free

falloc(3f)                                                          falloc(3f)



Name
       falloc, free, malloc - allocates memory

Syntax
       integer size
       integer malloc,addr
       external malloc
       addr = malloc ( size )

       integer nelem, elsize, clean, base(1), addr, offset
       external falloc
       call falloc ( nelem, elsize, clean, base, addr, offset )

       integer addr
       external free
       call free ( addr )

Description
       The falloc, malloc, and free routines provide a general-purpose memory
       allocation package.  The malloc function returns the address of a block
       of at least size bytes (see also malloc(3) ).

       The falloc subroutine allocates space for an array of nelem elements of
       size elsize and returns the address of the block in addr.  The elsize
       must be one of the following sizes: 1, 2, 4, or 8, and must match the
       size of the elements of base.  If base is an integer*4 array, elsize
       should be 4; if base is a real*8 array, elsize should be 8, and so on.

       The argument to free is the address of a block previously allocated by
       falloc or malloc; this space is made available for further allocation,
       but its contents are left undisturbed.  To free blocks allocated by
       falloc, use addr in calls to free; do not use base(offset+1).

Restrictions
       Grave disorder will result if the space assigned by malloc or falloc is
       overrun or if some random number is handed to free.

Diagnostics
       Both malloc and falloc set addr to zero if there is no available
       memory, if the area has been detectably corrupted by storing outside
       the bounds of a block, or if elsize is invalid.

Examples
       Examples 1, 2, and 3 show how to obtain memory and use it within a
       subprogram.

       Example 1:

             integer  malloc
             external malloc
             integer work(1)
             ...
             p = malloc (10*4)
             ifirst = (p - loc(work(1))/4
             do i = 1, n
                work(i+ifirst) = ...
             enddo
             ...
             call free (p)

       Example 2 (work is an integer array, elsize is 4):

             integer addr
             integer work(1), offset
             ...
             call falloc (n, sizeof(work(1)), 0, work, addr, offset)
             do i = 1, n
                work(offset+i) = ...
             enddo
             ...
             call free (addr)

       Example 3 (work is a real*8 array, elsize is 8):

             integer addr
             integer offset
             real*8 work(1)
             ...
             call falloc (n, sizeof(work(1)), 0, work, addr, offset)
             do i = 1, n
                work(offset+i) = ...
             enddo
             ...
             call free (addr)

       Example 4 reads in dimension information, allocates space for two
       arrays and two vectors, and calls subroutine doit to do the
       computations.

       Example 4:

             integer addr
             integer dummy(1), offs
             read *, k, l, m, n
             indm1   = 1
             indm2   = indm1 + k*l
             indm3   = indm2 + l*m
             indsym  = indm3 + k*m
             lsym    = n*(n+1)/2
             indv    = indsym + lsym
             indtot  = indv + m
             call falloc (indtot, sizeof(dummy(1)), 0, dummy,
            &             addr, offs)
             call doit (dummy(indm1+offs), dummy(indm2+offs),
            &           dummy(indm3+offs), dummy(indsym+offs),
            &           dummy(indv +offs), m, n, lsym )
             ...
             call free (addr)
             end
                ...
             subroutine doit (arr1, arr2, arr3, vsym, vec, m,
            &                 n, lsym)
             real arr1(k,l), arr2(l,m), arr3(k,m)
             real vsym(lsym), v2(m)
                ...

Files
       libU77.a

Bugs
       The memory address pointers addr should be integer*8 on 64 bit
       machines, such as DEC Alpha's and the SGI machines running IRIX64. On
       machines with a 32 bit memory the address pointers addr should be
       integer*4.

See Also
       loc(3), malloc(3)




                                                                    falloc(3f)