Subversion Repositories openrisc

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

 *

 * 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 "strcp_ca.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 CA)

        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 word of the program's

        allocated memory space.  This is so because, in several cases, strcpy

        will fetch ahead one word.  Disallowing the fetch ahead would impose

        a severe performance penalty.

        This program handles five cases:

        1) both arguments start on a word boundary

        2) neither are word aligned, but they are offset by the same amount

        3) source is word aligned, destination is not

        4) destination is word aligned, source is not

        5) neither is word aligned, and they are offset by differing amounts

        At the time of this writing, only g0 thru g7 and g13 are available

        for use in this leafproc;  other registers would have to be saved and

        restored.  These nine registers, plus tricky use of g14 are sufficient

        to implement the routine.  The registers are used as follows:

        g0  original dest ptr;  not modified, so that it may be returned.

        g1  src ptr;  shift count

        g2  dest ptr;  4 bytes of src

        g3  src ptr (word aligned)

        g4  dest ptr (word aligned)

        g5  0xff  --  byte extraction mask

        g6  lsw of double word for extraction of 4 bytes (little endian)

            msw of double word for extraction of 4 bytes (big endian)

        g7  msw of double word for extraction of 4 bytes (little endian)

            lsw of double word for extraction of 4 bytes (big endian)

        g13 return address

        g14 byte extracted.  When reaches null byte, which is zero, we will

            be in conformance with register conventions, and can return to

            the caller with a clear conscience.

        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.

*/

#if __i960_BIG_ENDIAN__

#define MSW g6

#define LSW g7

#else

#define LSW g6

#define MSW g7

#endif

        .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:

        notand  g0,3,g4         # extract word addr of start of dest

        lda     (g14),g13       # preserve return address

        and     g0,3,LSW        # extract byte offset of dest

        ld      (g4),MSW        # fetch word containing at least first byte

        shlo    3,LSW,g14       # get shift count for making mask for first word

        subi    1,0,LSW         # mask initially all ones

#if __i960_BIG_ENDIAN__

        shro    g14,LSW,LSW     # get mask for bytes needed from first word

        lda     0xff000000,g5   # byte extraction mask

#else

        shlo    g14,LSW,LSW     # get mask for bytes needed from first word

        lda     0xff,g5         # byte extraction mask

#endif

        notor   MSW,LSW,MSW     # set unneeded bytes to all ones

Lsearch_for_word_with_null:

        scanbyte 0,MSW          # check for null byte

        lda     4(g4),g4        # post-increment dest word pointer

        mov     MSW,LSW         # keep a copy of current word

        ld      (g4),MSW        # fetch next word of dest

        bno.t   Lsearch_for_word_with_null      # branch if null not found yet

        and     g5,LSW,g14      # extract byte

        cmpo    0,g14           # branch if null is first byte of word

        subo    4,g4,g4         # move dest word ptr back to word with null

        notand  g1,3,g3         # extract word addr of start of src

        lda     (g4),g2         # set dest byte ptr to 1st byte of word w/ null

        be.f    Lcase_14

Lsearch_for_null:

#if __i960_BIG_ENDIAN__

        shro    8,g5,g5         # move mask down to next byte

#else

        shlo    8,g5,g5         # move mask up to next byte

#endif

        lda     1(g2),g2        # move dest byte ptr to next byte

        and     g5,LSW,g14      # extract byte

        cmpobne.t 0,g14,Lsearch_for_null        # branch if null is not yet found

        lda     0xff,g5         # byte extraction mask

        b       Lcase_235.a

_strcpy:

#ifndef __PIC

        lda     Lrett,g14

#else

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

#endif

__strcpy:

        notand  g0,3,g4         # extract word addr of start of dest

        lda     (g14),g13       # preserve return address

        cmpo    g0,g4           # check alignment of dest

        lda     0xff,g5         # load mask for byte extraction

        notand  g1,3,g3         # extract word addr of start of src

        bne.f   Lcase_235       # branch if dest is NOT word aligned

Lcase_14:

        cmpo    g3,g1           # check alignment of src

        ld      (g3),LSW        # fetch word containing at least first byte

        shlo    3,g1,g1         # compute shift count

        lda     4(g3),g3        # advance src word addr

#if __i960_BIG_ENDIAN__

        lda     0xff,g5         # byte extraction mask

#endif

        bne.f   Lcase_4         # branch if src is NOT word aligned

Lcase_1:                                # src and dest are word aligned

        subo    4,g4,g4         # store is pre-incrementing;  back up dest addr

Lcase_1_wloop:                  # word copying loop

        scanbyte 0,LSW          # check for null byte in src word

        lda     (LSW),g2        # keep a copy of the src word

        addo    4,g4,g4         # pre-increment dest addr

        ld      (g3),LSW        # pre-fetch next word of src

        addo    4,g3,g3         # post-increment src addr

        bo.f    Lcase_1_cloop   # branch if word contains null byte

        st      g2,(g4)         # store word in dest string

        b       Lcase_1_wloop

Lcase_3_cloop:

Lcase_1_cloop:                  # character copying loop

#if __i960_BIG_ENDIAN__

        rotate  8,g2,g2         # move next byte into position for extraction

        and     g5,g2,g14       # extract next char

#else

        and     g5,g2,g14       # extract next char

        shro    8,g2,g2         # move next byte into position for extraction

#endif

        cmpo    0,g14           # check for null byte

        stob    g14,(g4)        # store the byte in dest

        lda     1(g4),g4        # post-increment dest byte addr

        bne.t   Lcase_1_cloop   # branch if null not reached

Lexit_code:

        bx      (g13)           # g0 = addr of dest;  g14 = 0

Lrett:

        ret

Lcase_3:                                # src is word aligned; dest is not

        addo    4,g4,g4         # move dest word ptr to first word boundary

        mov     LSW,MSW         # make copy of first word of src

        lda     0,g1            # initialize shift count to zero

Lcase_25:

Lcase_3_cloop_at_start:         # character copying loop for start of dest str

#if __i960_BIG_ENDIAN__

        rotate  8,MSW,MSW       # move next byte into position for extraction

        and     g5,MSW,g14      # extract next char

#else

        and     g5,MSW,g14      # extract next char

        shro    8,MSW,MSW       # move next byte into position for extraction

#endif

        cmpo    0,g14           # check for null byte

        stob    g14,(g2)        # store the byte in dest

        lda     1(g2),g2        # post-increment dest ptr

        be.f    Lexit_code      # branch if null byte reached

        cmpo    g2,g4           # have we reached word boundary in dest?

        lda     8(g1),g1        # augment the shift counter

        bne.t   Lcase_3_cloop_at_start

Lcase_4:

        ld      (g3),MSW        # fetch msw of operand for double shift

#if __i960_BIG_ENDIAN__

        subo    g1,0,g1         # Adjust shift count for big endian.

#endif

Lcase_3_wloop:

        eshro   g1,g6,g2        # extract 4 bytes of src

        lda     4(g3),g3        # post-increment src word addr

        scanbyte 0,g2           # check for null byte

        lda     (MSW),LSW       # move msw to lsw

        ld      (g3),MSW        # pre-fetch msw of operand for double shift

        bo.f    Lcase_3_cloop   # branch if word contains null byte

        st      g2,(g4)         # store 4 bytes to dest

        addo    4,g4,g4         # post-increment dest ptr

        b       Lcase_3_wloop

Lcase_235:

        lda     (g0),g2         # copy dest ptr

Lcase_235.a:

        cmpo    g3,g1           # check alignment of src

        ld      (g3),LSW        # fetch word containing at least first byte

        and     3,g1,g14        # compute shift count

        lda     4(g3),g3        # advance src word addr

        shlo    3,g14,g1

        be.t    Lcase_3         # branch if dest is word aligned

        or      g4,g14,g14      # is src earlier in word, later, or sync w/ dst

        ld      (g3),MSW        # pre-fetch second half

        cmpo    g2,g14          # < indicates first word of dest has more bytes

        lda     4(g4),g4        # move dest word addr to first word boundary

                                /* than first word of source. */

#if __i960_BIG_ENDIAN__

        subo    g1,0,g14        # Adjust shift count for big endian.

        eshro   g14,g6,g14      # extract four bytes

        bge.f   1f

#else

        eshro   g1,g6,g14       # extract four bytes

        bg.f    1f

#endif

        mov     MSW,LSW

        lda     4(g3),g3        # move src word addr to second word boundary

1:

        mov     g14,MSW

        b       Lcase_25

/* end of strcpy */