PROC (Identify Code Procedure)

The PROC directive identifies a block of code. By dividing the code into blocks, each of which performs a distinct function, you can clarify the overall function of the complete module.

The PROC directive also identifies the procedure distance to help insure that the assembler generates the appropriate instructions for calling and returning from the procedure while maintaining the integrity of the run-time stack.

Syntax

Procedure-Name PROC [Attributes] [Register-List] [Parameter-List]
   .
   .
   .
RET [Constant]
   .
   .
   .
Procedure-Name ENDP

Refer to the following sections for descriptions of the optional arguments to the PROC directive:

• Attributes
  
• Register-List
  
• Parameter-List
Remarks

You can execute the block of code identified by the PROC directive in-line, jump to it, or start it with a CALL instruction. If the PROC is called from code that has another ASSUME CS value, you must use the appropriate FAR, FAR16, or FAR32 distance attribute.

The NEAR attribute causes any RET instruction coded within the procedure to be an intra-segment return that pops a return offset from the stack. You can call a NEAR subroutine only from the same segment. However, the FAR attribute causes RET to be an inter-segment return that pops both a return offset and a segment base from the stack. You can call a FAR subroutine from any segment; a FAR subroutine is usually called from a segment other than the one containing the subroutine.

Example

In this example, the Near_Name subroutine is called by the Far_Name subroutine.

          PUBLIC   Far_Name
Far_Name  PROC     FAR
          CALL Near_Name
          RET               ;Pops return offset and seg base value
Far_Name  ENDP

          PUBLIC   Near_Name
Near_Name PROC     NEAR
          .
          .
          .
          RET               ;pops only return offset
Near_Name ENDP

You can call the Near_Name subroutine directly from a NEAR segment by using:

CALL Near_Name

A FAR segment can indirectly call the second subroutine by first calling the Far_Name subroutine with:

CALL Far_Name

A CALL to a forward-referenced symbol assumes the symbol is NEAR. If that symbol is FAR, the CALL must have an override, for example:

CALL FAR PTR Forward_Reference

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