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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
|
/*
* A simple resizable circular buffer.
*/
#include "rust_internal.h"
bool
is_power_of_two(size_t value) {
if (value > 0) {
return (value & (value - 1)) == 0;
}
return false;
}
circular_buffer::circular_buffer(rust_dom *dom, size_t unit_sz) :
dom(dom),
unit_sz(unit_sz),
_buffer_sz(next_power_of_two(
INITIAL_CIRCULAR_BUFFFER_SIZE_IN_UNITS * unit_sz)),
_next(0),
_unread(0),
_buffer((uint8_t *)dom->calloc(_buffer_sz)) {
A(dom, unit_sz, "Unit size must be larger than zero.");
dom->log(rust_log::MEM | rust_log::COMM,
"new circular_buffer(buffer_sz=%d, unread=%d)"
"-> circular_buffer=0x%" PRIxPTR,
_buffer_sz, _unread, this);
A(dom, _buffer, "Failed to allocate buffer.");
}
circular_buffer::~circular_buffer() {
dom->log(rust_log::MEM, "~circular_buffer 0x%" PRIxPTR, this);
I(dom, _buffer);
W(dom, _unread == 0,
"freeing circular_buffer with %d unread bytes", _unread);
dom->free(_buffer);
}
/**
* Copies the unread data from this buffer to the "dst" address.
*/
void
circular_buffer::transfer(void *dst) {
I(dom, dst);
I(dom, is_power_of_two(_buffer_sz));
uint8_t *ptr = (uint8_t *) dst;
for (size_t i = 0; i < _unread; i += unit_sz) {
memcpy(&ptr[i], &_buffer[(_next + i) & (_buffer_sz - 1)], unit_sz);
}
}
/**
* Copies the data at the "src" address into this buffer. The buffer is
* grown if it isn't large enough.
*/
void
circular_buffer::enqueue(void *src) {
I(dom, src);
I(dom, _unread <= _buffer_sz);
// Grow if necessary.
if (_unread + unit_sz > _buffer_sz) {
size_t new_buffer_sz = _buffer_sz << 1;
I(dom, new_buffer_sz <= MAX_CIRCULAR_BUFFFER_SIZE);
void *new_buffer = dom->malloc(new_buffer_sz);
transfer(new_buffer);
dom->free(_buffer);
_buffer = (uint8_t *)new_buffer;
_next = 0;
_buffer_sz = new_buffer_sz;
}
dom->log(rust_log::MEM | rust_log::COMM,
"circular_buffer enqueue "
"unread: %d, buffer_sz: %d, unit_sz: %d",
_unread, _buffer_sz, unit_sz);
I(dom, is_power_of_two(_buffer_sz));
I(dom, _unread < _buffer_sz);
I(dom, _unread + unit_sz <= _buffer_sz);
// Copy data
size_t i = (_next + _unread) & (_buffer_sz - 1);
memcpy(&_buffer[i], src, unit_sz);
_unread += unit_sz;
dom->log(rust_log::MEM | rust_log::COMM,
"circular_buffer pushed data at index: %d", i);
}
/**
* Copies data from this buffer to the "dst" address. The buffer is
* shrunk if possible. If the "dst" address is NULL, then the message
* is dequeued but is not copied.
*/
void
circular_buffer::dequeue(void *dst) {
I(dom, unit_sz > 0);
I(dom, _unread >= unit_sz);
I(dom, _unread <= _buffer_sz);
I(dom, _buffer);
dom->log(rust_log::MEM | rust_log::COMM,
"circular_buffer dequeue "
"unread: %d, buffer_sz: %d, unit_sz: %d",
_unread, _buffer_sz, unit_sz);
if (dst != NULL) {
memcpy(dst, &_buffer[_next], unit_sz);
}
dom->log(rust_log::MEM | rust_log::COMM,
"shifted data from index %d", _next);
_unread -= unit_sz;
_next += unit_sz;
I(dom, _next <= _buffer_sz);
if (_next == _buffer_sz) {
_next = 0;
}
// Shrink if possible.
if (_buffer_sz >= INITIAL_CIRCULAR_BUFFFER_SIZE_IN_UNITS * unit_sz &&
_unread <= _buffer_sz / 4) {
dom->log(rust_log::MEM | rust_log::COMM,
"circular_buffer is shrinking to %d bytes", _buffer_sz / 2);
void *tmp = dom->malloc(_buffer_sz / 2);
transfer(tmp);
_buffer_sz >>= 1;
dom->free(_buffer);
_buffer = (uint8_t *)tmp;
_next = 0;
}
}
uint8_t *
circular_buffer::peek() {
return &_buffer[_next];
}
bool
circular_buffer::is_empty() {
return _unread == 0;
}
size_t
circular_buffer::size() {
return _unread;
}
|
