int
fifo_insert(FIFO* fp, void* data)
{
long* lp;
int next_val; /* next value for wr_ptr */
int i;
log_debug_high("entered\n");
if (!fp)
{
log_debug_high("FIFO is null\n");
return -1;
}
next_val = fp->wr_ptr + 1;
if (next_val >= fp->entries)
next_val = 0;
if (next_val == fp->rd_ptr)
{
/* FIFO is full, expand it by 10 entries */
lp = (long *) malloc(sizeof(long) * (fp->entries + 10));
if (!lp)
{
log_debug_low("FIFO full; cannot expand, no memory\n");
return -1;
}
log_debug_low("FIFO full, expanding by 10 entries\n");
/* copy old data new location */
for (i = 0; i < (fp->entries - 1); i++)
{
lp[i] = fp->user_data[fp->rd_ptr++];
if (fp->rd_ptr >= fp->entries)
fp->rd_ptr = 0;
}
/* update pointers */
fp->rd_ptr = 0;
fp->wr_ptr = fp->entries - 1;
next_val = fp->entries;
fp->entries += 10;
/* free old data */
free(fp->user_data);
fp->user_data = lp;
}
log_debug_low("inserting data at index %d\n", fp->wr_ptr);
fp->user_data[fp->wr_ptr] = (long) data;
fp->wr_ptr = next_val;
return 0;
}
/**
* Initialize a FIFO that grows as required
*
* @param fp pointer to a FIFO
* @param num_entries initial size
*
* @return 0 on success, -1 on failure
*****************************************************************************/
int
fifo_init(FIFO* fp, int num_entries)
{
log_debug_high("entered\n");
/* validate params */
if (!fp)
{
log_debug_high("invalid parameters\n");
return -1;
}
if (num_entries < 1)
num_entries = 10;
fp->rd_ptr = 0;
fp->wr_ptr = 0;
fp->user_data = (long *) malloc(sizeof(long) * num_entries);
if (fp->user_data)
{
log_debug_low("FIFO created\n");
fp->entries = num_entries;
return 0;
}
else
{
log_error("FIFO create error; system out of memory\n");
fp->entries = 0;
return -1;
}
}
/**
* Remove an item from the head
*
* @param fp FIFO
*
* @param data on success, NULL on error
*****************************************************************************/
void*
fifo_remove(FIFO* fp)
{
long data;
log_debug_high("entered\n");
if (!fp)
{
log_debug_high("FIFO is null\n");
return 0;
}
if (fp->rd_ptr == fp->wr_ptr)
{
log_debug_high("FIFO is empty\n");
return 0;
}
log_debug_low("removing data at index %d\n", fp->rd_ptr);
data = fp->user_data[fp->rd_ptr++];
if (fp->rd_ptr >= fp->entries)
{
log_debug_high("FIFO rd_ptr wrapped around\n");
fp->rd_ptr = 0;
}
return (void *) data;
}
/**
* Return item from head, but do not remove it
*
* @param fp FIFO
*
* @param data on success, NULL on error
*****************************************************************************/
void*
fifo_peek(FIFO* fp)
{
log_debug_high("entered");
if (!fp)
{
log_debug_high("FIFO is null");
return 0;
}
if (fp->rd_ptr == fp->wr_ptr)
{
log_debug_high("FIFO is empty");
return 0;
}
log_debug_low("peeking data at index %d", fp->rd_ptr);
return (void *) fp->user_data[fp->rd_ptr];
}
