pqcrypto/crypto_kem/mceliece460896/clean/util.c

/*
  This file is for loading/storing data in a little-endian fashion
*/

#include "util.h"

#include "params.h"

void PQCLEAN_MCELIECE460896_CLEAN_store2(unsigned char *dest, gf a) {
    dest[0] = a & 0xFF;
    dest[1] = a >> 8;
}

uint16_t PQCLEAN_MCELIECE460896_CLEAN_load2(const unsigned char *src) {
    uint16_t a;

    a = src[1];
    a <<= 8;
    a |= src[0];

    return a & GFMASK;
}

uint32_t PQCLEAN_MCELIECE460896_CLEAN_load4(const unsigned char *in) {
    int i;
    uint32_t ret = in[3];

    for (i = 2; i >= 0; i--) {
        ret <<= 8;
        ret |= in[i];
    }

    return ret;
}

void PQCLEAN_MCELIECE460896_CLEAN_store8(unsigned char *out, uint64_t in) {
    out[0] = (in >> 0x00) & 0xFF;
    out[1] = (in >> 0x08) & 0xFF;
    out[2] = (in >> 0x10) & 0xFF;
    out[3] = (in >> 0x18) & 0xFF;
    out[4] = (in >> 0x20) & 0xFF;
    out[5] = (in >> 0x28) & 0xFF;
    out[6] = (in >> 0x30) & 0xFF;
    out[7] = (in >> 0x38) & 0xFF;
}

uint64_t PQCLEAN_MCELIECE460896_CLEAN_load8(const unsigned char *in) {
    int i;
    uint64_t ret = in[7];

    for (i = 6; i >= 0; i--) {
        ret <<= 8;
        ret |= in[i];
    }

    return ret;
}

gf PQCLEAN_MCELIECE460896_CLEAN_bitrev(gf a) {
    a = ((a & 0x00FF) << 8) | ((a & 0xFF00) >> 8);
    a = ((a & 0x0F0F) << 4) | ((a & 0xF0F0) >> 4);
    a = ((a & 0x3333) << 2) | ((a & 0xCCCC) >> 2);
    a = ((a & 0x5555) << 1) | ((a & 0xAAAA) >> 1);

    return a >> 3;
}