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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [i960/] [strchr_ca.S] - Blame information for rev 816

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1 148 jeremybenn
/*******************************************************************************
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 *
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 * Copyright (c) 1993 Intel Corporation
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 *
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 * Intel hereby grants you permission to copy, modify, and distribute this
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 * software and its documentation.  Intel grants this permission provided
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 * that the above copyright notice appears in all copies and that both the
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 * copyright notice and this permission notice appear in supporting
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 * documentation.  In addition, Intel grants this permission provided that
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 * you prominently mark as "not part of the original" any modifications
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 * made to this software or documentation, and that the name of Intel
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 * Corporation not be used in advertising or publicity pertaining to
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 * distribution of the software or the documentation without specific,
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 * written prior permission.
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 *
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 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
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 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
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 * OR FITNESS FOR A PARTICULAR PURPOSE.  Intel makes no guarantee or
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 * representations regarding the use of, or the results of the use of,
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 * the software and documentation in terms of correctness, accuracy,
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 * reliability, currentness, or otherwise; and you rely on the software,
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 * documentation and results solely at your own risk.
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 *
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 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
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 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
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 * OF ANY KIND.  IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
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 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
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 *
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 ******************************************************************************/
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        .file "strch_ca.s"
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#ifdef  __PIC
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        .pic
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#endif
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#ifdef  __PID
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        .pid
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#endif
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/*
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 * (c) copyright 1988,1993 Intel Corp., all rights reserved
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 */
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/*
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        procedure strchr  (optimized assembler version for the CA)
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        src_addr = strchr (src_addr, char)
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        return a pointer to the first byte that contains the indicated
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        byte in the source string.  Return null if the byte is not found.
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        Undefined behavior will occur if the end of the source string (i.e.
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        the terminating null byte) is in the last two words of the program's
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        allocated memory space.  This is so because, in several cases, strchr
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        will fetch ahead.  Disallowing the fetch ahead would impose a severe
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        performance penalty.
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        This program handles two cases:
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        1) the argument starts on a word boundary
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        2) the argument doesn't start on a word boundary
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        At the time of this writing, only g0 thru g7 and g13 are available
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        for use in this leafproc;  other registers would have to be saved and
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        restored.  These nine registers, plus tricky use of g14 are sufficient
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        to implement the routine.  The registers are used as follows:
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        g0  src ptr;  upon return it is a pointer to the matching byte, or null
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        g1  char to seek
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        g2  mask to avoid unimportant bytes in first word
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        g3  char to seek, broadcast to all four bytes
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        g4  word of the source string
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        g5  copy of the word
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        g6  extracted character
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        g7  byte extraction mask
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        g13 return address
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        g14
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*/
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        .globl  _strchr
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        .globl  __strchr
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        .leafproc       _strchr, __strchr
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        .align  2
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_strchr:
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#ifndef __PIC
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        lda     Lrett,g14
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#else
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        lda     Lrett-(.+8)(ip),g14
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#endif
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__strchr:
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        lda     0xff,g7         # byte extraction mask
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        and     g1,g7,g1        # make char an 8-bit ordinal
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        shlo    8,g1,g2         # broadcast the char to four bytes
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        or      g1,g2,g2
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        shlo    16,g2,g4
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        cmpo    g1,g7           # is char being sought 0xff?
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        or      g4,g2,g3
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         lda    (g14),g13       # preserve return address
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        notand  g0,3,g5         # extract word addr of start of src
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         lda    0,g14           # conform to register linkage standard
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        and     g0,3,g6         # extract byte offset of src
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         ld     (g5),g4         # fetch word containing at least first byte
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        shlo    3,g6,g6         # get shift count for making mask for first word
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         lda    4(g5),g0        # post-increment src word pointer
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        subi    1,0,g5          # mask initially all ones
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#if __i960_BIG_ENDIAN__
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        shro    g6,g5,g5        # get mask for bytes needed from first word
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#else
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        shlo    g6,g5,g5        # get mask for bytes needed from first word
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#endif
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        notor   g4,g5,g4        # set unneeded bytes to all ones
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         be.f   Lsearch_for_0xff        # branch if seeking 0xff
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Lsearch_for_word_with_char_or_null:
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        scanbyte g3,g4          # check for byte with char
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         lda    (g4),g5         # copy word
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        ld      (g0),g4         # fetch next word of src
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         bo.f   Lsearch_for_char        # branch if null found
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        scanbyte 0,g5           # check for null byte
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         lda    4(g0),g0        # post-increment src word pointer
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        bno.t   Lsearch_for_word_with_char_or_null      # branch if not null
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Lnot_found:
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        mov     0,g0            # char not found.  Return null
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Lexit_code:
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        bx      (g13)           # g0 = addr of char in src (or null);  g14 = 0
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Lrett:
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        ret
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Lsearch_for_char:
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        subo    5,g0,g0         # back up the byte pointer
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Lsearch_for_char.a:
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#if __i960_BIG_ENDIAN__
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        rotate  8,g5,g5         # shift word to position next byte
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#endif
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        and     g5,g7,g6        # extract byte
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        cmpo    g1,g6           # is it char?
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         lda    1(g0),g0        # bump src byte ptr
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#if ! __i960_BIG_ENDIAN__
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        shro    8,g5,g5         # shift word to position next byte
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#endif
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         be.f   Lexit_code
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        cmpobne.t 0,g6,Lsearch_for_char.a       # quit if null comes before char
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        b       Lnot_found
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Lsearch_for_0xff:
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        lda     0xf0f0f0f0,g2   # make first comparison mask for char=-1 case.
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        or      g5,g2,g2
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        and     g4,g2,g4        # make unimportant bytes of first word 0x0f
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         b      Lsearch_for_word_with_char_or_null
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/* end of strchr */
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