/*
* 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. 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
*/
/*
* We should unroll the loop, but at the moment this would
* gain nothing since the `std' instructions are what limits us.
*/
#ifdef MEMSET
/*
* void *
* memset(void *addr, int pattern, size_t len)
*/
ENTRY(memset)
! %o0 = addr, %o1 = pattern, %o2 = len
/*
* Expand the byte pattern to fill 64 bits in an even-aligned
* register pair; shuffle arguments to match those of bzero.
*/
and %o1, 0xff, %o3
mov %o2, %o1 ! shuffle argument
sll %o3, 8, %o2
or %o2, %o3, %o2
mov %o0, %g1 ! save original pointer
sll %o2, 16, %o3
or %o2, %o3, %o2
! Optimize a common case: addr and len are both multiples of 8.
or %o0, %o1, %o5
btst 7, %o5 ! ((addr | len) & 7) != 0?
bnz 1f ! if so, cannot optimize
mov %o2, %o3 ! in any case, complete pat expansion
#else
/*
* void
* bzero(void *addr, size_t len)
*/
ENTRY(bzero)
! %o0 = addr, %o1 = len
clr %o2
! Optimize a common case: addr and len are both multiples of 8.
or %o0, %o1, %o5
btst 7, %o5 ! ((addr | len) & 7) != 0?
bnz 1f ! if so, cannot optimize
clr %o3 ! in any case, we want o3=0
#endif
/* `Good' operands, can just store doubles. */
0:
deccc 8, %o1 ! while ((len -= 8) >= 0)
bge,a 0b
std %o2, [%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 %o2, [%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 %o2, [%o0] ! *addr = 0;
inc %o0 ! addr++;
dec %o1 ! len--;
btst 2, %o0 ! }
1:
bz,a 1f ! if (addr & 2) {
btst 4, %o0
sth %o2, [%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 %o2, [%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 %o2, [%o0] ! do {
2: ! *(quad *)addr = 0;
inc 8, %o0 ! addr += 8;
deccc 8, %o1 ! } while ((len -= 8) >= 0);
bge,a 2b
std %o2, [%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 %o2, [%o0] ! *(int *)addr = 0;
inc 4, %o0 ! addr += 4;
1:
bz 1f ! if (len & 2) {
btst 1, %o1
sth %o2, [%o0] ! *(short *)addr = 0;
inc 2, %o0 ! addr += 2;
1:
bnz,a 1f ! if (len & 1)
stb %o2, [%o0] ! *addr = 0;
1:
retl
#ifdef MEMSET
mov %g1, %o0 ! restore original pointer
#else
nop
#endif
