Subversion Repositories scarts

/*******************************************************************************

 *

 * Copyright (c) 1993 Intel Corporation

 *

 * Intel hereby grants you permission to copy, modify, and distribute this

 * software and its documentation.  Intel grants this permission provided

 * that the above copyright notice appears in all copies and that both the

 * copyright notice and this permission notice appear in supporting

 * documentation.  In addition, Intel grants this permission provided that

 * you prominently mark as "not part of the original" any modifications

 * made to this software or documentation, and that the name of Intel

 * Corporation not be used in advertising or publicity pertaining to

 * distribution of the software or the documentation without specific,

 * written prior permission.

 *

 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR

 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY

 * OR FITNESS FOR A PARTICULAR PURPOSE.  Intel makes no guarantee or

 * representations regarding the use of, or the results of the use of,

 * the software and documentation in terms of correctness, accuracy,

 * reliability, currentness, or otherwise; and you rely on the software,

 * documentation and results solely at your own risk.

 *

 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,

 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES

 * OF ANY KIND.  IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM

 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.

 *

 ******************************************************************************/

        .file "strcpy.s"

#ifdef  __PIC

        .pic

#endif

#ifdef  __PID

        .pid

#endif

/*

 * (c) copyright 1988,1993 Intel Corp., all rights reserved

 */

/*

        procedure strcpy  (optimized assembler version for the 80960K series)

        procedure strcat  (optimized assembler version for the 80960K series)

        dest_addr = strcpy (dest_addr, src_addr)

        copy the null terminated string pointed to by src_addr to

        the string space pointed to by dest_addr.  Return the original

        dest_addr.

        This routine will fail if the source and destination string

        overlap (in particular, if the end of the source is overlapped

        by the beginning of the destination).  The behavior is undefined.

        This is acceptable according to the draft C standard.

        Undefined behavior will also occur if the end of the source string

        (i.e. the terminating null byte) is in the last two words of the

        program's allocated memory space.  This is so because strcpy fetches

        ahead.  Disallowing the fetch ahead would impose a severe performance

        penalty.

        Strategy:

        Fetch the source string and store the destination string by words

        until the null byte is encountered.  When the word with the null

        byte is reached, store it by bytes up through the null byte only.

        Tactics:

        1) Do NOT try to fetch and store the words in a word aligned manner

        because, in my judgement, the performance degradation experienced due

        to non-aligned accesses does NOT outweigh the time and complexity added

        by the preamble and convoluted body that would be necessary to assure

        alignment.  This is supported by the intuition that most source and

        destination strings will be word aligned to begin with.

        procedure strcat

        dest_addr = strcat (dest_addr, src_addr)

        Appends the string pointed to by src_addr to the string pointed

        to by dest_addr.  The first character of the source string is

        copied to the location initially occupied by the trailing null

        byte of the destination string.  Thereafter, characters are copied

        from the source to the destination up thru the null byte that

        trails the source string.

        See the strcpy routine, above, for its caveats, as they apply here too.

        Strategy:

        Skip to the end (null byte) of the destination string, and then drop

        into the strcpy code.

        Tactics:

        Skipping to the null byte is Ldone by reading the destination string

        in long-words and scanbyte'ing them, then examining the bytes of the

        word that contains the null byte, until the address of the null byte is

        known.  Then we drop into the strcpy routine.  It is probable (approx.

        three out of four times) that the destination string as strcpy sees

        it will NOT be word aligned (i.e. that the null byte won't be the

        last byte of a word).  But it is not worth the complication to that

        routine to force word aligned memory accesses to be gaurenteed.

*/

        .globl _strcpy, _strcat

        .globl __strcpy, __strcat

        .leafproc _strcpy,__strcpy

        .leafproc _strcat,__strcat

        .align    2

_strcat:

#ifndef __PIC

        lda     Lrett,g14

#else

        lda     Lrett-(.+8)(ip),g14

#endif

__strcat:

        mov     g14,g13         # preserve return address

        ldl     (g0),g4         # fetch first two words

        addo    8,g0,g2         # post-increment src word pointer

        lda     0xff,g3         # byte extraction mask

Lsearch_for_word_with_null_byte:

        scanbyte 0,g4           # check for null byte

        mov     g5,g7           # copy second word

        bo.f    Lsearch_for_null        # branch if null found

        scanbyte 0,g7           # check for null byte

        ldl     (g2),g4         # fetch next pair of word of src

        addo    8,g2,g2         # post-increment src word pointer

        bno     Lsearch_for_word_with_null_byte # branch if null not found yet

        subo    4,g2,g2         # back up the byte pointer

        mov     g7,g4           # move word with null to search word

Lsearch_for_null:

        subo    9,g2,g5         # back up the byte pointer

Lsearch_for_null.a:

        and     g4,g3,g6        # extract byte

        cmpo    0,g6            # is it null?

        addo    1,g5,g5         # bump src byte ptr

        shro    8,g4,g4         # shift word to position next byte

        bne     Lsearch_for_null.a

        b       Lend_of_dest_found

_strcpy:

#ifndef __PIC

        lda     Lrett,g14

#else

        lda     Lrett-(.+8)(ip),g14

#endif

__strcpy:

        mov     g0, g5

Lend_of_dest_found:

        ld      (g1), g2        # fetch first word of source

        mov     g14,g6          # preserve return address

        lda     0xff, g3        # byte extraction mask = 0xff;

Lwloop:                         # word copying loop

        addo    4, g1, g1       # post-increment source ptr

        scanbyte 0, g2          # does source word contain null byte?

        mov     g2, g4          # save a copy of the source word

        be      Lcloop          # branch if null present

        ld      (g1), g2        # pre-fetch next word of source

        st      g4, (g5)        # store current word

        addo    4, g5, g5       # post-increment dest ptr

        b       Lwloop

Lcloop:                         # character copying loop

        and     g3, g4, g14     # extract next char

        shro    8, g4, g4       # position word for next byte extraction

        cmpo    0, g14          # is it null?

        stob    g14, (g5)       # store the byte

        addo    1, g5, g5       # post-increment dest ptr

        bne     Lcloop          # quit if null encountered

        bx      (g6)            # g0 = dest string address; g14 = 0

Lrett:

        ret