// file: $isip/class/algo/FourierTransform/FourierTransformFh.h
// version: $Id: FourierTransformFh.h 6436 2001-03-05 23:59:37Z peng $
//

// This file defines the functions required by the FHT code
//
// this header file is a part of the public domain fht code by ron mayer.
// this is supposedly proprietary.
//
// this code is based on the algorithm as described in the work by ron
// mayer whose code is available as a free-ware. the algorithm is
// described in the paper:
//
//  Hsieh S. Hou, "the fast hartley transform algorithm", IEEE
//  Transactions on Computers, pp. 147-153, February 1987.
//

// isip include files
//

// make sure definitions are only made once
//
#ifndef ISIP_FT_FHT
#define ISIP_FT_FHT

// the fht code seems to require these macro definitions
// it is called from within the fht routine and cannot be
// removed.
//
#ifdef FT_FHT_GOOD_TRIG
#else
#define FT_FHT_FAST_TRIG
#endif

#if defined(FT_FHT_GOOD_TRIG)

#define FHT_SWAP(a,b,t) {(t)=(a);(a)=(b);(b)=(t);}

#define TRIG_VARS					         \
      int32 t_lam = 0; \
#define TRIG_INIT(k,c,s)					 \
     {								 \
      int32 i;							 \
      for (i=2 ; i<=k ; ++i) {					 \
         coswrk[i]=costab[i];sinwrk[i]=sintab[i];
      }		 \
      t_lam = 0;					         \
      c = 1;							 \
      s = 0;							 \
     }

#define TRIG_NEXT(k,c,s)					 \
      { \
	 int32 i,j;	                                         \
	 ++(t_lam);	  					 \
	 for (i=0 ; !(1 << i))&(int32)t_lam) ; ++i);	 \
         i = k - i;					 \
         s = sinwrk[i];                                          \
         p = t_lam;						 \
         c = coswrk[i];						 \
	 fprintf(stdout, "%d\n", (t_lam));                       \
         if (i>1)   						 \
            {	    						 \
             for (j=k-i+2 ; (1<<j)&(int32)t_lam ; ++j);		 \
             j = k - j;                                          \
	     sinwrk[i] = halsec[i] * (sinwrk[i - 1] + sinwrk[j]);  \
             coswrk[i] = halsec[i] * (coswrk[i - 1] + coswrk[j]);  \
            } \
     }

#define TRIG_RESET(k,c,s)

#endif

#if defined(FT_FHT_FAST_TRIG)
#define TRIG_VARS					 \
     float64 t_c,t_s;
#define TRIG_INIT(k,c,s)				 \
    {				        		 \
     t_c  = costab[k];				         \
     t_s  = sintab[k];				         \
     c    = 1;				    		 \
     s    = 0;				    		 \
    }
#define TRIG_NEXT(k,c,s)				 \
    {                                                    \
     float64 t = c;\
     c   = t * t_c -  s * t_s;	    		 \
     s   = t * t_s + s * t_c;			 \
     }
#define TRIG_RESET(k,c,s)
#endif

static float64 costab[20]=
    {
      .00000000000000000000000000000000000000000000000000,
      .70710678118654752440084436210484903928483593768847,
      .92387953251128675612818318939678828682241662586364,
      .98078528040323044912618223613423903697393373089333,
      .99518472667219688624483695310947992157547486872985,
      .99879545620517239271477160475910069444320361470461,
      .99969881869620422011576564966617219685006108125772,
      .99992470183914454092164649119638322435060646880221,
      .99998117528260114265699043772856771617391725094433,
      .99999529380957617151158012570011989955298763362218,
      .99999882345170190992902571017152601904826792288976,
      .99999970586288221916022821773876567711626389934930,
      .99999992646571785114473148070738785694820115568892,
      .99999998161642929380834691540290971450507605124278,
      .99999999540410731289097193313960614895889430318945,
      .99999999885102682756267330779455410840053741619428
    };

static float64 sintab[20]=
    {
      1.0000000000000000000000000000000000000000000000000,
      .70710678118654752440084436210484903928483593768846,
      .38268343236508977172845998403039886676134456248561,
      .19509032201612826784828486847702224092769161775195,
      .09801714032956060199419556388864184586113667316749,
      .04906767432741801425495497694268265831474536302574,
      .02454122852291228803173452945928292506546611923944,
      .01227153828571992607940826195100321214037231959176,
      .00613588464915447535964023459037258091705788631738,
      .00306795676296597627014536549091984251894461021344,
      .00153398018628476561230369715026407907995486457522,
      .00076699031874270452693856835794857664314091945205,
      .00038349518757139558907246168118138126339502603495,
      .00019174759731070330743990956198900093346887403385,
      .00009587379909597734587051721097647635118706561284,
      .00004793689960306688454900399049465887274686668768
    };

// end of file
// 
#endif