From 354bb40e75d94466e91fe6960523612c9d17ccfb Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 2 Nov 2017 23:11:29 +0300
Subject: Add implementation

---
 mysql/mysys/mf_radix.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 mysql/mysys/mf_radix.c

(limited to 'mysql/mysys/mf_radix.c')

diff --git a/mysql/mysys/mf_radix.c b/mysql/mysys/mf_radix.c
new file mode 100644
index 0000000..aa112df
--- /dev/null
+++ b/mysql/mysys/mf_radix.c
@@ -0,0 +1,59 @@
+/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+/*
+  Radixsort for pointers to fixed length strings.
+  A very quick sort for not to long (< 20 char) strings.
+  Neads a extra buffers of number_of_elements pointers but is
+  2-3 times faster than quicksort
+*/
+
+#include "mysys_priv.h"
+#include <m_string.h>
+
+	/* Radixsort */
+
+my_bool radixsort_is_appliccable(uint n_items, size_t size_of_element)
+{
+  return size_of_element <= 20 && n_items >= 1000 && n_items < 100000;
+}
+
+void radixsort_for_str_ptr(uchar **base, uint number_of_elements, size_t size_of_element, uchar **buffer)
+{
+  uchar **end,**ptr,**buffer_ptr;
+  uint32 *count_ptr,*count_end,count[256];
+  int pass;
+
+  end=base+number_of_elements; count_end=count+256;
+  for (pass=(int) size_of_element-1 ; pass >= 0 ; pass--)
+  {
+    memset(count, 0, sizeof(uint32)*256);
+    for (ptr= base ; ptr < end ; ptr++)
+      count[ptr[0][pass]]++;
+    if (count[0] == number_of_elements)
+      goto next;
+    for (count_ptr=count+1 ; count_ptr < count_end ; count_ptr++)
+    {
+      if (*count_ptr == number_of_elements)
+	goto next;
+      (*count_ptr)+= *(count_ptr-1);
+    }
+    for (ptr= end ; ptr-- != base ;)
+      buffer[--count[ptr[0][pass]]]= *ptr;
+    for (ptr=base, buffer_ptr=buffer ; ptr < end ;)
+      (*ptr++) = *buffer_ptr++;
+  next:;
+  }
+}
-- 
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