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root/gclib/gclib/GBitField.h
Revision: 18
Committed: Mon Jul 18 21:00:21 2011 UTC (7 years, 9 months ago) by gpertea
File size: 2183 byte(s)
Log Message:
added a few more source files, test code

Line File contents
1 // This class provides a generic bit field implementation for an
2 // arbitrary number of bits. Based on code written by irfan.hamid@gmail.com
3 //
4 // Implementation notes:
5 // // The bit field is implemented as an array of unsigned int that is
6 // allocated at object creation.
7 //
8 // field: The array that represents the bit field itself
9 // bit_count: The total number of bits in the bit field
10
11 #ifndef __GBITFIELD_H__
12 #define __GBITFIELD_H__
13 #include "GBase.h"
14 #define SZ_UINT sizeof(unsigned int)
15
16 class GBitField {
17 protected:
18 unsigned int *field;
19 unsigned int bit_count;
20
21 public:
22 // The constructor takes an int param which gives the number of
23 // bits in this bit field.
24 GBitField (int bc) {
25 bit_count = bc;
26 GMALLOC(field, ceil(bc/SZ_UINT*8));
27 }
28 ~GBitField () {
29 GFREE(field);
30 }
31
32 // This function sets the corresponding bit in the field equal to v
33 // (or 1, if v was not given)
34 // Returns: 0 on success, -1 on error.
35 int set(int bit, int v=1) {
36 // Sanity check
37 if (bit >= bit_count || !field)
38 return -1;
39 // The correct index into the vector will be given by bit/SZ_UNIT. The
40 // index into the correct vector element is given by bit%SZ_UNIT, to
41 // achieve this, simply left shift 0x01 the appropriate number of times.
42 if (v==0) {
43 field[bit/SZ_UINT] &= ~(1 << (bit%(SZ_UINT*8)-1));
44 }
45 else {
46 field[bit/SZ_UINT] |= (1 << (bit%(SZ_UINT*8)-1));
47 }
48 return 0;
49 }
50
51 // This function returns the value of the corresponding bit.
52 // Returns: The value of the bit, if the field is initialized and bit index is
53 // within bounds, -1 otherwise.
54 int get(int bit) {
55 if (bit >= bit_count || !field)
56 return -1;
57 return (field[bit/SZ_UINT] & (0x00000001 << (bit%(SZ_UINT*8)-1)) ? 1 : 0);
58 }
59
60 // This function sets the corresponding bit in the field equal to 0.
61 // Returns: 0 on success, -1 on error.
62 int reset(int bit) {
63 if (bit >= bit_count || !field)
64 return -1;
65 field[bit/SZ_UINT] &= ~(0x00000001 << (bit%(SZ_UINT*8)-1));
66 return 0;
67 }
68 };
69
70
71
72 #endif