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diff --git a/audio_codec/libraac/fft.c b/audio_codec/libraac/fft.c new file mode 100644 index 0000000..e17a2bd --- a/dev/null +++ b/audio_codec/libraac/fft.c @@ -0,0 +1,393 @@ +/* ***** BEGIN LICENSE BLOCK ***** + * Source last modified: $Id: fft.c,v 1.1 2005/02/26 01:47:34 jrecker Exp $ + * + * Portions Copyright (c) 1995-2005 RealNetworks, Inc. All Rights Reserved. + * + * The contents of this file, and the files included with this file, + * are subject to the current version of the RealNetworks Public + * Source License (the "RPSL") available at + * http://www.helixcommunity.org/content/rpsl unless you have licensed + * the file under the current version of the RealNetworks Community + * Source License (the "RCSL") available at + * http://www.helixcommunity.org/content/rcsl, in which case the RCSL + * will apply. You may also obtain the license terms directly from + * RealNetworks. You may not use this file except in compliance with + * the RPSL or, if you have a valid RCSL with RealNetworks applicable + * to this file, the RCSL. Please see the applicable RPSL or RCSL for + * the rights, obligations and limitations governing use of the + * contents of the file. + * + * This file is part of the Helix DNA Technology. RealNetworks is the + * developer of the Original Code and owns the copyrights in the + * portions it created. + * + * This file, and the files included with this file, is distributed + * and made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY + * KIND, EITHER EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS + * ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET + * ENJOYMENT OR NON-INFRINGEMENT. + * + * Technology Compatibility Kit Test Suite(s) Location: + * http://www.helixcommunity.org/content/tck + * + * Contributor(s): + * + * ***** END LICENSE BLOCK ***** */ + +/************************************************************************************** + * Fixed-point HE-AAC decoder + * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) + * February 2005 + * + * fft.c - Ken's optimized radix-4 DIT FFT, optional radix-8 first pass for odd log2(N) + **************************************************************************************/ + +#include "coder.h" + +#include "assembly.h" + + +#define NUM_FFT_SIZES 2 +static const int nfftTab[NUM_FFT_SIZES] = {64, 512}; +static const int nfftlog2Tab[NUM_FFT_SIZES] = {6, 9}; + +#define SQRT1_2 0x5a82799a /* sqrt(1/2) in Q31 */ + +#define swapcplx(p0,p1) \ + t = p0; t1 = *(&(p0)+1); p0 = p1; *(&(p0)+1) = *(&(p1)+1); p1 = t; *(&(p1)+1) = t1 + +/************************************************************************************** + * Function: BitReverse + * + * Description: Ken's fast in-place bit reverse, using super-small table + * + * Inputs: buffer of samples + * table index (for transform size) + * + * Outputs: bit-reversed samples in same buffer + * + * Return: none + **************************************************************************************/ +static void BitReverse(int *inout, int tabidx) +{ + int *part0, *part1; + int a, b, t, t1; + const unsigned char* tab = bitrevtab + bitrevtabOffset[tabidx]; + int nbits = nfftlog2Tab[tabidx]; + + part0 = inout; + part1 = inout + (1 << nbits); + + while ((a = *tab++) != 0) { + b = *tab++; + + swapcplx(part0[4 * a + 0], part0[4 * b + 0]); /* 0xxx0 <-> 0yyy0 */ + swapcplx(part0[4 * a + 2], part1[4 * b + 0]); /* 0xxx1 <-> 1yyy0 */ + swapcplx(part1[4 * a + 0], part0[4 * b + 2]); /* 1xxx0 <-> 0yyy1 */ + swapcplx(part1[4 * a + 2], part1[4 * b + 2]); /* 1xxx1 <-> 1yyy1 */ + } + + do { + swapcplx(part0[4 * a + 2], part1[4 * a + 0]); /* 0xxx1 <-> 1xxx0 */ + } while ((a = *tab++) != 0); +} + +/************************************************************************************** + * Function: R4FirstPass + * + * Description: radix-4 trivial pass for decimation-in-time FFT + * + * Inputs: buffer of (bit-reversed) samples + * number of R4 butterflies per group (i.e. nfft / 4) + * + * Outputs: processed samples in same buffer + * + * Return: none + * + * Notes: assumes 2 guard bits, gains no integer bits, + * guard bits out = guard bits in - 2 + **************************************************************************************/ +static void R4FirstPass(int *x, int bg) +{ + int ar, ai, br, bi, cr, ci, dr, di; + + for (; bg != 0; bg--) { + + ar = x[0] + x[2]; + br = x[0] - x[2]; + ai = x[1] + x[3]; + bi = x[1] - x[3]; + cr = x[4] + x[6]; + dr = x[4] - x[6]; + ci = x[5] + x[7]; + di = x[5] - x[7]; + + /* max per-sample gain = 4.0 (adding 4 inputs together) */ + x[0] = ar + cr; + x[4] = ar - cr; + x[1] = ai + ci; + x[5] = ai - ci; + x[2] = br + di; + x[6] = br - di; + x[3] = bi - dr; + x[7] = bi + dr; + + x += 8; + } +} + +/************************************************************************************** + * Function: R8FirstPass + * + * Description: radix-8 trivial pass for decimation-in-time FFT + * + * Inputs: buffer of (bit-reversed) samples + * number of R8 butterflies per group (i.e. nfft / 8) + * + * Outputs: processed samples in same buffer + * + * Return: none + * + * Notes: assumes 3 guard bits, gains 1 integer bit + * guard bits out = guard bits in - 3 (if inputs are full scale) + * or guard bits in - 2 (if inputs bounded to +/- sqrt(2)/2) + * see scaling comments in code + **************************************************************************************/ +static void R8FirstPass(int *x, int bg) +{ + int ar, ai, br, bi, cr, ci, dr, di; + int sr, si, tr, ti, ur, ui, vr, vi; + int wr, wi, xr, xi, yr, yi, zr, zi; + + for (; bg != 0; bg--) { + + ar = x[0] + x[2]; + br = x[0] - x[2]; + ai = x[1] + x[3]; + bi = x[1] - x[3]; + cr = x[4] + x[6]; + dr = x[4] - x[6]; + ci = x[5] + x[7]; + di = x[5] - x[7]; + + sr = ar + cr; + ur = ar - cr; + si = ai + ci; + ui = ai - ci; + tr = br - di; + vr = br + di; + ti = bi + dr; + vi = bi - dr; + + ar = x[ 8] + x[10]; + br = x[ 8] - x[10]; + ai = x[ 9] + x[11]; + bi = x[ 9] - x[11]; + cr = x[12] + x[14]; + dr = x[12] - x[14]; + ci = x[13] + x[15]; + di = x[13] - x[15]; + + /* max gain of wr/wi/yr/yi vs input = 2 + * (sum of 4 samples >> 1) + */ + wr = (ar + cr) >> 1; + yr = (ar - cr) >> 1; + wi = (ai + ci) >> 1; + yi = (ai - ci) >> 1; + + /* max gain of output vs input = 4 + * (sum of 4 samples >> 1 + sum of 4 samples >> 1) + */ + x[ 0] = (sr >> 1) + wr; + x[ 8] = (sr >> 1) - wr; + x[ 1] = (si >> 1) + wi; + x[ 9] = (si >> 1) - wi; + x[ 4] = (ur >> 1) + yi; + x[12] = (ur >> 1) - yi; + x[ 5] = (ui >> 1) - yr; + x[13] = (ui >> 1) + yr; + + ar = br - di; + cr = br + di; + ai = bi + dr; + ci = bi - dr; + + /* max gain of xr/xi/zr/zi vs input = 4*sqrt(2)/2 = 2*sqrt(2) + * (sum of 8 samples, multiply by sqrt(2)/2, implicit >> 1 from Q31) + */ + xr = MULSHIFT32(SQRT1_2, ar - ai); + xi = MULSHIFT32(SQRT1_2, ar + ai); + zr = MULSHIFT32(SQRT1_2, cr - ci); + zi = MULSHIFT32(SQRT1_2, cr + ci); + + /* max gain of output vs input = (2 + 2*sqrt(2) ~= 4.83) + * (sum of 4 samples >> 1, plus xr/xi/zr/zi with gain of 2*sqrt(2)) + * in absolute terms, we have max gain of appx 9.656 (4 + 0.707*8) + * but we also gain 1 int bit (from MULSHIFT32 or from explicit >> 1) + */ + x[ 6] = (tr >> 1) - xr; + x[14] = (tr >> 1) + xr; + x[ 7] = (ti >> 1) - xi; + x[15] = (ti >> 1) + xi; + x[ 2] = (vr >> 1) + zi; + x[10] = (vr >> 1) - zi; + x[ 3] = (vi >> 1) - zr; + x[11] = (vi >> 1) + zr; + + x += 16; + } +} + +/************************************************************************************** + * Function: R4Core + * + * Description: radix-4 pass for decimation-in-time FFT + * + * Inputs: buffer of samples + * number of R4 butterflies per group + * number of R4 groups per pass + * pointer to twiddle factors tables + * + * Outputs: processed samples in same buffer + * + * Return: none + * + * Notes: gain 2 integer bits per pass (see scaling comments in code) + * min 1 GB in + * gbOut = gbIn - 1 (short block) or gbIn - 2 (long block) + * uses 3-mul, 3-add butterflies instead of 4-mul, 2-add + **************************************************************************************/ +static void R4Core(int *x, int bg, int gp, int *wtab) +{ + int ar, ai, br, bi, cr, ci, dr, di, tr, ti; + int wd, ws, wi; + int i, j, step; + int *xptr, *wptr; + + for (; bg != 0; gp <<= 2, bg >>= 2) { + + step = 2 * gp; + xptr = x; + + /* max per-sample gain, per group < 1 + 3*sqrt(2) ~= 5.25 if inputs x are full-scale + * do 3 groups for long block, 2 groups for short block (gain 2 int bits per group) + * + * very conservative scaling: + * group 1: max gain = 5.25, int bits gained = 2, gb used = 1 (2^3 = 8) + * group 2: max gain = 5.25^2 = 27.6, int bits gained = 4, gb used = 1 (2^5 = 32) + * group 3: max gain = 5.25^3 = 144.7, int bits gained = 6, gb used = 2 (2^8 = 256) + */ + for (i = bg; i != 0; i--) { + + wptr = wtab; + + for (j = gp; j != 0; j--) { + + ar = xptr[0]; + ai = xptr[1]; + xptr += step; + + /* gain 2 int bits for br/bi, cr/ci, dr/di (MULSHIFT32 by Q30) + * gain 1 net GB + */ + ws = wptr[0]; + wi = wptr[1]; + br = xptr[0]; + bi = xptr[1]; + wd = ws + 2 * wi; + tr = MULSHIFT32(wi, br + bi); + br = MULSHIFT32(wd, br) - tr; /* cos*br + sin*bi */ + bi = MULSHIFT32(ws, bi) + tr; /* cos*bi - sin*br */ + xptr += step; + + ws = wptr[2]; + wi = wptr[3]; + cr = xptr[0]; + ci = xptr[1]; + wd = ws + 2 * wi; + tr = MULSHIFT32(wi, cr + ci); + cr = MULSHIFT32(wd, cr) - tr; + ci = MULSHIFT32(ws, ci) + tr; + xptr += step; + + ws = wptr[4]; + wi = wptr[5]; + dr = xptr[0]; + di = xptr[1]; + wd = ws + 2 * wi; + tr = MULSHIFT32(wi, dr + di); + dr = MULSHIFT32(wd, dr) - tr; + di = MULSHIFT32(ws, di) + tr; + wptr += 6; + + tr = ar; + ti = ai; + ar = (tr >> 2) - br; + ai = (ti >> 2) - bi; + br = (tr >> 2) + br; + bi = (ti >> 2) + bi; + + tr = cr; + ti = ci; + cr = tr + dr; + ci = di - ti; + dr = tr - dr; + di = di + ti; + + xptr[0] = ar + ci; + xptr[1] = ai + dr; + xptr -= step; + xptr[0] = br - cr; + xptr[1] = bi - di; + xptr -= step; + xptr[0] = ar - ci; + xptr[1] = ai - dr; + xptr -= step; + xptr[0] = br + cr; + xptr[1] = bi + di; + xptr += 2; + } + xptr += 3 * step; + } + wtab += 3 * step; + } +} + + +/************************************************************************************** + * Function: R4FFT + * + * Description: Ken's very fast in-place radix-4 decimation-in-time FFT + * + * Inputs: table index (for transform size) + * buffer of samples (non bit-reversed) + * + * Outputs: processed samples in same buffer + * + * Return: none + * + * Notes: assumes 5 guard bits in for nfft <= 512 + * gbOut = gbIn - 4 (assuming input is from PreMultiply) + * gains log2(nfft) - 2 int bits total + * so gain 7 int bits (LONG), 4 int bits (SHORT) + **************************************************************************************/ +void R4FFT(int tabidx, int *x) +{ + int order = nfftlog2Tab[tabidx]; + int nfft = nfftTab[tabidx]; + + /* decimation in time */ + BitReverse(x, tabidx); + + if (order & 0x1) { + /* long block: order = 9, nfft = 512 */ + R8FirstPass(x, nfft >> 3); /* gain 1 int bit, lose 2 GB */ + R4Core(x, nfft >> 5, 8, (int *)twidTabOdd); /* gain 6 int bits, lose 2 GB */ + } else { + /* short block: order = 6, nfft = 64 */ + R4FirstPass(x, nfft >> 2); /* gain 0 int bits, lose 2 GB */ + R4Core(x, nfft >> 4, 4, (int *)twidTabEven); /* gain 4 int bits, lose 1 GB */ + } +} |