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authorTheo de Raadt <deraadt@cvs.openbsd.org>1995-10-18 08:53:40 +0000
committerTheo de Raadt <deraadt@cvs.openbsd.org>1995-10-18 08:53:40 +0000
commitd6583bb2a13f329cf0332ef2570eb8bb8fc0e39c (patch)
treeece253b876159b39c620e62b6c9b1174642e070e /lib/libc/arch/sparc/string/bzero.S
initial import of NetBSD tree
Diffstat (limited to 'lib/libc/arch/sparc/string/bzero.S')
-rw-r--r--lib/libc/arch/sparc/string/bzero.S146
1 files changed, 146 insertions, 0 deletions
diff --git a/lib/libc/arch/sparc/string/bzero.S b/lib/libc/arch/sparc/string/bzero.S
new file mode 100644
index 00000000000..b9a5528cfc0
--- /dev/null
+++ b/lib/libc/arch/sparc/string/bzero.S
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 1992, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * 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.
+ *
+ * from: Header: bzero.s,v 1.1 92/06/25 12:52:46 torek Exp
+ * $Id: bzero.S,v 1.1 1995/10/18 08:41:41 deraadt Exp $
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+ .asciz "@(#)bzero.s 8.1 (Berkeley) 6/4/93"
+#endif /* LIBC_SCCS and not lint */
+
+#include "DEFS.h"
+
+/*
+ * bzero(addr, len)
+ *
+ * We should unroll the loop, but at the moment this would
+ * gain nothing since the `std' instructions are what limits us.
+ */
+ENTRY(bzero)
+ ! %o0 = addr, %o1 = len
+
+ ! Optimize a common case: addr and len are both multiples of 8.
+ or %o0, %o1, %o2
+ btst 7, %o2 ! ((addr | len) & 7) != 0?
+ bnz 1f ! if so, cannot optimize
+ clr %g1 ! in any case, we want g1=0
+
+ /* `Good' operands, can just store doubles. */
+0:
+ deccc 8, %o1 ! while ((len -= 8) >= 0)
+ bge,a 0b
+ std %g0, [%o0 + %o1] ! *(quad *)(addr + len) = 0;
+ retl
+ nop
+
+ /*
+ * Either the address is unaligned, or the count is not a
+ * multiple of 8, or both. We will have to align the address
+ * in order to use anything `better' than stb.
+ */
+1:
+ cmp %o1, 15 ! len >= 15?
+ bge,a Lstd ! yes, use std
+ btst 1, %o0 ! (but first check alignment)
+
+ ! not enough to bother: do byte-at-a-time loop.
+2:
+ deccc %o1 ! while (--len >= 0)
+ bge,a 2b
+ stb %g0, [%o0 + %o1] ! addr[len] = 0;
+ retl
+ nop
+
+Lstd:
+ /*
+ * There are at least 15 bytes to zero.
+ * We may have to zero some initial stuff to align
+ * the address.
+ */
+ bz,a 1f ! if (addr & 1) {
+ btst 2, %o0
+ stb %g0, [%o0] ! *addr = 0;
+ inc %o0 ! addr++;
+ dec %o1 ! len--;
+ btst 2, %o0 ! }
+1:
+ bz,a 1f ! if (addr & 2) {
+ btst 4, %o0
+ sth %g0, [%o0] ! *(short *)addr = 0;
+ inc 2, %o0 ! addr += 2;
+ dec 2, %o1 ! len -= 2;
+ btst 4, %o0 ! }
+1:
+ bz 1f ! if (addr & 4) {
+ dec 8, %o1
+ st %g0, [%o0] ! *(int *)addr = 0;
+ inc 4, %o0 ! addr += 4;
+ dec 4, %o1 ! len -= 4;
+ ! }
+ /*
+ * Address is double word aligned; len is 8 less than
+ * the number of bytes remaining (i.e., len is 0 if
+ * the remaining count is 8, 1 if it is 9, etc.).
+ */
+1:
+ std %g0, [%o0] ! do {
+2: ! *(quad *)addr = 0;
+ inc 8, %o0 ! addr += 8;
+ deccc 8, %o1 ! } while ((len -= 8) >= 0);
+ bge,a 2b
+ std %g0, [%o0]
+
+ /*
+ * Len is in [-8..-1] where -8 => done, -7 => 1 byte to zero,
+ * -6 => two bytes, etc. Mop up this remainder, if any.
+ */
+ btst 4, %o1
+ bz 1f ! if (len & 4) {
+ btst 2, %o1
+ st %g0, [%o0] ! *(int *)addr = 0;
+ inc 4, %o0 ! addr += 4;
+1:
+ bz 1f ! if (len & 2) {
+ btst 1, %o1
+ sth %g0, [%o0] ! *(short *)addr = 0;
+ inc 2, %o0 ! addr += 2;
+1:
+ bnz,a 1f ! if (len & 1)
+ stb %g0, [%o0] ! *addr = 0;
+1:
+ retl
+ nop