cc65/libsrc/runtime/ldec.s

;
; Piotr Fusik, 09.03.2018
; originally by Ullrich von Bassewitz
;
; CC65 runtime: Decrement eax by value in Y
;

        .export         deceaxy
        .importzp       sreg, tmp1

deceaxy:
        sty     tmp1
        sec
        sbc     tmp1
        bcs     @L9

; Borrow from X.

        dex
        cpx     #$FF
        bne     @L9

; X wrapped from zero to $FF, borrow from sreg.

        dec     sreg
        cpx     sreg
        bne     @L9

; sreg wrapped from zero to $FF, borrow from sreg+1.

        dec     sreg+1

; Done.

@L9:    rts
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81 2000-05-28 13:40:48 +00:00			`;`
Fix coding style. 2018-03-09 17:48:24 +00:00			`; Piotr Fusik, 09.03.2018`
Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`; originally by Ullrich von Bassewitz`
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81 2000-05-28 13:40:48 +00:00			`;`
			`; CC65 runtime: Decrement eax by value in Y`
			`;`

Removed (pretty inconsistently used) tab chars from source code base. 2013-05-09 11:56:54 +00:00			`.export deceaxy`
			`.importzp sreg, tmp1`
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81 2000-05-28 13:40:48 +00:00
			`deceaxy:`
Removed (pretty inconsistently used) tab chars from source code base. 2013-05-09 11:56:54 +00:00			`sty tmp1`
			`sec`
			`sbc tmp1`
Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`bcs @L9`
Fix coding style. 2018-03-09 17:48:24 +00:00
			`; Borrow from X.`

Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`dex`
Fix coding style. 2018-03-09 17:48:24 +00:00			`cpx #$FF`
Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`bne @L9`
Fix coding style. 2018-03-09 17:48:24 +00:00
			`; X wrapped from zero to $FF, borrow from sreg.`

Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`dec sreg`
			`cpx sreg`
			`bne @L9`
Fix coding style. 2018-03-09 17:48:24 +00:00
			`; sreg wrapped from zero to $FF, borrow from sreg+1.`

Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`dec sreg+1`
Fix coding style. 2018-03-09 17:48:24 +00:00
			`; Done.`

Optimize deceaxy. 2018-03-07 19:45:50 +00:00			`@L9: rts`
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81 2000-05-28 13:40:48 +00:00