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

   1 /*
   2  * uldiv.c
   3  *
   4  *  Created on: Aug 12, 2009
   5  *      Author: misc
   6  */
   7
   8 #include <inttypes.h>
   9
  10 void __attribute__((noreturn)) __aeabi_ldiv0(uint64_t);
  11
  12 uint64_t __uldiv(uint64_t a, uint64_t b)
  13 {
  14         uint64_t ret = 0;
  15         if (b == 0)
  16         {
  17                 __aeabi_ldiv0(a);
  18         }
  19         else if (b > a)
  20         {
  21                 return 0;
  22         }
  23         else
  24         {
  25                 int first_bit_a = __builtin_clz(a >> 32);
  26                 int first_bit_b = __builtin_clz(b >> 32);
  27
  28                 if (first_bit_a == 32)
  29                     first_bit_a += __builtin_clz(a & 0xffffffff);
  30                 if (first_bit_b == 32)
  31                     first_bit_b += __builtin_clz(b & 0xffffffff);
  32
  33                 uint64_t mask = 0x00000001ULL << (first_bit_b-first_bit_a);
  34                 b <<= (first_bit_b - first_bit_a);
  35
  36                 do
  37                 {
  38                         if (a >= b)
  39                         {
  40                                 ret |= mask;
  41                                 a -= b;
  42                         }
  43
  44                         mask >>=1;
  45                         b >>=1;
  46                 } while(mask);
  47         }
  48         return ret;
  49 }
  50
  51 uint64_t __uldivmod_helper(uint64_t a, uint64_t b, uint64_t *remainder)
  52 {
  53         uint64_t quotient;
  54
  55         quotient = __uldiv(a, b);
  56
  57         *remainder = a - b * quotient;
  58
  59         return quotient;
  60 }