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56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA */
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/*
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Radixsort for pointers to fixed length strings.
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A very quick sort for not to long (< 20 char) strings.
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Neads a extra buffers of number_of_elements pointers but is
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2-3 times faster than quicksort
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*/
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#include "mysys_priv.h"
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#include <m_string.h>
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/* Radixsort */
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void radixsort_for_str_ptr(uchar **base, uint number_of_elements, size_s size_of_element, uchar **buffer)
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{
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uchar **end,**ptr,**buffer_ptr;
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uint32 *count_ptr,*count_end,count[256];
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int pass;
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end=base+number_of_elements; count_end=count+256;
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for (pass=(int) size_of_element-1 ; pass >= 0 ; pass--)
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{
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bzero((gptr) count,sizeof(uint32)*256);
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for (ptr= base ; ptr < end ; ptr++)
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count[ptr[0][pass]]++;
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if (count[0] == number_of_elements)
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goto next;
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for (count_ptr=count+1 ; count_ptr < count_end ; count_ptr++)
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{
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if (*count_ptr == number_of_elements)
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goto next;
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(*count_ptr)+= *(count_ptr-1);
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}
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for (ptr= end ; ptr-- != base ;)
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buffer[--count[ptr[0][pass]]]= *ptr;
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for (ptr=base, buffer_ptr=buffer ; ptr < end ;)
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(*ptr++) = *buffer_ptr++;
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next:;
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}
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}
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