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ringbuffer: converted to item_size units

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this fixes a number of indexing bugs
This commit is contained in:
Andrew Tridgell 2013-09-11 14:36:44 +10:00 committed by Lorenz Meier
parent cefc7ac00e
commit 760b3ab2e7
1 changed files with 22 additions and 20 deletions
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42
src/drivers/device/ringbuffer.h
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@ -155,21 +155,21 @@ public:
void print_info(const char *name);
private:
unsigned _ring_size;
unsigned _num_items;
const size_t _item_size;
char *_buf;
volatile unsigned _head; /**< insertion point */
volatile unsigned _tail; /**< removal point */
volatile unsigned _head; /**< insertion point in _item_size units */
volatile unsigned _tail; /**< removal point in _item_size units */
unsigned _next(unsigned index);
};
RingBuffer::RingBuffer(unsigned ring_size, size_t item_size) :
_ring_size((ring_size + 1) * item_size),
RingBuffer::RingBuffer(unsigned num_items, size_t item_size) :
_num_items(num_items),
_item_size(item_size),
_buf(new char[_ring_size]),
_head(ring_size),
_tail(ring_size)
_buf(new char[(_num_items+1) * item_size]),
_head(_num_items),
_tail(_num_items)
{}
RingBuffer::~RingBuffer()
@ -181,7 +181,7 @@ RingBuffer::~RingBuffer()
unsigned
RingBuffer::_next(unsigned index)
{
return (0 == index) ? _ring_size : (index - _item_size);
return (0 == index) ? _num_items : (index - 1);
}
bool
@ -199,7 +199,7 @@ RingBuffer::full()
unsigned
RingBuffer::size()
{
return (_buf != nullptr) ? _ring_size : 0;
return (_buf != nullptr) ? _num_items : 0;
}
void
@ -216,7 +216,7 @@ RingBuffer::put(const void *val, size_t val_size)
if (next != _tail) {
if ((val_size == 0) || (val_size > _item_size))
val_size = _item_size;
memcpy(&_buf[_head], val, val_size);
memcpy(&_buf[_head * _item_size], val, val_size);
_head = next;
return true;
} else {
@ -377,7 +377,7 @@ RingBuffer::get(void *val, size_t val_size)
/* go ahead and read from this index */
if (val != NULL)
memcpy(val, &_buf[candidate], val_size);
memcpy(val, &_buf[candidate * _item_size], val_size);
/* if the tail pointer didn't change, we got our item */
} while (!__sync_bool_compare_and_swap(&_tail, candidate, next));
@ -466,9 +466,7 @@ RingBuffer::space(void)
tail = _tail;
} while (head != _head);
unsigned reported_space = (tail >= head) ? (_ring_size - (tail - head)) : (head - tail - 1);
return reported_space / _item_size;
return (tail >= head) ? (_num_items - (tail - head)) : (head - tail - 1);
}
unsigned
@ -478,21 +476,20 @@ RingBuffer::count(void)
* Note that due to the conservative nature of space(), this may
* over-estimate the number of items in the buffer.
*/
return (_ring_size / _item_size) - space();
return _num_items - space();
}
bool
RingBuffer::resize(unsigned new_size)
{
unsigned new_ring_size = (new_size + 1) * _item_size;
char *old_buffer;
char *new_buffer = new char [new_ring_size];
char *new_buffer = new char [(new_size+1) * _item_size];
if (new_buffer == nullptr) {
return false;
}
old_buffer = _buf;
_buf = new_buffer;
_ring_size = new_ring_size;
_num_items = new_size;
_head = new_size;
_tail = new_size;
delete[] old_buffer;
@ -503,5 +500,10 @@ void
RingBuffer::print_info(const char *name)
{
printf("%s %u/%u (%u/%u @ %p)\n",
name, _ring_size/_item_size, _head, _tail, _buf);
name,
_num_items,
_num_items * _item_size,
_head,
_tail,
_buf);
}