/********************************************************************

 *                                                                  *

 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *

 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *

 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *

 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *

 *                                                                  *

 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *

 * by the Xiph.Org Foundation http://www.xiph.org/                  *

 *                                                                  *

 ********************************************************************

  function: lookup based functions

  last mod: $Id: lookup.c 16227 2009-07-08 06:58:46Z xiphmont $

 ********************************************************************/

#include <math.h>

#include "lookup.h"

#include "lookup_data.h"

#include "os.h"

#include "misc.h"

#ifdef FLOAT_LOOKUP

/* interpolated lookup based cos function, domain 0 to PI only */

float vorbis_coslook(float a){

  double d=a*(.31830989*(float)COS_LOOKUP_SZ);

  int i=vorbis_ftoi(d-.5);

  return COS_LOOKUP[i]+ (d-i)*(COS_LOOKUP[i+1]-COS_LOOKUP[i]);

}

/* interpolated 1./sqrt(p) where .5 <= p < 1. */

float vorbis_invsqlook(float a){

  double d=a*(2.f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ;

  int i=vorbis_ftoi(d-.5f);

  return INVSQ_LOOKUP[i]+ (d-i)*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]);

}

/* interpolated 1./sqrt(p) where .5 <= p < 1. */

float vorbis_invsq2explook(int a){

  return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN];

}

#include <stdio.h>

/* interpolated lookup based fromdB function, domain -140dB to 0dB only */

float vorbis_fromdBlook(float a){

  int i=vorbis_ftoi(a*((float)(-(1<

  return (i<0)?1.f:

    ((i>=(FROMdB_LOOKUP_SZ<

     FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);

}

#endif

#ifdef INT_LOOKUP

/* interpolated 1./sqrt(p) where .5 <= a < 1. (.100000... to .111111...) in

   16.16 format

   returns in m.8 format */

long vorbis_invsqlook_i(long a,long e){

  long i=(a&0x7fff)>>(INVSQ_LOOKUP_I_SHIFT-1);

  long d=(a&INVSQ_LOOKUP_I_MASK)<<(16-INVSQ_LOOKUP_I_SHIFT); /*  0.16 */

  long val=INVSQ_LOOKUP_I[i]-                                /*  1.16 */

    (((INVSQ_LOOKUP_I[i]-INVSQ_LOOKUP_I[i+1])*               /*  0.16 */

      d)>>16);                                               /* result 1.16 */

  e+=32;

  if(e&1)val=(val*5792)>>13; /* multiply val by 1/sqrt(2) */

  e=(e>>1)-8;

  return(val>>e);

}

/* interpolated lookup based fromdB function, domain -140dB to 0dB only */

/* a is in n.12 format */

float vorbis_fromdBlook_i(long a){

  int i=(-a)>>(12-FROMdB2_SHIFT);

  return (i<0)?1.f:

    ((i>=(FROMdB_LOOKUP_SZ<

     FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);

}

/* interpolated lookup based cos function, domain 0 to PI only */

/* a is in 0.16 format, where 0==0, 2^^16-1==PI, return 0.14 */

long vorbis_coslook_i(long a){

  int i=a>>COS_LOOKUP_I_SHIFT;

  int d=a&COS_LOOKUP_I_MASK;

  return COS_LOOKUP_I[i]- ((d*(COS_LOOKUP_I[i]-COS_LOOKUP_I[i+1]))>>

                           COS_LOOKUP_I_SHIFT);

}

#endif