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Dave Chinner
fa993e5130
Mostly scripted like all the others, manually added tags to Makefile and build/config input files. Signed-off-by: Dave Chinner <dchinner@redhat.com>
65 lines
2.6 KiB
C
65 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2000 Silicon Graphics, Inc.
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* All Rights Reserved.
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*/
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#ifndef _PATTERN_H_
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#define _PATTERN_H_
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/*
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* pattern_check(buf, buflen, pat, patlen, patshift)
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*
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* Check a buffer of length buflen against repeated occurrances of
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* a pattern whose length is patlen. Patshift can be used to rotate
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* the pattern by patshift bytes to the left.
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*
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* Patshift may be greater than patlen, the pattern will be rotated by
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* (patshift % patshift) bytes.
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*
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* pattern_check returns -1 if the buffer does not contain repeated
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* occurrances of the indicated pattern (shifted by patshift).
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*
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* The algorithm used to check the buffer relies on the fact that buf is
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* supposed to be repeated copies of pattern. The basic algorithm is
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* to validate the first patlen bytes of buf against the pat argument
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* passed in - then validate the next patlen bytes against the 1st patlen
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* bytes - the next (2*patlen) bytes against the 1st (2*pathen) bytes, and
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* so on. This algorithm only works when the assumption of a buffer full
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* of repeated copies of a pattern holds, and gives MUCH better results
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* then walking the buffer byte by byte.
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*
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* Performance wise, It appears to be about 5% slower than doing a straight
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* memcmp of 2 buffers, but the big win is that it does not require a
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* 2nd comparison buffer, only the pattern.
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*/
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int pattern_check( char * , int , char * , int , int );
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/*
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* pattern_fill(buf, buflen, pat, patlen, patshift)
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*
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* Fill a buffer of length buflen with repeated occurrances of
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* a pattern whose length is patlen. Patshift can be used to rotate
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* the pattern by patshift bytes to the left.
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*
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* Patshift may be greater than patlen, the pattern will be rotated by
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* (patshift % patlen) bytes.
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*
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* If buflen is not a multiple of patlen, a partial pattern will be written
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* in the last part of the buffer. This implies that a buffer which is
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* shorter than the pattern length will receive only a partial pattern ...
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*
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* pattern_fill always returns 0 - no validation of arguments is done.
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*
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* The algorithm used to fill the buffer relies on the fact that buf is
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* supposed to be repeated copies of pattern. The basic algorithm is
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* to fill the first patlen bytes of buf with the pat argument
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* passed in - then copy the next patlen bytes with the 1st patlen
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* bytes - the next (2*patlen) bytes with the 1st (2*pathen) bytes, and
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* so on. This algorithm only works when the assumption of a buffer full
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* of repeated copies of a pattern holds, and gives MUCH better results
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* then filling the buffer 1 byte at a time.
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*/
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int pattern_fill( char * , int , char * , int , int );
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#endif
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