77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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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. 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 UNIVERSITY 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 UNIVERSITY 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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/*
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* This file is shared between libc and the kernel, so don't put anything
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* in here that won't work in both contexts.
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*/
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#ifdef _KERNEL
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#include <types.h>
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#include <lib.h>
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#else
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#include <stdint.h>
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#include <string.h>
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#endif
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/*
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* Standard (well, semi-standard) C string function - zero a block of
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* memory.
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*/
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void
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bzero(void *vblock, size_t len)
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{
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char *block = vblock;
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size_t i;
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/*
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* For performance, optimize the common case where the pointer
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* and the length are word-aligned, and write word-at-a-time
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* instead of byte-at-a-time. Otherwise, write bytes.
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*
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* The alignment logic here should be portable. We rely on the
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* compiler to be reasonably intelligent about optimizing the
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* divides and moduli out. Fortunately, it is.
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*/
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if ((uintptr_t)block % sizeof(long) == 0 &&
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len % sizeof(long) == 0) {
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long *lb = (long *)block;
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for (i=0; i<len/sizeof(long); i++) {
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lb[i] = 0;
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}
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}
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else {
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for (i=0; i<len; i++) {
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block[i] = 0;
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}
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}
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}
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