# ultoa_ncheck.S

/* Copyright (c) 2012  Georg-Johann Lay

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

#define val_lo  r22
#define val_hi  r23
#define val_hlo r24
#define val_hhi r25
#define str_lo  r20

#define counter r19
#define digit   r26
#define sign    r27

ENTRY   __ultoa_ncheck
clr     sign

ENTRY   __ultoa_common
X_movw  ZL, str_lo

1:  ; Saves one iteration of the digit-loop:
; If val < radix we can use the low byte of val as digit
mov     digit, val_lo
cpc     val_hi, __zero_reg__
cpc     val_hlo, __zero_reg__
cpc     val_hhi, __zero_reg__
; now C is set, if val < radix
sbc     counter, counter
bst     counter, 0
brts    4f
; counter == 0 here

; If val >= radix, then pop one digit from val
clr     digit

2:  ; Vanilla 32:8 quotient and remainder to pop the digit
; digit <- val % radix
; val   <- val / radix
lsl     val_lo
rol     val_hi
rol     val_hlo
rol     val_hhi
rol     digit
brlo    3f
; val |= 1
inc     val_lo
3:  ; Loop the 32 bits
subi    counter, 8              ; 256 / 8 == 32 loops
brne    2b

4:  ; Convert the digit to ASCII...
subi    digit, -'0'
cpi     digit, '9'+1
brlo    5f
subi    digit, '0'-'a'+10
5:  ; ... and store it to the reversed string
st      Z+, digit

; Popped all digits?
brtc    1b

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

; Terminate the string with '\0'
7:      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__ */