一个通用的swap子程序

weixing1531 · 发表于 2024-4-1 12:17:45

本帖最后由 weixing1531 于 2024-4-1 12:39 编辑

在Fortran wiki 上看到这个有趣的代码
测试了一下，快速排序慢3倍，堆排序慢35%

[Fortran] 纯文本查看 复制代码

module M_swap
private
public swap
contains
   subroutine swap(lhs,rhs)
      use iso_c_binding
      implicit none
      class(*),intent(inout) :: lhs, rhs
      class(*), allocatable :: temp
! Copy N bytes of SRC to DEST, no aliasing or overlapping allowed.
! extern void *memcpy (void *dest, const void *src, size_t n);
      interface
         subroutine  s_memcpy(dest, src, n) bind(C,name='memcpy')
            use iso_c_binding
            integer(c_intptr_t), value, intent(in) :: dest
            integer(c_intptr_t), value, intent(in) :: src
            integer(c_size_t), value :: n
         end subroutine s_memcpy
      end interface
      temp=lhs
      call s_memcpy(loc(lhs),  loc(rhs), storage_size(lhs, kind=c_size_t)/8_c_size_t )
      call s_memcpy(loc(rhs), loc(temp), storage_size(rhs, kind=c_size_t)/8_c_size_t )
   end subroutine swap
end module M_swap