Buffer Operations

The following routines provide access to the data in a cpc_buf_t structure.

int cpc_buf_get(cpc_t *cpc, cpc_buf_t *buf, int index, uint64_t *val);
int cpc_buf_set(cpc_t *cpc, cpc_buf_t *buf, int index, uint64_t *val);
hrtime_t cpc_buf_hrtime(cpc_t *cpc, cpc_buf_t *buf);
uint64_t cpc_buf_tick(cpc_t *cpc, cpc_buf_t *buf);
int cpc_buf_sub(cpc_t *cpc, cpc_buf_t *result, cpc_buf_t *left
      cpc_buf_t *right);
int cpc_buf_add(cpc_t *cpc, cpc_buf_t *result, cpc_buf_t *left,
      cpc_buf_t *right);
int cpc_buf_copy(cpc_t *cpc, cpc_buf_t *dest, cpc_buf_t *src);
void cpc_buf_zero(cpc_t *cpc, cpc_buf_t *buf);

The cpc_buf_get() function retrieves the value of the counter that is identified by the index parameter. The index parameter is a value that is returned by the cpc_set_add_request() function before the set is bound. The cpc_buf_get() function stores the value of the counter at the location indicated by the val parameter.

The cpc_buf_set() function sets the value of the counter that is identified by the index parameter. The index parameter is a value that is returned by the cpc_set_add_request() function before the set is bound. The cpc_buf_set() function sets the counter's value to the value at the location indicated by the val parameter. Neither the cpc_buf_get() function nor the cpc_buf_set() function change the preset of the corresponding CPC request.

The cpc_buf_hrtime() function returns the high resolution timestamp that indicates when the hardware was sampled. The cpc_buf_tick() function returns the number of CPU clock cycles that have elapsed while the LWP is running.

The cpc_buf_sub() function computes the difference between the counters and tick values that are specified in the left and right parameters. The cpc_buf_sub() function stores the results in result. A given invocation of the cpc_buf_sub() function must have all cpc_buf_t values originate from the same cpc_set_t structure. The result index contains the result of the left - right computation for each request index in the buffers. The result index also contains the tick difference. The cpc_buf_sub() function sets the high-resolution timestamp of the destination buffer to the most recent time of the left or right buffers.

The cpc_buf_add() function computes the total of the counters and tick values that are specified in the left and right parameters. The cpc_buf_add() function stores the results in result. A given invocation of the cpc_buf_add() function must have all cpc_buf_t values originate from the same cpc_set_t structure. The result index contains the result of the left + right computation for each request index in the buffers. The result index also contains the tick total. The cpc_buf_add() function sets the high-resolution timestamp of the destination buffer to the most recent time of the left or right buffers.

The cpc_buf_copy() function makes dest identical to src.

The cpc_buf_zero() function sets everything in buf to zero.