Author Topic: Adapting 4 Level Grey Code (Read 3222 times)

ACagliano · « **on:** January 13, 2015, 02:49:51 pm »

I'm trying to borrow the Axe code for 4-lvl greyscale. So as I've done before, its the code from p_Disp4Lvl to __Disp4LvlEnd. However, the line I can't wrap my head around is:

Code: [Select]

call $3F00+sub_Safety
What is this? How do I adapt that line for use in my own code?

Sorunome · « **Reply #1 on:** January 13, 2015, 02:52:54 pm »

IDK but this is the adapted one i ripped from axe for reuben2:

Code: [Select]

Interrupt:
	exx
	xor a
	out (3),a ; ack interrupts
	call Disp4Lvl
	ld a,INTRPT_MASK
	out (3),a ; reenable interrupts
	exx
	ei
	ret
Disp4Lvl:
	ld    hl,appbackupscreen
	ld    de,plotsscreen
	push  hl
	ld    a,$07
	out   ($10),a		     ;?? cc into
	ld    a,%11011011
	or    a
	ld    hl,flags+asm_flag2
	inc   (hl)
	jr    z,__Disp4Lvlskip
	rra
	ld    b,(hl)
	inc   b
	jr    z,__Disp4Lvlskip
	rra
	ld    (hl),-2
__Disp4LvlSkip:
	ex    af,af'
	pop   hl
	ld    a,$80
__Disp4LvlEntry:
	out   ($10),a		     ;76+cc into, 71cc loop
	push  af
	ex    (sp),hl		     ;waste
	ex    (sp),hl		     ;waste
	nop			   ;waste
	ld    a,$20
	out   ($10),a		     ;71cc into
	ld    b,12
__Disp4LvlLoop:
	ex    af,af'
	rra
	ld    c,a
	ex    af,af'
	ld    a,(de)
	xor   (hl)
	and   c
	xor   (hl)
	inc   de
	inc   hl
	out   ($11),a		     ;71cc into, 77cc loop
	djnz  __Disp4LvlLoop
	inc   bc		    ;waste
	ex    af,af'
	rra
	ex    af,af'
	pop   af
	inc   a
	bit   6,a
	jr    z,__Disp4LvlEntry
__Disp4LvlDone:
	ld    a,$05
	out   ($10),a		     ;73cc into
	ret

Author Topic: Adapting 4 Level Grey Code (Read 3222 times)

ACagliano

Adapting 4 Level Grey Code

Sorunome

Re: Adapting 4 Level Grey Code