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

   1 /*
   2  * ldiv.c
   3  *
   4  *  Created on: Aug 12, 2009
   5  *      Author: misc
   6  */
   7
   8
   9 #include <inttypes.h>
  10
  11 void __attribute__((noreturn)) __aeabi_ldiv0(uint64_t);
  12
  13 int64_t __ldiv(int64_t a, int64_t b)
  14 {
  15         int32_t sign = ((int32_t)(a >> 32))^((int32_t)(b >> 32));
  16         int64_t ret = 0;
  17
  18         if (a < 0)
  19                 a = -a;
  20         if (b < 0)
  21                 b = -b;
  22
  23         if (b == 0)
  24         {
  25                 __aeabi_ldiv0(a);
  26         }
  27         else if (b > a)
  28         {
  29                 return 0;
  30         }
  31         else
  32         {
  33                 int first_bit_a = __builtin_clz(a >> 32);
  34                 int first_bit_b = __builtin_clz(b >> 32);
  35
  36                 if (first_bit_a == 32)
  37                     first_bit_a += __builtin_clz(a & 0xffffffff);
  38                 if (first_bit_b == 32)
  39                     first_bit_b += __builtin_clz(b & 0xffffffff);
  40
  41                 uint64_t mask = 0x00000001ULL << (first_bit_b-first_bit_a);
  42                 b <<= (first_bit_b - first_bit_a);
  43
  44                 do
  45                 {
  46                         if (a >= b)
  47                         {
  48                                 ret |= mask;
  49                                 a -= b;
  50                         }
  51
  52                         mask >>=1;
  53                         b >>=1;
  54                 } while(mask);
  55         }
  56
  57         if (sign < 0)
  58                 ret = -ret;
  59
  60         return ret;
  61 }
  62
  63 int64_t __ldivmod_helper(int64_t a, int64_t b, int64_t *remainder)
  64 {
  65         int64_t quotient;
  66
  67         quotient = __ldiv(a, b);
  68
  69         *remainder = a - b * quotient;
  70
  71         return quotient;
  72 }