Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
/* ring_buffer.h: Simple ring buffer API */

/*
 * Copyright (c) 2015 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */
/** @file */

#ifndef ZEPHYR_INCLUDE_RING_BUFFER_H_
#define ZEPHYR_INCLUDE_RING_BUFFER_H_

#include <kernel.h>
#include <misc/util.h>
#include <errno.h>
#include <string.h>

#ifdef __cplusplus
extern "C" {
#endif

#define SIZE32_OF(x) (sizeof((x))/sizeof(u32_t))

/**
 * @brief A structure to represent a ring buffer
 */
struct ring_buf {
	u32_t head;	 /**< Index in buf for the head element */
	u32_t tail;	 /**< Index in buf for the tail element */
	union ring_buf_misc {
		struct ring_buf_misc_item_mode {
			u32_t dropped_put_count; /**< Running tally of the
						   * number of failed put
						   * attempts.
						   */
		} item_mode;
		struct ring_buf_misc_byte_mode {
			u32_t tmp_tail;
			u32_t tmp_head;
		} byte_mode;
	} misc;
	u32_t size;   /**< Size of buf in 32-bit chunks */

	union ring_buf_buffer {
		u32_t *buf32;	 /**< Memory region for stored entries */
		u8_t *buf8;
	} buf;
	u32_t mask;   /**< Modulo mask if size is a power of 2 */
};

/**
 * @defgroup ring_buffer_apis Ring Buffer APIs
 * @ingroup kernel_apis
 * @{
 */

/**
 * @brief Statically define and initialize a high performance ring buffer.
 *
 * This macro establishes a ring buffer whose size must be a power of 2;
 * that is, the ring buffer contains 2^pow 32-bit words, where @a pow is
 * the specified ring buffer size exponent. A high performance ring buffer
 * doesn't require the use of modulo arithmetic operations to maintain itself.
 *
 * The ring buffer can be accessed outside the module where it is defined
 * using:
 *
 * @code extern struct ring_buf <name>; @endcode
 *
 * @param name Name of the ring buffer.
 * @param pow Ring buffer size exponent.
 */
#define RING_BUF_ITEM_DECLARE_POW2(name, pow) \
	static u32_t _ring_buffer_data_##name[BIT(pow)]; \
	struct ring_buf name = { \
		.size = (BIT(pow)),	  \
		.mask = (BIT(pow)) - 1, \
		.buf = { .buf32 = _ring_buffer_data_##name } \
	}

/** @deprecated Renamed to RING_BUF_ITEM_DECLARE_POW2. */
#define SYS_RING_BUF_DECLARE_POW2(name, pow) \
	__DEPRECATED_MACRO RING_BUF_ITEM_DECLARE_POW2(name, pow)

/**
 * @brief Statically define and initialize a standard ring buffer.
 *
 * This macro establishes a ring buffer of an arbitrary size. A standard
 * ring buffer uses modulo arithmetic operations to maintain itself.
 *
 * The ring buffer can be accessed outside the module where it is defined
 * using:
 *
 * @code extern struct ring_buf <name>; @endcode
 *
 * @param name Name of the ring buffer.
 * @param size32 Size of ring buffer (in 32-bit words).
 */
#define RING_BUF_ITEM_DECLARE_SIZE(name, size32) \
	static u32_t _ring_buffer_data_##name[size32]; \
	struct ring_buf name = { \
		.size = size32, \
		.buf = { .buf32 = _ring_buffer_data_##name} \
	}

/** @deprecated Renamed to RING_BUF_ITEM_DECLARE_SIZE. */
#define SYS_RING_BUF_DECLARE_SIZE(name, size32) \
	__DEPRECATED_MACRO RING_BUF_ITEM_DECLARE_SIZE(name, size32)

/**
 * @brief Statically define and initialize a ring buffer for byte data.
 *
 * This macro establishes a ring buffer of an arbitrary size.
 *
 * The ring buffer can be accessed outside the module where it is defined
 * using:
 *
 * @code extern struct ring_buf <name>; @endcode
 *
 * @param name  Name of the ring buffer.
 * @param size8 Size of ring buffer (in bytes).
 */
#define RING_BUF_DECLARE(name, size8) \
	static u8_t _ring_buffer_data_##name[size8]; \
	struct ring_buf name = { \
		.size = size8, \
		.buf = { .buf8 = _ring_buffer_data_##name} \
	}


/**
 * @brief Initialize a ring buffer.
 *
 * This routine initializes a ring buffer, prior to its first use. It is only
 * used for ring buffers not defined using RING_BUF_DECLARE,
 * RING_BUF_ITEM_DECLARE_POW2 or RING_BUF_ITEM_DECLARE_SIZE.
 *
 * Setting @a size to a power of 2 establishes a high performance ring buffer
 * that doesn't require the use of modulo arithmetic operations to maintain
 * itself.
 *
 * @param buf Address of ring buffer.
 * @param size Ring buffer size (in 32-bit words or bytes).
 * @param data Ring buffer data area (u32_t data[size] or u8_t data[size] for
 *	       bytes mode).
 */
static inline void ring_buf_init(struct ring_buf *buf, u32_t size, void *data)
{
	memset(buf, 0, sizeof(struct ring_buf));
	buf->size = size;
	buf->buf.buf32 = (u32_t *)data;
	if (is_power_of_two(size)) {
		buf->mask = size - 1;
	} else {
		buf->mask = 0U;
	}
}

/** @deprecated Renamed to ring_buf_init. */
__deprecated static inline void sys_ring_buf_init(struct ring_buf *buf,
						  u32_t size, u32_t *data)
{
	ring_buf_init(buf, size, data);
}

/** @brief Determine free space based on ring buffer parameters.
 *
 * @note Function for internal use.
 *
 * @param size Ring buffer size.
 * @param head Ring buffer head.
 * @param tail Ring buffer tail.
 *
 *  @return Ring buffer free space (in 32-bit words or bytes).
 */
static inline int z_ring_buf_custom_space_get(u32_t size, u32_t head,
					      u32_t tail)
{
	if (tail < head) {
		return head - tail - 1;
	}

	/* buf->tail > buf->head */
	return (size - tail) + head - 1;
}

/**
 * @brief Determine if a ring buffer is empty.
 *
 * @param buf Address of ring buffer.
 *
 * @return 1 if the ring buffer is empty, or 0 if not.
 */
static inline int ring_buf_is_empty(struct ring_buf *buf)
{
	return (buf->head == buf->tail);
}
/** @deprecated Renamed to ring_buf_is_empty. */
__deprecated static inline int sys_ring_buf_is_empty(struct ring_buf *buf)
{
	return ring_buf_is_empty(buf);
}

/**
 * @brief Determine free space in a ring buffer.
 *
 * @param buf Address of ring buffer.
 *
 * @return Ring buffer free space (in 32-bit words or bytes).
 */
static inline int ring_buf_space_get(struct ring_buf *buf)
{
	return z_ring_buf_custom_space_get(buf->size, buf->head, buf->tail);
}

/** @deprecated Renamed to ring_buf_space_get. */
__deprecated static inline int sys_ring_buf_space_get(struct ring_buf *buf)
{
	return ring_buf_space_get(buf);
}

/**
 * @brief Write a data item to a ring buffer.
 *
 * This routine writes a data item to ring buffer @a buf. The data item
 * is an array of 32-bit words (from zero to 1020 bytes in length),
 * coupled with a 16-bit type identifier and an 8-bit integer value.
 *
 * @warning
 * Use cases involving multiple writers to the ring buffer must prevent
 * concurrent write operations, either by preventing all writers from
 * being preempted or by using a mutex to govern writes to the ring buffer.
 *
 * @param buf Address of ring buffer.
 * @param type Data item's type identifier (application specific).
 * @param value Data item's integer value (application specific).
 * @param data Address of data item.
 * @param size32 Data item size (number of 32-bit words).
 *
 * @retval 0 Data item was written.
 * @retval -EMSGSIZE Ring buffer has insufficient free space.
 */
int ring_buf_item_put(struct ring_buf *buf, u16_t type, u8_t value,
		      u32_t *data, u8_t size32);


/** @deprecated Renamed to ring_buf_item_put. */
__deprecated static inline int sys_ring_buf_put(struct ring_buf *buf,
						u16_t type, u8_t value,
						u32_t *data, u8_t size32)
{
	return ring_buf_item_put(buf, type, value, data, size32);
}

/**
 * @brief Read a data item from a ring buffer.
 *
 * This routine reads a data item from ring buffer @a buf. The data item
 * is an array of 32-bit words (up to 1020 bytes in length),
 * coupled with a 16-bit type identifier and an 8-bit integer value.
 *
 * @warning
 * Use cases involving multiple reads of the ring buffer must prevent
 * concurrent read operations, either by preventing all readers from
 * being preempted or by using a mutex to govern reads to the ring buffer.
 *
 * @param buf Address of ring buffer.
 * @param type Area to store the data item's type identifier.
 * @param value Area to store the data item's integer value.
 * @param data Area to store the data item.
 * @param size32 Size of the data item storage area (number of 32-bit chunks).
 *
 * @retval 0 Data item was fetched; @a size32 now contains the number of
 *         32-bit words read into data area @a data.
 * @retval -EAGAIN Ring buffer is empty.
 * @retval -EMSGSIZE Data area @a data is too small; @a size32 now contains
 *         the number of 32-bit words needed.
 */
int ring_buf_item_get(struct ring_buf *buf, u16_t *type, u8_t *value,
		      u32_t *data, u8_t *size32);

/** @deprecated Renamed to ring_buf_item_get. */
__deprecated static inline int sys_ring_buf_get(struct ring_buf *buf,
						u16_t *type, u8_t *value,
						u32_t *data, u8_t *size32)
{
	return ring_buf_item_get(buf, type, value, data, size32);
}

/**
 * @brief Allocate buffer for writing data to a ring buffer.
 *
 * With this routine, memory copying can be reduced since internal ring buffer
 * can be used directly by the user. Once data is written to allocated area
 * number of bytes written can be confirmed (see @ref ring_buf_put_finish).
 *
 * @warning
 * Use cases involving multiple writers to the ring buffer must prevent
 * concurrent write operations, either by preventing all writers from
 * being preempted or by using a mutex to govern writes to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and item access
 * (calls prefixed with ring_buf_item_).
 *
 * @param[in]  buf  Address of ring buffer.
 * @param[out] data Pointer to the address. It is set to a location within
 *		    ring buffer.
 * @param[in]  size Requested allocation size (in bytes).
 *
 * @return Size of allocated buffer which can be smaller than requested if
 *	   there is not enough free space or buffer wraps.
 */
u32_t ring_buf_put_claim(struct ring_buf *buf, u8_t **data, u32_t size);

/**
 * @brief Indicate number of bytes written to allocated buffers.
 *
 * @warning
 * Use cases involving multiple writers to the ring buffer must prevent
 * concurrent write operations, either by preventing all writers from
 * being preempted or by using a mutex to govern writes to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and item access
 * (calls prefixed with ring_buf_item_).
 *
 * @param  buf  Address of ring buffer.
 * @param  size Number of valid bytes in the allocated buffers.
 *
 * @retval 0 Successful operation.
 * @retval -EINVAL Provided @a size exceeds free space in the ring buffer.
 */
int ring_buf_put_finish(struct ring_buf *buf, u32_t size);

/**
 * @brief Write (copy) data to a ring buffer.
 *
 * This routine writes data to a ring buffer @a buf.
 *
 * @warning
 * Use cases involving multiple writers to the ring buffer must prevent
 * concurrent write operations, either by preventing all writers from
 * being preempted or by using a mutex to govern writes to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and item access
 * (calls prefixed with ring_buf_item_).
 *
 * @param buf Address of ring buffer.
 * @param data Address of data.
 * @param size Data size (in bytes).
 *
 * @retval Number of bytes written.
 */
u32_t ring_buf_put(struct ring_buf *buf, const u8_t *data, u32_t size);

/**
 * @brief Get address of a valid data in a ring buffer.
 *
 * With this routine, memory copying can be reduced since internal ring buffer
 * can be used directly by the user. Once data is processed it can be freed
 * using @ref ring_buf_get_finish.
 *
 * @warning
 * Use cases involving multiple reads of the ring buffer must prevent
 * concurrent read operations, either by preventing all readers from
 * being preempted or by using a mutex to govern reads to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and item access
 * (calls prefixed with ring_buf_item_).
 *
 * @param[in]  buf  Address of ring buffer.
 * @param[out] data Pointer to the address. It is set to a location within
 *		    ring buffer.
 * @param[in]  size Requested size (in bytes).
 *
 * @return Number of valid bytes in the provided buffer which can be smaller
 *	   than requested if there is not enough free space or buffer wraps.
 */
u32_t ring_buf_get_claim(struct ring_buf *buf, u8_t **data, u32_t size);

/**
 * @brief Indicate number of bytes read from claimed buffer.
 *
 * @warning
 * Use cases involving multiple reads of the ring buffer must prevent
 * concurrent read operations, either by preventing all readers from
 * being preempted or by using a mutex to govern reads to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and  item mode
 * (calls prefixed with ring_buf_item_).
 *
 * @param  buf  Address of ring buffer.
 * @param  size Number of bytes that can be freed.
 *
 * @retval 0 Successful operation.
 * @retval -EINVAL Provided @a size exceeds valid bytes in the ring buffer.
 */
int ring_buf_get_finish(struct ring_buf *buf, u32_t size);

/**
 * @brief Read data from a ring buffer.
 *
 * This routine reads data from a ring buffer @a buf.
 *
 * @warning
 * Use cases involving multiple reads of the ring buffer must prevent
 * concurrent read operations, either by preventing all readers from
 * being preempted or by using a mutex to govern reads to the ring buffer.
 *
 * @warning
 * Ring buffer instance should not mix byte access and  item mode
 * (calls prefixed with ring_buf_item_).
 *
 * @param buf  Address of ring buffer.
 * @param data Address of the output buffer.
 * @param size Data size (in bytes).
 *
 * @retval Number of bytes written to the output buffer.
 */
u32_t ring_buf_get(struct ring_buf *buf, u8_t *data, u32_t size);

/**
 * @}
 */

#ifdef __cplusplus
}
#endif

#endif /* ZEPHYR_INCLUDE_RING_BUFFER_H_ */