CLS/Fade out ASM Sub-routine

[tubz74]

This is a small clear screen, that sort of fades out the screen pixel by pixel to the background colour.  I took it from one of the Melbourne house books, can't remember which one though.

No idea if it breaks anything else, but I've not had any issues.

Code:

SUB CLSFadeOut() ' Fade out Screen Clearing     ASM         LD DE,08feh         NXTFADE:             LD A,E             RLCA             RLCA             RLCA             LD E,A             LD HL,4000H             LD BC,0018H             NXT:                 LD A, (HL)                 AND E                 LD (HL),A                 INC HL             DJNZ NXT             DEC C             JR NZ,NXT             DEC D         JR NZ,NXTFADE         LD A,(5C8DH)         LD (HL),A         LD D,H         LD E,L         INC DE         LD BC,02C0H         LDIR         LD A,(5C48H)         LD (HL),A         LD C,3FH         LDIR     END ASM END SUB

[boriel]

Good one!
No, it won't break anything (only IX should be preserved (push/pop) before the function returns).
Also, it's recommended to make your labels private. To do so:
Wrap your ASM routine between

Code:

PROC ... ENDP

directives.
Declare your labels locals after PROC, with:
LOCAL NXTFADE, NXT
:-)

If your code is BSD / MIT / Apache I can put it in the standard library for other people to use it.

[tubz74]

Happy for it to be used however by whoever - which ever licence doesn't require anything from me or from the user.