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  1. /*
  2.  * Copyright (C) 2006 Josef Cejka
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <division.h>
  30.  
  31. #define ABSVAL(x) ( (x) > 0 ? (x) : -(x))
  32. #define SGN(x) ( (x) >= 0 ? 1 : 0 )
  33.                      
  34. static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)
  35. {
  36.     unsigned int result;
  37.     int steps = sizeof(unsigned int) * 8;
  38.    
  39.     *remainder = 0;
  40.     result = 0;
  41.    
  42.     if (b == 0) {
  43.         /* FIXME: division by zero */
  44.         return 0;
  45.     }
  46.    
  47.     if ( a < b) {
  48.         *remainder = a;
  49.         return 0;
  50.     }
  51.  
  52.     for ( ; steps > 0; steps--) {
  53.         /* shift one bit to remainder */
  54.         *remainder = ( (*remainder) << 1) | (( a >> 31) & 0x1);
  55.         result <<= 1;
  56.        
  57.         if (*remainder >= b) {
  58.                 *remainder -= b;
  59.                 result |= 0x1;
  60.         }
  61.         a <<= 1;
  62.     }
  63.  
  64.     return result;
  65. }
  66.  
  67.  
  68. static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder)
  69. {
  70.     unsigned long long result;
  71.     int steps = sizeof(unsigned long long) * 8;
  72.    
  73.     *remainder = 0;
  74.     result = 0;
  75.    
  76.     if (b == 0) {
  77.         /* FIXME: division by zero */
  78.         return 0;
  79.     }
  80.    
  81.     if ( a < b) {
  82.         *remainder = a;
  83.         return 0;
  84.     }
  85.  
  86.     for ( ; steps > 0; steps--) {
  87.         /* shift one bit to remainder */
  88.         *remainder = ( (*remainder) << 1) | ((a >> 63) & 0x1);
  89.         result <<= 1;
  90.        
  91.         if (*remainder >= b) {
  92.                 *remainder -= b;
  93.                 result |= 0x1;
  94.         }
  95.         a <<= 1;
  96.     }
  97.  
  98.     return result;
  99. }
  100.  
  101. /* 32bit integer division */
  102. int __divsi3(int a, int b)
  103. {
  104.     unsigned int rem;
  105.     int result;
  106.    
  107.     result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);
  108.  
  109.     if ( SGN(a) == SGN(b)) return result;
  110.     return -result;
  111. }
  112.  
  113. /* 64bit integer division */
  114. long long __divdi3(long long a, long long b)
  115. {
  116.     unsigned long long rem;
  117.     long long result;
  118.    
  119.     result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);
  120.  
  121.     if ( SGN(a) == SGN(b)) return result;
  122.     return -result;
  123. }
  124.  
  125. /* 32bit unsigned integer division */
  126. unsigned int __udivsi3(unsigned int a, unsigned int b)
  127. {
  128.     unsigned int rem;
  129.     return divandmod32(a, b, &rem);
  130. }
  131.  
  132. /* 64bit unsigned integer division */
  133. unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
  134. {
  135.     unsigned long long  rem;
  136.     return divandmod64(a, b, &rem);
  137. }
  138.  
  139. /* 32bit remainder of the signed division */
  140. int __modsi3(int a, int b)
  141. {
  142.     unsigned int rem;
  143.     divandmod32(a, b, &rem);
  144.    
  145.     /* if divident is negative, remainder must be too */
  146.     if (!(SGN(a))) {
  147.         return -((int)rem);
  148.     }
  149.    
  150.     return (int)rem;
  151. }
  152.  
  153. /* 64bit remainder of the signed division */
  154. long long __moddi3(long long a,long  long b)
  155. {
  156.     unsigned long long rem;
  157.     divandmod64(a, b, &rem);
  158.    
  159.     /* if divident is negative, remainder must be too */
  160.     if (!(SGN(a))) {
  161.         return -((long long)rem);
  162.     }
  163.    
  164.     return (long long)rem;
  165. }
  166.  
  167. /* 32bit remainder of the unsigned division */
  168. unsigned int __umodsi3(unsigned int a, unsigned int b)
  169. {
  170.     unsigned int rem;
  171.     divandmod32(a, b, &rem);
  172.     return rem;
  173. }
  174.  
  175. /* 64bit remainder of the unsigned division */
  176. unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
  177. {
  178.     unsigned long long rem;
  179.     divandmod64(a, b, &rem);
  180.     return rem;
  181. }
  182.  
  183. unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c)
  184. {
  185.     return divandmod64(a, b, c);
  186. }
  187.  
  188.  
  189.