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INVOKE

Visual Studio 2010

Calls the procedure at the address given by expression, passing the arguments on the stack or in registers according to the standard calling conventions of the language type.

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INVOKE expression [[, arguments]]

Remarks

Each argument passed to the procedure may be an expression, a register pair, or an address expression (an expression preceded by ADDR).

Other Resources

Directives Reference

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FAQ

Example using INVOKE vs calling the function manually

Here is an example calling printf using both INVOKE and doing the call manually

; #########################################################################
; Explore assembly , learning Macro Assembly for Microsoft X86
; #########################################################################

    .386
    .model flat,C          ; 32 bit memory model
    option casemap :none    ; Case sensitive

; #########################################################################

.data
    fmt    db    "Result is %d",13,10,0
    szHello db    "Hello World %d",13,10,0
.code
includelib MSVCRT

; Prototype needed by INVOKE
printf    PROTO arg1:Ptr Byte, printlist: VARARG

wmain proc PUBLIC
    ;==============
    ; Locals on the stack
    ;==============

    LOCAL idx        :DWORD
    LOCAL cnt        :DWORD
    LOCAL clBuffer[128]    :BYTE

    ;==============
    ; Initialize
    ;==============
    mov idx,1000
    mov cnt,0

    .WHILE idx > 0
        sub idx,1
        add cnt,2
        INVOKE printf,ADDR fmt,cnt
    .ENDW

    ; Here we use the old fashioned way of manually setting up the stack, calling the function, then cleaning up the stack
    ; In the loop above all we had to do was use INVOKE which handles this for us
    push 1
    push offset szHello
    call printf
    add esp,8

    xor eax,eax
    ret
wmain endp
END

I have a more examples at hybridmachine.com : http://www.hybridmachine.com/wp-content/uploads/2012/03/explore_masm.zip

History

3/2/2012
hybridmachine