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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "tx_priv.h"
int ff_tx_type_is_mdct(enum AVTXType type)
{
switch (type) {
case AV_TX_FLOAT_MDCT:
case AV_TX_DOUBLE_MDCT:
case AV_TX_INT32_MDCT:
return 1;
default:
return 0;
}
}
/* Calculates the modular multiplicative inverse */
static av_always_inline int mulinv(int n, int m)
{
n = n % m;
for (int x = 1; x < m; x++)
if (((n * x) % m) == 1)
return x;
av_assert0(0); /* Never reached */
return 0;
}
/* Guaranteed to work for any n, m where gcd(n, m) == 1 */
int ff_tx_gen_compound_mapping(AVTXContext *s)
{
int *in_map, *out_map;
const int n = s->n;
const int m = s->m;
const int inv = s->inv;
const int len = n*m;
const int m_inv = mulinv(m, n);
const int n_inv = mulinv(n, m);
const int mdct = ff_tx_type_is_mdct(s->type);
if (!(s->pfatab = av_malloc(2*len*sizeof(*s->pfatab))))
return AVERROR(ENOMEM);
in_map = s->pfatab;
out_map = s->pfatab + n*m;
/* Ruritanian map for input, CRT map for output, can be swapped */
for (int j = 0; j < m; j++) {
for (int i = 0; i < n; i++) {
/* Shifted by 1 to simplify MDCTs */
in_map[j*n + i] = ((i*m + j*n) % len) << mdct;
out_map[(i*m*m_inv + j*n*n_inv) % len] = i*m + j;
}
}
/* Change transform direction by reversing all ACs */
if (inv) {
for (int i = 0; i < m; i++) {
int *in = &in_map[i*n + 1]; /* Skip the DC */
for (int j = 0; j < ((n - 1) >> 1); j++)
FFSWAP(int, in[j], in[n - j - 2]);
}
}
/* Our 15-point transform is also a compound one, so embed its input map */
if (n == 15) {
for (int k = 0; k < m; k++) {
int tmp[15];
memcpy(tmp, &in_map[k*15], 15*sizeof(*tmp));
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 3; j++)
in_map[k*15 + i*3 + j] = tmp[(i*3 + j*5) % 15];
}
}
}
return 0;
}
static inline int split_radix_permutation(int i, int m, int inverse)
{
m >>= 1;
if (m <= 1)
return i & 1;
if (!(i & m))
return split_radix_permutation(i, m, inverse) * 2;
m >>= 1;
return split_radix_permutation(i, m, inverse) * 4 + 1 - 2*(!(i & m) ^ inverse);
}
int ff_tx_gen_ptwo_revtab(AVTXContext *s, int invert_lookup)
{
const int m = s->m, inv = s->inv;
if (!(s->revtab = av_malloc(s->m*sizeof(*s->revtab))))
return AVERROR(ENOMEM);
if (!(s->revtab_c = av_malloc(m*sizeof(*s->revtab_c))))
return AVERROR(ENOMEM);
/* Default */
for (int i = 0; i < m; i++) {
int k = -split_radix_permutation(i, m, inv) & (m - 1);
if (invert_lookup)
s->revtab[i] = s->revtab_c[i] = k;
else
s->revtab[i] = s->revtab_c[k] = i;
}
return 0;
}
int ff_tx_gen_ptwo_inplace_revtab_idx(AVTXContext *s, int *revtab)
{
int nb_inplace_idx = 0;
if (!(s->inplace_idx = av_malloc(s->m*sizeof(*s->inplace_idx))))
return AVERROR(ENOMEM);
/* The first coefficient is always already in-place */
for (int src = 1; src < s->m; src++) {
int dst = revtab[src];
int found = 0;
if (dst <= src)
continue;
/* This just checks if a closed loop has been encountered before,
* and if so, skips it, since to fully permute a loop we must only
* enter it once. */
do {
for (int j = 0; j < nb_inplace_idx; j++) {
if (dst == s->inplace_idx[j]) {
found = 1;
break;
}
}
dst = revtab[dst];
} while (dst != src && !found);
if (!found)
s->inplace_idx[nb_inplace_idx++] = src;
}
s->inplace_idx[nb_inplace_idx++] = 0;
return 0;
}
static void parity_revtab_generator(int *revtab, int n, int inv, int offset,
int is_dual, int dual_high, int len,
int basis, int dual_stride)
{
len >>= 1;
if (len <= basis) {
int k1, k2, *even, *odd, stride;
is_dual = is_dual && dual_stride;
dual_high = is_dual & dual_high;
stride = is_dual ? FFMIN(dual_stride, len) : 0;
even = &revtab[offset + dual_high*(stride - 2*len)];
odd = &even[len + (is_dual && !dual_high)*len + dual_high*len];
for (int i = 0; i < len; i++) {
k1 = -split_radix_permutation(offset + i*2 + 0, n, inv) & (n - 1);
k2 = -split_radix_permutation(offset + i*2 + 1, n, inv) & (n - 1);
*even++ = k1;
*odd++ = k2;
if (stride && !((i + 1) % stride)) {
even += stride;
odd += stride;
}
}
return;
}
parity_revtab_generator(revtab, n, inv, offset,
0, 0, len >> 0, basis, dual_stride);
parity_revtab_generator(revtab, n, inv, offset + (len >> 0),
1, 0, len >> 1, basis, dual_stride);
parity_revtab_generator(revtab, n, inv, offset + (len >> 0) + (len >> 1),
1, 1, len >> 1, basis, dual_stride);
}
void ff_tx_gen_split_radix_parity_revtab(int *revtab, int len, int inv,
int basis, int dual_stride)
{
basis >>= 1;
if (len < basis)
return;
av_assert0(!dual_stride || !(dual_stride & (dual_stride - 1)));
av_assert0(dual_stride <= basis);
parity_revtab_generator(revtab, len, inv, 0, 0, 0, len, basis, dual_stride);
}
av_cold void av_tx_uninit(AVTXContext **ctx)
{
if (!(*ctx))
return;
av_free((*ctx)->pfatab);
av_free((*ctx)->exptab);
av_free((*ctx)->revtab);
av_free((*ctx)->revtab_c);
av_free((*ctx)->inplace_idx);
av_free((*ctx)->tmp);
av_freep(ctx);
}
av_cold int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
int inv, int len, const void *scale, uint64_t flags)
{
int err;
AVTXContext *s = av_mallocz(sizeof(*s));
if (!s)
return AVERROR(ENOMEM);
switch (type) {
case AV_TX_FLOAT_FFT:
case AV_TX_FLOAT_MDCT:
if ((err = ff_tx_init_mdct_fft_float(s, tx, type, inv, len, scale, flags)))
goto fail;
if (ARCH_X86)
ff_tx_init_float_x86(s, tx);
break;
case AV_TX_DOUBLE_FFT:
case AV_TX_DOUBLE_MDCT:
if ((err = ff_tx_init_mdct_fft_double(s, tx, type, inv, len, scale, flags)))
goto fail;
break;
case AV_TX_INT32_FFT:
case AV_TX_INT32_MDCT:
if ((err = ff_tx_init_mdct_fft_int32(s, tx, type, inv, len, scale, flags)))
goto fail;
break;
default:
err = AVERROR(EINVAL);
goto fail;
}
*ctx = s;
return 0;
fail:
av_tx_uninit(&s);
*tx = NULL;
return err;
}
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