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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/vax/strrchr.s
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+/*
+ * Copyright (c) 1988 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+ .asciz "@(#)strrchr.s 5.4 (Berkeley) 6/1/90"
+#endif /* LIBC_SCCS and not lint */
+
+/*
+ * Find the last occurence of c in the string cp.
+ * Return pointer to match or null pointer.
+ *
+ * char *
+ * strrchr(cp, c)
+ * char *cp, c;
+ */
+#include "DEFS.h"
+
+ .lcomm tbl,256
+
+ENTRY(strrchr, 0)
+ movzwl $65535,r4 /* handy 65535 */
+ movq 4(ap),r1 /* r1 = cp; r2 = c */
+ movzbl r2,r2
+ beql Lzero /* special case for c == '\0' */
+
+ clrl r5 /* r5 = pointer to last match */
+
+/*
+ * Fancy scanc version. Alas, it is not reentrant.
+ */
+ movab tbl,r3 /* r3 = address of table */
+ bbss $0,(r3),Lreent /* ensure not reentering */
+ movab (r3)[r2],r4
+ incb (r4) /* mark both '\0' and c */
+0:
+ scanc $65535,(r1),(r3),$1 /* look for c or '\0' */
+ beql 0b /* keep looking */
+ tstb (r1)
+ beql 1f /* done if '\0' */
+ movab (r1)+,r5 /* save most recently found, and skip over it */
+ jbr 0b /* keep looking */
+1:
+ movl r5,r0 /* return last found (if any) */
+ clrb (r4) /* clean up table */
+ clrb (r3)
+ ret
+
+/*
+ * Special case for \0.
+ */
+Lzero:
+ locc $0,r4,(r1) /* just find end of string */
+ beql Lzero /* still looking */
+ movl r1,r0 /* found it */
+ ret
+
+/*
+ * Slower reentrant version is two two-step searches. The first
+ * phase runs until we know where the string ends; it locates any
+ * occurrences of c within a 65535-byte block. Once we have found
+ * the end of the string, we find any further occurrences before
+ * that location.
+ */
+Lreent:
+0: /* first phase */
+ movl r1,r3
+ locc $0,r4,(r3) /* look for '\0' */
+ bneq 1f
+ locc r2,r4,(r3) /* continue phase 1 search for c */
+ beql 0b
+ movab (r1)+,r5 /* found c: save and increment pointer */
+ brb 0b /* and continue */
+
+1: /* second phase */
+ subl3 r3,r1,r0 /* length of short block */
+ movl r3,r1
+2:
+ locc r2,r0,(r1) /* look for c */
+ beql 3f /* skip if not found */
+ movab (r1)+,r5 /* save pointer as before */
+ sobgtr r0,2b /* adjust count and loop */
+3:
+ movl r5,r0 /* return stashed pointer */
+ ret