGIT in[], unsigned int amount) {
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assert(amount < DIGIT_SIZE_b);
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if ( amount == 0 ) {
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return;
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}
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unsigned int j;
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DIGIT mask;
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mask = ((DIGIT)0x01 << amount) - 1;
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for (j = length - 1; j > 0 ; j--) {
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in[j] >>= amount;
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in[j] |= (in[j - 1] & mask) << (DIGIT_SIZE_b - amount);
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}
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in[j] >>= amount;
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}
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/* PRE: MAX ALLOWED ROTATION AMOUNT : DIGIT_SIZE_b */
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void PQCLEAN_LEDAKEMLT32_CLEAN_left_bit_shift_n(size_t length, DIGIT in[], unsigned int amount) {
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assert(amount < DIGIT_SIZE_b);
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if ( amount == 0 ) {
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return;
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}
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size_t j;
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DIGIT mask;
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mask = ~(((DIGIT)0x01 << (DIGIT_SIZE_b - amount)) - 1);
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for (j = 0 ; j < length - 1 ; j++) {
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in[j] <<= amount;
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in[j] |= (in[j + 1] & mask) >> (DIGIT_SIZE_b - amount);
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}
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in[j] <<= amount;
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}
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void PQCLEAN_LEDAKEMLT32_CLEAN_gf2x_mul_comb(int nr, DIGIT Res[],
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int na, const DIGIT A[],
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int nb, const DIGIT B[]) {
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int i, j, k;
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DIGIT u, h;
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memset(Res, 0x00, nr * sizeof(DIGIT));
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for (k = DIGIT_SIZE_b - 1; k > 0; k--) {
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for (i = na - 1; i >= 0; i--) {
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if ( A[i] & (((DIGIT)0x1) << k) ) {
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for (j = nb - 1; j >= 0; j--) {
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Res[i + j + 1] ^= B[j];
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}
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}
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}
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u = Res[na + nb - 1];
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Res[na + nb - 1] = u << 0x1;
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for (j = 1; j < na + nb; ++j) {
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h = u >> (DIGIT_SIZE_b - 1);
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u = Res[na + nb - 1 - j];
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Res[na + nb - 1 - j] = h ^ (u << 0x1);
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}
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}
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for (i = na - 1; i >= 0; i--) {
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if ( A[i] & ((DIGIT)0x1) ) {
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for (j = nb - 1; j >= 0; j--) {
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Res[i + j + 1] ^= B[j];
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}
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}
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}
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}
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static inline void gf2x_exact_div_x_plus_one(const int na, DIGIT A[]) {
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DIGIT t = 0;
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for (int i = na - 1; i >= 0; i--) {
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t ^= A[i];
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for (int j = 1; j <= DIGIT_SIZE_b / 2; j = j * 2) {
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t ^= t << (unsigned) j;
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}
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A[i] = t;
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t >>= DIGIT_SIZE_b - 1;
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}
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}
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