# strcat_PF.S

/* Copyright (c) 2006, Carlos Lamas

based on libc/pmstring/strcat_P.S which is

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
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* 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
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE. */

/* $Id$ */

#if !defined(__AVR_TINY__)

#include "macros.inc"

#define dest_b1 r25
#define dest_b0 r24
#define src_b3 r23
#define src_b2 r22
#define src_b1 r21
#define src_b0 r20

/** \ingroup avr_pgmspace
\fn char *strcat_PF (char *dst, uint_farptr_t src)
\brief Concatenates two strings

The strcat_PF() function is similar to strcat() except that the \e src
string must be located in program space (flash) and is addressed using
a far pointer

\param dst A pointer to the destination string in SRAM
\param src A far pointer to the string to be appended in Flash

\returns The strcat_PF() function returns a pointer to the resulting
string \e dst. The contents of RAMPZ SFR are undefined when the function
returns */

#if !defined(__DOXYGEN__)

.text
.global _U(strcat_PF)
.type   _U(strcat_PF), @function

_U(strcat_PF):

X_movw  ZL, src_b0
LPM_R0_ZPLUS_INIT src_b2
X_movw  XL, dest_b0

.L_strcat_PF_skip:

ld      __tmp_reg__, X+
tst     __tmp_reg__
brne    .L_strcat_PF_skip
sbiw    XL, 1           ; undo post-increment

.L_strcat_PF_loop:

LPM_R0_ZPLUS_NEXT src_b2
st      X+, r0
tst     r0
brne    .L_strcat_PF_loop
LPM_R0_ZPLUS_FINI src_b2
; return dest (unchanged)

ret

.L_strcat_PF_end:

.size   _U(strcat_PF), .L_strcat_PF_end - _U(strcat_PF)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */