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/*
atoi.S
Contributors:
Created by Reiner Patommel
Changes: Jochen Pernsteiner, Marek Michalkiewicz
THIS SOFTWARE IS NOT COPYRIGHTED
This source code is offered for use in the public domain. You may
use, modify or distribute it freely.
This code is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
DISCLAIMED. This includes but is not limited to warranties of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "macros.inc"
#define str_hi r25
#define str_lo r24
#define num_hi r25
#define num_lo r24
#define sign r19
#define tmp r18
; int atoi(const char *string)
.text
.global _U(atoi)
.type _U(atoi), @function
/*
Skip leading spaces and tabs. Process optional sign. Stop conversion
on detection of a non-numeric character. Return 0 if string contains
no numeric characters. No check is performed whether the value is within
the range of an 'int' i.e. 32768 becomes -32768.
*/
_U(atoi):
LOAD_Z(str_lo, str_hi) ; set pointer to string
CLR num_lo
CLR num_hi
CLR sign ; sign
.atoi_loop:
LD tmp, Z+ ; get (next) character
TST tmp ; is it end of string
BREQ .atoi_sig
CPI tmp, ' ' ; if space, skip
BREQ .atoi_loop
CPI tmp, '\t' ; if tab, skip
BREQ .atoi_loop
CPI tmp, '\n' ; skip other whitespace
BREQ .atoi_loop
CPI tmp, '\f'
BREQ .atoi_loop
CPI tmp, '\r'
BREQ .atoi_loop
CPI tmp, '\v'
BREQ .atoi_loop
CPI tmp, '+' ; if '+' go on
BREQ .atoi_loop2
CPI tmp, '-' ; if '-' remember sign
BRNE .atoi_digit
.atoi_neg:
LDI sign, 1 ; remember number is negative
.atoi_loop2:
LD tmp, Z+
TST tmp
BREQ .atoi_sig
.atoi_digit:
CPI tmp, '0' ; test on [0 .. 9]
BRLT .atoi_sig
CPI tmp, '9'+1
BRGE .atoi_sig
SUBI tmp, '0' ; make figure a number
XCALL __mulhi_const_10 ; r25:r24 *= 10
ADD num_lo, tmp ; num = (num * 10) + (tmp - '0')
ADC num_hi, __zero_reg__
RJMP .atoi_loop2 ; next figure
.atoi_sig:
CP num_lo, __zero_reg__
CPC num_hi, __zero_reg__ ; did we get a number?
BREQ .atoi_done ; no, drop sign and return
TST sign ; positive number?
BREQ .atoi_done
COM num_lo
COM num_hi
ADIW num_lo, 1 ; make number negative
.atoi_done:
RET
.atoi_end:
.size _U(atoi), .atoi_end - _U(atoi)
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