The LOCAL directive defines local stack variables from within a code procedure.

Syntax

LOCAL Local-Spec [, [LineBreak] Local-Spec ...]

Local-Spec:


Local-Name [:Type-Declaration]
Local-Name[Count] [:Type-Declaration]

The optional LineBreak entry allows you to end a Local-Spec entry with a comma, enter an optional EndOfLine-Comment followed by a physical NewLine character, then continue with a new Local-Spec on the next line.
Remarks

The LOCAL assembler directive can only appear within the body of a procedure. If used, the LOCAL directive(s) must immediately follow the PROC statement that encloses them, and they must appear before any instructions, code labels, or directives that modify the location counter. Multiple LOCAL directives may appear in succession.

Each Local-Name is defined as a Numeric-EquateName that is visible only from within the body of the procedure. The value assigned to the variable name is an expression that defines the type of the variable and its location on the stack relative to the value of the frame pointer (the BP or EBP register). The assembler reserves space on the stack for each local variable and automatically calculates their locations. After all Local-Spec entries have been processed, the assembler allocates the space by generating instructions to adjust the stack pointer. The assembler also generates instructions to restore the state of the stack and frame pointers when the procedure exits.

The optional [Count] entry can be used to indicate that the variable is a simple "array" of values, where Count is a constant expression. If used, the square brackets surrounding the Count must be specified. Use of this notation is discouraged however, because it does not associate a "true array" data type with the variable, and cannot be viewed as such from within a symbolic debugger. ALP allows the variable to be associated with a "true array" data type through use of the native Type-Declaration syntax.

The Type-Declaration field specifies the data type to be associated with the Local-Name. If this field is omitted, the data type defaults to WORD if the procedure is defined within a USE16 segment, and DWORD if the procedure is defined within a USE32 segment.

Example

; bootdrv.asm : Returns value of OS/2 boot drive as exit code
; assemble as : alp +Od bootdrv.asm
; link as     : link386 /de bootdrv;

        .386                        ; Assemble for 32-bit processors
        .model flat,syscall         ; OS/2 flat model/calling convention
        .stack 4096

        EXTERN DosExit:PROC         ; OS/2 DosExit() API
        EXTERN DosQuerySysInfo:PROC ; OS/2 DosQuerySysInfo() API
        INCLUDELIB os2386.lib       ; link with these routines

; These are values taken from OS/2 API headers.  See the OS/2 Toolkit
; Control Program Programming Guide and Reference for more information.

EXIT_PROCESS    EQU  1              ; for DosExit
QSV_BOOT_DRIVE  EQU  5              ; For DosQuerySysInfo

ULONG   TYPEDEF DWORD               ; use OS/2 type convention

        .code                       ; open code segment

main    PROC
        LOCAL BootDrive:ULONG       ; place to put value of boot drive

        ; Push parameters to DosQuerySysInfo onto the stack

        PUSH  sizeof BootDrive      ; arg 4: size of output buffer
        LEA   EAX,BootDrive         ; arg 3: Address of buffer
        PUSH  EAX
        PUSH  QSV_BOOT_DRIVE        ; arg 2: last ordinal value to return
        PUSH  QSV_BOOT_DRIVE        ; arg 1: first ordinal, same as last
        CALL  DosQuerySysInfo       ; invoke API
        ADD   ESP,DWORD * 4         ; remove the parameters from the stack

        CMP   EAX,0                 ; Did the API succeed?
        MOV   EAX,0                 ;   if not, use zero as a return code
        JNZ   SomeKindOfError       ;   and skip around to the exit logic
        MOV   EAX,BootDrive         ; else, return the boot drive value
SomeKindOfError:
        push  EAX                   ; exit code
        push  EXIT_PROCESS          ; terminates all threads
        call  DosExit               ; exit to calling process
        RET                         ; never executed
main    ENDP

        END   main

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