softfloat/SoftFloat-3/source/s_countLeadingZeros64.c

   1
   2 #include <stdint.h>
   3 #include "primitives.h"
   4
   5 int softfloat_countLeadingZeros64( uint64_t a )
   6 {
   7     int count;
   8     uint32_t a32;
   9
  10     count = 32;
  11     a32 = a;
  12     if ( UINT64_C( 0x100000000 ) <= a ) {
  13         count = 0;
  14         a32 = a>>32;
  15     }
  16     /*------------------------------------------------------------------------
  17     | From here, result is current count + count leading zeros of `a32'.
  18     *------------------------------------------------------------------------*/
  19     if ( a32 < 0x10000 ) {
  20         count += 16;
  21         a32 <<= 16;
  22     }
  23     if ( a32 < 0x1000000 ) {
  24         count += 8;
  25         a32 <<= 8;
  26     }
  27     count += softfloat_countLeadingZeros8[ a32>>24 ];
  28     return count;
  29
  30 }
  31