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106 lines
3.5 KiB
ArmAsm
106 lines
3.5 KiB
ArmAsm
/*
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* Copyright (c) 1988 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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.asciz "@(#)strchr.s 5.4 (Berkeley) 6/1/90"
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#endif /* LIBC_SCCS and not lint */
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/*
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* Find the first occurence of c in the string cp.
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* Return pointer to match or null pointer.
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*
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* char *
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* strchr(cp, c)
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* char *cp, c;
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*/
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#include "DEFS.h"
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.lcomm tbl,256
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ENTRY(strchr, 0)
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movzwl $65535,r4 /* handy constant */
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movq 4(ap),r1 /* r1 = cp; r2 = c */
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movzbl r2,r2
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beql Lzero /* special case for c == '\0' */
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/*
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* Fancy scanc version. Alas, it is not reentrant.
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*/
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movab tbl,r3 /* r3 = base of table */
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bbss $0,(r3),Lreent /* ensure not reentering */
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movab (r3)[r2],r5
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incb (r5) /* mark both '\0' and c */
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0:
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scanc r4,(r1),(r3),$1 /* look for c or '\0' */
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beql 0b /* still looking */
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movl r1,r0 /* return whatever we found */
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tstb (r0)
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bneq 1f # unless it was '\0':
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clrl r0 # then return NULL
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1:
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clrb (r5) /* clean up table */
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clrb (r3)
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ret
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/*
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* Special case for \0.
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*/
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Lzero:
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locc r2,r4,(r1) /* just find end of string */
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beql Lzero /* still looking */
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movl r1,r0 /* found it */
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ret
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/*
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* Slower reentrant version is two two-step searches. The first
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* phase runs until we know where the string ends; it locates the
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* first occurrence of c within a 65535-byte block. If we find
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* the end of the string first, we switch to the second phase,
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* were we look only up to the known end of string.
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*/
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Lreent:
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0: /* first phase */
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movl r1,r3
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locc $0,r4,(r3) /* look for '\0' */
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bneq 1f
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locc r2,r4,(r3) /* look for c */
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beql 0b /* not found: reset pointer and loop */
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movl r1,r0 /* found: return it */
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ret
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1: /* second phase */
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subl3 r3,r1,r0 /* length of short block */
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locc r2,r0,(r3) /* look for c */
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beql 2f /* not found: return NULL */
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movl r1,r0
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2: ret
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