-rw-r--r-- 1080 libmceliece-20240726/crypto_kem/348864/vec/transpose.h raw
/*
This file is for matrix transposition
*/
#ifndef TRANSPOSE_H
#define TRANSPOSE_H
#include <stdint.h>
/* input: in, a 64x64 matrix over GF(2) */
/* output: out, transpose of in */
static inline void transpose_64x64(uint64_t * out, uint64_t * in)
{
int i, j, s, d;
uint64_t x, y;
uint64_t masks[6][2] = {
{0x5555555555555555, 0xAAAAAAAAAAAAAAAA},
{0x3333333333333333, 0xCCCCCCCCCCCCCCCC},
{0x0F0F0F0F0F0F0F0F, 0xF0F0F0F0F0F0F0F0},
{0x00FF00FF00FF00FF, 0xFF00FF00FF00FF00},
{0x0000FFFF0000FFFF, 0xFFFF0000FFFF0000},
{0x00000000FFFFFFFF, 0xFFFFFFFF00000000}
};
for (i = 0; i < 64; i++)
out[i] = in[i];
for (d = 5; d >= 0; d--)
{
s = 1 << d;
for (i = 0; i < 64; i += s*2)
for (j = i; j < i+s; j++)
{
x = (out[j] & masks[d][0]) | ((out[j+s] & masks[d][0]) << s);
y = ((out[j] & masks[d][1]) >> s) | (out[j+s] & masks[d][1]);
out[j+0] = x;
out[j+s] = y;
}
}
}
#endif