Specifying the Size of a CALL or JMP Instruction in MASM

Last reviewed: January 23, 1995
Article ID: Q50405

The information in this article applies to:

Microsoft Macro Assembler for MS-DOS, versions 5.1, 5.1a, 6.0, 6.0a, and 6.0b

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 reference words: kbinf 5.10 5.10a 6.00 6.00a 6.00b
KBCategory: kbprg
KBSubCategory: MASMLngIss

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: January 23, 1995
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.