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mdct15: simplify prereindexing and forward transform postrotation

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Equivalent.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
pull/265/head
Rostislav Pehlivanov 8 years ago
parent 2e08bbb282
commit 0563a5d175
1 changed files with 18 additions and 19 deletions
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  1. 37
      libavcodec/mdct15.c

37
libavcodec/mdct15.c
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@ -80,7 +80,7 @@ static inline int init_pfa_reindex_tabs(MDCT15Context *s)
const int q_post = (((j*inv_1)/15) + (i*inv_2)) >> b_ptwo;
const int k_pre = 15*i + (j - q_pre*15)*(1 << b_ptwo);
const int k_post = i*inv_2*15 + j*inv_1 - 15*q_post*l_ptwo;
s->pfa_prereindex[i*15 + j] = k_pre;
s->pfa_prereindex[i*15 + j] = k_pre << 1;
s->pfa_postreindex[k_post] = l_ptwo*j + i;
}
}
@ -173,16 +173,16 @@ static void mdct15(MDCT15Context *s, float *dst, const float *src, ptrdiff_t str
/* Folding and pre-reindexing */
for (i = 0; i < l_ptwo; i++) {
for (j = 0; j < 15; j++) {
float re, im;
const int k = s->pfa_prereindex[i*15 + j];
if (k < len8) {
re = -src[2*k+len3] - src[len3-1-2*k];
im = -src[len4+2*k] + src[len4-1-2*k];
FFTComplex tmp, exp = s->twiddle_exptab[k >> 1];
if (k < len4) {
tmp.re = -src[ len4 + k] + src[1*len4 - 1 - k];
tmp.im = -src[ len3 + k] - src[1*len3 - 1 - k];
} else {
re = src[2*k-len4] - src[1*len3-1-2*k];
im = -src[2*k+len4] - src[5*len4-1-2*k];
tmp.re = -src[ len4 + k] - src[5*len4 - 1 - k];
tmp.im = src[-len4 + k] - src[1*len3 - 1 - k];
}
CMUL(fft15in[j].re, fft15in[j].im, re, im, s->twiddle_exptab[k].re, -s->twiddle_exptab[k].im);
CMUL(fft15in[j].im, fft15in[j].re, tmp.re, tmp.im, exp.re, exp.im);
}
s->fft15(s->tmp + s->ptwo_fft.revtab[i], fft15in, s->exptab, l_ptwo);
}
@ -193,16 +193,13 @@ static void mdct15(MDCT15Context *s, float *dst, const float *src, ptrdiff_t str
/* Reindex again, apply twiddles and output */
for (i = 0; i < len8; i++) {
float re0, im0, re1, im1;
const int i0 = len8 + i, i1 = len8 - i - 1;
const int s0 = s->pfa_postreindex[i0], s1 = s->pfa_postreindex[i1];
CMUL(im1, re0, s->tmp[s1].re, s->tmp[s1].im, s->twiddle_exptab[i1].im, s->twiddle_exptab[i1].re);
CMUL(im0, re1, s->tmp[s0].re, s->tmp[s0].im, s->twiddle_exptab[i0].im, s->twiddle_exptab[i0].re);
dst[2*i1*stride ] = re0;
dst[2*i1*stride + stride] = im0;
dst[2*i0*stride ] = re1;
dst[2*i0*stride + stride] = im1;
CMUL(dst[2*i1*stride + stride], dst[2*i0*stride], s->tmp[s0].re, s->tmp[s0].im,
s->twiddle_exptab[i0].im, s->twiddle_exptab[i0].re);
CMUL(dst[2*i0*stride + stride], dst[2*i1*stride], s->tmp[s1].re, s->tmp[s1].im,
s->twiddle_exptab[i1].im, s->twiddle_exptab[i1].re);
}
}
@ -218,8 +215,8 @@ static void imdct15_half(MDCT15Context *s, float *dst, const float *src,
for (i = 0; i < l_ptwo; i++) {
for (j = 0; j < 15; j++) {
const int k = s->pfa_prereindex[i*15 + j];
FFTComplex tmp = { *(in2 - 2*k*stride), *(in1 + 2*k*stride) };
CMUL3(fft15in[j], tmp, s->twiddle_exptab[k]);
FFTComplex tmp = { in2[-k*stride], in1[k*stride] };
CMUL3(fft15in[j], tmp, s->twiddle_exptab[k >> 1]);
}
s->fft15(s->tmp + s->ptwo_fft.revtab[i], fft15in, s->exptab, l_ptwo);
}
@ -233,8 +230,10 @@ static void imdct15_half(MDCT15Context *s, float *dst, const float *src,
const int i0 = len8 + i, i1 = len8 - i - 1;
const int s0 = s->pfa_postreindex[i0], s1 = s->pfa_postreindex[i1];
CMUL(z[i1].re, z[i0].im, s->tmp[s1].im, s->tmp[s1].re, s->twiddle_exptab[i1].im, s->twiddle_exptab[i1].re);
CMUL(z[i0].re, z[i1].im, s->tmp[s0].im, s->tmp[s0].re, s->twiddle_exptab[i0].im, s->twiddle_exptab[i0].re);
CMUL(z[i1].re, z[i0].im, s->tmp[s1].im, s->tmp[s1].re,
s->twiddle_exptab[i1].im, s->twiddle_exptab[i1].re);
CMUL(z[i0].re, z[i1].im, s->tmp[s0].im, s->tmp[s0].re,
s->twiddle_exptab[i0].im, s->twiddle_exptab[i0].re);
}
}

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