4.16.1 atol.S

/* Copyright (c) 2002, 2007 Reiner Patommel
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   * Neither the name of the copyright holders nor the names of
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  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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/* $Id$ */

/*
   atol.S

   Contributors:
     Created by Reiner Patommel
     Modified by Reiner Patommel 8 Feb 2003, Bug #2481
     Modified by Reiner Patommel 13 May 2003, (DOXYGEN)

   TODO: this implementation uses an inline isspace(). If Avr-libc will
   use locales other than C/POSIX it is needed to call an external isspace().
   
   ATTENTION: an external __mulsi_const_10() function is used: nonstandart
   call conventions: some registers and bit T must be nochanged.
 */

/** \file */
/** \ingroup avr_stdlib
    \fn long atol(const char *s)
    \brief Convert a string to a long integer.

    The atol() function converts the initial portion of the string
    pointed to by \p s to long integer representation. In contrast to

        \code strtol(s, (char **)NULL, 10); \endcode

    this function does not detect overflow (\c errno is not changed and
    the result value is not predictable), uses smaller memory (flash and
    stack) and works more quickly.
*/

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define str_hi      r25
#define str_lo      r24
#define num_hi_hi   r25
#define num_hi_lo   r24
#define num_lo_hi   r23
#define num_lo_lo   r22
#define tmp     r17

    ASSEMBLY_CLIB_SECTION
    .global _U(atol)
    .type   _U(atol), @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.
 */

/* This fact is used below. */
.if ('\t'-9) | ('\n'-10) | ('\f'-12) | ('\r'-13)    ; '\v' is 11
  .err
.endif

_U(atol):
    PUSH    tmp
    X_movw  ZL, str_lo      ; set pointer to string
    CLR num_hi_hi
    CLR num_hi_lo
    X_movw  num_lo_lo, num_hi_lo    ; clear number
    CLT             ; clear sign

.L_atol_loop:
    LD  tmp, Z+         ; get (next) character
    CPI tmp, ' '        ; skip whitespace
    BREQ    .L_atol_loop
    CPI tmp, '\t'
    BRLO    1f
    CPI tmp, '\r'+1
    BRLO    .L_atol_loop
1:
    CPI tmp, '+'        ; if '+' go on
    BREQ    .L_atol_loop2
    CPI tmp, '-'        ; if '-' remember sign
    BRNE    .L_atol_digit
    SET             ; remember number is negative
    RJMP    .L_atol_loop2

2:  XCALL   __mulsi_const_10    ; r25:r24:r23:r22 *= 10
    ADD num_lo_lo, tmp      ; num = (num * 10) + (tmp - '0')
    ADC num_lo_hi, __zero_reg__
    ADC num_hi_lo, __zero_reg__
    ADC num_hi_hi, __zero_reg__
.L_atol_loop2:
    LD  tmp, Z+
.L_atol_digit:
    SUBI    tmp, '0'        ; make figure a number
    CPI tmp, 10
    BRLO    2b

    BRTC    .L_atol_done        ; positive number? -> return
    COM num_hi_hi
    COM num_hi_lo
    COM num_lo_hi
    NEG num_lo_lo
    SBCI    num_lo_hi, 0xff
    SBCI    num_hi_lo, 0xff
    SBCI    num_hi_hi, 0xff     ; make number negative

.L_atol_done:
    POP tmp
    RET

.L_atol_end:
    .size _U(atol), .L_atol_end - _U(atol)

#endif /* not __DOXYGEN__ */