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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
/**
* OpenAL cross platform audio library
* Copyright (C) 1999-2007 by authors.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include "ringbuffer.h"
#include <algorithm>
#include <climits>
#include <stdexcept>
#include "almalloc.h"
RingBufferPtr RingBuffer::Create(std::size_t sz, std::size_t elem_sz, int limit_writes)
{
std::size_t power_of_two{0u};
if(sz > 0)
{
power_of_two = sz;
power_of_two |= power_of_two>>1;
power_of_two |= power_of_two>>2;
power_of_two |= power_of_two>>4;
power_of_two |= power_of_two>>8;
power_of_two |= power_of_two>>16;
if constexpr(SIZE_MAX > UINT_MAX)
power_of_two |= power_of_two>>32;
}
++power_of_two;
if(power_of_two <= sz || power_of_two > std::numeric_limits<std::size_t>::max()/elem_sz)
throw std::overflow_error{"Ring buffer size overflow"};
const std::size_t bufbytes{power_of_two * elem_sz};
RingBufferPtr rb{new(FamCount(bufbytes)) RingBuffer{bufbytes}};
rb->mWriteSize = limit_writes ? sz : (power_of_two-1);
rb->mSizeMask = power_of_two - 1;
rb->mElemSize = elem_sz;
return rb;
}
void RingBuffer::reset() noexcept
{
mWritePtr.store(0, std::memory_order_relaxed);
mReadPtr.store(0, std::memory_order_relaxed);
std::fill_n(mBuffer.begin(), (mSizeMask+1)*mElemSize, std::byte{});
}
std::size_t RingBuffer::read(void *dest, std::size_t cnt) noexcept
{
const std::size_t free_cnt{readSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_read{std::min(cnt, free_cnt)};
std::size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{read_ptr + to_read};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - read_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_read;
n2 = 0;
}
auto outiter = std::copy_n(mBuffer.begin() + read_ptr*mElemSize, n1*mElemSize,
static_cast<std::byte*>(dest));
read_ptr += n1;
if(n2 > 0)
{
std::copy_n(mBuffer.begin(), n2*mElemSize, outiter);
read_ptr += n2;
}
mReadPtr.store(read_ptr, std::memory_order_release);
return to_read;
}
std::size_t RingBuffer::peek(void *dest, std::size_t cnt) const noexcept
{
const std::size_t free_cnt{readSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_read{std::min(cnt, free_cnt)};
std::size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{read_ptr + to_read};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - read_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_read;
n2 = 0;
}
auto outiter = std::copy_n(mBuffer.begin() + read_ptr*mElemSize, n1*mElemSize,
static_cast<std::byte*>(dest));
if(n2 > 0)
std::copy_n(mBuffer.begin(), n2*mElemSize, outiter);
return to_read;
}
std::size_t RingBuffer::write(const void *src, std::size_t cnt) noexcept
{
const std::size_t free_cnt{writeSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_write{std::min(cnt, free_cnt)};
std::size_t write_ptr{mWritePtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{write_ptr + to_write};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - write_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_write;
n2 = 0;
}
auto srcbytes = static_cast<const std::byte*>(src);
std::copy_n(srcbytes, n1*mElemSize, mBuffer.begin() + write_ptr*mElemSize);
write_ptr += n1;
if(n2 > 0)
{
std::copy_n(srcbytes + n1*mElemSize, n2*mElemSize, mBuffer.begin());
write_ptr += n2;
}
mWritePtr.store(write_ptr, std::memory_order_release);
return to_write;
}
auto RingBuffer::getReadVector() const noexcept -> DataPair
{
DataPair ret;
std::size_t w{mWritePtr.load(std::memory_order_acquire)};
std::size_t r{mReadPtr.load(std::memory_order_acquire)};
w &= mSizeMask;
r &= mSizeMask;
const std::size_t free_cnt{(w-r) & mSizeMask};
const std::size_t cnt2{r + free_cnt};
if(cnt2 > mSizeMask+1)
{
/* Two part vector: the rest of the buffer after the current read ptr,
* plus some from the start of the buffer. */
ret.first.buf = const_cast<std::byte*>(mBuffer.data() + r*mElemSize);
ret.first.len = mSizeMask+1 - r;
ret.second.buf = const_cast<std::byte*>(mBuffer.data());
ret.second.len = cnt2 & mSizeMask;
}
else
{
/* Single part vector: just the rest of the buffer */
ret.first.buf = const_cast<std::byte*>(mBuffer.data() + r*mElemSize);
ret.first.len = free_cnt;
ret.second.buf = nullptr;
ret.second.len = 0;
}
return ret;
}
auto RingBuffer::getWriteVector() const noexcept -> DataPair
{
DataPair ret;
std::size_t w{mWritePtr.load(std::memory_order_acquire)};
std::size_t r{mReadPtr.load(std::memory_order_acquire) + mWriteSize - mSizeMask};
w &= mSizeMask;
r &= mSizeMask;
const std::size_t free_cnt{(r-w-1) & mSizeMask};
const std::size_t cnt2{w + free_cnt};
if(cnt2 > mSizeMask+1)
{
/* Two part vector: the rest of the buffer after the current write ptr,
* plus some from the start of the buffer. */
ret.first.buf = const_cast<std::byte*>(mBuffer.data() + w*mElemSize);
ret.first.len = mSizeMask+1 - w;
ret.second.buf = const_cast<std::byte*>(mBuffer.data());
ret.second.len = cnt2 & mSizeMask;
}
else
{
ret.first.buf = const_cast<std::byte*>(mBuffer.data() + w*mElemSize);
ret.first.len = free_cnt;
ret.second.buf = nullptr;
ret.second.len = 0;
}
return ret;
}
|
