DOCUMENT:Q95414 06-MAY-2001 [masm] TITLE :PRB: INVOKE Pushes SS to Convert NEAR PTR to FAR PTR PRODUCT :Microsoft Macro Assembler PROD/VER::6.0,6.0a,6.0b,6.1,6.11,6.1a OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Macro Assembler (MASM), versions 6.0, 6.0a, 6.0b, 6.1, 6.1a, 6.11 ------------------------------------------------------------------------------- SYMPTOMS ======== When an application passes a parameter of type NEAR PTR to a routine that expects an argument of type FAR PTR, the INVOKE directive converts the NEAR PTR to a FAR PTR by pushing the SS segment register on the stack. The assembler does not issue any warnings when it applies this conversion. In a situation where SS does not equal DS, as in a Windows dynamic-link library (DLL), INVOKE may generate incorrect code. CAUSE ===== When the assembler converts a NEAR PTR to a FAR PTR, it uses the SS segment register when it has no other information about the appropriate segment value. RESOLUTION ========== When your application passes a NEAR PTR parameter to a function that expects a FAR PTR, specify the segment register to use in the conversion by adding the appropriate segment prefix (cs:, ds:, es:, or ss:) to the parameter. The code example below demonstrates this method. Sample Code ----------- ; Assemble options needed: none .MODEL small, C, farstack func1 PROTO arg1:FAR PTR BYTE .CODE func2 PROC, arg2:NEAR PTR BYTE INVOKE func1, arg2 ; This pushes ss:arg2 ret func2 ENDP func3 PROC, arg2:NEAR PTR BYTE INVOKE func1, ds:arg2 ; This pushes ds:arg2 ret func3 ENDP END Additional query words: 6.00 6.00a 6.00b 6.10 6.10a ====================================================================== Keywords : Technology : kbMASMsearch kbAudDeveloper kbMASM600 kbMASM610 kbMASM611 kbMASM610a kbMASM600a kbMASM600b Version : :6.0,6.0a,6.0b,6.1,6.11,6.1a Issue type : kbprb ============================================================================= 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. Copyright Microsoft Corporation 2001.