mp_ring: remove unused function

This was needed for ao_jack.c., but not anymore.

mpvcore/mp_ring.c

@@ -87,31 +87,6 @@ int mp_ring_read(struct mp_ring *buffer, unsigned char *dest, int len)
     return read_len;
 }
 
-int mp_ring_read_cb(struct mp_ring *buffer, void *ctx, int len,
-        void (*func)(void*, void*, int))
-{
-    // The point of this function is defining custom read behaviour, assume
-    // it's a programmers error if func is null.
-    assert(func);
-
-    int size     = mp_ring_size(buffer);
-    int buffered = mp_ring_buffered(buffer);
-    int read_len = FFMIN(len, buffered);
-    int read_ptr = mp_ring_get_rpos(buffer) % size;
-
-    int len1 = FFMIN(size - read_ptr, read_len);
-    int len2 = read_len - len1;
-
-    func(ctx, buffer->buffer + read_ptr, len1);
-    if (len2 > 0)
-        func(ctx, buffer->buffer, len2);
-
-    mp_atomic_add_and_fetch(&buffer->rpos, read_len);
-    mp_memory_barrier();
-
-    return read_len;
-}
-
 int mp_ring_write(struct mp_ring *buffer, unsigned char *src, int len)
 {
     int size      = mp_ring_size(buffer);

mpvcore/mp_ring.h

@@ -46,28 +46,6 @@ struct mp_ring *mp_ring_new(void *talloc_ctx, int size);
  */
 int mp_ring_read(struct mp_ring *buffer, unsigned char *dest, int len);
 
-/**
- * Read data from the ringbuffer
- *
- * This function behaves similarly to `av_fifo_generic_read` and was actually
- * added for compatibility with code that was written for it.
- * This function will drain the returned amount of bytes from the ringbuffer
- * so you don't have to handle that in inside `func`.
- *
- * buffer: target ringbuffer instance
- * ctx:    context for the callback function
- * len:    maximum number of bytes to read
- * func:   callback function to customize reading behaviour. It will be called
- *         by `mp_ring_read_cb` with the following parameters:
- *           ctx: context data provided to `mp_ring_read_cb`
- *           src: source buffer to read from
- *           len: the *exact* amount of bytes to read. These will be drained
- *                by the ring after this callback is called.
- * return: number of bytes read
- */
-int mp_ring_read_cb(struct mp_ring *buffer, void *ctx, int len,
-        void (*func)(void *ctx, void *src, int len));
-
 /**
  * Write data to the ringbuffer
  *