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Q50405: Specifying the Size of a CALL or JMP Instruction in MASM

Article: Q50405
Product(s): Microsoft Macro Assembler
Version(s): 5.0,5.1,5.1a,6.0,6.0a,6.0b
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 5.0, 5.1, 5.1a, 6.0, 6.0a, 6.0b 
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SUMMARY
=======

The PTR operator can be used to specify the size of a register indirect operand
for a CALL or JMP instruction. However, the qualifying operators are not NEAR
and FAR, but WORD and DWORD. For example, to make a near jump to label xxx, use

     JMP WORD PTR xxx

MORE INFORMATION
================

The following example demonstrates how to generate an indirect far call and an
indirect far jump in MASM.

Sample Code
-----------

  ; Assemble options needed: none

            .model  large
            .data
  jumptable DD      routine1
            DD      routine2

            .code
  start:    MOV     ax, @data
            MOV     ds, ax
            CALL    DWORD PTR  jumptable
            JMP     DWORD PTR  jumptable+4
            RET

  cseg      SEGMENT word public 'code'
  routine1  PROC
            RET
  routine1  ENDP

  routine2  PROC
            RET
  routine2  ENDP
  cseg      ENDS

            END     start

Additional query words: kbinf 5.10 5.10a 6.00 6.00a 6.00b

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM600 kbMASM500 kbMASM600a kbMASM510a kbMASM600b
Version           : :5.0,5.1,5.1a,6.0,6.0a,6.0b

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