Fortran77代码中的动态内存分配（PNL分配器）

Question

I am working on an application, which is written primarily in Fortan77. Since fortran77 does not support dynamic memory allocation, the code utilizes the PNL Dynamic Memory Allocator: http://www.emsl.pnl.gov/docs/global/ma/MAapi.html

However can someone provide an explanation for:

   int_mb(index + i)

what does int_mb and similarly dlb_mb return?

If cost is an integer, what would dlb_mb(cost) specify?

Thank you for your time.

Answer 1

However can someone provide an explanation for: int_mb(index + i)

That sets (eg zeroes) allocated memory.

http://www.emsl.pnl.gov/docs/global/ma/MA_alloc_get.html

#include "mafdecls.h"

      logical ok
      integer mhandle
      integer index
      integer i

      ok = MA_alloc_get(MT_INT, 5, 'heap int block', mhandle, index)
      if (ok) then
          do 10 i = 0, 4
              int_mb(index + i) = 0
10        continue
      endif

---

what does int_mb and similarly dlb_mb return?

dbl_mb that is.

From https://svn.pnl.gov/svn/hpctools/trunk/ga/ma/mafdecls.fh.in (user: anonymous, pw: anonymous) I'd guess they return the previous value at that mem. loc.; simply try out by invoking twice in a row and assigning different values, then trace the second return val.

Answer 2

When you initialize an array using ma_alloc_get , you specify what memory type you are allocating (int = mt_int , double = mt_dbl , etc.) and it gives you back a memory handle and an index. The index is used to access specific values within the MA array.

Let's say you've allocated an array of integers and index is your index. int_mb(index) would be the first element in that array. Therefore, int_mb(index + i) would be element i+1 .

dbl_mb(cost) would be the double located at cost in the double block. a = dbl_mb(cost) would access this value while dbl_mb(cost) = 123.45 would set the value, provided that cost points to an initialized block of memory.

I personally like to think of 'mt' as 'memory type' and 'mb' as 'memory block', since that's what they are essentially doing. 'mt' variables are internal integers so the allocator knows which memory block to allocate to and 'mb' calls are accessing specific locations on that block.

You can read more on their API page .

Answer 3

Use Fortran 90+ dynamic memory allocation. There is absolutely no reason for MA to exist anymore except as a historical artifact in NWChem.