/*
  * arbitrary precision integers
  * Copyright (c) 2004 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

  */

 /**

  * @file

  * arbitrary precision integers

  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 
 #include "common.h"
 #include "integer.h"

 #include "avassert.h"

 
 AVInteger av_add_i(AVInteger a, AVInteger b){
     int i, carry=0;

     for(i=0; i<AV_INTEGER_SIZE; i++){
         carry= (carry>>16) + a.v[i] + b.v[i];
         a.v[i]= carry;
     }
     return a;
 }
 
 AVInteger av_sub_i(AVInteger a, AVInteger b){
     int i, carry=0;

     for(i=0; i<AV_INTEGER_SIZE; i++){
         carry= (carry>>16) + a.v[i] - b.v[i];
         a.v[i]= carry;
     }
     return a;
 }
 
 int av_log2_i(AVInteger a){
     int i;
 
     for(i=AV_INTEGER_SIZE-1; i>=0; i--){
         if(a.v[i])
             return av_log2_16bit(a.v[i]) + 16*i;
     }
     return -1;
 }
 
 AVInteger av_mul_i(AVInteger a, AVInteger b){
     AVInteger out;
     int i, j;
     int na= (av_log2_i(a)+16) >> 4;
     int nb= (av_log2_i(b)+16) >> 4;

     memset(&out, 0, sizeof(out));

     for(i=0; i<na; i++){
         unsigned int carry=0;

         if(a.v[i])
             for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){
                 carry= (carry>>16) + out.v[j] + a.v[i]*b.v[j-i];
                 out.v[j]= carry;
             }
     }
 
     return out;
 }
 
 int av_cmp_i(AVInteger a, AVInteger b){

     int i;

     int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1];
     if(v) return (v>>16)|1;

     for(i=AV_INTEGER_SIZE-2; i>=0; i--){
         int v= a.v[i] - b.v[i];
         if(v) return (v>>16)|1;
     }
     return 0;
 }
 
 AVInteger av_shr_i(AVInteger a, int s){
     AVInteger out;
     int i;
 
     for(i=0; i<AV_INTEGER_SIZE; i++){

         unsigned int index= i + (s>>4);

         unsigned int v=0;

         if(index+1<AV_INTEGER_SIZE) v = a.v[index+1]<<16;
         if(index  <AV_INTEGER_SIZE) v+= a.v[index  ];

         out.v[i]= v >> (s&15);
     }
     return out;
 }
 
 AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){
     int i= av_log2_i(a) - av_log2_i(b);
     AVInteger quot_temp;
     if(!quot) quot = &quot_temp;

     av_assert2((int16_t)a.v[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b.v[AV_INTEGER_SIZE-1] >= 0);
     av_assert2(av_log2_i(b)>=0);

     if(i > 0)
         b= av_shr_i(b, -i);

     memset(quot, 0, sizeof(AVInteger));
 
     while(i-- >= 0){
         *quot= av_shr_i(*quot, -1);
         if(av_cmp_i(a, b) >= 0){
             a= av_sub_i(a, b);
             quot->v[0] += 1;
         }
         b= av_shr_i(b, 1);
     }
     return a;
 }
 
 AVInteger av_div_i(AVInteger a, AVInteger b){
     AVInteger quot;
     av_mod_i(&quot, a, b);
     return quot;
 }
 
 AVInteger av_int2i(int64_t a){
     AVInteger out;
     int i;

     for(i=0; i<AV_INTEGER_SIZE; i++){
         out.v[i]= a;
         a>>=16;
     }
     return out;
 }
 
 int64_t av_i2int(AVInteger a){
     int i;
     int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1];

     for(i= AV_INTEGER_SIZE-2; i>=0; i--){
         out = (out<<16) + a.v[i];
     }
     return out;
 }
 

 #ifdef TEST

 
 const uint8_t ff_log2_tab[256]={
         0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
         5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
 };
 

 int main(void){

     int64_t a,b;
 
     for(a=7; a<256*256*256; a+=13215){
         for(b=3; b<256*256*256; b+=27118){
             AVInteger ai= av_int2i(a);
             AVInteger bi= av_int2i(b);

             av_assert0(av_i2int(ai) == a);
             av_assert0(av_i2int(bi) == b);
             av_assert0(av_i2int(av_add_i(ai,bi)) == a+b);
             av_assert0(av_i2int(av_sub_i(ai,bi)) == a-b);
             av_assert0(av_i2int(av_mul_i(ai,bi)) == a*b);
             av_assert0(av_i2int(av_shr_i(ai, 9)) == a>>9);
             av_assert0(av_i2int(av_shr_i(ai,-9)) == a<<9);
             av_assert0(av_i2int(av_shr_i(ai, 17)) == a>>17);
             av_assert0(av_i2int(av_shr_i(ai,-17)) == a<<17);
             av_assert0(av_log2_i(ai) == av_log2(a));
             av_assert0(av_i2int(av_div_i(ai,bi)) == a/b);

         }
     }

     return 0;

 }
 #endif