61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/* bsearch( const void *, const void *, size_t, size_t, int(*)( const void *, const void * ) )
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This file is part of the Public Domain C Library (PDCLib).
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Permission is granted to use, modify, and / or redistribute at will.
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*/
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#include <stdlib.h>
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#ifndef REGTEST
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void * bsearch( const void * key, const void * base, size_t nmemb, size_t size, int (*compar)( const void *, const void * ) )
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{
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const void * pivot;
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int rc;
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size_t corr;
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while ( nmemb )
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{
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/* algorithm needs -1 correction if remaining elements are an even number. */
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corr = nmemb % 2;
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nmemb /= 2;
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pivot = (const char *)base + (nmemb * size);
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rc = compar( key, pivot );
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if ( rc > 0 )
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{
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base = (const char *)pivot + size;
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/* applying correction */
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nmemb -= ( 1 - corr );
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}
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else if ( rc == 0 )
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{
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return (void *)pivot;
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}
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}
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return NULL;
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}
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#endif
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#ifdef TEST
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#include "_PDCLIB_test.h"
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static int compare( const void * left, const void * right )
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{
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return *( (unsigned char *)left ) - *( (unsigned char *)right );
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}
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int main( void )
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{
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TESTCASE( bsearch( "e", abcde, 4, 1, compare ) == NULL );
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TESTCASE( bsearch( "e", abcde, 5, 1, compare ) == &abcde[4] );
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TESTCASE( bsearch( "a", abcde + 1, 4, 1, compare ) == NULL );
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TESTCASE( bsearch( "0", abcde, 1, 1, compare ) == NULL );
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TESTCASE( bsearch( "a", abcde, 1, 1, compare ) == &abcde[0] );
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TESTCASE( bsearch( "a", abcde, 0, 1, compare ) == NULL );
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TESTCASE( bsearch( "e", abcde, 3, 2, compare ) == &abcde[4] );
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TESTCASE( bsearch( "b", abcde, 3, 2, compare ) == NULL );
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return TEST_RESULTS;
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}
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#endif
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