cirbuf.cpp
1.92 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
#include "cirbuf.h"
#include <iostream>
#include <exception>
#include <stdexcept>
#include <cassert>
#include <cstring>
CirBuf::CirBuf(size_t size) :
size(size)
{
buf = (char*)malloc(size);
if (buf == NULL)
throw std::runtime_error("Malloc error constructing client.");
#ifndef NDEBUG
memset(buf, 0, size);
#endif
}
CirBuf::~CirBuf()
{
if (buf)
free(buf);
}
uint CirBuf::usedBytes() const
{
int result = (head - tail) & (size-1);
return result;
}
uint CirBuf::freeSpace() const
{
int result = (tail - (head + 1)) & (size-1);
return result;
}
int CirBuf::maxWriteSize() const
{
int end = size - 1 - head;
int n = (end + tail) & (size-1);
int result = n <= end ? n : end+1;
return result;
}
int CirBuf::maxReadSize() const
{
int end = size - tail;
int n = (head + end) & (size-1);
int result = n < end ? n : end;
return result;
}
char *CirBuf::headPtr()
{
return &buf[head];
}
char *CirBuf::tailPtr()
{
return &buf[tail];
}
void CirBuf::advanceHead(int n)
{
head = (head + n) & (size -1);
assert(tail != head); // Putting things in the buffer must never end on tail, because tail == head == empty.
}
void CirBuf::advanceTail(int n)
{
tail = (tail + n) & (size -1);
}
int CirBuf::peakAhead(int offset) const
{
int b = buf[(tail + offset) & (size - 1)];
return b;
}
void CirBuf::doubleSize()
{
uint newSize = size * 2;
char *newBuf = (char*)realloc(buf, newSize);
if (newBuf == NULL)
throw std::runtime_error("Malloc error doubling buffer size.");
uint maxRead = maxReadSize();
buf = newBuf;
if (head < tail)
{
std::memcpy(&buf[tail + maxRead], buf, head);
}
head = tail + usedBytes();
size = newSize;
std::cout << "New buf size: " << size << std::endl;
#ifdef TESTING
memset(&buf[head], 5, maxWriteSize() + 2);
#endif
}
uint CirBuf::getSize() const
{
return size;
}