Synopsis #

Header: fxcg/display.h
Syscall index: 0x1D7F
Function signature: void EnableDisplayHeader(int action, int value)

If action is 0, GetKey will not automatically show the status area. If action is 2 and value is not 0, GetKey will show the status area automatically.

Parameters #

• action If action == 0 clear pointer GetKeyShowStatusArea. If action == 2 set pointer GetKeyShowStatusArea to value. If action is any other value return value at GetKeyShowStatusArea unmodified.
• value Used only if action == 2

Returns #

Whether or not GetKey should show the status area. This may be modified depending on the value of action.

Comments #

Different versions of the OS use a different point (GetKeyShowStatusArea), so this syscall should be used instead of manually setting the pointer.

OS 3.60 uses 0xFD802148 as the address of GetKeyShowStatusArea.

! If r4==0 clear GetKeyShowStatusArea
! If r4==2 set GetKeyShowStatusArea to r5
! Other values of r4 will cause the function to simply return the contents of GetKeyShowStatusArea

EnableDisplayHeader:
        tst r4, r4
        bf  r4NonZero   ! Branch if r4 is non-zero
        mov.l   #GetKeyShowStatusArea, r4 ! If r4 is zero set r4 to GetKeyShowStatusArea
        mov #0, r2
        bra EnableDisplayHeader_exit
        mov.l   r2, @r4     ! Before branching clear the contents of GetKeyShowStatusArea
! ---------------------------------------------------------------------------

r4NonZero:
        mov r4, r0
        cmp/eq  #2, r0
        bf  EnableDisplayHeader_exit ! Branch if r4!=2 without delay
        mov.l   #GetKeyShowStatusArea, r4
        mov.l   r5, @r4

EnableDisplayHeader_exit:
        mov.l   #GetKeyShowStatusArea, r4
        rts
        mov.l   @r4, r0     ! Return the contents of GetKeyShowStatusArea
! End of function EnableDisplayHeader