98 lines
2.1 KiB
C
98 lines
2.1 KiB
C
/*
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* bsearch.c
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*
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* This is something I found on watmath. I've made some minor changes for use
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* in this package.
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*
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* 92/06/04 11:35:15
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*/
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#if 0
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#ifndef lint
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static char *RCSid = "$OHeader: /usr/mfcf/src/accounts/libuw/RCS/bsearch.c,v 1.1 88/06/11 20:41:48 root Exp $";
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#endif
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#endif
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#include "defs.h"
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#ifdef USE_MYBSEARCH
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#ifdef USE_SCCS_IDS
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static char const SCCSid[] = "@(#) mytinfo bsearch.c 3.4 92/06/04 public domain, By Ross Ridge";
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#endif
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#ifdef USE_SHORT_BSEARCH
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#define fast_int short
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#else
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#define fast_int mysize_t
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#endif
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/*
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* bsearch - find an element of a sorted vector
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*
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* found = bsearch(key, array, dimension, width, compare)
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* returns a pointer to the specified element in the array,
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* or (char*)0 if the element can't be found.
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* key
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* pointer to the element to be searched for in the array
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* array
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* address of an array of elements
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* dimension
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* number of elements in the array
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* width
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* sizeof(type) of each element
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* compare
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* pointer to a function taking (char *) pointers to two elements
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* and returning <0, 0, or >0 as the first element comes before,
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* at, or after the second element. A compare function is provided
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* for comparing strings.
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*/
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#if 0
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/*
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* $OLog: bsearch.c,v $
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* Revision 1.1 88/06/11 20:41:48 root
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* Initial revision
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*
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*/
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#endif
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static anyptr
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bsearch(key, array, dimension, iwidth, compare)
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anyptr key;
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anyptr array;
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int dimension;
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mysize_t iwidth;
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compar_fn compare;
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{
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register fast_int start; /* offset to start of current interval */
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register fast_int end; /* offset to end+1 of current interval */
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register fast_int middle; /* offset to middle of current interval */
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auto int status;
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register fast_int width;
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width = iwidth / sizeof(char);
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start = 0;
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middle = 0;
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end = dimension;
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while (start < end) {
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middle = (start + end) / 2;
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status = (*compare)(key, ((char *)array + middle*width));
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if (status < 0)
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end = middle;
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else if (status > 0)
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start = middle + 1;
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else return (anyptr)(((char *)array) + middle*width);
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}
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return 0;
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}
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#endif /* USE_MYBSEARCH */
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