Repository navigation
Expand file tree
/
Copy pathSDL_dataqueue.c
More file actions
323 lines (265 loc) · 9.2 KB
/
Copy pathSDL_dataqueue.c
File metadata and controls
323 lines (265 loc) · 9.2 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
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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
/*
Simple DirectMedia Layer
Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "./SDL_internal.h"
#include "SDL.h"
#include "./SDL_dataqueue.h"
typedef struct SDL_DataQueuePacket
{
size_t datalen; /* bytes currently in use in this packet. */
size_t startpos; /* bytes currently consumed in this packet. */
struct SDL_DataQueuePacket *next; /* next item in linked list. */
Uint8 data[SDL_VARIABLE_LENGTH_ARRAY]; /* packet data */
} SDL_DataQueuePacket;
struct SDL_DataQueue
{
SDL_mutex *lock;
SDL_DataQueuePacket *head; /* device fed from here. */
SDL_DataQueuePacket *tail; /* queue fills to here. */
SDL_DataQueuePacket *pool; /* these are unused packets. */
size_t packet_size; /* size of new packets */
size_t queued_bytes; /* number of bytes of data in the queue. */
};
static void SDL_FreeDataQueueList(SDL_DataQueuePacket *packet)
{
while (packet) {
SDL_DataQueuePacket *next = packet->next;
SDL_free(packet);
packet = next;
}
}
SDL_DataQueue *SDL_NewDataQueue(const size_t _packetlen, const size_t initialslack)
{
SDL_DataQueue *queue = (SDL_DataQueue *)SDL_calloc(1, sizeof(SDL_DataQueue));
if (queue == NULL) {
SDL_OutOfMemory();
} else {
const size_t packetlen = _packetlen ? _packetlen : 1024;
const size_t wantpackets = (initialslack + (packetlen - 1)) / packetlen;
size_t i;
queue->packet_size = packetlen;
queue->lock = SDL_CreateMutex();
if (!queue->lock) {
SDL_free(queue);
return NULL;
}
for (i = 0; i < wantpackets; i++) {
SDL_DataQueuePacket *packet = (SDL_DataQueuePacket *)SDL_malloc(sizeof(SDL_DataQueuePacket) + packetlen);
if (packet) { /* don't care if this fails, we'll deal later. */
packet->datalen = 0;
packet->startpos = 0;
packet->next = queue->pool;
queue->pool = packet;
}
}
}
return queue;
}
void SDL_FreeDataQueue(SDL_DataQueue *queue)
{
if (queue) {
SDL_FreeDataQueueList(queue->head);
SDL_FreeDataQueueList(queue->pool);
SDL_DestroyMutex(queue->lock);
SDL_free(queue);
}
}
void SDL_ClearDataQueue(SDL_DataQueue *queue, const size_t slack)
{
const size_t packet_size = queue ? queue->packet_size : 1;
const size_t slackpackets = (slack + (packet_size - 1)) / packet_size;
SDL_DataQueuePacket *packet;
SDL_DataQueuePacket *prev = NULL;
size_t i;
if (queue == NULL) {
return;
}
SDL_LockMutex(queue->lock);
packet = queue->head;
/* merge the available pool and the current queue into one list. */
if (packet) {
queue->tail->next = queue->pool;
} else {
packet = queue->pool;
}
/* Remove the queued packets from the device. */
queue->tail = NULL;
queue->head = NULL;
queue->queued_bytes = 0;
queue->pool = packet;
/* Optionally keep some slack in the pool to reduce memory allocation pressure. */
for (i = 0; packet && (i < slackpackets); i++) {
prev = packet;
packet = packet->next;
}
if (prev) {
prev->next = NULL;
} else {
queue->pool = NULL;
}
SDL_UnlockMutex(queue->lock);
SDL_FreeDataQueueList(packet); /* free extra packets */
}
/* You must hold queue->lock before calling this! */
static SDL_DataQueuePacket *AllocateDataQueuePacket(SDL_DataQueue *queue)
{
SDL_DataQueuePacket *packet;
SDL_assert(queue != NULL);
packet = queue->pool;
if (packet != NULL) {
/* we have one available in the pool. */
queue->pool = packet->next;
} else {
/* Have to allocate a new one! */
packet = (SDL_DataQueuePacket *)SDL_malloc(sizeof(SDL_DataQueuePacket) + queue->packet_size);
if (packet == NULL) {
return NULL;
}
}
packet->datalen = 0;
packet->startpos = 0;
packet->next = NULL;
SDL_assert((queue->head != NULL) == (queue->queued_bytes != 0));
if (queue->tail == NULL) {
queue->head = packet;
} else {
queue->tail->next = packet;
}
queue->tail = packet;
return packet;
}
int SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *_data, const size_t _len)
{
size_t len = _len;
const Uint8 *data = (const Uint8 *)_data;
const size_t packet_size = queue ? queue->packet_size : 0;
SDL_DataQueuePacket *orighead;
SDL_DataQueuePacket *origtail;
size_t origlen;
size_t datalen;
if (queue == NULL) {
return SDL_InvalidParamError("queue");
}
SDL_LockMutex(queue->lock);
orighead = queue->head;
origtail = queue->tail;
origlen = origtail ? origtail->datalen : 0;
while (len > 0) {
SDL_DataQueuePacket *packet = queue->tail;
SDL_assert(packet == NULL || (packet->datalen <= packet_size));
if (packet == NULL || (packet->datalen >= packet_size)) {
/* tail packet missing or completely full; we need a new packet. */
packet = AllocateDataQueuePacket(queue);
if (packet == NULL) {
/* uhoh, reset so we've queued nothing new, free what we can. */
if (origtail == NULL) {
packet = queue->head; /* whole queue. */
} else {
packet = origtail->next; /* what we added to existing queue. */
origtail->next = NULL;
origtail->datalen = origlen;
}
queue->head = orighead;
queue->tail = origtail;
queue->pool = NULL;
SDL_UnlockMutex(queue->lock);
SDL_FreeDataQueueList(packet); /* give back what we can. */
return SDL_OutOfMemory();
}
}
datalen = SDL_min(len, packet_size - packet->datalen);
SDL_memcpy(packet->data + packet->datalen, data, datalen);
data += datalen;
len -= datalen;
packet->datalen += datalen;
queue->queued_bytes += datalen;
}
SDL_UnlockMutex(queue->lock);
return 0;
}
size_t
SDL_PeekIntoDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
{
size_t len = _len;
Uint8 *buf = (Uint8 *)_buf;
Uint8 *ptr = buf;
SDL_DataQueuePacket *packet;
if (queue == NULL) {
return 0;
}
SDL_LockMutex(queue->lock);
for (packet = queue->head; len && packet; packet = packet->next) {
const size_t avail = packet->datalen - packet->startpos;
const size_t cpy = SDL_min(len, avail);
SDL_assert(queue->queued_bytes >= avail);
SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
ptr += cpy;
len -= cpy;
}
SDL_UnlockMutex(queue->lock);
return (size_t)(ptr - buf);
}
size_t
SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
{
size_t len = _len;
Uint8 *buf = (Uint8 *)_buf;
Uint8 *ptr = buf;
SDL_DataQueuePacket *packet;
if (queue == NULL) {
return 0;
}
SDL_LockMutex(queue->lock);
while ((len > 0) && ((packet = queue->head) != NULL)) {
const size_t avail = packet->datalen - packet->startpos;
const size_t cpy = SDL_min(len, avail);
SDL_assert(queue->queued_bytes >= avail);
SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
packet->startpos += cpy;
ptr += cpy;
queue->queued_bytes -= cpy;
len -= cpy;
if (packet->startpos == packet->datalen) { /* packet is done, put it in the pool. */
queue->head = packet->next;
SDL_assert((packet->next != NULL) || (packet == queue->tail));
packet->next = queue->pool;
queue->pool = packet;
}
}
SDL_assert((queue->head != NULL) == (queue->queued_bytes != 0));
if (queue->head == NULL) {
queue->tail = NULL; /* in case we drained the queue entirely. */
}
SDL_UnlockMutex(queue->lock);
return (size_t)(ptr - buf);
}
size_t
SDL_CountDataQueue(SDL_DataQueue *queue)
{
size_t retval = 0;
if (queue) {
SDL_LockMutex(queue->lock);
retval = queue->queued_bytes;
SDL_UnlockMutex(queue->lock);
}
return retval;
}
SDL_mutex *SDL_GetDataQueueMutex(SDL_DataQueue *queue)
{
return queue ? queue->lock : NULL;
}
/* vi: set ts=4 sw=4 expandtab: */