/*
** FFT and FHT routines
**  Copyright 1988, 1993; Ron Mayer
**  
**  fht(fz,n);
**      Does a hartley transform of "n" points in the array "fz".
**      
** NOTE: This routine uses at least 2 patented algorithms, and may be
**       under the restrictions of a bunch of different organizations.
**       Although I wrote it completely myself; it is kind of a derivative
**       of a routine I once authored and released under the GPL, so it
**       may fall under the free software foundation's restrictions;
**       it was worked on as a Stanford Univ project, so they claim
**       some rights to it; it was further optimized at work here, so
**       I think this company claims parts of it.  The patents are
**       held by R. Bracewell (the FHT algorithm) and O. Buneman (the
**       trig generator), both at Stanford Univ.
**       If it were up to me, I'd say go do whatever you want with it;
**       but it would be polite to give credit to the following people
**       if you use this anywhere:
**           Euler     - probable inventor of the fourier transform.
**           Gauss     - probable inventor of the FFT.
**           Hartley   - probable inventor of the hartley transform.
**           Buneman   - for a really cool trig generator
**           Mayer(me) - for authoring this particular version and
**                       including all the optimizations in one package.
**       Thanks,
**       Ron Mayer; mayer@acuson.com
**
*/
#include <stdio.h>
#include <math.h>
#include "common.h"
#include "fft.h"
#define         SQRT2                   1.4142135623730951454746218587388284504414


static FLOAT costab[20] = {
  .00000000000000000000000000000000000000000000000000,
  .70710678118654752440084436210484903928483593768847,
  .92387953251128675612818318939678828682241662586364,
  .98078528040323044912618223613423903697393373089333,
  .99518472667219688624483695310947992157547486872985,
  .99879545620517239271477160475910069444320361470461,
  .99969881869620422011576564966617219685006108125772,
  .99992470183914454092164649119638322435060646880221,
  .99998117528260114265699043772856771617391725094433,
  .99999529380957617151158012570011989955298763362218,
  .99999882345170190992902571017152601904826792288976,
  .99999970586288221916022821773876567711626389934930,
  .99999992646571785114473148070738785694820115568892,
  .99999998161642929380834691540290971450507605124278,
  .99999999540410731289097193313960614895889430318945,
  .99999999885102682756267330779455410840053741619428
};
static FLOAT sintab[20] = {
  1.0000000000000000000000000000000000000000000000000,
  .70710678118654752440084436210484903928483593768846,
  .38268343236508977172845998403039886676134456248561,
  .19509032201612826784828486847702224092769161775195,
  .09801714032956060199419556388864184586113667316749,
  .04906767432741801425495497694268265831474536302574,
  .02454122852291228803173452945928292506546611923944,
  .01227153828571992607940826195100321214037231959176,
  .00613588464915447535964023459037258091705788631738,
  .00306795676296597627014536549091984251894461021344,
  .00153398018628476561230369715026407907995486457522,
  .00076699031874270452693856835794857664314091945205,
  .00038349518757139558907246168118138126339502603495,
  .00019174759731070330743990956198900093346887403385,
  .00009587379909597734587051721097647635118706561284,
  .00004793689960306688454900399049465887274686668768
};

/* This is a simplified version for n an even power of 2 */
/* MFC: In the case of LayerII encoding, n==1024 always. */

static void fht (FLOAT * fz)
{
  int i, k, k1, k2, k3, k4, kx;
  FLOAT *fi, *fn, *gi;
  FLOAT t_c, t_s;

  FLOAT a;
  static const struct {
    unsigned short k1, k2;
  } k1k2tab[8 * 62] = {
    {
    0x020, 0x010}
    , {
    0x040, 0x008}
    , {
    0x050, 0x028}
    , {
    0x060, 0x018}
    , {
    0x068, 0x058}
    , {
    0x070, 0x038}
    , {
    0x080, 0x004}
    , {
    0x088, 0x044}
    , {
    0x090, 0x024}
    , {
    0x098, 0x064}
    , {
    0x0a0, 0x014}
    , {
    0x0a4, 0x094}
    , {
    0x0a8, 0x054}
    , {
    0x0b0, 0x034}
    , {
    0x0b8, 0x074}
    , {
    0x0c0, 0x00c}
    , {
    0x0c4, 0x08c}
    , {
    0x0c8, 0x04c}
    , {
    0x0d0, 0x02c}
    , {
    0x0d4, 0x0ac}
    , {
    0x0d8, 0x06c}
    , {
    0x0e0, 0x01c}
    , {
    0x0e4, 0x09c}
    , {
    0x0e8, 0x05c}
    , {
    0x0ec, 0x0dc}
    , {
    0x0f0, 0x03c}
    , {
    0x0f4, 0x0bc}
    , {
    0x0f8, 0x07c}
    , {
    0x100, 0x002}
    , {
    0x104, 0x082}
    , {
    0x108, 0x042}
    , {
    0x10c, 0x0c2}
    , {
    0x110, 0x022}
    , {
    0x114, 0x0a2}
    , {
    0x118, 0x062}
    , {
    0x11c, 0x0e2}
    , {
    0x120, 0x012}
    , {
    0x122, 0x112}
    , {
    0x124, 0x092}
    , {
    0x128, 0x052}
    , {
    0x12c, 0x0d2}
    , {
    0x130, 0x032}
    , {
    0x134, 0x0b2}
    , {
    0x138, 0x072}
    , {
    0x13c, 0x0f2}
    , {
    0x140, 0x00a}
    , {
    0x142, 0x10a}
    , {
    0x144, 0x08a}
    , {
    0x148, 0x04a}
    , {
    0x14c, 0x0ca}
    , {
    0x150, 0x02a}
    , {
    0x152, 0x12a}
    , {
    0x154, 0x0aa}
    , {
    0x158, 0x06a}
    , {
    0x15c, 0x0ea}
    , {
    0x160, 0x01a}
    , {
    0x162, 0x11a}
    , {
    0x164, 0x09a}
    , {
    0x168, 0x05a}
    , {
    0x16a, 0x15a}
    , {
    0x16c, 0x0da}
    , {
    0x170, 0x03a}
    , {
    0x172, 0x13a}
    , {
    0x174, 0x0ba}
    , {
    0x178, 0x07a}
    , {
    0x17c, 0x0fa}
    , {
    0x180, 0x006}
    , {
    0x182, 0x106}
    , {
    0x184, 0x086}
    , {
    0x188, 0x046}
    , {
    0x18a, 0x146}
    , {
    0x18c, 0x0c6}
    , {
    0x190, 0x026}
    , {
    0x192, 0x126}
    , {
    0x194, 0x0a6}
    , {
    0x198, 0x066}
    , {
    0x19a, 0x166}
    , {
    0x19c, 0x0e6}
    , {
    0x1a0, 0x016}
    , {
    0x1a2, 0x116}
    , {
    0x1a4, 0x096}
    , {
    0x1a6, 0x196}
    , {
    0x1a8, 0x056}
    , {
    0x1aa, 0x156}
    , {
    0x1ac, 0x0d6}
    , {
    0x1b0, 0x036}
    , {
    0x1b2, 0x136}
    , {
    0x1b4, 0x0b6}
    , {
    0x1b8, 0x076}
    , {
    0x1ba, 0x176}
    , {
    0x1bc, 0x0f6}
    , {
    0x1c0, 0x00e}
    , {
    0x1c2, 0x10e}
    , {
    0x1c4, 0x08e}
    , {
    0x1c6, 0x18e}
    , {
    0x1c8, 0x04e}
    , {
    0x1ca, 0x14e}
    , {
    0x1cc, 0x0ce}
    , {
    0x1d0, 0x02e}
    , {
    0x1d2, 0x12e}
    , {
    0x1d4, 0x0ae}
    , {
    0x1d6, 0x1ae}
    , {
    0x1d8, 0x06e}
    , {
    0x1da, 0x16e}
    , {
    0x1dc, 0x0ee}
    , {
    0x1e0, 0x01e}
    , {
    0x1e2, 0x11e}
    , {
    0x1e4, 0x09e}
    , {
    0x1e6, 0x19e}
    , {
    0x1e8, 0x05e}
    , {
    0x1ea, 0x15e}
    , {
    0x1ec, 0x0de}
    , {
    0x1ee, 0x1de}
    , {
    0x1f0, 0x03e}
    , {
    0x1f2, 0x13e}
    , {
    0x1f4, 0x0be}
    , {
    0x1f6, 0x1be}
    , {
    0x1f8, 0x07e}
    , {
    0x1fa, 0x17e}
    , {
    0x1fc, 0x0fe}
    , {
    0x200, 0x001}
    , {
    0x202, 0x101}
    , {
    0x204, 0x081}
    , {
    0x206, 0x181}
    , {
    0x208, 0x041}
    , {
    0x20a, 0x141}
    , {
    0x20c, 0x0c1}
    , {
    0x20e, 0x1c1}
    , {
    0x210, 0x021}
    , {
    0x212, 0x121}
    , {
    0x214, 0x0a1}
    , {
    0x216, 0x1a1}
    , {
    0x218, 0x061}
    , {
    0x21a, 0x161}
    , {
    0x21c, 0x0e1}
    , {
    0x21e, 0x1e1}
    , {
    0x220, 0x011}
    , {
    0x221, 0x211}
    , {
    0x222, 0x111}
    , {
    0x224, 0x091}
    , {
    0x226, 0x191}
    , {
    0x228, 0x051}
    , {
    0x22a, 0x151}
    , {
    0x22c, 0x0d1}
    , {
    0x22e, 0x1d1}
    , {
    0x230, 0x031}
    , {
    0x232, 0x131}
    , {
    0x234, 0x0b1}
    , {
    0x236, 0x1b1}
    , {
    0x238, 0x071}
    , {
    0x23a, 0x171}
    , {
    0x23c, 0x0f1}
    , {
    0x23e, 0x1f1}
    , {
    0x240, 0x009}
    , {
    0x241, 0x209}
    , {
    0x242, 0x109}
    , {
    0x244, 0x089}
    , {
    0x246, 0x189}
    , {
    0x248, 0x049}
    , {
    0x24a, 0x149}
    , {
    0x24c, 0x0c9}
    , {
    0x24e, 0x1c9}
    , {
    0x250, 0x029}
    , {
    0x251, 0x229}
    , {
    0x252, 0x129}
    , {
    0x254, 0x0a9}
    , {
    0x256, 0x1a9}
    , {
    0x258, 0x069}
    , {
    0x25a, 0x169}
    , {
    0x25c, 0x0e9}
    , {
    0x25e, 0x1e9}
    , {
    0x260, 0x019}
    , {
    0x261, 0x219}
    , {
    0x262, 0x119}
    , {
    0x264, 0x099}
    , {
    0x266, 0x199}
    , {
    0x268, 0x059}
    , {
    0x269, 0x259}
    , {
    0x26a, 0x159}
    , {
    0x26c, 0x0d9}
    , {
    0x26e, 0x1d9}
    , {
    0x270, 0x039}
    , {
    0x271, 0x239}
    , {
    0x272, 0x139}
    , {
    0x274, 0x0b9}
    , {
    0x276, 0x1b9}
    , {
    0x278, 0x079}
    , {
    0x27a, 0x179}
    , {
    0x27c, 0x0f9}
    , {
    0x27e, 0x1f9}
    , {
    0x280, 0x005}
    , {
    0x281, 0x205}
    , {
    0x282, 0x105}
    , {
    0x284, 0x085}
    , {
    0x286, 0x185}
    , {
    0x288, 0x045}
    , {
    0x289, 0x245}
    , {
    0x28a, 0x145}
    , {
    0x28c, 0x0c5}
    , {
    0x28e, 0x1c5}
    , {
    0x290, 0x025}
    , {
    0x291, 0x225}
    , {
    0x292, 0x125}
    , {
    0x294, 0x0a5}
    , {
    0x296, 0x1a5}
    , {
    0x298, 0x065}
    , {
    0x299, 0x265}
    , {
    0x29a, 0x165}
    , {
    0x29c, 0x0e5}
    , {
    0x29e, 0x1e5}
    , {
    0x2a0, 0x015}
    , {
    0x2a1, 0x215}
    , {
    0x2a2, 0x115}
    , {
    0x2a4, 0x095}
    , {
    0x2a5, 0x295}
    , {
    0x2a6, 0x195}
    , {
    0x2a8, 0x055}
    , {
    0x2a9, 0x255}
    , {
    0x2aa, 0x155}
    , {
    0x2ac, 0x0d5}
    , {
    0x2ae, 0x1d5}
    , {
    0x2b0, 0x035}
    , {
    0x2b1, 0x235}
    , {
    0x2b2, 0x135}
    , {
    0x2b4, 0x0b5}
    , {
    0x2b6, 0x1b5}
    , {
    0x2b8, 0x075}
    , {
    0x2b9, 0x275}
    , {
    0x2ba, 0x175}
    , {
    0x2bc, 0x0f5}
    , {
    0x2be, 0x1f5}
    , {
    0x2c0, 0x00d}
    , {
    0x2c1, 0x20d}
    , {
    0x2c2, 0x10d}
    , {
    0x2c4, 0x08d}
    , {
    0x2c5, 0x28d}
    , {
    0x2c6, 0x18d}
    , {
    0x2c8, 0x04d}
    , {
    0x2c9, 0x24d}
    , {
    0x2ca, 0x14d}
    , {
    0x2cc, 0x0cd}
    , {
    0x2ce, 0x1cd}
    , {
    0x2d0, 0x02d}
    , {
    0x2d1, 0x22d}
    , {
    0x2d2, 0x12d}
    , {
    0x2d4, 0x0ad}
    , {
    0x2d5, 0x2ad}
    , {
    0x2d6, 0x1ad}
    , {
    0x2d8, 0x06d}
    , {
    0x2d9, 0x26d}
    , {
    0x2da, 0x16d}
    , {
    0x2dc, 0x0ed}
    , {
    0x2de, 0x1ed}
    , {
    0x2e0, 0x01d}
    , {
    0x2e1, 0x21d}
    , {
    0x2e2, 0x11d}
    , {
    0x2e4, 0x09d}
    , {
    0x2e5, 0x29d}
    , {
    0x2e6, 0x19d}
    , {
    0x2e8, 0x05d}
    , {
    0x2e9, 0x25d}
    , {
    0x2ea, 0x15d}
    , {
    0x2ec, 0x0dd}
    , {
    0x2ed, 0x2dd}
    , {
    0x2ee, 0x1dd}
    , {
    0x2f0, 0x03d}
    , {
    0x2f1, 0x23d}
    , {
    0x2f2, 0x13d}
    , {
    0x2f4, 0x0bd}
    , {
    0x2f5, 0x2bd}
    , {
    0x2f6, 0x1bd}
    , {
    0x2f8, 0x07d}
    , {
    0x2f9, 0x27d}
    , {
    0x2fa, 0x17d}
    , {
    0x2fc, 0x0fd}
    , {
    0x2fe, 0x1fd}
    , {
    0x300, 0x003}
    , {
    0x301, 0x203}
    , {
    0x302, 0x103}
    , {
    0x304, 0x083}
    , {
    0x305, 0x283}
    , {
    0x306, 0x183}
    , {
    0x308, 0x043}
    , {
    0x309, 0x243}
    , {
    0x30a, 0x143}
    , {
    0x30c, 0x0c3}
    , {
    0x30d, 0x2c3}
    , {
    0x30e, 0x1c3}
    , {
    0x310, 0x023}
    , {
    0x311, 0x223}
    , {
    0x312, 0x123}
    , {
    0x314, 0x0a3}
    , {
    0x315, 0x2a3}
    , {
    0x316, 0x1a3}
    , {
    0x318, 0x063}
    , {
    0x319, 0x263}
    , {
    0x31a, 0x163}
    , {
    0x31c, 0x0e3}
    , {
    0x31d, 0x2e3}
    , {
    0x31e, 0x1e3}
    , {
    0x320, 0x013}
    , {
    0x321, 0x213}
    , {
    0x322, 0x113}
    , {
    0x323, 0x313}
    , {
    0x324, 0x093}
    , {
    0x325, 0x293}
    , {
    0x326, 0x193}
    , {
    0x328, 0x053}
    , {
    0x329, 0x253}
    , {
    0x32a, 0x153}
    , {
    0x32c, 0x0d3}
    , {
    0x32d, 0x2d3}
    , {
    0x32e, 0x1d3}
    , {
    0x330, 0x033}
    , {
    0x331, 0x233}
    , {
    0x332, 0x133}
    , {
    0x334, 0x0b3}
    , {
    0x335, 0x2b3}
    , {
    0x336, 0x1b3}
    , {
    0x338, 0x073}
    , {
    0x339, 0x273}
    , {
    0x33a, 0x173}
    , {
    0x33c, 0x0f3}
    , {
    0x33d, 0x2f3}
    , {
    0x33e, 0x1f3}
    , {
    0x340, 0x00b}
    , {
    0x341, 0x20b}
    , {
    0x342, 0x10b}
    , {
    0x343, 0x30b}
    , {
    0x344, 0x08b}
    , {
    0x345, 0x28b}
    , {
    0x346, 0x18b}
    , {
    0x348, 0x04b}
    , {
    0x349, 0x24b}
    , {
    0x34a, 0x14b}
    , {
    0x34c, 0x0cb}
    , {
    0x34d, 0x2cb}
    , {
    0x34e, 0x1cb}
    , {
    0x350, 0x02b}
    , {
    0x351, 0x22b}
    , {
    0x352, 0x12b}
    , {
    0x353, 0x32b}
    , {
    0x354, 0x0ab}
    , {
    0x355, 0x2ab}
    , {
    0x356, 0x1ab}
    , {
    0x358, 0x06b}
    , {
    0x359, 0x26b}
    , {
    0x35a, 0x16b}
    , {
    0x35c, 0x0eb}
    , {
    0x35d, 0x2eb}
    , {
    0x35e, 0x1eb}
    , {
    0x360, 0x01b}
    , {
    0x361, 0x21b}
    , {
    0x362, 0x11b}
    , {
    0x363, 0x31b}
    , {
    0x364, 0x09b}
    , {
    0x365, 0x29b}
    , {
    0x366, 0x19b}
    , {
    0x368, 0x05b}
    , {
    0x369, 0x25b}
    , {
    0x36a, 0x15b}
    , {
    0x36b, 0x35b}
    , {
    0x36c, 0x0db}
    , {
    0x36d, 0x2db}
    , {
    0x36e, 0x1db}
    , {
    0x370, 0x03b}
    , {
    0x371, 0x23b}
    , {
    0x372, 0x13b}
    , {
    0x373, 0x33b}
    , {
    0x374, 0x0bb}
    , {
    0x375, 0x2bb}
    , {
    0x376, 0x1bb}
    , {
    0x378, 0x07b}
    , {
    0x379, 0x27b}
    , {
    0x37a, 0x17b}
    , {
    0x37c, 0x0fb}
    , {
    0x37d, 0x2fb}
    , {
    0x37e, 0x1fb}
    , {
    0x380, 0x007}
    , {
    0x381, 0x207}
    , {
    0x382, 0x107}
    , {
    0x383, 0x307}
    , {
    0x384, 0x087}
    , {
    0x385, 0x287}
    , {
    0x386, 0x187}
    , {
    0x388, 0x047}
    , {
    0x389, 0x247}
    , {
    0x38a, 0x147}
    , {
    0x38b, 0x347}
    , {
    0x38c, 0x0c7}
    , {
    0x38d, 0x2c7}
    , {
    0x38e, 0x1c7}
    , {
    0x390, 0x027}
    , {
    0x391, 0x227}
    , {
    0x392, 0x127}
    , {
    0x393, 0x327}
    , {
    0x394, 0x0a7}
    , {
    0x395, 0x2a7}
    , {
    0x396, 0x1a7}
    , {
    0x398, 0x067}
    , {
    0x399, 0x267}
    , {
    0x39a, 0x167}
    , {
    0x39b, 0x367}
    , {
    0x39c, 0x0e7}
    , {
    0x39d, 0x2e7}
    , {
    0x39e, 0x1e7}
    , {
    0x3a0, 0x017}
    , {
    0x3a1, 0x217}
    , {
    0x3a2, 0x117}
    , {
    0x3a3, 0x317}
    , {
    0x3a4, 0x097}
    , {
    0x3a5, 0x297}
    , {
    0x3a6, 0x197}
    , {
    0x3a7, 0x397}
    , {
    0x3a8, 0x057}
    , {
    0x3a9, 0x257}
    , {
    0x3aa, 0x157}
    , {
    0x3ab, 0x357}
    , {
    0x3ac, 0x0d7}
    , {
    0x3ad, 0x2d7}
    , {
    0x3ae, 0x1d7}
    , {
    0x3b0, 0x037}
    , {
    0x3b1, 0x237}
    , {
    0x3b2, 0x137}
    , {
    0x3b3, 0x337}
    , {
    0x3b4, 0x0b7}
    , {
    0x3b5, 0x2b7}
    , {
    0x3b6, 0x1b7}
    , {
    0x3b8, 0x077}
    , {
    0x3b9, 0x277}
    , {
    0x3ba, 0x177}
    , {
    0x3bb, 0x377}
    , {
    0x3bc, 0x0f7}
    , {
    0x3bd, 0x2f7}
    , {
    0x3be, 0x1f7}
    , {
    0x3c0, 0x00f}
    , {
    0x3c1, 0x20f}
    , {
    0x3c2, 0x10f}
    , {
    0x3c3, 0x30f}
    , {
    0x3c4, 0x08f}
    , {
    0x3c5, 0x28f}
    , {
    0x3c6, 0x18f}
    , {
    0x3c7, 0x38f}
    , {
    0x3c8, 0x04f}
    , {
    0x3c9, 0x24f}
    , {
    0x3ca, 0x14f}
    , {
    0x3cb, 0x34f}
    , {
    0x3cc, 0x0cf}
    , {
    0x3cd, 0x2cf}
    , {
    0x3ce, 0x1cf}
    , {
    0x3d0, 0x02f}
    , {
    0x3d1, 0x22f}
    , {
    0x3d2, 0x12f}
    , {
    0x3d3, 0x32f}
    , {
    0x3d4, 0x0af}
    , {
    0x3d5, 0x2af}
    , {
    0x3d6, 0x1af}
    , {
    0x3d7, 0x3af}
    , {
    0x3d8, 0x06f}
    , {
    0x3d9, 0x26f}
    , {
    0x3da, 0x16f}
    , {
    0x3db, 0x36f}
    , {
    0x3dc, 0x0ef}
    , {
    0x3dd, 0x2ef}
    , {
    0x3de, 0x1ef}
    , {
    0x3e0, 0x01f}
    , {
    0x3e1, 0x21f}
    , {
    0x3e2, 0x11f}
    , {
    0x3e3, 0x31f}
    , {
    0x3e4, 0x09f}
    , {
    0x3e5, 0x29f}
    , {
    0x3e6, 0x19f}
    , {
    0x3e7, 0x39f}
    , {
    0x3e8, 0x05f}
    , {
    0x3e9, 0x25f}
    , {
    0x3ea, 0x15f}
    , {
    0x3eb, 0x35f}
    , {
    0x3ec, 0x0df}
    , {
    0x3ed, 0x2df}
    , {
    0x3ee, 0x1df}
    , {
    0x3ef, 0x3df}
    , {
    0x3f0, 0x03f}
    , {
    0x3f1, 0x23f}
    , {
    0x3f2, 0x13f}
    , {
    0x3f3, 0x33f}
    , {
    0x3f4, 0x0bf}
    , {
    0x3f5, 0x2bf}
    , {
    0x3f6, 0x1bf}
    , {
    0x3f7, 0x3bf}
    , {
    0x3f8, 0x07f}
    , {
    0x3f9, 0x27f}
    , {
    0x3fa, 0x17f}
    , {
    0x3fb, 0x37f}
    , {
    0x3fc, 0x0ff}
    , {
    0x3fd, 0x2ff}
    , {
    0x3fe, 0x1ff}
  };
  {
    int i;
    for (i = 0; i < sizeof k1k2tab / sizeof k1k2tab[0]; ++i) {
      k1 = k1k2tab[i].k1;
      k2 = k1k2tab[i].k2;
      a = fz[k1];
      fz[k1] = fz[k2];
      fz[k2] = a;
    }
  }

  for (fi = fz, fn = fz + 1024; fi < fn; fi += 4) {
    FLOAT f0, f1, f2, f3;
    f1 = fi[0] - fi[1];
    f0 = fi[0] + fi[1];
    f3 = fi[2] - fi[3];
    f2 = fi[2] + fi[3];
    fi[2] = (f0 - f2);
    fi[0] = (f0 + f2);
    fi[3] = (f1 - f3);
    fi[1] = (f1 + f3);
  }

  k = 0;
  do {
    FLOAT s1, c1;
    k += 2;
    k1 = 1 << k;
    k2 = k1 << 1;
    k4 = k2 << 1;
    k3 = k2 + k1;
    kx = k1 >> 1;
    fi = fz;
    gi = fi + kx;
    fn = fz + 1024;
    do {
      FLOAT g0, f0, f1, g1, f2, g2, f3, g3;
      f1 = fi[0] - fi[k1];
      f0 = fi[0] + fi[k1];
      f3 = fi[k2] - fi[k3];
      f2 = fi[k2] + fi[k3];
      fi[k2] = f0 - f2;
      fi[0] = f0 + f2;
      fi[k3] = f1 - f3;
      fi[k1] = f1 + f3;
      g1 = gi[0] - gi[k1];
      g0 = gi[0] + gi[k1];
      g3 = SQRT2 * gi[k3];
      g2 = SQRT2 * gi[k2];
      gi[k2] = g0 - g2;
      gi[0] = g0 + g2;
      gi[k3] = g1 - g3;
      gi[k1] = g1 + g3;
      gi += k4;
      fi += k4;
    }
    while (fi < fn);
    t_c = costab[k];
    t_s = sintab[k];
    c1 = 1;
    s1 = 0;
    for (i = 1; i < kx; i++) {
      FLOAT c2, s2;
      FLOAT t = c1;
      c1 = t * t_c - s1 * t_s;
      s1 = t * t_s + s1 * t_c;
      c2 = c1 * c1 - s1 * s1;
      s2 = 2 * (c1 * s1);
      fn = fz + 1024;
      fi = fz + i;
      gi = fz + k1 - i;
      do {
	FLOAT a, b, g0, f0, f1, g1, f2, g2, f3, g3;
	b = s2 * fi[k1] - c2 * gi[k1];
	a = c2 * fi[k1] + s2 * gi[k1];
	f1 = fi[0] - a;
	f0 = fi[0] + a;
	g1 = gi[0] - b;
	g0 = gi[0] + b;
	b = s2 * fi[k3] - c2 * gi[k3];
	a = c2 * fi[k3] + s2 * gi[k3];
	f3 = fi[k2] - a;
	f2 = fi[k2] + a;
	g3 = gi[k2] - b;
	g2 = gi[k2] + b;
	b = s1 * f2 - c1 * g3;
	a = c1 * f2 + s1 * g3;
	fi[k2] = f0 - a;
	fi[0] = f0 + a;
	gi[k3] = g1 - b;
	gi[k1] = g1 + b;
	b = c1 * g2 - s1 * f3;
	a = s1 * g2 + c1 * f3;
	gi[k2] = g0 - a;
	gi[0] = g0 + a;
	fi[k3] = f1 - b;
	fi[k1] = f1 + b;
	gi += k4;
	fi += k4;
      }
      while (fi < fn);
    }
  }
  while (k4 < 1024);
}

#ifdef NEWATAN
#define ATANSIZE 2000
#define ATANSCALE 50.0
  static FLOAT atan_t[ATANSIZE];

INLINE FLOAT atan_table(FLOAT y, FLOAT x) {
  int index;
  double index_d = ATANSCALE * fabs(y/x);

  // Don't cast an infinite to an int, that's undefined behaviour
  if (isfinite(index_d)) {
      index = (int)(ATANSCALE * fabs(y/x));
  }
  else {
      index = ATANSIZE-1;
  }

  if (index>=ATANSIZE)
    index = ATANSIZE-1;

  if (y>0 && x<0)
    return( PI - atan_t[index] );

  if (y<0 && x>0)
    return( -atan_t[index] );

  if (y<0 && x<0)
    return( atan_t[index] - PI );

  return(atan_t[index]);
}

void atan_table_init(void) {
  int i;
  for (i=0;i<ATANSIZE;i++)
    atan_t[i] = atan((double)i/ATANSCALE);
}

#endif //NEWATAN

/* For variations on psycho model 2:
   N always equals 1024
   BUT in the returned values, no energy/phi is used at or above an index of 513 */
void psycho_2_fft (FLOAT * x_real, FLOAT * energy, FLOAT * phi) 
     /* got rid of size "N" argument as it is always 1024 for layerII */
{
  FLOAT a, b;
  int i, j;
#ifdef NEWATAN
  static int init=0;

  if (!init) {
    atan_table_init();
    init++;
  }
#endif


  fht (x_real);


  energy[0] = x_real[0] * x_real[0];

  for (i = 1, j = 1023; i < 512; i++, j--) {
    a = x_real[i];
    b = x_real[j];
    /* MFC FIXME Mar03 Why is this divided by 2.0?
       if a and b are the real and imaginary components then
       r = sqrt(a^2 + b^2),
       but, back in the psycho2 model, they calculate r=sqrt(energy), 
       which, if you look at the original equation below is different */
    energy[i] = (a * a + b * b) / 2.0;
    if (energy[i] < 0.0005) {
      energy[i] = 0.0005;
      phi[i] = 0;
    } else	
#ifdef NEWATAN
      {		
	phi[i] = atan_table(-a, b) + PI/4;
      }
#else
      {
      phi[i] = atan2(-(double)a, (double)b) + PI/4;
      }
#endif
  }
  energy[512] = x_real[512] * x_real[512];
  phi[512] = atan2 (0.0, (double) x_real[512]);
}


void psycho_1_fft (FLOAT * x_real, FLOAT * energy, int N)
{
  FLOAT a, b;
  int i, j;

  fht (x_real);

  energy[0] = x_real[0] * x_real[0];

  for (i = 1, j = N - 1; i < N / 2; i++, j--) {
    a = x_real[i];
    b = x_real[j];
    energy[i] = (a * a + b * b) / 2.0;
  }
  energy[N / 2] = x_real[N / 2] * x_real[N / 2];
}