arch/arm-all/arm-aeabi/uldiv.c

   1 /*
   2     Copyright © 2009-2014, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <inttypes.h>
   7
   8 void __attribute__((noreturn)) __aeabi_ldiv0(uint64_t);
   9
  10 uint64_t __uldiv(uint64_t a, uint64_t b)
  11 {
  12         uint64_t ret = 0;
  13         if (b == 0)
  14         {
  15                 __aeabi_ldiv0(a);
  16         }
  17         else if (b > a)
  18         {
  19                 return 0;
  20         }
  21         else
  22         {
  23                 int first_bit_a = __builtin_clz(a >> 32);
  24                 int first_bit_b = __builtin_clz(b >> 32);
  25
  26                 if (first_bit_a == 32)
  27                     first_bit_a += __builtin_clz(a & 0xffffffff);
  28                 if (first_bit_b == 32)
  29                     first_bit_b += __builtin_clz(b & 0xffffffff);
  30
  31                 uint64_t mask = 0x00000001ULL << (first_bit_b-first_bit_a);
  32                 b <<= (first_bit_b - first_bit_a);
  33
  34                 do
  35                 {
  36                         if (a >= b)
  37                         {
  38                                 ret |= mask;
  39                                 a -= b;
  40                         }
  41
  42                         mask >>=1;
  43                         b >>=1;
  44                 } while(mask);
  45         }
  46         return ret;
  47 }
  48
  49 uint64_t __uldivmod_helper(uint64_t a, uint64_t b, uint64_t *remainder)
  50 {
  51         uint64_t quotient;
  52
  53         quotient = __uldiv(a, b);
  54
  55         *remainder = a - b * quotient;
  56
  57         return quotient;
  58 }