EnableDisplayHeader

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 pointer (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 0xFD80178C
! End of function EnableDisplayHeader