在Perl中，有没有比打包打包更快的方法来获取浮点位？

Question

Is there a faster way to get floating point bits than pack/unpack in Perl? It is not necessary to be IEEE754

Answer 1

Your question makes no sense. You're asking for the fast way to do something the slow way. If we knew what you really wanted to do , we could provide a better solution.

use strict;
use warnings;
use feature qw( say );

use Inline C => <<'__EOS__';

   void cast_double_to_uv(SV* sv) {
      dXSARGS;

      double d = (double)SvNV(sv);
      UV uv;

      if (sizeof(uv) < sizeof(double))
         croak("Integers too small to hold a double.");

      if (BYTEORDER == 0x1234) {
         /* Little-endian */
         memcpy(&uv, &d, sizeof(double));

         if (sizeof(uv) > sizeof(double))
            memset(((char*)&uv)+sizeof(double), 0, sizeof(double)-sizeof(uv));
      } else {
         /* Big-endian */
         if (sizeof(uv) > sizeof(double))
            memset(&uv, 0, sizeof(double)-sizeof(uv));

         memcpy(((char*)&uv)+sizeof(double)-sizeof(uv), &d, sizeof(double));
      }

      XSRETURN_UV(uv);
   }

__EOS__

say cast_double_to_uv(5.5);