ba96f37758
Some of the routines were using artificially limited builtin already, drop the explicit limit. The use of builtins allows quite often allows the compiler to elide the call or most zeroing to begin with. For instance, if the target object is 32 bytes in size and gets zeroed + has 16 bytes initialized, the compiler can just add code to zero out the rest. Note not all the primites have asm variants and some of the existing ones are not optimized. Maintaines are strongly encourage to take a look (regardless of this change).
147 lines
4.2 KiB
C
147 lines
4.2 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1987, 1993
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* The Regents of the University of California. 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. 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/libkern.h>
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#include <machine/endian.h>
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typedef const void *cvp;
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typedef const unsigned char *ustring;
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typedef unsigned long ul;
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typedef const unsigned long *culp;
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/*
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* bcmp -- vax cmpc3 instruction
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*/
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int
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(bcmp)(const void *b1, const void *b2, size_t length)
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{
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#if BYTE_ORDER == LITTLE_ENDIAN
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/*
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* The following code is endian specific. Changing it from
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* little-endian to big-endian is fairly trivial, but making
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* it do both is more difficult.
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*
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* Note that this code will reference the entire longword which
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* includes the final byte to compare. I don't believe this is
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* a problem since AFAIK, objects are not protected at smaller
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* than longword boundaries.
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*/
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int shl, shr, len = length;
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ustring p1 = b1, p2 = b2;
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ul va, vb;
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if (len == 0)
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return (0);
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/*
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* align p1 to a longword boundary
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*/
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while ((long)p1 & (sizeof(long) - 1)) {
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if (*p1++ != *p2++)
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return (1);
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if (--len <= 0)
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return (0);
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}
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/*
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* align p2 to longword boundary and calculate the shift required to
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* align p1 and p2
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*/
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shr = (long)p2 & (sizeof(long) - 1);
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if (shr != 0) {
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p2 -= shr; /* p2 now longword aligned */
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shr <<= 3; /* offset in bits */
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shl = (sizeof(long) << 3) - shr;
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va = *(culp)p2;
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p2 += sizeof(long);
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while ((len -= sizeof(long)) >= 0) {
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vb = *(culp)p2;
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p2 += sizeof(long);
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if (*(culp)p1 != (va >> shr | vb << shl))
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return (1);
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p1 += sizeof(long);
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va = vb;
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}
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/*
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* At this point, len is between -sizeof(long) and -1,
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* representing 0 .. sizeof(long)-1 bytes remaining.
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*/
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if (!(len += sizeof(long)))
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return (0);
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len <<= 3; /* remaining length in bits */
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/*
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* The following is similar to the `if' condition
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* inside the above while loop. The ?: is necessary
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* to avoid accessing the longword after the longword
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* containing the last byte to be compared.
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*/
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return ((((va >> shr | ((shl < len) ? *(culp)p2 << shl : 0)) ^
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*(culp)p1) & ((1L << len) - 1)) != 0);
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} else {
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/* p1 and p2 have common alignment so no shifting needed */
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while ((len -= sizeof(long)) >= 0) {
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if (*(culp)p1 != *(culp)p2)
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return (1);
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p1 += sizeof(long);
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p2 += sizeof(long);
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}
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/*
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* At this point, len is between -sizeof(long) and -1,
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* representing 0 .. sizeof(long)-1 bytes remaining.
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*/
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if (!(len += sizeof(long)))
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return (0);
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return (((*(culp)p1 ^ *(culp)p2)
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& ((1L << (len << 3)) - 1)) != 0);
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}
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#else
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const char *p1, *p2;
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if (length == 0)
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return(0);
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p1 = b1;
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p2 = b2;
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do
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if (*p1++ != *p2++)
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break;
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while (--length);
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return(length);
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#endif
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}
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