Add search fist non zero bit for bitarray. This implemention is platform independent...

Signed off by Lafras Henning <lafras@xietel.com>.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@5005 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/bertos/struct/bitarray.c b/bertos/struct/bitarray.c
new file mode 100644 (file)
index 0000000..971a313
--- /dev/null
+++ b/bertos/struct/bitarray.c
@@ -0,0 +1,92 @@
+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2011 Develer S.r.l. (http://www.develer.com/)
+ * -->
+ *
+ * \brief Bitarray module
+ *
+ * \author Daniele Basile <asterix@develer.com>
+ *
+ */
+
+#include "bitarray.h"
+
+#include <string.h>
+
+// De Bruijn constant coefficents.
+static const uint8_t DeBruijn_coefficents[32] =
+{
+  0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
+  31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
+};
+
+/**
+ * Return the position of the first bit non zero in bitarray
+ *
+ * \param bitx BitArray context
+ * \param idx Starting bit
+ * \param offset Number of bits to test
+ * \return Position in bitarray when firt bit non zero occur,  -1 otherwise
+ */
+int bitarray_firstSetBit(BitArray *bitx)
+{
+       ASSERT(bitx);
+
+       uint32_t *b = (uint32_t *)bitx->array;
+       int pos =  -1;
+       int curr = 0;
+       int i = 0;
+       size_t bytes = bitx->size;
+
+       while (bytes)
+       {
+               if (bytes < 4)
+               {
+                       uint32_t data = 0;
+                       memcpy(&data, &b[i], bytes);
+
+                       if (data == 0)
+                               return -1;
+
+                       return (DeBruijn_coefficents[((uint32_t)((data & -data) * 0x077CB531U)) >> 27] + curr);
+               }
+
+               if (b[i])
+               {
+                       pos = DeBruijn_coefficents[((uint32_t)((b[i] & -b[i]) * 0x077CB531U)) >> 27] + curr;
+                       break;
+               }
+
+               bytes -= 4;
+               curr += 32;
+               i++;
+       }
+
+       return pos;
+}

diff --git a/bertos/struct/bitarray.h b/bertos/struct/bitarray.h
index 83a0ef16acfe1c1eba06fc545b6edcf4b81645a3..791d46767ccc5012378640154108b79fa5aaa1d4 100644 (file)
--- a/bertos/struct/bitarray.h
+++ b/bertos/struct/bitarray.h
@@ -238,6 +238,8 @@ INLINE void bitarray_dump(BitArray *bitx)
                kprintf("..%02x [%d]\n", bitx->array[i / 8], i);
 }
 
+int bitarray_firstSetBit(BitArray *bitx);
+
 /**
  * Init a BitArray.
  *

diff --git a/bertos/struct/bitarray_test.c b/bertos/struct/bitarray_test.c
index b917d0f4d60ec89fbf51c576b2b0d020db674843..0dad3a270ef9796c87bb8b92f305beb9591120fd 100644 (file)
--- a/bertos/struct/bitarray_test.c
+++ b/bertos/struct/bitarray_test.c
@@ -45,18 +45,30 @@
 
 #define TEST1_LEN   31
 #define TEST2_LEN   17
+#define TEST3_LEN   16
+#define TEST4_LEN   23
+#define TEST5_LEN   72
 
 BITARRAY_ALLOC(test1, TEST1_LEN);
 BITARRAY_ALLOC(test2, TEST2_LEN);
+BITARRAY_ALLOC(test3, TEST3_LEN);
+BITARRAY_ALLOC(test4, TEST4_LEN);
+BITARRAY_ALLOC(test5, TEST5_LEN);
 
 BitArray bitx1;
 BitArray bitx2;
+BitArray bitx3;
+BitArray bitx4;
+BitArray bitx5;
 
 int bitarray_testSetup(void)
 {
        kdbg_init();
        bitarray_init(&bitx1, TEST1_LEN, test1, sizeof(test1));
        bitarray_init(&bitx2, TEST2_LEN, test2, sizeof(test2));
+       bitarray_init(&bitx3, TEST3_LEN, test3, sizeof(test3));
+       bitarray_init(&bitx4, TEST4_LEN, test4, sizeof(test4));
+       bitarray_init(&bitx5, TEST5_LEN, test5, sizeof(test5));
        return 0;
 }
 
@@ -117,6 +129,40 @@ int bitarray_testRun(void)
        if (bitarray_isFull(&bitx2))
                goto error;
 
+       kprintf("Test 3\n");
+       bitarray_set(&bitx3, 12);
+       bitarray_dump(&bitx3);
+       int pos = 0;
+       pos = bitarray_firstSetBit(&bitx3);
+       if (pos != 12)
+               goto error;
+
+       kprintf("Test 4\n");
+       bitarray_set(&bitx4, TEST4_LEN);
+       bitarray_dump(&bitx4);
+       pos = 0;
+       pos = bitarray_firstSetBit(&bitx4);
+       if (pos != 23)
+               goto error;
+
+       kprintf("Test 5\n");
+       bitarray_set(&bitx5, 71);
+       bitarray_dump(&bitx5);
+       pos = 0;
+       pos = bitarray_firstSetBit(&bitx5);
+       kprintf("pos %d\n", pos);
+       if (pos != 71)
+               goto error;
+
+       kprintf("Test 6\n");
+       bitarray_clear(&bitx5, 71);
+       bitarray_set(&bitx5, 5);
+       bitarray_dump(&bitx5);
+       pos = 0;
+       pos = bitarray_firstSetBit(&bitx5);
+       if (pos != 5)
+               goto error;
+
        return 0;
 
 error: