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mdct15: simplify x86 exptab permutation

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Removes an unneeded copy and does the 5-point permute in-place.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2018-05-07 23:16:37 +01:00
parent a72d0fb973
commit 29eb1c51d7
1 changed files with 24 additions and 29 deletions
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53
libavcodec/x86/mdct15_init.c
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@ -33,32 +33,35 @@ void ff_fft15_avx(FFTComplex *out, FFTComplex *in, FFTComplex *exptab, ptrdiff_t
static void perm_twiddles(MDCT15Context *s)
{
int k;
FFTComplex exp_5point[4];
FFTComplex tmp[30];
FFTComplex tmp[21], tmp2[30];
memcpy(tmp, s->exptab, sizeof(FFTComplex)*21);
/* 5-point FFT twiddles */
s->exptab[60].re = s->exptab[60].im = s->exptab[19].re;
s->exptab[61].re = s->exptab[61].im = s->exptab[19].im;
s->exptab[62].re = s->exptab[62].im = s->exptab[20].re;
s->exptab[63].re = s->exptab[63].im = s->exptab[20].im;
/* 15-point FFT twiddles */
for (k = 0; k < 5; k++) {
tmp2[6*k + 0] = tmp[k + 0];
tmp2[6*k + 2] = tmp[k + 5];
tmp2[6*k + 4] = tmp[k + 10];
tmp[6*k + 0] = s->exptab[k + 0];
tmp[6*k + 2] = s->exptab[k + 5];
tmp[6*k + 4] = s->exptab[k + 10];
tmp2[6*k + 1] = tmp[2 * (k + 0)];
tmp2[6*k + 3] = tmp[2 * (k + 5)];
tmp2[6*k + 5] = tmp[2 * k + 5 ];
tmp[6*k + 1] = s->exptab[2 * (k + 0)];
tmp[6*k + 3] = s->exptab[2 * (k + 5)];
tmp[6*k + 5] = s->exptab[2 * k + 5 ];
}
for (k = 0; k < 6; k++) {
FFTComplex ac_exp[] = {
{ tmp2[6*1 + k].re, tmp2[6*1 + k].re },
{ tmp2[6*2 + k].re, tmp2[6*2 + k].re },
{ tmp2[6*3 + k].re, tmp2[6*3 + k].re },
{ tmp2[6*4 + k].re, tmp2[6*4 + k].re },
{ tmp2[6*1 + k].im, -tmp2[6*1 + k].im },
{ tmp2[6*2 + k].im, -tmp2[6*2 + k].im },
{ tmp2[6*3 + k].im, -tmp2[6*3 + k].im },
{ tmp2[6*4 + k].im, -tmp2[6*4 + k].im },
{ tmp[6*1 + k].re, tmp[6*1 + k].re },
{ tmp[6*2 + k].re, tmp[6*2 + k].re },
{ tmp[6*3 + k].re, tmp[6*3 + k].re },
{ tmp[6*4 + k].re, tmp[6*4 + k].re },
{ tmp[6*1 + k].im, -tmp[6*1 + k].im },
{ tmp[6*2 + k].im, -tmp[6*2 + k].im },
{ tmp[6*3 + k].im, -tmp[6*3 + k].im },
{ tmp[6*4 + k].im, -tmp[6*4 + k].im },
};
memcpy(s->exptab + 8*k, ac_exp, 8*sizeof(FFTComplex));
}
@ -66,21 +69,13 @@ static void perm_twiddles(MDCT15Context *s)
/* Specialcase when k = 0 */
for (k = 0; k < 3; k++) {
FFTComplex dc_exp[] = {
{ tmp2[2*k + 0].re, -tmp2[2*k + 0].im },
{ tmp2[2*k + 0].im, tmp2[2*k + 0].re },
{ tmp2[2*k + 1].re, -tmp2[2*k + 1].im },
{ tmp2[2*k + 1].im, tmp2[2*k + 1].re },
{ tmp[2*k + 0].re, -tmp[2*k + 0].im },
{ tmp[2*k + 0].im, tmp[2*k + 0].re },
{ tmp[2*k + 1].re, -tmp[2*k + 1].im },
{ tmp[2*k + 1].im, tmp[2*k + 1].re },
};
memcpy(s->exptab + 8*6 + 4*k, dc_exp, 4*sizeof(FFTComplex));
}
/* 5-point FFT twiddles */
exp_5point[0].re = exp_5point[0].im = tmp[19].re;
exp_5point[1].re = exp_5point[1].im = tmp[19].im;
exp_5point[2].re = exp_5point[2].im = tmp[20].re;
exp_5point[3].re = exp_5point[3].im = tmp[20].im;
memcpy(s->exptab + 8*6 + 4*3, exp_5point, 4*sizeof(FFTComplex));
}
av_cold void ff_mdct15_init_x86(MDCT15Context *s)