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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. /** @addtogroup genarch
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #include <genarch/softint/division.h>
  36.  
  37. #define ABSVAL(x) ((x) > 0 ? (x) : -(x))
  38. #define SGN(x) ((x) >= 0 ? 1 : 0)
  39.                      
  40. static unsigned int divandmod32(unsigned int a, unsigned int b,
  41.     unsigned int *remainder)
  42. {
  43.     unsigned int result;
  44.     int steps = sizeof(unsigned int) * 8;
  45.    
  46.     *remainder = 0;
  47.     result = 0;
  48.    
  49.     if (b == 0) {
  50.         /* FIXME: division by zero */
  51.         return 0;
  52.     }
  53.    
  54.     if (a < b) {
  55.         *remainder = a;
  56.         return 0;
  57.     }
  58.  
  59.     for (; steps > 0; steps--) {
  60.         /* shift one bit to remainder */
  61.         *remainder = ((*remainder) << 1) | (( a >> 31) & 0x1);
  62.         result <<= 1;
  63.        
  64.         if (*remainder >= b) {
  65.             *remainder -= b;
  66.             result |= 0x1;
  67.         }
  68.         a <<= 1;
  69.     }
  70.  
  71.     return result;
  72. }
  73.  
  74.  
  75. static unsigned long long divandmod64(unsigned long long a,
  76.     unsigned long long b, unsigned long long *remainder)
  77. {
  78.     unsigned long long result;
  79.     int steps = sizeof(unsigned long long) * 8;
  80.    
  81.     *remainder = 0;
  82.     result = 0;
  83.    
  84.     if (b == 0) {
  85.         /* FIXME: division by zero */
  86.         return 0;
  87.     }
  88.    
  89.     if (a < b) {
  90.         *remainder = a;
  91.         return 0;
  92.     }
  93.  
  94.     for (; steps > 0; steps--) {
  95.         /* shift one bit to remainder */
  96.         *remainder = ((*remainder) << 1) | ((a >> 63) & 0x1);
  97.         result <<= 1;
  98.        
  99.         if (*remainder >= b) {
  100.             *remainder -= b;
  101.             result |= 0x1;
  102.         }
  103.         a <<= 1;
  104.     }
  105.  
  106.     return result;
  107. }
  108.  
  109. /* 32bit integer division */
  110. int __divsi3(int a, int b)
  111. {
  112.     unsigned int rem;
  113.     int result;
  114.    
  115.     result = (int) divandmod32(ABSVAL(a), ABSVAL(b), &rem);
  116.  
  117.     if (SGN(a) == SGN(b))
  118.         return result;
  119.     return -result;
  120. }
  121.  
  122. /* 64bit integer division */
  123. long long __divdi3(long long a, long long b)
  124. {
  125.     unsigned long long rem;
  126.     long long result;
  127.    
  128.     result = (long long) divandmod64(ABSVAL(a), ABSVAL(b), &rem);
  129.  
  130.     if (SGN(a) == SGN(b))
  131.         return result;
  132.     return -result;
  133. }
  134.  
  135. /* 32bit unsigned integer division */
  136. unsigned int __udivsi3(unsigned int a, unsigned int b)
  137. {
  138.     unsigned int rem;
  139.     return divandmod32(a, b, &rem);
  140. }
  141.  
  142. /* 64bit unsigned integer division */
  143. unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
  144. {
  145.     unsigned long long  rem;
  146.     return divandmod64(a, b, &rem);
  147. }
  148.  
  149. /* 32bit remainder of the signed division */
  150. int __modsi3(int a, int b)
  151. {
  152.     unsigned int rem;
  153.     divandmod32(a, b, &rem);
  154.    
  155.     /* if divident is negative, remainder must be too */
  156.     if (!(SGN(a))) {
  157.         return -((int) rem);
  158.     }
  159.    
  160.     return (int) rem;
  161. }
  162.  
  163. /* 64bit remainder of the signed division */
  164. long long __moddi3(long long a,long  long b)
  165. {
  166.     unsigned long long rem;
  167.     divandmod64(a, b, &rem);
  168.    
  169.     /* if divident is negative, remainder must be too */
  170.     if (!(SGN(a))) {
  171.         return -((long long) rem);
  172.     }
  173.    
  174.     return (long long) rem;
  175. }
  176.  
  177. /* 32bit remainder of the unsigned division */
  178. unsigned int __umodsi3(unsigned int a, unsigned int b)
  179. {
  180.     unsigned int rem;
  181.     divandmod32(a, b, &rem);
  182.     return rem;
  183. }
  184.  
  185. /* 64bit remainder of the unsigned division */
  186. unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
  187. {
  188.     unsigned long long rem;
  189.     divandmod64(a, b, &rem);
  190.     return rem;
  191. }
  192.  
  193. unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b,
  194.     unsigned long long *c)
  195. {
  196.     return divandmod64(a, b, c);
  197. }
  198.  
  199. /** @}
  200.  */
  201.