forked from len0rd/rockbox
d884af2b99
imdct and windowing are all in fixed point. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27302 a1c6a512-1295-4272-9138-f99709370657
51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
#include <inttypes.h>
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#include "wmapro_mdct.h"
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#include "mdct_tables.h" /* for sincos_lookup_wmap */
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#include "../lib/mdct_lookup.h" /* for revtab */
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#include "../lib/fft.h" /* for FFT data structures */
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#include "codeclib.h"
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#include "../lib/codeclib_misc.h" /* for XNPROD31 */
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void imdct_half(unsigned int nbits, int32_t *output, const int32_t *input){
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int k, n8, n4, n2, n, j;
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//const uint16_t *revtab = s->revtab;
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const int32_t *in1, *in2;
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FFTComplex *z = (FFTComplex *)output;
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n = 1 << nbits;
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n2 = n >> 1;
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n4 = n >> 2;
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n8 = n >> 3;
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const int32_t *T = sincos_lookup_wmap + ((n2) - (1<<7));
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/* pre rotation */
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const int revtab_shift = (14- nbits);
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in1 = input;
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in2 = input + n2 - 1;
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int step = 2<<(12-nbits);
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for(k = 0; k < n4; k++) {
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j=revtab[k]>>revtab_shift;
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XNPROD31(*in2, *in1, T[1]<<16, T[0]<<16, &z[j].re, &z[j].im );
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in1 += 2;
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in2 -= 2;
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T += 2;
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}
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ff_fft_calc_c(nbits-2, z);
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/* post rotation + reordering */
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T = sincos_lookup_wmap + ((n2) - (1<<7)) + n4;
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const int32_t *V = T;
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for(k = 0; k < n8; k++) {
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int32_t r0, i0, r1, i1;
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XNPROD31(z[n8-k-1].im, z[n8-k-1].re, T[0]<<16, T[1]<<16, &r0, &i1 );
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XNPROD31(z[n8+k ].im, z[n8+k ].re, V[0]<<16, V[1]<<16, &r1, &i0 );
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z[n8-k-1].re = r0;
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z[n8-k-1].im = i0;
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z[n8+k ].re = r1;
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z[n8+k ].im = i1;
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T-=2;
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V+=2;
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}
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}
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