C.7.1. Subroutines FMSIMG, FMSRMG, FMSCMG

PURPOSE

To allocate memory for data storage.

SYNOPSIS

CALL FMSIMG (IMD, LOC, LEN)

CALL FMSRMG (RMD, LOC, LEN)

CALL FMSCMG (CMD, LOC, LEN)

INPUT PARAMETERS

IMD(*) = Integer array(FMSIMG)
RMD(*) = Real array (FMSRMG)
CMD(*) = Complex array (FMSCMG).
This is the array you use in your program to reference the allocated memory. This array must be defined by a POINTER or aligned on a natural address boundary as explained below.
LEN = Integer.
The number of words of the appropriate data type to allocate.

OUTPUT PARAMETERS:

LOC = Integer.
Starting address of allocated memory in IMD, RMD or CMD, relative to the address you provided. If you have dimensioned IMD, RMD and CMD starting at 0 in your program, LOC will be the subscript of these arrays.

FMS PARAMETERS:

The following FMS Parameters are especially important to this routine:

Parameter	Description
MAXMD	Amount of memory to use
MDUSED	Amount of memory already used
SHOW	Display reports

DESCRIPTION:

These subroutines provide your program with access to the FMS memory manager.

The first step is to declare an array in your program that you will use to reference the allocated memory. There are currently two mechanisms used to do this.

Machines supporting FORTRAN pointers
If your machine supports the FORTRAN POINTER statement, the reference arrays are obtained by including the POINTER statements for the arrays and obtaining the pointer values by calling FMSIGT, as follows:

        POINTER (CMD_PTR, CMD)
        POINTER (RMD_PTR, RMD)
        POINTER (IMD_PTR, IMD)
        COMPLEX*16 CMD(0:1)
        REAL*8     RMD(0:1)
        INTEGER    IMD(0:1)
        ...
        CALL FMSIGT ('MEMPTR',CMD_PTR)
        CALL FMSIGT ('MEMPTR',RMD_PTR)
        CALL FMSIGT ('MEMPTR',IMD_PTR)

Machines not supporting FORTRAN pointers
If your machine does not support the FORTRAN POINTER statement, the reference arrays are obtained as follows:
```
        COMMON CMD
        EQUIVALENCE (IMD, RMD, CMD)
        COMPLEX*16 CMD(0:1)
        REAL*8     RMD(0:1)
        INTEGER    IMD(0:1)
```
On most machines, FMS automatically aligns BLANK COMMON on a 16-byte boundary. You should not be concerned if you use BLANK COMMON for other purposes. FMS does not store any data in CMD(0:1). It simply uses the arrays IMD, RMD and CMD as reference points for the allocated memory.

Once the reference arrays are established in your subroutine, you call FMSIMG to allocate LEN integer words starting at IMD(LOC), FMSRMG to allocate LEN REAL*8 words starting at RMD(LOC), or FMSCMG to allocate LEN COMPLEX*16 words starting at CMD(LOC).

The value of LOC returned is relative to the array value you provide on the call. For example, if you make the call:

        CALL FMSIMG (IMD(10), LOC, LEN)

the allocated memory will start at IMD(10+LOC).

You may make the value of LOC be an actual subscript of the array by dimensioning the array to start at 0,

	INTEGER IMD (0:1)

Then when you call the memory allocation subroutine

	CALL FMSIMG (IMD, LOC, LEN)

the allocated memory will start at IMD(LOC).

Examples

As an example, to allocate storage for the FMS profile vector LOWEQ(NUMEQ) call FMSIMG as follows:

	CALL FMSIMG (IMD, LLOWEQ, NUMEQ)

You may address LOWEQ(I) as

	IMD(LLOWEQ-1+I)

You may also pass the LOWEQ array to a subroutine as

	CALL RSDI (IMD(LLOWEQ), NUMEQ, 'LUA', LUA)

When storage for LOWEQ(NUMEQ) is no longer required, you may return it to FMS.

	CALL FMSIMR (IMD, LLOWEQ, NUMEQ)

You may allocate storage for several arrays with a single call by requesting the total length. For example, to allocate storage for A(N), B(N) and C(N) use

	CALL FMSRMG (RMD, LA, 3*N)
	LB = LA + N
	LC = LB + N