;-------------------------------------------------------------------------
;   abs.s - standard C library function
;
;   Copyright (C) 2023, Gabriele Gorla
;
;   This library is free software; you can redistribute it and/or modify it
;   under the terms of the GNU General Public License as published by the
;   Free Software Foundation; either version 2, or (at your option) any
;   later version.
;
;   This library is distributed in the hope that it will be useful,
;   but WITHOUT ANY WARRANTY; without even the implied warranty of
;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;   GNU General Public License for more details.
;
;   You should have received a copy of the GNU General Public License
;   along with this library; see the file COPYING. If not, write to the
;   Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
;   MA 02110-1301, USA.
;
;   As a special exception, if you link this library with other files,
;   some of which are compiled with SDCC, to produce an executable,
;   this library does not by itself cause the resulting executable to
;   be covered by the GNU General Public License. This exception does
;   not however invalidate any other reasons why the executable file
;   might be covered by the GNU General Public License.
;-------------------------------------------------------------------------

	.module _abs

;--------------------------------------------------------
; exported symbols
;--------------------------------------------------------
	.globl _abs
	.globl ___negax

;--------------------------------------------------------
; code
;--------------------------------------------------------

	.area CODE
_abs:
	cpx #0x00
	bpl skip
___negax:
  	sec
	eor #0xff
	adc #0x00
	pha
	txa
	eor #0xff
	adc #0x00
	tax
	pla
skip:
	rts

