trunk/src/ringbuffer.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003 by Benno Senoner and Christian Schoenebeck         *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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 General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef RINGBUFFER_H
#define RINGBUFFER_H

#define DEFAULT_WRAP_ELEMENTS 1024

#include <string.h>
#include <stdio.h>
#include <asm/atomic.h>

#include <sys/types.h>
#include <pthread.h>

template<class T>
class RingBuffer
{
public:
    RingBuffer (int sz, int wrap_elements = DEFAULT_WRAP_ELEMENTS) {
            int power_of_two;

            this->wrap_elements = wrap_elements;

            for (power_of_two = 1;
                 1<<power_of_two < sz;
                 power_of_two++);

            size = 1<<power_of_two;
            size_mask = size;
            size_mask -= 1;
            atomic_set(&write_ptr, 0);
            atomic_set(&read_ptr, 0);
            buf = new T[size + wrap_elements];
    };

    virtual ~RingBuffer() {
            delete [] buf;
    }

    /**
     * Sets all remaining write space elements to zero. The write pointer
     * will currently not be incremented after, but that might change in
     * future.
     */
    inline void fill_write_space_with_null() {
             int w = atomic_read(&write_ptr),
                 r = atomic_read(&read_ptr);
             memset(get_write_ptr(), 0, write_space_to_end());
             if (r && w >= r) {
               memset(get_buffer_begin(), 0, r - 1);
             }

             // set the wrap space elements to null
             if (wrap_elements) memset(&buf[size], 0, wrap_elements);
           }

    __inline int  read (T *dest, int cnt);
    __inline int  write (T *src, int cnt);

    inline int push(T* src) { return write(src,1); }
    inline int pop(T* dst)  { return read(dst,1);  }

    __inline T *get_buffer_begin();

    __inline T *get_read_ptr(void) {
      return(&buf[atomic_read(&read_ptr)]);
    }

    /**
     * Returns a pointer to the element from the current read position,
     * advanced by \a offset elements.
     */
    /*inline T* get_read_ptr(int offset) {
        int r = atomic_read(&read_ptr);
        r += offset;
        r &= size_mask;
        return &buf[r];
    }*/

    __inline T *get_write_ptr();
    __inline void increment_read_ptr(int cnt) {
               atomic_set(&read_ptr , (atomic_read(&read_ptr) + cnt) & size_mask);
             }                
    __inline void set_read_ptr(int val) {
               atomic_set(&read_ptr , val);
             }                

    __inline void increment_write_ptr(int cnt) {
               atomic_set(&write_ptr,  (atomic_read(&write_ptr) + cnt) & size_mask);
             }                

    /* this function increments the write_ptr by cnt, if the buffer wraps then
       subtract size from the write_ptr value so that it stays within 0<write_ptr<size
       use this function to increment the write ptr after you filled the buffer
       with a number of elements given by write_space_to_end_with_wrap().
       This ensures that the data that is written to the buffer fills up all
       the wrap space that resides past the regular buffer. The wrap_space is needed for
       interpolation. So that the audio thread sees the ringbuffer like a linear space
       which allows us to use faster routines.
       When the buffer wraps the wrap part is memcpy()ied to the beginning of the buffer
       and the write ptr incremented accordingly.       
    */
    __inline void increment_write_ptr_with_wrap(int cnt) {
               int w=atomic_read(&write_ptr);
               w += cnt;
               if(w >= size) {
                 w -= size;
                 memcpy(&buf[0], &buf[size], w*sizeof(T));
//printf("DEBUG !!!! increment_write_ptr_with_wrap: buffer wrapped, elements wrapped = %d (wrap_elements %d)\n",w,wrap_elements);
               } 
               atomic_set(&write_ptr, w);
             }                

    /* this function returns the available write space in the buffer
       when the read_ptr > write_ptr it returns the space inbetween, otherwise
       when the read_ptr < write_ptr it returns the space between write_ptr and
       the buffer end, including the wrap_space.
       There is an exception to it. When read_ptr <= wrap_elements. In that
       case we return the write space to buffer end (-1) without the wrap_elements,
       this is needed because a subsequent increment_write_ptr which copies the
       data that resides into the wrap space to the beginning of the buffer and increments
       the write_ptr would cause the write_ptr overstepping the read_ptr which would be an error.
       So basically the if(r<=wrap_elements) we return the buffer space to end - 1 which
       ensures that at the next call there will be one element free to write before the buffer wraps
       and usually (except in EOF situations) the next write_space_to_end_with_wrap() will return
       1 + wrap_elements which ensures that the wrap part gets fully filled with data
    */
    __inline int write_space_to_end_with_wrap() {
              int w, r;

              w = atomic_read(&write_ptr);
              r = atomic_read(&read_ptr);
//printf("write_space_to_end: w=%d r=%d\n",w,r);
              if(r > w) {
                //printf("DEBUG: write_space_to_end_with_wrap: r>w r=%d w=%d val=%d\n",r,w,r - w - 1);
                return(r - w - 1);
              }
              if(r <= wrap_elements) {
                //printf("DEBUG: write_space_to_end_with_wrap: ATTENTION r <= wrap_elements: r=%d w=%d val=%d\n",r,w,size - w -1);
                return(size - w -1);
              }
              if(r) {
                //printf("DEBUG: write_space_to_end_with_wrap: r=%d w=%d val=%d\n",r,w,size - w + wrap_elements);
                return(size - w + wrap_elements);
              }
              //printf("DEBUG: write_space_to_end_with_wrap: r=0 w=%d val=%d\n",w,size - w - 1 + wrap_elements);
              return(size - w - 1 + wrap_elements);
            }

           /* this function adjusts the number of elements to write into the ringbuffer
              in a way that the size boundary is avoided and that the wrap space always gets
              entirely filled.
              cnt contains the write_space_to_end_with_wrap() amount while 
              capped_cnt contains a capped amount of samples to read. 
              normally capped_cnt == cnt but in some cases eg when the disk thread needs
              to refill tracks with smaller blocks because lots of streams require immediate
              refill because lots of notes were started simultaneously.
              In that case we set for example capped_cnt to a fixed amount (< cnt, eg 64k),
              which helps to reduce the buffer refill latencies that occur between streams.
              the first if() checks if the current write_ptr + capped_cnt resides within
              the wrap area but is < size+wrap_elements. in that case we cannot return 
              capped_cnt because it would lead to a write_ptr wrapping and only a partial fill
              of wrap space which would lead to errors. So we simply return cnt which ensures
              that the the entire wrap space will get filled correctly.
              In all other cases (which are not problematic because no write_ptr wrapping 
              occurs) we simply return capped_cnt.
           */
    __inline int adjust_write_space_to_avoid_boundary(int cnt, int capped_cnt) {
               int w;
               w = atomic_read(&write_ptr);
               if((w+capped_cnt) >= size && (w+capped_cnt) < (size+wrap_elements)) {
//printf("adjust_write_space_to_avoid_boundary returning cnt = %d\n",cnt);
                 return(cnt);
               }
//printf("adjust_write_space_to_avoid_boundary returning capped_cnt = %d\n",capped_cnt);
               return(capped_cnt);
             }

    __inline int write_space_to_end() {
              int w, r;

              w = atomic_read(&write_ptr);
              r = atomic_read(&read_ptr);
//printf("write_space_to_end: w=%d r=%d\n",w,r);
              if(r > w) return(r - w - 1);
              if(r) return(size - w);
              return(size - w - 1);
            }

    __inline int read_space_to_end() {
              int w, r;

              w = atomic_read(&write_ptr);
              r = atomic_read(&read_ptr);
              if(w >= r) return(w - r);
              return(size - r);
            }
    __inline void init() {
                   atomic_set(&write_ptr, 0);
                   atomic_set(&read_ptr, 0);
                 //  wrap=0;
            }

    int write_space () {
            int w, r;

            w = atomic_read(&write_ptr);
            r = atomic_read(&read_ptr);

            if (w > r) {
                    return ((r - w + size) & size_mask) - 1;
            } else if (w < r) {
                    return (r - w) - 1;
            } else {
                    return size - 1;
            }
    }

    int read_space () {
            int w, r;

            w = atomic_read(&write_ptr);
            r = atomic_read(&read_ptr);

            if (w >= r) {
                    return w - r;
            } else {
                    return (w - r + size) & size_mask;
            }
    }

    int size;
    int wrap_elements;

  protected:
    T *buf;
    atomic_t write_ptr;
    atomic_t read_ptr;
    int size_mask;
};

template<class T> T *
RingBuffer<T>::get_write_ptr (void) {
  return(&buf[atomic_read(&write_ptr)]);
}

template<class T> T *
RingBuffer<T>::get_buffer_begin (void) {
  return(buf);
}


template<class T> int
RingBuffer<T>::read (T *dest, int cnt)

{
        int free_cnt;
        int cnt2;
        int to_read;
        int n1, n2;
        int priv_read_ptr;

        priv_read_ptr=atomic_read(&read_ptr);

        if ((free_cnt = read_space ()) == 0) {
                return 0;
        }

        to_read = cnt > free_cnt ? free_cnt : cnt;
        
        cnt2 = priv_read_ptr + to_read;

        if (cnt2 > size) {
                n1 = size - priv_read_ptr;
                n2 = cnt2 & size_mask;
        } else {
                n1 = to_read;
                n2 = 0;
        }
        
        memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
        priv_read_ptr = (priv_read_ptr + n1) & size_mask;

        if (n2) {
                memcpy (dest+n1, buf, n2 * sizeof (T));
                priv_read_ptr = n2;
        }

        atomic_set(&read_ptr, priv_read_ptr);
        return to_read;
}

template<class T> int
RingBuffer<T>::write (T *src, int cnt)

{
        int free_cnt;
        int cnt2;
        int to_write;
        int n1, n2;
        int priv_write_ptr;

        priv_write_ptr=atomic_read(&write_ptr);

        if ((free_cnt = write_space ()) == 0) {
                return 0;
        }

        to_write = cnt > free_cnt ? free_cnt : cnt;
        
        cnt2 = priv_write_ptr + to_write;

        if (cnt2 > size) {
                n1 = size - priv_write_ptr;
                n2 = cnt2 & size_mask;
        } else {
                n1 = to_write;
                n2 = 0;
        }

        memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
        priv_write_ptr = (priv_write_ptr + n1) & size_mask;

        if (n2) {
                memcpy (buf, src+n1, n2 * sizeof (T));
                priv_write_ptr = n2;
        }
        atomic_set(&write_ptr, priv_write_ptr);
        return to_write;
}


#endif /* RINGBUFFER_H */
1	schoenebeck	9	/***************************************************************************
2			* *
3			* LinuxSampler - modular, streaming capable sampler *
4			* *
5			* Copyright (C) 2003 by Benno Senoner and Christian Schoenebeck *
6			* *
7			* This program is free software; you can redistribute it and/or modify *
8			* it under the terms of the GNU General Public License as published by *
9			* the Free Software Foundation; either version 2 of the License, or *
10			* (at your option) any later version. *
11			* *
12			* This program is distributed in the hope that it will be useful, *
13			* but WITHOUT ANY WARRANTY; without even the implied warranty of *
14			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
15			* GNU General Public License for more details. *
16			* *
17			* You should have received a copy of the GNU General Public License *
18			* along with this program; if not, write to the Free Software *
19			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
20			* MA 02111-1307 USA *
21			***************************************************************************/
22
23			#ifndef RINGBUFFER_H
24			#define RINGBUFFER_H
25
26			#define DEFAULT_WRAP_ELEMENTS 1024
27
28			#include <string.h>
29			#include <stdio.h>
30			#include <asm/atomic.h>
31
32			#include <sys/types.h>
33			#include <pthread.h>
34
35			template<class T>
36			class RingBuffer
37			{
38			public:
39			RingBuffer (int sz, int wrap_elements = DEFAULT_WRAP_ELEMENTS) {
40			int power_of_two;
41
42			this->wrap_elements = wrap_elements;
43
44			for (power_of_two = 1;
45			1<<power_of_two < sz;
46			power_of_two++);
47
48			size = 1<<power_of_two;
49			size_mask = size;
50			size_mask -= 1;
51			atomic_set(&write_ptr, 0);
52			atomic_set(&read_ptr, 0);
53			buf = new T[size + wrap_elements];
54			};
55
56			virtual ~RingBuffer() {
57			delete [] buf;
58			}
59
60			/**
61			* Sets all remaining write space elements to zero. The write pointer
62			* will currently not be incremented after, but that might change in
63			* future.
64			*/
65			inline void fill_write_space_with_null() {
66			int w = atomic_read(&write_ptr),
67			r = atomic_read(&read_ptr);
68			memset(get_write_ptr(), 0, write_space_to_end());
69			if (r && w >= r) {
70			memset(get_buffer_begin(), 0, r - 1);
71			}
72
73			// set the wrap space elements to null
74			if (wrap_elements) memset(&buf[size], 0, wrap_elements);
75			}
76
77			__inline int read (T *dest, int cnt);
78			__inline int write (T *src, int cnt);
79	schoenebeck	18
80			inline int push(T* src) { return write(src,1); }
81			inline int pop(T* dst) { return read(dst,1); }
82
83	schoenebeck	9	__inline T *get_buffer_begin();
84
85			__inline T *get_read_ptr(void) {
86			return(&buf[atomic_read(&read_ptr)]);
87			}
88
89	schoenebeck	18	/**
90			* Returns a pointer to the element from the current read position,
91			* advanced by \a offset elements.
92			*/
93			/inline T get_read_ptr(int offset) {
94			int r = atomic_read(&read_ptr);
95			r += offset;
96			r &= size_mask;
97			return &buf[r];
98			}*/
99
100	schoenebeck	9	__inline T *get_write_ptr();
101			__inline void increment_read_ptr(int cnt) {
102			atomic_set(&read_ptr , (atomic_read(&read_ptr) + cnt) & size_mask);
103			}
104			__inline void set_read_ptr(int val) {
105			atomic_set(&read_ptr , val);
106			}
107
108			__inline void increment_write_ptr(int cnt) {
109			atomic_set(&write_ptr, (atomic_read(&write_ptr) + cnt) & size_mask);
110			}
111
112			/* this function increments the write_ptr by cnt, if the buffer wraps then
113			subtract size from the write_ptr value so that it stays within 0<write_ptr<size
114			use this function to increment the write ptr after you filled the buffer
115			with a number of elements given by write_space_to_end_with_wrap().
116			This ensures that the data that is written to the buffer fills up all
117			the wrap space that resides past the regular buffer. The wrap_space is needed for
118			interpolation. So that the audio thread sees the ringbuffer like a linear space
119			which allows us to use faster routines.
120			When the buffer wraps the wrap part is memcpy()ied to the beginning of the buffer
121			and the write ptr incremented accordingly.
122			*/
123			__inline void increment_write_ptr_with_wrap(int cnt) {
124			int w=atomic_read(&write_ptr);
125			w += cnt;
126			if(w >= size) {
127			w -= size;
128			memcpy(&buf[0], &buf[size], w*sizeof(T));
129			//printf("DEBUG !!!! increment_write_ptr_with_wrap: buffer wrapped, elements wrapped = %d (wrap_elements %d)\n",w,wrap_elements);
130			}
131			atomic_set(&write_ptr, w);
132			}
133
134			/* this function returns the available write space in the buffer
135			when the read_ptr > write_ptr it returns the space inbetween, otherwise
136			when the read_ptr < write_ptr it returns the space between write_ptr and
137			the buffer end, including the wrap_space.
138			There is an exception to it. When read_ptr <= wrap_elements. In that
139			case we return the write space to buffer end (-1) without the wrap_elements,
140			this is needed because a subsequent increment_write_ptr which copies the
141			data that resides into the wrap space to the beginning of the buffer and increments
142			the write_ptr would cause the write_ptr overstepping the read_ptr which would be an error.
143			So basically the if(r<=wrap_elements) we return the buffer space to end - 1 which
144			ensures that at the next call there will be one element free to write before the buffer wraps
145			and usually (except in EOF situations) the next write_space_to_end_with_wrap() will return
146			1 + wrap_elements which ensures that the wrap part gets fully filled with data
147			*/
148			__inline int write_space_to_end_with_wrap() {
149			int w, r;
150
151			w = atomic_read(&write_ptr);
152			r = atomic_read(&read_ptr);
153			//printf("write_space_to_end: w=%d r=%d\n",w,r);
154			if(r > w) {
155			//printf("DEBUG: write_space_to_end_with_wrap: r>w r=%d w=%d val=%d\n",r,w,r - w - 1);
156			return(r - w - 1);
157			}
158			if(r <= wrap_elements) {
159			//printf("DEBUG: write_space_to_end_with_wrap: ATTENTION r <= wrap_elements: r=%d w=%d val=%d\n",r,w,size - w -1);
160			return(size - w -1);
161			}
162			if(r) {
163			//printf("DEBUG: write_space_to_end_with_wrap: r=%d w=%d val=%d\n",r,w,size - w + wrap_elements);
164			return(size - w + wrap_elements);
165			}
166			//printf("DEBUG: write_space_to_end_with_wrap: r=0 w=%d val=%d\n",w,size - w - 1 + wrap_elements);
167			return(size - w - 1 + wrap_elements);
168			}
169
170			/* this function adjusts the number of elements to write into the ringbuffer
171			in a way that the size boundary is avoided and that the wrap space always gets
172			entirely filled.
173			cnt contains the write_space_to_end_with_wrap() amount while
174			capped_cnt contains a capped amount of samples to read.
175			normally capped_cnt == cnt but in some cases eg when the disk thread needs
176			to refill tracks with smaller blocks because lots of streams require immediate
177			refill because lots of notes were started simultaneously.
178			In that case we set for example capped_cnt to a fixed amount (< cnt, eg 64k),
179			which helps to reduce the buffer refill latencies that occur between streams.
180			the first if() checks if the current write_ptr + capped_cnt resides within
181			the wrap area but is < size+wrap_elements. in that case we cannot return
182			capped_cnt because it would lead to a write_ptr wrapping and only a partial fill
183			of wrap space which would lead to errors. So we simply return cnt which ensures
184			that the the entire wrap space will get filled correctly.
185			In all other cases (which are not problematic because no write_ptr wrapping
186			occurs) we simply return capped_cnt.
187			*/
188			__inline int adjust_write_space_to_avoid_boundary(int cnt, int capped_cnt) {
189			int w;
190			w = atomic_read(&write_ptr);
191			if((w+capped_cnt) >= size && (w+capped_cnt) < (size+wrap_elements)) {
192			//printf("adjust_write_space_to_avoid_boundary returning cnt = %d\n",cnt);
193			return(cnt);
194			}
195			//printf("adjust_write_space_to_avoid_boundary returning capped_cnt = %d\n",capped_cnt);
196			return(capped_cnt);
197			}
198
199			__inline int write_space_to_end() {
200			int w, r;
201
202			w = atomic_read(&write_ptr);
203			r = atomic_read(&read_ptr);
204			//printf("write_space_to_end: w=%d r=%d\n",w,r);
205			if(r > w) return(r - w - 1);
206			if(r) return(size - w);
207			return(size - w - 1);
208			}
209
210			__inline int read_space_to_end() {
211			int w, r;
212
213			w = atomic_read(&write_ptr);
214			r = atomic_read(&read_ptr);
215			if(w >= r) return(w - r);
216			return(size - r);
217			}
218			__inline void init() {
219			atomic_set(&write_ptr, 0);
220			atomic_set(&read_ptr, 0);
221			// wrap=0;
222			}
223
224			int write_space () {
225			int w, r;
226
227			w = atomic_read(&write_ptr);
228			r = atomic_read(&read_ptr);
229
230			if (w > r) {
231			return ((r - w + size) & size_mask) - 1;
232			} else if (w < r) {
233			return (r - w) - 1;
234			} else {
235			return size - 1;
236			}
237			}
238
239			int read_space () {
240			int w, r;
241
242			w = atomic_read(&write_ptr);
243			r = atomic_read(&read_ptr);
244
245			if (w >= r) {
246			return w - r;
247			} else {
248			return (w - r + size) & size_mask;
249			}
250			}
251
252			int size;
253			int wrap_elements;
254
255			protected:
256			T *buf;
257			atomic_t write_ptr;
258			atomic_t read_ptr;
259			int size_mask;
260			};
261
262			template<class T> T *
263			RingBuffer<T>::get_write_ptr (void) {
264			return(&buf[atomic_read(&write_ptr)]);
265			}
266
267			template<class T> T *
268			RingBuffer<T>::get_buffer_begin (void) {
269			return(buf);
270			}
271
272
273
274			template<class T> int
275			RingBuffer<T>::read (T *dest, int cnt)
276
277			{
278			int free_cnt;
279			int cnt2;
280			int to_read;
281			int n1, n2;
282			int priv_read_ptr;
283
284			priv_read_ptr=atomic_read(&read_ptr);
285
286			if ((free_cnt = read_space ()) == 0) {
287			return 0;
288			}
289
290			to_read = cnt > free_cnt ? free_cnt : cnt;
291
292			cnt2 = priv_read_ptr + to_read;
293
294			if (cnt2 > size) {
295			n1 = size - priv_read_ptr;
296			n2 = cnt2 & size_mask;
297			} else {
298			n1 = to_read;
299			n2 = 0;
300			}
301
302			memcpy (dest, &buf[priv_read_ptr], n1 * sizeof (T));
303			priv_read_ptr = (priv_read_ptr + n1) & size_mask;
304
305			if (n2) {
306			memcpy (dest+n1, buf, n2 * sizeof (T));
307			priv_read_ptr = n2;
308			}
309
310			atomic_set(&read_ptr, priv_read_ptr);
311			return to_read;
312			}
313
314			template<class T> int
315			RingBuffer<T>::write (T *src, int cnt)
316
317			{
318			int free_cnt;
319			int cnt2;
320			int to_write;
321			int n1, n2;
322			int priv_write_ptr;
323
324			priv_write_ptr=atomic_read(&write_ptr);
325
326			if ((free_cnt = write_space ()) == 0) {
327			return 0;
328			}
329
330			to_write = cnt > free_cnt ? free_cnt : cnt;
331
332			cnt2 = priv_write_ptr + to_write;
333
334			if (cnt2 > size) {
335			n1 = size - priv_write_ptr;
336			n2 = cnt2 & size_mask;
337			} else {
338			n1 = to_write;
339			n2 = 0;
340			}
341
342			memcpy (&buf[priv_write_ptr], src, n1 * sizeof (T));
343			priv_write_ptr = (priv_write_ptr + n1) & size_mask;
344
345			if (n2) {
346			memcpy (buf, src+n1, n2 * sizeof (T));
347			priv_write_ptr = n2;
348			}
349			atomic_set(&write_ptr, priv_write_ptr);
350			return to_write;
351			}
352
353
354			#endif /* RINGBUFFER_H */