utoa_ncheck.S

/* Copyright (c) 2012  Georg-Johann Lay
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.
   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
     from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */

#if     !defined (__DOXYGEN__)
#if     !defined (__AVR_TINY__)

#include "asmdef.h"

/* char *__utoa_ncheck (unsigned val, char *s, unsigned char radix)
   This function is the utoa() without checking the radix for 2..36 margins.
 */

#define val_lo  r24
#define val_hi  r25
#define str_lo  r22
#define radix   r20

#define counter r21
#define digit   r26
#define sign    r27

ENTRY   __utoa_ncheck
        clr     sign

ENTRY   __utoa_common
        X_movw  ZL, str_lo
        clr     counter

1:  ; Vanilla 16:8 quotient and remainder to pop the digit
    ; digit <- val % radix
    ; val   <- val / radix
        clr     digit

2:      lsl     val_lo
        rol     val_hi
        rol     digit
        cp      digit, radix
        brlo    3f
        sub     digit, radix
        inc     val_lo
3:      subi    counter, 16             ; 256 / 16 == 16 loops
        brne    2b

    ; Convert the digit to ASCII...
        subi    digit, -'0'
        cpi     digit, '9'+1
        brlo    4f
        subi    digit, '0'-'a'+10
4:  ; ... and store it to the reversed string
        st      Z+, digit

    ; Iterate until all digits are sucked out of VAL.
        sbiw    val_lo, 0
        brne    1b

    ; Store the sign (if any)
        cpse    sign, __zero_reg__
        st      Z+, sign

    ; Terminate the string with '\0'
        st      Z+, __zero_reg__

    ; Reverse the string and return the original string pointer
        X_movw  r24, str_lo
        XJMP    _U(strrev)

ENDFUNC

#endif  /* !__AVR_TINY__ */
#endif  /* !__DOXYGEN__ */