/*    Copyright (C) 1991-2000 Barry Vercoe, John ffitch

    This file is part of Csound.

    The Csound Library is free software; you can redistribute it
    and/or modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    Csound is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with Csound; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA
*/

#include "csdl.h" /*                                      PANS.C        */
#include <math.h>

extern void perferror(char *s);
extern FUNC * ftfind(MYFLT *argp);

typedef struct {
        OPDS    h;
        MYFLT   *r1, *r2, *asig, *kx, *ifn, *imode, *ioffset;
        MYFLT   xmul;
        long    xoff;
        FUNC    *ftp;
} PANS;

void pansset(PANS *p)
{
    FUNC *ftp;

    if ((ftp = ftfind(p->ifn)) == NULL)
      return;
    p->ftp = ftp;
    if (*p->imode)
      p->xmul = (MYFLT)ftp->flen;
    else
      p->xmul = FL(1.0);
    if (*p->ioffset)
      p->xoff = ftp->flen >> 1;
    else
      p->xoff = 0;
}

void pans(PANS *p)
{
    MYFLT       *r1, *r2, *sigp, ch1, ch2;
    long        xndx, flen;
    int nsmps = ksmps;
    FUNC        *ftp;

    ftp = p->ftp;
    if (ftp==NULL) {        /* RWD fix */
      perferror("pans: not initialised");
      return;
    }
    flen = ftp->flen;
    xndx = (long)(*p->kx * p->xmul) - p->xoff;
    if (xndx < 0L || xndx > flen) {
      if (xndx < 0)             xndx = 0;
      else if (xndx > flen)     xndx = flen;
    }
    ch2 = *(ftp->ftable + xndx);
    ch1 = *(ftp->ftable + flen - xndx);
    r1 = p->r1;
    r2 = p->r2;
    sigp = p->asig;
    do {
      *r1++ = *sigp * ch1;
      *r2++ = *sigp * ch2;
      sigp++;
    }
    while (--nsmps);
}

#define S       sizeof

static OENTRY localops[] = {
  { "pans",  S(PANS), 5,   "aa",   "akioo",  (SUBR)pansset, NULL, (SUBR)pans }
};

long opcode_size(void)
{
    return sizeof(localops);
}

OENTRY *opcode_init(GLOBALS *xx)
{
    pcglob = xx;
    return localops;
}