| 249 |
int size; |
int size; |
| 250 |
int wrap_elements; |
int wrap_elements; |
| 251 |
|
|
| 252 |
|
/** |
| 253 |
|
* Independent, random access reading from a RingBuffer. This class |
| 254 |
|
* allows to read from a RingBuffer without being forced to free read |
| 255 |
|
* data while reading / positioning. |
| 256 |
|
*/ |
| 257 |
|
template<class _T> |
| 258 |
|
class _NonVolatileReader { |
| 259 |
|
public: |
| 260 |
|
int read_space() { |
| 261 |
|
int r = read_ptr; |
| 262 |
|
int w = atomic_read(&pBuf->write_ptr); |
| 263 |
|
return (w >= r) ? w - r : (w - r + pBuf->size) & pBuf->size_mask; |
| 264 |
|
} |
| 265 |
|
|
| 266 |
|
/** |
| 267 |
|
* Reads one element from the NonVolatileReader's current read |
| 268 |
|
* position and copies it to the variable pointed by \a dst and |
| 269 |
|
* finally increments the NonVolatileReader's read position by |
| 270 |
|
* one. |
| 271 |
|
* |
| 272 |
|
* @param dst - where the element is copied to |
| 273 |
|
* @returns 1 on success, 0 otherwise |
| 274 |
|
*/ |
| 275 |
|
int pop(T* dst) { return read(dst,1); } |
| 276 |
|
|
| 277 |
|
/** |
| 278 |
|
* Reads \a cnt elements from the NonVolatileReader's current |
| 279 |
|
* read position and copies it to the buffer pointed by \a dest |
| 280 |
|
* and finally increments the NonVolatileReader's read position |
| 281 |
|
* by the number of read elements. |
| 282 |
|
* |
| 283 |
|
* @param dest - destination buffer |
| 284 |
|
* @param cnt - number of elements to read |
| 285 |
|
* @returns number of read elements |
| 286 |
|
*/ |
| 287 |
|
int read(T* dest, int cnt) { |
| 288 |
|
int free_cnt; |
| 289 |
|
int cnt2; |
| 290 |
|
int to_read; |
| 291 |
|
int n1, n2; |
| 292 |
|
int priv_read_ptr; |
| 293 |
|
|
| 294 |
|
priv_read_ptr = read_ptr; |
| 295 |
|
|
| 296 |
|
if ((free_cnt = read_space()) == 0) return 0; |
| 297 |
|
|
| 298 |
|
to_read = cnt > free_cnt ? free_cnt : cnt; |
| 299 |
|
|
| 300 |
|
cnt2 = priv_read_ptr + to_read; |
| 301 |
|
|
| 302 |
|
if (cnt2 > pBuf->size) { |
| 303 |
|
n1 = pBuf->size - priv_read_ptr; |
| 304 |
|
n2 = cnt2 & pBuf->size_mask; |
| 305 |
|
} else { |
| 306 |
|
n1 = to_read; |
| 307 |
|
n2 = 0; |
| 308 |
|
} |
| 309 |
|
|
| 310 |
|
memcpy(dest, &pBuf->buf[priv_read_ptr], n1 * sizeof(T)); |
| 311 |
|
priv_read_ptr = (priv_read_ptr + n1) & pBuf->size_mask; |
| 312 |
|
|
| 313 |
|
if (n2) { |
| 314 |
|
memcpy(dest+n1, pBuf->buf, n2 * sizeof(T)); |
| 315 |
|
priv_read_ptr = n2; |
| 316 |
|
} |
| 317 |
|
|
| 318 |
|
this->read_ptr = priv_read_ptr; |
| 319 |
|
return to_read; |
| 320 |
|
} |
| 321 |
|
protected: |
| 322 |
|
_NonVolatileReader(RingBuffer<_T>* pBuf) { |
| 323 |
|
this->pBuf = pBuf; |
| 324 |
|
this->read_ptr = atomic_read(&pBuf->read_ptr); |
| 325 |
|
} |
| 326 |
|
|
| 327 |
|
RingBuffer<_T>* pBuf; |
| 328 |
|
int read_ptr; |
| 329 |
|
|
| 330 |
|
friend class RingBuffer<_T>; |
| 331 |
|
}; |
| 332 |
|
|
| 333 |
|
typedef _NonVolatileReader<T> NonVolatileReader; |
| 334 |
|
|
| 335 |
|
NonVolatileReader get_non_volatile_reader() { return NonVolatileReader(this); } |
| 336 |
|
|
| 337 |
protected: |
protected: |
| 338 |
T *buf; |
T *buf; |
| 339 |
atomic_t write_ptr; |
atomic_t write_ptr; |
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