[Nasm-users] Setting/Clearing OF

[Robert A. <e.a...@st...>]

Hi,

How do I set or clear the overflow flag? I can save it easily enough, but I don't know how to set or clear it. This is for part of a handler for animation scripts for a Win32 game.

;-------------------------------------------------------------------------------
;    void __declspec(naked) __stdcall SetCurrentUnitExFlags(void) {
SetCurrentUnitExFlags:
    lahf
    mov   CL, AH
 
    ; Bit 1 is already set, so if OF is set, do nothing
    jo    .SetConditionFlags
    ; Clear bit 1
    btr   CL, 1
.SetConditionFlags
    call  GetCurrentUnitID
    imul  EAX, UnitEx.Size
    mov   byte [ExtendedUnitNode + EAX + UnitEx.ConditionFlags], CL
    ret
;    }

;-------------------------------------------------------------------------------
;    void __declspec(naked) __stdcall GetCurrentUnitExFlags(void) {
GetCurrentUnitExFlags:
    call  GetCurrentUnitID
    imul  EAX, UnitEx.Size
    mov   AH, byte [ExtendedUnitNode + EAX + UnitEx.ConditionFlags]
    bts   AH, 1
    jnc   .BitNotSet
    
    ; How do I set OF?
    
    lahf
    ret
    
.BitNotSet:

    ; How do I clear OF?
    
    lahf
    ret
;    }


Thank you for your time
Robert

--------------------------------------------------------------------------------
Robert Alegrid
RMIT University
Student #3164658
BP-079 Physics
BP-083 Mathematics


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