sync to latest liba52 release (0.7.4)

CVS patchset: 2543
CVS date: 2002/08/28 20:27:56

1 files changed, 347 insertions, 318 deletions

diff --git a/src/liba52/imdct.c b/src/liba52/imdct.c
index cf4236555..648c95ede 100644
--- a/src/liba52/imdct.c
+++ b/src/liba52/imdct.c
@@ -1,8 +1,13 @@
 /*
  * imdct.c
- * Copyright (C) 1999-2001 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
+ * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
+ * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
+ *
+ * The ifft algorithms in this file have been largely inspired by Dan
+ * Bernstein's work, djbfft, available at http://cr.yp.to/djbfft.html
  *
  * This file is part of a52dec, a free ATSC A-52 stream decoder.
+ * See http://liba52.sourceforge.net/ for updates.
  *
  * a52dec is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -21,383 +26,407 @@
 
 #include "config.h"
 
-#include <inttypes.h>
 #include <math.h>
-
-#include "xineutils.h"
+#include <stdio.h>
+#ifdef LIBA52_DJBFFT
+#include <fftc4.h>
+#endif
+#ifndef M_PI
+#define M_PI 3.1415926535897932384626433832795029
+#endif
+#include <inttypes.h>
 
 #include "a52.h"
 #include "a52_internal.h"
-
-void (* imdct_256) (sample_t data[], sample_t delay[], sample_t bias);
-void (* imdct_512) (sample_t data[], sample_t delay[], sample_t bias);
+#include "xineutils.h"
 
 typedef struct complex_s {
     sample_t real;
     sample_t imag;
 } complex_t;
 
-
-/* 128 point bit-reverse LUT */
-static uint8_t bit_reverse_512[] = {
-	0x00, 0x40, 0x20, 0x60, 0x10, 0x50, 0x30, 0x70, 
-	0x08, 0x48, 0x28, 0x68, 0x18, 0x58, 0x38, 0x78, 
-	0x04, 0x44, 0x24, 0x64, 0x14, 0x54, 0x34, 0x74, 
-	0x0c, 0x4c, 0x2c, 0x6c, 0x1c, 0x5c, 0x3c, 0x7c, 
-	0x02, 0x42, 0x22, 0x62, 0x12, 0x52, 0x32, 0x72, 
-	0x0a, 0x4a, 0x2a, 0x6a, 0x1a, 0x5a, 0x3a, 0x7a, 
-	0x06, 0x46, 0x26, 0x66, 0x16, 0x56, 0x36, 0x76, 
-	0x0e, 0x4e, 0x2e, 0x6e, 0x1e, 0x5e, 0x3e, 0x7e, 
-	0x01, 0x41, 0x21, 0x61, 0x11, 0x51, 0x31, 0x71, 
-	0x09, 0x49, 0x29, 0x69, 0x19, 0x59, 0x39, 0x79, 
-	0x05, 0x45, 0x25, 0x65, 0x15, 0x55, 0x35, 0x75, 
-	0x0d, 0x4d, 0x2d, 0x6d, 0x1d, 0x5d, 0x3d, 0x7d, 
-	0x03, 0x43, 0x23, 0x63, 0x13, 0x53, 0x33, 0x73, 
-	0x0b, 0x4b, 0x2b, 0x6b, 0x1b, 0x5b, 0x3b, 0x7b, 
-	0x07, 0x47, 0x27, 0x67, 0x17, 0x57, 0x37, 0x77, 
-	0x0f, 0x4f, 0x2f, 0x6f, 0x1f, 0x5f, 0x3f, 0x7f};
-
-static uint8_t bit_reverse_256[] = {
-	0x00, 0x20, 0x10, 0x30, 0x08, 0x28, 0x18, 0x38, 
-	0x04, 0x24, 0x14, 0x34, 0x0c, 0x2c, 0x1c, 0x3c, 
-	0x02, 0x22, 0x12, 0x32, 0x0a, 0x2a, 0x1a, 0x3a, 
-	0x06, 0x26, 0x16, 0x36, 0x0e, 0x2e, 0x1e, 0x3e, 
-	0x01, 0x21, 0x11, 0x31, 0x09, 0x29, 0x19, 0x39, 
-	0x05, 0x25, 0x15, 0x35, 0x0d, 0x2d, 0x1d, 0x3d, 
-	0x03, 0x23, 0x13, 0x33, 0x0b, 0x2b, 0x1b, 0x3b, 
-	0x07, 0x27, 0x17, 0x37, 0x0f, 0x2f, 0x1f, 0x3f};
-
-static complex_t buf[128];
-
-/* Twiddle factor LUT */
-static complex_t w_1[1];
-static complex_t w_2[2];
-static complex_t w_4[4];
-static complex_t w_8[8];
-static complex_t w_16[16];
-static complex_t w_32[32];
-static complex_t w_64[64];
-static complex_t * w[7] = {w_1, w_2, w_4, w_8, w_16, w_32, w_64};
+static uint8_t fftorder[] = {
+      0,128, 64,192, 32,160,224, 96, 16,144, 80,208,240,112, 48,176,
+      8,136, 72,200, 40,168,232,104,248,120, 56,184, 24,152,216, 88,
+      4,132, 68,196, 36,164,228,100, 20,148, 84,212,244,116, 52,180,
+    252,124, 60,188, 28,156,220, 92, 12,140, 76,204,236,108, 44,172,
+      2,130, 66,194, 34,162,226, 98, 18,146, 82,210,242,114, 50,178,
+     10,138, 74,202, 42,170,234,106,250,122, 58,186, 26,154,218, 90,
+    254,126, 62,190, 30,158,222, 94, 14,142, 78,206,238,110, 46,174,
+      6,134, 70,198, 38,166,230,102,246,118, 54,182, 22,150,214, 86
+};
+
+/* Root values for IFFT */
+static sample_t roots16[3];
+static sample_t roots32[7];
+static sample_t roots64[15];
+static sample_t roots128[31];
 
 /* Twiddle factors for IMDCT */
-static sample_t xcos1[128];
-static sample_t xsin1[128];
-static sample_t xcos2[64];
-static sample_t xsin2[64];
-
-/* Windowing function for Modified DCT - Thank you acroread */
-sample_t imdct_window[] = {
-	0.00014, 0.00024, 0.00037, 0.00051, 0.00067, 0.00086, 0.00107, 0.00130,
-	0.00157, 0.00187, 0.00220, 0.00256, 0.00297, 0.00341, 0.00390, 0.00443,
-	0.00501, 0.00564, 0.00632, 0.00706, 0.00785, 0.00871, 0.00962, 0.01061,
-	0.01166, 0.01279, 0.01399, 0.01526, 0.01662, 0.01806, 0.01959, 0.02121,
-	0.02292, 0.02472, 0.02662, 0.02863, 0.03073, 0.03294, 0.03527, 0.03770,
-	0.04025, 0.04292, 0.04571, 0.04862, 0.05165, 0.05481, 0.05810, 0.06153,
-	0.06508, 0.06878, 0.07261, 0.07658, 0.08069, 0.08495, 0.08935, 0.09389,
-	0.09859, 0.10343, 0.10842, 0.11356, 0.11885, 0.12429, 0.12988, 0.13563,
-	0.14152, 0.14757, 0.15376, 0.16011, 0.16661, 0.17325, 0.18005, 0.18699,
-	0.19407, 0.20130, 0.20867, 0.21618, 0.22382, 0.23161, 0.23952, 0.24757,
-	0.25574, 0.26404, 0.27246, 0.28100, 0.28965, 0.29841, 0.30729, 0.31626,
-	0.32533, 0.33450, 0.34376, 0.35311, 0.36253, 0.37204, 0.38161, 0.39126,
-	0.40096, 0.41072, 0.42054, 0.43040, 0.44030, 0.45023, 0.46020, 0.47019,
-	0.48020, 0.49022, 0.50025, 0.51028, 0.52031, 0.53033, 0.54033, 0.55031,
-	0.56026, 0.57019, 0.58007, 0.58991, 0.59970, 0.60944, 0.61912, 0.62873,
-	0.63827, 0.64774, 0.65713, 0.66643, 0.67564, 0.68476, 0.69377, 0.70269,
-	0.71150, 0.72019, 0.72877, 0.73723, 0.74557, 0.75378, 0.76186, 0.76981,
-	0.77762, 0.78530, 0.79283, 0.80022, 0.80747, 0.81457, 0.82151, 0.82831,
-	0.83496, 0.84145, 0.84779, 0.85398, 0.86001, 0.86588, 0.87160, 0.87716,
-	0.88257, 0.88782, 0.89291, 0.89785, 0.90264, 0.90728, 0.91176, 0.91610,
-	0.92028, 0.92432, 0.92822, 0.93197, 0.93558, 0.93906, 0.94240, 0.94560,
-	0.94867, 0.95162, 0.95444, 0.95713, 0.95971, 0.96217, 0.96451, 0.96674,
-	0.96887, 0.97089, 0.97281, 0.97463, 0.97635, 0.97799, 0.97953, 0.98099,
-	0.98236, 0.98366, 0.98488, 0.98602, 0.98710, 0.98811, 0.98905, 0.98994,
-	0.99076, 0.99153, 0.99225, 0.99291, 0.99353, 0.99411, 0.99464, 0.99513,
-	0.99558, 0.99600, 0.99639, 0.99674, 0.99706, 0.99736, 0.99763, 0.99788,
-	0.99811, 0.99831, 0.99850, 0.99867, 0.99882, 0.99895, 0.99908, 0.99919,
-	0.99929, 0.99938, 0.99946, 0.99953, 0.99959, 0.99965, 0.99969, 0.99974,
-	0.99978, 0.99981, 0.99984, 0.99986, 0.99988, 0.99990, 0.99992, 0.99993,
-	0.99994, 0.99995, 0.99996, 0.99997, 0.99998, 0.99998, 0.99998, 0.99999,
-	0.99999, 0.99999, 0.99999, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000,
-	1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000 };
-
-
-static inline void swap_cmplx(complex_t *a, complex_t *b)
+static complex_t pre1[128];
+static complex_t post1[64];
+static complex_t pre2[64];
+static complex_t post2[32];
+
+static sample_t a52_imdct_window[256];
+
+static void (* ifft128) (complex_t * buf);
+static void (* ifft64) (complex_t * buf);
+
+static inline void ifft2 (complex_t * buf)
 {
-    complex_t tmp;
+    double r, i;
+
+    r = buf[0].real;
+    i = buf[0].imag;
+    buf[0].real += buf[1].real;
+    buf[0].imag += buf[1].imag;
+    buf[1].real = r - buf[1].real;
+    buf[1].imag = i - buf[1].imag;
+}
 
-    tmp = *a;
-    *a = *b;
-    *b = tmp;
+static inline void ifft4 (complex_t * buf)
+{
+    double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
+
+    tmp1 = buf[0].real + buf[1].real;
+    tmp2 = buf[3].real + buf[2].real;
+    tmp3 = buf[0].imag + buf[1].imag;
+    tmp4 = buf[2].imag + buf[3].imag;
+    tmp5 = buf[0].real - buf[1].real;
+    tmp6 = buf[0].imag - buf[1].imag;
+    tmp7 = buf[2].imag - buf[3].imag;
+    tmp8 = buf[3].real - buf[2].real;
+
+    buf[0].real = tmp1 + tmp2;
+    buf[0].imag = tmp3 + tmp4;
+    buf[2].real = tmp1 - tmp2;
+    buf[2].imag = tmp3 - tmp4;
+    buf[1].real = tmp5 + tmp7;
+    buf[1].imag = tmp6 + tmp8;
+    buf[3].real = tmp5 - tmp7;
+    buf[3].imag = tmp6 - tmp8;
 }
 
+/* the basic split-radix ifft butterfly */
+
+#define BUTTERFLY(a0,a1,a2,a3,wr,wi) do {	\
+    tmp5 = a2.real * wr + a2.imag * wi;		\
+    tmp6 = a2.imag * wr - a2.real * wi;		\
+    tmp7 = a3.real * wr - a3.imag * wi;		\
+    tmp8 = a3.imag * wr + a3.real * wi;		\
+    tmp1 = tmp5 + tmp7;				\
+    tmp2 = tmp6 + tmp8;				\
+    tmp3 = tmp6 - tmp8;				\
+    tmp4 = tmp7 - tmp5;				\
+    a2.real = a0.real - tmp1;			\
+    a2.imag = a0.imag - tmp2;			\
+    a3.real = a1.real - tmp3;			\
+    a3.imag = a1.imag - tmp4;			\
+    a0.real += tmp1;				\
+    a0.imag += tmp2;				\
+    a1.real += tmp3;				\
+    a1.imag += tmp4;				\
+} while (0)
+
+/* split-radix ifft butterfly, specialized for wr=1 wi=0 */
+
+#define BUTTERFLY_ZERO(a0,a1,a2,a3) do {	\
+    tmp1 = a2.real + a3.real;			\
+    tmp2 = a2.imag + a3.imag;			\
+    tmp3 = a2.imag - a3.imag;			\
+    tmp4 = a3.real - a2.real;			\
+    a2.real = a0.real - tmp1;			\
+    a2.imag = a0.imag - tmp2;			\
+    a3.real = a1.real - tmp3;			\
+    a3.imag = a1.imag - tmp4;			\
+    a0.real += tmp1;				\
+    a0.imag += tmp2;				\
+    a1.real += tmp3;				\
+    a1.imag += tmp4;				\
+} while (0)
+
+/* split-radix ifft butterfly, specialized for wr=wi */
+
+#define BUTTERFLY_HALF(a0,a1,a2,a3,w) do {	\
+    tmp5 = (a2.real + a2.imag) * w;		\
+    tmp6 = (a2.imag - a2.real) * w;		\
+    tmp7 = (a3.real - a3.imag) * w;		\
+    tmp8 = (a3.imag + a3.real) * w;		\
+    tmp1 = tmp5 + tmp7;				\
+    tmp2 = tmp6 + tmp8;				\
+    tmp3 = tmp6 - tmp8;				\
+    tmp4 = tmp7 - tmp5;				\
+    a2.real = a0.real - tmp1;			\
+    a2.imag = a0.imag - tmp2;			\
+    a3.real = a1.real - tmp3;			\
+    a3.imag = a1.imag - tmp4;			\
+    a0.real += tmp1;				\
+    a0.imag += tmp2;				\
+    a1.real += tmp3;				\
+    a1.imag += tmp4;				\
+} while (0)
+
+static inline void ifft8 (complex_t * buf)
+{
+    double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
 
+    ifft4 (buf);
+    ifft2 (buf + 4);
+    ifft2 (buf + 6);
+    BUTTERFLY_ZERO (buf[0], buf[2], buf[4], buf[6]);
+    BUTTERFLY_HALF (buf[1], buf[3], buf[5], buf[7], roots16[1]);
+}
 
-static inline complex_t cmplx_mult(complex_t a, complex_t b)
+static void ifft_pass (complex_t * buf, sample_t * weight, int n)
 {
-    complex_t ret;
+    complex_t * buf1;
+    complex_t * buf2;
+    complex_t * buf3;
+    double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
+    int i;
+
+    buf++;
+    buf1 = buf + n;
+    buf2 = buf + 2 * n;
+    buf3 = buf + 3 * n;
+
+    BUTTERFLY_ZERO (buf[-1], buf1[-1], buf2[-1], buf3[-1]);
+
+    i = n - 1;
+
+    do {
+	BUTTERFLY (buf[0], buf1[0], buf2[0], buf3[0], weight[n], weight[2*i]);
+	buf++;
+	buf1++;
+	buf2++;
+	buf3++;
+	weight++;
+    } while (--i);
+}
 
-    ret.real = a.real * b.real - a.imag * b.imag;
-    ret.imag = a.real * b.imag + a.imag * b.real;
+static void ifft16 (complex_t * buf)
+{
+    ifft8 (buf);
+    ifft4 (buf + 8);
+    ifft4 (buf + 12);
+    ifft_pass (buf, roots16 - 4, 4);
+}
 
-    return ret;
+static void ifft32 (complex_t * buf)
+{
+    ifft16 (buf);
+    ifft8 (buf + 16);
+    ifft8 (buf + 24);
+    ifft_pass (buf, roots32 - 8, 8);
 }
 
-void
-imdct_do_512(sample_t data[],sample_t delay[], sample_t bias)
+static void ifft64_c (complex_t * buf)
 {
-    int i,k;
-    int p,q;
-    int m;
-    int two_m;
-    int two_m_plus_one;
-
-    sample_t tmp_a_i;
-    sample_t tmp_a_r;
-    sample_t tmp_b_i;
-    sample_t tmp_b_r;
-
-    sample_t *data_ptr;
-    sample_t *delay_ptr;
-    sample_t *window_ptr;
-	
-    /* 512 IMDCT with source and dest data in 'data' */
+    ifft32 (buf);
+    ifft16 (buf + 32);
+    ifft16 (buf + 48);
+    ifft_pass (buf, roots64 - 16, 16);
+}
+
+static void ifft128_c (complex_t * buf)
+{
+    ifft32 (buf);
+    ifft16 (buf + 32);
+    ifft16 (buf + 48);
+    ifft_pass (buf, roots64 - 16, 16);
+
+    ifft32 (buf + 64);
+    ifft32 (buf + 96);
+    ifft_pass (buf, roots128 - 32, 32);
+}
+
+void a52_imdct_512 (sample_t * data, sample_t * delay, sample_t bias)
+{
+    int i, k;
+    sample_t t_r, t_i, a_r, a_i, b_r, b_i, w_1, w_2;
+    const sample_t * window = a52_imdct_window;
+    complex_t buf[128];
 	
-    /* Pre IFFT complex multiply plus IFFT cmplx conjugate */
-    for( i=0; i < 128; i++) {
-	/* z[i] = (X[256-2*i-1] + j * X[2*i]) * (xcos1[i] + j * xsin1[i]) ; */ 
-	buf[i].real =         (data[256-2*i-1] * xcos1[i])  -  (data[2*i]       * xsin1[i]);
-	buf[i].imag = -1.0 * ((data[2*i]       * xcos1[i])  +  (data[256-2*i-1] * xsin1[i]));
-    }
+    for (i = 0; i < 128; i++) {
+	k = fftorder[i];
+	t_r = pre1[i].real;
+	t_i = pre1[i].imag;
 
-    /* Bit reversed shuffling */
-    for(i=0; i<128; i++) {
-	k = bit_reverse_512[i];
-	if (k < i)
-	    swap_cmplx(&buf[i],&buf[k]);
+	buf[i].real = t_i * data[255-k] + t_r * data[k];
+	buf[i].imag = t_r * data[255-k] - t_i * data[k];
     }
 
-    /* FFT Merge */
-    for (m=0; m < 7; m++) {
-	if(m)
-	    two_m = (1 << m);
-	else
-	    two_m = 1;
-
-	two_m_plus_one = (1 << (m+1));
-
-	for(k = 0; k < two_m; k++) {
-	    for(i = 0; i < 128; i += two_m_plus_one) {
-		p = k + i;
-		q = p + two_m;
-		tmp_a_r = buf[p].real;
-		tmp_a_i = buf[p].imag;
-		tmp_b_r = buf[q].real * w[m][k].real - buf[q].imag * w[m][k].imag;
-		tmp_b_i = buf[q].imag * w[m][k].real + buf[q].real * w[m][k].imag;
-		buf[p].real = tmp_a_r + tmp_b_r;
-		buf[p].imag =  tmp_a_i + tmp_b_i;
-		buf[q].real = tmp_a_r - tmp_b_r;
-		buf[q].imag =  tmp_a_i - tmp_b_i;
-	    }
-	}
-    }
+    ifft128 (buf);
 
-    /* Post IFFT complex multiply  plus IFFT complex conjugate*/
-    for( i=0; i < 128; i++) {
+    /* Post IFFT complex multiply plus IFFT complex conjugate*/
+    /* Window and convert to real valued signal */
+    for (i = 0; i < 64; i++) {
 	/* y[n] = z[n] * (xcos1[n] + j * xsin1[n]) ; */
-	tmp_a_r =        buf[i].real;
-	tmp_a_i = -1.0 * buf[i].imag;
-	buf[i].real =(tmp_a_r * xcos1[i])  -  (tmp_a_i  * xsin1[i]);
-	buf[i].imag =(tmp_a_r * xsin1[i])  +  (tmp_a_i  * xcos1[i]);
+	t_r = post1[i].real;
+	t_i = post1[i].imag;
+
+	a_r = t_r * buf[i].real     + t_i * buf[i].imag;
+	a_i = t_i * buf[i].real     - t_r * buf[i].imag;
+	b_r = t_i * buf[127-i].real + t_r * buf[127-i].imag;
+	b_i = t_r * buf[127-i].real - t_i * buf[127-i].imag;
+
+	w_1 = window[2*i];
+	w_2 = window[255-2*i];
+	data[2*i]     = delay[2*i] * w_2 - a_r * w_1 + bias;
+	data[255-2*i] = delay[2*i] * w_1 + a_r * w_2 + bias;
+	delay[2*i] = a_i;
+
+	w_1 = window[2*i+1];
+	w_2 = window[254-2*i];
+	data[2*i+1]   = delay[2*i+1] * w_2 + b_r * w_1 + bias;
+	data[254-2*i] = delay[2*i+1] * w_1 - b_r * w_2 + bias;
+	delay[2*i+1] = b_i;
     }
-	
-    data_ptr = data;
-    delay_ptr = delay;
-    window_ptr = imdct_window;
+}
 
-    /* Window and convert to real valued signal */
-    for(i=0; i< 64; i++) { 
-	*data_ptr++   = -buf[64+i].imag   * *window_ptr++ + *delay_ptr++ + bias; 
-	*data_ptr++   =  buf[64-i-1].real * *window_ptr++ + *delay_ptr++ + bias; 
-    }
+void a52_imdct_256(sample_t * data, sample_t * delay, sample_t bias)
+{
+    int i, k;
+    sample_t t_r, t_i, a_r, a_i, b_r, b_i, c_r, c_i, d_r, d_i, w_1, w_2;
+    const sample_t * window = a52_imdct_window;
+    complex_t buf1[64], buf2[64];
 
-    for(i=0; i< 64; i++) { 
-	*data_ptr++  = -buf[i].real       * *window_ptr++ + *delay_ptr++ + bias; 
-	*data_ptr++  =  buf[128-i-1].imag * *window_ptr++ + *delay_ptr++ + bias; 
-    }
+    /* Pre IFFT complex multiply plus IFFT cmplx conjugate */
+    for (i = 0; i < 64; i++) {
+	k = fftorder[i];
+	t_r = pre2[i].real;
+	t_i = pre2[i].imag;
 
-    /* The trailing edge of the window goes into the delay line */
-    delay_ptr = delay;
+	buf1[i].real = t_i * data[254-k] + t_r * data[k];
+	buf1[i].imag = t_r * data[254-k] - t_i * data[k];
 
-    for(i=0; i< 64; i++) { 
-	*delay_ptr++  = -buf[64+i].real   * *--window_ptr; 
-	*delay_ptr++  =  buf[64-i-1].imag * *--window_ptr; 
+	buf2[i].real = t_i * data[255-k] + t_r * data[k+1];
+	buf2[i].imag = t_r * data[255-k] - t_i * data[k+1];
     }
 
-    for(i=0; i<64; i++) {
-	*delay_ptr++  =  buf[i].imag       * *--window_ptr; 
-	*delay_ptr++  = -buf[128-i-1].real * *--window_ptr; 
+    ifft64 (buf1);
+    ifft64 (buf2);
+
+    /* Post IFFT complex multiply */
+    /* Window and convert to real valued signal */
+    for (i = 0; i < 32; i++) {
+	/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */ 
+	t_r = post2[i].real;
+	t_i = post2[i].imag;
+
+	a_r = t_r * buf1[i].real    + t_i * buf1[i].imag;
+	a_i = t_i * buf1[i].real    - t_r * buf1[i].imag;
+	b_r = t_i * buf1[63-i].real + t_r * buf1[63-i].imag;
+	b_i = t_r * buf1[63-i].real - t_i * buf1[63-i].imag;
+
+	c_r = t_r * buf2[i].real    + t_i * buf2[i].imag;
+	c_i = t_i * buf2[i].real    - t_r * buf2[i].imag;
+	d_r = t_i * buf2[63-i].real + t_r * buf2[63-i].imag;
+	d_i = t_r * buf2[63-i].real - t_i * buf2[63-i].imag;
+
+	w_1 = window[2*i];
+	w_2 = window[255-2*i];
+	data[2*i]     = delay[2*i] * w_2 - a_r * w_1 + bias;
+	data[255-2*i] = delay[2*i] * w_1 + a_r * w_2 + bias;
+	delay[2*i] = c_i;
+
+	w_1 = window[128+2*i];
+	w_2 = window[127-2*i];
+	data[128+2*i] = delay[127-2*i] * w_2 + a_i * w_1 + bias;
+	data[127-2*i] = delay[127-2*i] * w_1 - a_i * w_2 + bias;
+	delay[127-2*i] = c_r;
+
+	w_1 = window[2*i+1];
+	w_2 = window[254-2*i];
+	data[2*i+1]   = delay[2*i+1] * w_2 - b_i * w_1 + bias;
+	data[254-2*i] = delay[2*i+1] * w_1 + b_i * w_2 + bias;
+	delay[2*i+1] = d_r;
+
+	w_1 = window[129+2*i];
+	w_2 = window[126-2*i];
+	data[129+2*i] = delay[126-2*i] * w_2 + b_r * w_1 + bias;
+	data[126-2*i] = delay[126-2*i] * w_1 - b_r * w_2 + bias;
+	delay[126-2*i] = d_i;
     }
 }
 
-void
-imdct_do_256(sample_t data[],sample_t delay[],sample_t bias)
+static double besselI0 (double x)
 {
-    int i,k;
-    int p,q;
-    int m;
-    int two_m;
-    int two_m_plus_one;
-
-    sample_t tmp_a_i;
-    sample_t tmp_a_r;
-    sample_t tmp_b_i;
-    sample_t tmp_b_r;
+    double bessel = 1;
+    int i = 100;
 
-    sample_t *data_ptr;
-    sample_t *delay_ptr;
-    sample_t *window_ptr;
+    do
+	bessel = bessel * x / (i * i) + 1;
+    while (--i);
+    return bessel;
+}
 
-    complex_t *buf_1, *buf_2;
+void a52_imdct_init (uint32_t mm_accel)
+{
+    int i, k;
+    double sum;
+
+    /* compute imdct window - kaiser-bessel derived window, alpha = 5.0 */
+    sum = 0;
+    for (i = 0; i < 256; i++) {
+	sum += besselI0 (i * (256 - i) * (5 * M_PI / 256) * (5 * M_PI / 256));
+	a52_imdct_window[i] = sum;
+    }
+    sum++;
+    for (i = 0; i < 256; i++)
+	a52_imdct_window[i] = sqrt (a52_imdct_window[i] / sum);
 
-    buf_1 = &buf[0];
-    buf_2 = &buf[64];
+    for (i = 0; i < 3; i++)
+	roots16[i] = cos ((M_PI / 8) * (i + 1));
 
-    /* Pre IFFT complex multiply plus IFFT cmplx conjugate */
-    for(k=0; k<64; k++) { 
-	/* X1[k] = X[2*k]  */
-	/* X2[k] = X[2*k+1]     */
-
-	p = 2 * (128-2*k-1);
-	q = 2 * (2 * k);
-
-	/* Z1[k] = (X1[128-2*k-1] + j * X1[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
-	buf_1[k].real =         data[p] * xcos2[k] - data[q] * xsin2[k];
-	buf_1[k].imag = -1.0f * (data[q] * xcos2[k] + data[p] * xsin2[k]); 
-	/* Z2[k] = (X2[128-2*k-1] + j * X2[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
-	buf_2[k].real =          data[p + 1] * xcos2[k] - data[q + 1] * xsin2[k];
-	buf_2[k].imag = -1.0f * ( data[q + 1] * xcos2[k] + data[p + 1] * xsin2[k]); 
-    }
+    for (i = 0; i < 7; i++)
+	roots32[i] = cos ((M_PI / 16) * (i + 1));
 
-    /* IFFT Bit reversed shuffling */
-    for(i=0; i<64; i++) { 
-	k = bit_reverse_256[i];
-	if (k < i) {
-	    swap_cmplx(&buf_1[i],&buf_1[k]);
-	    swap_cmplx(&buf_2[i],&buf_2[k]);
-	}
-    }
+    for (i = 0; i < 15; i++)
+	roots64[i] = cos ((M_PI / 32) * (i + 1));
 
-    /* FFT Merge */
-    for (m=0; m < 6; m++) {
-	two_m = (1 << m);
-	two_m_plus_one = (1 << (m+1));
-
-	/* FIXME */
-	if(m)
-	    two_m = (1 << m);
-	else
-	    two_m = 1;
-
-	for(k = 0; k < two_m; k++) {
-	    for(i = 0; i < 64; i += two_m_plus_one) {
-		p = k + i;
-		q = p + two_m;
-		/* Do block 1 */
-		tmp_a_r = buf_1[p].real;
-		tmp_a_i = buf_1[p].imag;
-		tmp_b_r = buf_1[q].real * w[m][k].real - buf_1[q].imag * w[m][k].imag;
-		tmp_b_i = buf_1[q].imag * w[m][k].real + buf_1[q].real * w[m][k].imag;
-		buf_1[p].real = tmp_a_r + tmp_b_r;
-		buf_1[p].imag =  tmp_a_i + tmp_b_i;
-		buf_1[q].real = tmp_a_r - tmp_b_r;
-		buf_1[q].imag =  tmp_a_i - tmp_b_i;
-
-		/* Do block 2 */
-		tmp_a_r = buf_2[p].real;
-		tmp_a_i = buf_2[p].imag;
-		tmp_b_r = buf_2[q].real * w[m][k].real - buf_2[q].imag * w[m][k].imag;
-		tmp_b_i = buf_2[q].imag * w[m][k].real + buf_2[q].real * w[m][k].imag;
-		buf_2[p].real = tmp_a_r + tmp_b_r;
-		buf_2[p].imag =  tmp_a_i + tmp_b_i;
-		buf_2[q].real = tmp_a_r - tmp_b_r;
-		buf_2[q].imag =  tmp_a_i - tmp_b_i;
-	    }
-	}
-    }
+    for (i = 0; i < 31; i++)
+	roots128[i] = cos ((M_PI / 64) * (i + 1));
 
-    /* Post IFFT complex multiply */
-    for( i=0; i < 64; i++) {
-	/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */ 
-	tmp_a_r =  buf_1[i].real;
-	tmp_a_i = -buf_1[i].imag;
-	buf_1[i].real =(tmp_a_r * xcos2[i])  -  (tmp_a_i  * xsin2[i]);
-	buf_1[i].imag =(tmp_a_r * xsin2[i])  +  (tmp_a_i  * xcos2[i]);
-	/* y2[n] = z2[n] * (xcos2[n] + j * xsin2[n]) ; */ 
-	tmp_a_r =  buf_2[i].real;
-	tmp_a_i = -buf_2[i].imag;
-	buf_2[i].real =(tmp_a_r * xcos2[i])  -  (tmp_a_i  * xsin2[i]);
-	buf_2[i].imag =(tmp_a_r * xsin2[i])  +  (tmp_a_i  * xcos2[i]);
+    for (i = 0; i < 64; i++) {
+	k = fftorder[i] / 2 + 64;
+	pre1[i].real = cos ((M_PI / 256) * (k - 0.25));
+	pre1[i].imag = sin ((M_PI / 256) * (k - 0.25));
     }
-	
-    data_ptr = data;
-    delay_ptr = delay;
-    window_ptr = imdct_window;
 
-    /* Window and convert to real valued signal */
-    for(i=0; i< 64; i++) { 
-	*data_ptr++  = -buf_1[i].imag      * *window_ptr++ + *delay_ptr++ + bias;
-	*data_ptr++  =  buf_1[64-i-1].real * *window_ptr++ + *delay_ptr++ + bias;
+    for (i = 64; i < 128; i++) {
+	k = fftorder[i] / 2 + 64;
+	pre1[i].real = -cos ((M_PI / 256) * (k - 0.25));
+	pre1[i].imag = -sin ((M_PI / 256) * (k - 0.25));
     }
 
-    for(i=0; i< 64; i++) {
-	*data_ptr++  = -buf_1[i].real      * *window_ptr++ + *delay_ptr++ + bias;
-	*data_ptr++  =  buf_1[64-i-1].imag * *window_ptr++ + *delay_ptr++ + bias;
+    for (i = 0; i < 64; i++) {
+	post1[i].real = cos ((M_PI / 256) * (i + 0.5));
+	post1[i].imag = sin ((M_PI / 256) * (i + 0.5));
     }
-	
-    delay_ptr = delay;
 
-    for(i=0; i< 64; i++) {
-	*delay_ptr++ = -buf_2[i].real      * *--window_ptr;
-	*delay_ptr++ =  buf_2[64-i-1].imag * *--window_ptr;
+    for (i = 0; i < 64; i++) {
+	k = fftorder[i] / 4;
+	pre2[i].real = cos ((M_PI / 128) * (k - 0.25));
+	pre2[i].imag = sin ((M_PI / 128) * (k - 0.25));
     }
 
-    for(i=0; i< 64; i++) {
-	*delay_ptr++ =  buf_2[i].imag      * *--window_ptr;
-	*delay_ptr++ = -buf_2[64-i-1].real * *--window_ptr;
+    for (i = 0; i < 32; i++) {
+	post2[i].real = cos ((M_PI / 128) * (i + 0.5));
+	post2[i].imag = sin ((M_PI / 128) * (i + 0.5));
     }
-}
 
-void imdct_init (uint32_t mm_accel)
-{
-#ifdef LIBA52_MLIB
-    if (mm_accel & MM_ACCEL_MLIB) {
-	imdct_512 = imdct_do_512_mlib;
-	imdct_256 = imdct_do_256_mlib;
+#ifdef LIBA52_DJBFFT
+    if (mm_accel & MM_ACCEL_DJBFFT) {
+	fprintf (stderr, "Using djbfft for IMDCT transform\n");
+	ifft128 = (void (*) (complex_t *)) fftc4_un128;
+	ifft64 = (void (*) (complex_t *)) fftc4_un64;
     } else
 #endif
     {
-	int i, j, k;
-
-	/* Twiddle factors to turn IFFT into IMDCT */
-	for (i = 0; i < 128; i++) {
-	    xcos1[i] = -cos ((M_PI / 2048) * (8 * i + 1));
-	    xsin1[i] = -sin ((M_PI / 2048) * (8 * i + 1));
-	}
-
-	/* More twiddle factors to turn IFFT into IMDCT */
-	for (i = 0; i < 64; i++) {
-	    xcos2[i] = -cos ((M_PI / 1024) * (8 * i + 1));
-	    xsin2[i] = -sin ((M_PI / 1024) * (8 * i + 1));
-	}
-
-	for (i = 0; i < 7; i++) {
-	    j = 1 << i;
-	    for (k = 0; k < j; k++) {
-		w[i][k].real = cos (-M_PI * k / j);
-		w[i][k].imag = sin (-M_PI * k / j);
-	    }
-	}
-	imdct_512 = imdct_do_512;
-	imdct_256 = imdct_do_256;
+	fprintf (stderr, "No accelerated IMDCT transform found\n");
+	ifft128 = ifft128_c;
+	ifft64 = ifft64_c;
     }
 }