-rw-r--r-- 7729 libmceliece-20240726/crypto_kem/460896/vec/fft_tr.c raw
/*
This file is for transpose of the Gao-Mateer FFT
Functions with names ending with _tr are (roughly) the transpose of the corresponding functions in fft.c
For the implementation strategy, see
https://eprint.iacr.org/2017/793.pdf
*/
// 20221230 djb: split these arrays into separate .c files
// 20221230 djb: rename consts array as fft_consts
// 20221230 djb: rename s array as fft_scalars_4x
// 20221230 djb: add linker lines
// linker define fft_tr
// linker use vec_mul
// linker use fft_scalars_4x fft_consts
#include "fft_tr.h"
#include "fft_scalars_4x.h"
#include "fft_consts.h"
#include "transpose.h"
#include <stdint.h>
static void radix_conversions_tr(vec in[][ GFBITS ])
{
int i, j, k;
const vec mask[6][2] =
{
{0x2222222222222222, 0x4444444444444444},
{0x0C0C0C0C0C0C0C0C, 0x3030303030303030},
{0x00F000F000F000F0, 0x0F000F000F000F00},
{0x0000FF000000FF00, 0x00FF000000FF0000},
{0x00000000FFFF0000, 0x0000FFFF00000000},
{0xFFFFFFFF00000000, 0x00000000FFFFFFFF}
};
//
for (j = 6; j >= 0; j--)
{
if (j < 6)
{
vec_mul(in[0], in[0], fft_scalars_4x[j][0]); // scaling
vec_mul(in[1], in[1], fft_scalars_4x[j][1]); // scaling
vec_mul(in[2], in[2], fft_scalars_4x[j][2]); // scaling
vec_mul(in[3], in[3], fft_scalars_4x[j][3]); // scaling
}
for (k = j; k <= 4; k++)
for (i = 0; i < GFBITS; i++)
{
in[0][i] ^= (in[0][i] & mask[k][0]) << (1 << k);
in[0][i] ^= (in[0][i] & mask[k][1]) << (1 << k);
in[1][i] ^= (in[1][i] & mask[k][0]) << (1 << k);
in[1][i] ^= (in[1][i] & mask[k][1]) << (1 << k);
in[2][i] ^= (in[2][i] & mask[k][0]) << (1 << k);
in[2][i] ^= (in[2][i] & mask[k][1]) << (1 << k);
in[3][i] ^= (in[3][i] & mask[k][0]) << (1 << k);
in[3][i] ^= (in[3][i] & mask[k][1]) << (1 << k);
}
if (j <= 5)
for (i = 0; i < GFBITS; i++)
{
in[1][i] ^= in[0][i] >> 32;
in[1][i] ^= in[1][i] << 32;
in[3][i] ^= in[2][i] >> 32;
in[3][i] ^= in[3][i] << 32;
}
for (i = 0; i < GFBITS; i++)
in[3][i] ^= in[2][i] ^= in[1][i];
}
}
static void butterflies_tr(vec out[][ GFBITS ], vec in[][ GFBITS ])
{
int i, j, k, s, b;
vec tmp[ GFBITS ];
vec pre[6][2][ GFBITS ];
vec buf[2][64];
uint64_t consts_ptr = 128;
const unsigned char reversal[128] =
{
0, 64, 32, 96, 16, 80, 48, 112,
8, 72, 40, 104, 24, 88, 56, 120,
4, 68, 36, 100, 20, 84, 52, 116,
12, 76, 44, 108, 28, 92, 60, 124,
2, 66, 34, 98, 18, 82, 50, 114,
10, 74, 42, 106, 26, 90, 58, 122,
6, 70, 38, 102, 22, 86, 54, 118,
14, 78, 46, 110, 30, 94, 62, 126,
1, 65, 33, 97, 17, 81, 49, 113,
9, 73, 41, 105, 25, 89, 57, 121,
5, 69, 37, 101, 21, 85, 53, 117,
13, 77, 45, 109, 29, 93, 61, 125,
3, 67, 35, 99, 19, 83, 51, 115,
11, 75, 43, 107, 27, 91, 59, 123,
7, 71, 39, 103, 23, 87, 55, 119,
15, 79, 47, 111, 31, 95, 63, 127
};
const uint16_t beta[6] = {5246, 5306, 6039, 6685, 4905, 6755};
//
for (i = 6; i >= 0; i--)
{
s = 1 << i;
consts_ptr -= s;
for (j = 0; j < 128; j += 2*s)
for (k = j; k < j+s; k++)
{
for (b = 0; b < GFBITS; b++) in[k][b] ^= in[k+s][b];
vec_mul(tmp, in[k], fft_consts[ consts_ptr + (k-j) ]);
for (b = 0; b < GFBITS; b++) in[k+s][b] ^= tmp[b];
}
}
for (i = 0; i < GFBITS; i++)
{
for (k = 0; k < 128; k++)
(&buf[0][0])[ k ] = in[ reversal[k] ][i];
transpose_64x64(buf[0], buf[0]);
transpose_64x64(buf[1], buf[1]);
for (k = 0; k < 2; k++)
{
pre[0][k][i] = buf[k][32]; buf[k][33] ^= buf[k][32];
pre[1][k][i] = buf[k][33]; buf[k][35] ^= buf[k][33];
pre[0][k][i] ^= buf[k][35]; buf[k][34] ^= buf[k][35];
pre[2][k][i] = buf[k][34]; buf[k][38] ^= buf[k][34];
pre[0][k][i] ^= buf[k][38]; buf[k][39] ^= buf[k][38];
pre[1][k][i] ^= buf[k][39]; buf[k][37] ^= buf[k][39];
pre[0][k][i] ^= buf[k][37]; buf[k][36] ^= buf[k][37];
pre[3][k][i] = buf[k][36]; buf[k][44] ^= buf[k][36];
pre[0][k][i] ^= buf[k][44]; buf[k][45] ^= buf[k][44];
pre[1][k][i] ^= buf[k][45]; buf[k][47] ^= buf[k][45];
pre[0][k][i] ^= buf[k][47]; buf[k][46] ^= buf[k][47];
pre[2][k][i] ^= buf[k][46]; buf[k][42] ^= buf[k][46];
pre[0][k][i] ^= buf[k][42]; buf[k][43] ^= buf[k][42];
pre[1][k][i] ^= buf[k][43]; buf[k][41] ^= buf[k][43];
pre[0][k][i] ^= buf[k][41]; buf[k][40] ^= buf[k][41];
pre[4][k][i] = buf[k][40]; buf[k][56] ^= buf[k][40];
pre[0][k][i] ^= buf[k][56]; buf[k][57] ^= buf[k][56];
pre[1][k][i] ^= buf[k][57]; buf[k][59] ^= buf[k][57];
pre[0][k][i] ^= buf[k][59]; buf[k][58] ^= buf[k][59];
pre[2][k][i] ^= buf[k][58]; buf[k][62] ^= buf[k][58];
pre[0][k][i] ^= buf[k][62]; buf[k][63] ^= buf[k][62];
pre[1][k][i] ^= buf[k][63]; buf[k][61] ^= buf[k][63];
pre[0][k][i] ^= buf[k][61]; buf[k][60] ^= buf[k][61];
pre[3][k][i] ^= buf[k][60]; buf[k][52] ^= buf[k][60];
pre[0][k][i] ^= buf[k][52]; buf[k][53] ^= buf[k][52];
pre[1][k][i] ^= buf[k][53]; buf[k][55] ^= buf[k][53];
pre[0][k][i] ^= buf[k][55]; buf[k][54] ^= buf[k][55];
pre[2][k][i] ^= buf[k][54]; buf[k][50] ^= buf[k][54];
pre[0][k][i] ^= buf[k][50]; buf[k][51] ^= buf[k][50];
pre[1][k][i] ^= buf[k][51]; buf[k][49] ^= buf[k][51];
pre[0][k][i] ^= buf[k][49]; buf[k][48] ^= buf[k][49];
pre[5][k][i] = buf[k][48]; buf[k][16] ^= buf[k][48];
pre[0][k][i] ^= buf[k][16]; buf[k][17] ^= buf[k][16];
pre[1][k][i] ^= buf[k][17]; buf[k][19] ^= buf[k][17];
pre[0][k][i] ^= buf[k][19]; buf[k][18] ^= buf[k][19];
pre[2][k][i] ^= buf[k][18]; buf[k][22] ^= buf[k][18];
pre[0][k][i] ^= buf[k][22]; buf[k][23] ^= buf[k][22];
pre[1][k][i] ^= buf[k][23]; buf[k][21] ^= buf[k][23];
pre[0][k][i] ^= buf[k][21]; buf[k][20] ^= buf[k][21];
pre[3][k][i] ^= buf[k][20]; buf[k][28] ^= buf[k][20];
pre[0][k][i] ^= buf[k][28]; buf[k][29] ^= buf[k][28];
pre[1][k][i] ^= buf[k][29]; buf[k][31] ^= buf[k][29];
pre[0][k][i] ^= buf[k][31]; buf[k][30] ^= buf[k][31];
pre[2][k][i] ^= buf[k][30]; buf[k][26] ^= buf[k][30];
pre[0][k][i] ^= buf[k][26]; buf[k][27] ^= buf[k][26];
pre[1][k][i] ^= buf[k][27]; buf[k][25] ^= buf[k][27];
pre[0][k][i] ^= buf[k][25]; buf[k][24] ^= buf[k][25];
pre[4][k][i] ^= buf[k][24]; buf[k][8] ^= buf[k][24];
pre[0][k][i] ^= buf[k][8]; buf[k][9] ^= buf[k][8];
pre[1][k][i] ^= buf[k][9]; buf[k][11] ^= buf[k][9];
pre[0][k][i] ^= buf[k][11]; buf[k][10] ^= buf[k][11];
pre[2][k][i] ^= buf[k][10]; buf[k][14] ^= buf[k][10];
pre[0][k][i] ^= buf[k][14]; buf[k][15] ^= buf[k][14];
pre[1][k][i] ^= buf[k][15]; buf[k][13] ^= buf[k][15];
pre[0][k][i] ^= buf[k][13]; buf[k][12] ^= buf[k][13];
pre[3][k][i] ^= buf[k][12]; buf[k][4] ^= buf[k][12];
pre[0][k][i] ^= buf[k][4]; buf[k][5] ^= buf[k][4];
pre[1][k][i] ^= buf[k][5]; buf[k][7] ^= buf[k][5];
pre[0][k][i] ^= buf[k][7]; buf[k][6] ^= buf[k][7];
pre[2][k][i] ^= buf[k][6]; buf[k][2] ^= buf[k][6];
pre[0][k][i] ^= buf[k][2]; buf[k][3] ^= buf[k][2];
pre[1][k][i] ^= buf[k][3]; buf[k][1] ^= buf[k][3];
pre[0][k][i] ^= buf[k][1]; out[k][i] = buf[k][0] ^ buf[k][1];
}
}
for (j = 0; j < GFBITS; j++) tmp[j] = vec_setbits((beta[0] >> j) & 1);
vec_mul(out[2], pre[0][0], tmp);
vec_mul(out[3], pre[0][1], tmp);
for (i = 1; i < 6; i++)
{
for (j = 0; j < GFBITS; j++) tmp[j] = vec_setbits((beta[i] >> j) & 1);
vec_mul(pre[i][0], pre[i][0], tmp);
vec_mul(pre[i][1], pre[i][1], tmp);
for (b = 0; b < GFBITS; b++)
{
out[2][b] ^= pre[i][0][b];
out[3][b] ^= pre[i][1][b];
}
}
}
/* justifying the length of the output */
static void postprocess(vec out[4][GFBITS])
{
int i;
for (i = 0; i < GFBITS; i++)
out[3][i] = 0;
}
void fft_tr(vec out[][GFBITS], vec in[][ GFBITS ])
{
butterflies_tr(out, in);
radix_conversions_tr(out);
postprocess(out);
}