123 lines
2.6 KiB
C
123 lines
2.6 KiB
C
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/* @(#)cmpmbytes.c 1.2 11/08/16 Copyright 1988, 1995-2011 J. Schilling */
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#include <schily/mconfig.h>
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#ifndef lint
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static UConst char sccsid[] =
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"@(#)cmpmbytes.c 1.2 11/08/16 Copyright 1988, 1995-2011 J. Schilling";
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#endif
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/*
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* compare data
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* Return the difference from the first differing characters
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*
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* Copyright (c) 1988, 1995-2011 J. Schilling
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*/
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/*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* See the file CDDL.Schily.txt in this distribution for details.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file CDDL.Schily.txt from this distribution.
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*/
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#include <schily/standard.h>
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#include <schily/align.h>
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#include <schily/types.h>
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#include <schily/schily.h>
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#define DO8(a) a; a; a; a; a; a; a; a;
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/*
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* Return the difference from the first differing characters
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* This interface is compatible to memcmp()
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*/
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EXPORT int
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cmpmbytes(fromp, top, cnt)
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const void *fromp;
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const void *top;
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ssize_t cnt;
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{
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register const char *from = (char *)fromp;
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register const char *to = (char *)top;
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register ssize_t n;
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register ssize_t i;
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/*
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* If we change cnt to be unsigned, check for == instead of <=
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*/
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if ((n = cnt) <= 0)
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return (0);
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/*
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* Compare byte-wise until properly aligned for a long pointer.
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*/
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i = sizeof (long) - 1;
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while (--n >= 0 && --i >= 0 && !l2aligned(from, to)) {
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if (*to++ != *from++)
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goto cdiff;
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}
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n++;
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if (n >= (ssize_t)(8 * sizeof (long))) {
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if (l2aligned(from, to)) {
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register const long *froml = (const long *)from;
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register const long *tol = (const long *)to;
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register ssize_t rem = n % (8 * sizeof (long));
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n /= (8 * sizeof (long));
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do {
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/* BEGIN CSTYLED */
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DO8(
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if (*tol++ != *froml++)
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break;
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);
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/* END CSTYLED */
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} while (--n > 0);
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if (n > 0) {
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--froml;
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--tol;
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to = (const char *)tol;
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from = (const char *)froml;
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goto ldiff;
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}
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to = (const char *)tol;
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from = (const char *)froml;
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n = rem;
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}
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if (n >= 8) {
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n -= 8;
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do {
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/* BEGIN CSTYLED */
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DO8(
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if (*to++ != *from++)
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goto cdiff;
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);
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/* END CSTYLED */
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} while ((n -= 8) >= 0);
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n += 8;
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}
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if (n > 0) do {
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if (*to++ != *from++)
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goto cdiff;
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} while (--n > 0);
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return (0);
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}
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if (n > 0) do {
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if (*to++ != *from++)
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goto cdiff;
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} while (--n > 0);
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return (0);
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ldiff:
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n = sizeof (long);
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do {
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if (*to++ != *from++)
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goto cdiff;
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} while (--n > 0);
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cdiff:
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return (*((unsigned char *)--from) - *((unsigned char *)--to));
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}
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