/**
* \brief Tries to reads an item from the buffer.
*
* If the buffer cannot currently be read from, this operation returns
* with an appropriate status code.
*
* \param item out: The read item. If the return code is false, the
* value is undefined.
* \returns true if an item was read, false otherwise
*/
inline bool tryRead(register rbdata_t *item) {
assert(NULL != item);
// loop until the buffer has a full slot
if (!canRead()) return false;
// fetch fresh
_MemoryBarrier();
// since we read, the fill level will be decreased
--_fillLevel;
// write to the current write index
*item = _buffer[_read_index];
// advance the read pointer
_read_index = (_read_index+1) & this->_sizeMask;
// since we read, the capacity will be increased
++_capacity;
// there we go
_MemoryBarrier();
return true;
}
int main(void)
{
void *ptrs[6];
uint8_t i;
for (i = 0; i < 6; i++)
{
void *p = malloc(10);
if (p == NULL) return __LINE__;
ptrs[i] = p;
}
free(ptrs[5]);
_MemoryBarrier();
/* Freelist must be still empty, and __brkval reduced. */
if (__flp != NULL) return __LINE__;
if ((char *)(ptrs[5]) - 2 != __brkval) return __LINE__;
free(ptrs[4]);
_MemoryBarrier();
/* Still no entry, and __brkval further down. */
if (__flp != NULL) return __LINE__;
if ((char *)(ptrs[4]) - 2 != __brkval) return __LINE__;
struct __freelist *ofp = __flp;
free(ptrs[1]);
_MemoryBarrier();
/* One entry added. */
if ((char *)(ptrs[1]) - 2 != (void *)__flp) return __LINE__;
if (__flp->sz != 10) return __LINE__;
if (__flp->nx != (void *)ofp) return __LINE__;
free(ptrs[3]);
_MemoryBarrier();
/* __brkval lowered again. */
if (__flp->nx != NULL) return __LINE__;
if ((char *)(ptrs[3]) - 2 != __brkval) return __LINE__;
free(ptrs[2]);
_MemoryBarrier();
/* ...and again. */
if (__flp->nx != NULL) return __LINE__;
if ((char *)(ptrs[1]) - 2 != __brkval) return __LINE__;
return 0;
}
/**
* \brief Tries to write an item to the buffer.
*
* If the buffer cannot currently be written to, this operation returns
* with an appropriate status code.
*
* \param item The item to write.
* \returns true if the write operation succeeded, false otherwise
*/
inline bool tryWrite(register const rbdata_t item) {
// test if the buffer has a free slot
if (!canWrite()) return false;
// fetch fresh
_MemoryBarrier();
// since we write, the capacity will be reduced
--_capacity;
// write to the current write index
_buffer[_write_index] = item;
// advance the write pointer
_write_index = (_write_index+1) & this->_sizeMask;
// since we write, the fill level will be increased
++_fillLevel;
// There we go
_MemoryBarrier();
return true;
}