/*
  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *

  * This file is part of FFmpeg.
  *
  * FFmpeg 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.

  *

  * FFmpeg 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 FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #ifndef AVUTIL_SOFTFLOAT_H
 #define AVUTIL_SOFTFLOAT_H

 #include <stdint.h>

 #include "common.h"

 #define MIN_EXP -126
 #define MAX_EXP  126
 #define ONE_BITS 29
 
 typedef struct SoftFloat{
     int32_t  exp;
     int32_t mant;
 }SoftFloat;
 

 static av_const SoftFloat av_normalize_sf(SoftFloat a){

     if(a.mant){
 #if 1
         while((a.mant + 0x20000000U)<0x40000000U){
             a.mant += a.mant;
             a.exp  -= 1;
         }
 #else
         int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));
         a.exp   -= s;
         a.mant <<= s;
 #endif
         if(a.exp < MIN_EXP){
             a.exp = MIN_EXP;
             a.mant= 0;
         }
     }else{
         a.exp= MIN_EXP;
     }
     return a;
 }
 

 static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){

 #if 1
     if(a.mant + 0x40000000 < 0){
         a.exp++;
         a.mant>>=1;
     }
     return a;
 #elif 1
     int t= a.mant + 0x40000000 < 0;
     return (SoftFloat){a.exp+t, a.mant>>t};
 #else
     int t= (a.mant + 0x40000000U)>>31;
     return (SoftFloat){a.exp+t, a.mant>>t};
 #endif
 }
 
 /**

  * @return Will not be more denormalized than a+b. So if either input is
  *         normalized, then the output will not be worse then the other input.
  *         If both are normalized, then the output will be normalized.

  */

 static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){

     a.exp += b.exp;
     a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
     return av_normalize1_sf(a);
 }
 
 /**

  * b has to be normalized and not zero.
  * @return Will not be more denormalized than a.

  */

 static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){

     a.exp -= b.exp+1;
     a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
     return av_normalize1_sf(a);
 }
 

 static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){

     int t= a.exp - b.exp;
     if(t<0) return (a.mant >> (-t)) -  b.mant      ;
     else    return  a.mant          - (b.mant >> t);
 }
 

 static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){

     int t= a.exp - b.exp;
     if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});
     else    return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >>   t )});
 }
 

 static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){

     return av_add_sf(a, (SoftFloat){b.exp, -b.mant});
 }
 
 //FIXME sqrt, log, exp, pow, sin, cos
 

 static inline av_const SoftFloat av_int2sf(int v, int frac_bits){

     return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});
 }
 
 /**

  * Rounding is to -inf.

  */

 static inline av_const int av_sf2int(SoftFloat v, int frac_bits){

     v.exp += frac_bits - ONE_BITS;
     if(v.exp >= 0) return v.mant <<  v.exp ;
     else           return v.mant >>(-v.exp);
 }

 #endif /* AVUTIL_SOFTFLOAT_H */