Tips & tricks¶
Application buffer size¶
Buffer size shall always be 1
byte bigger than anticipated data size.
When application uses buffer for some data block N
times, it is advised to set buffer size to 1
byte more than N * block_size
is.
This is due to R
and W
pointers alignment.
Note
For more information, check How it works.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | #include "lwrb/lwrb.h"
/* Number of data blocks to write */
#define N 3
/* Create custom data structure */
/* Data is array of 2 32-bit words, 8-bytes */
uint32_t d[2];
/* Create buffer structures */
lwrb_t buff_1;
lwrb_t buff_2;
/* Create data for buffers. Use sizeof structure, multiplied by N (for N instances) */
/* Buffer with + 1 bytes bigger memory */
uint8_t buff_data_1[sizeof(d) * N + 1];
/* Buffer without + 1 at the end */
uint8_t buff_data_2[sizeof(d) * N];
/* Write result values */
size_t len_1;
size_t len_2;
/* Initialize buffers */
lwrb_init(&buff_1, buff_data_1, sizeof(buff_data_1));
lwrb_init(&buff_2, buff_data_2, sizeof(buff_data_2));
/* Write data to buffer */
for (size_t i = 0; i < N; ++i) {
/* Prepare data */
d.a = i;
d.b = i * 2;
/* Write data to both buffers, memory copy from d to buffer */
len_1 = lwrb_write(&buff_1, d, sizeof(d));
len_2 = lwrb_write(&buff_2, d, sizeof(d));
/* Print results */
printf("Write buffer 1: %d/%d bytes; buffer 2: %d/%d\r\n",
(int)len_1, (int)sizeof(d),
(int)len_2, (int)sizeof(d));
}
|
When the code is executed, it produces following output:
Write: buffer 1: 8/8; buffer 2: 8/8
Write: buffer 1: 8/8; buffer 2: 8/8
Write: buffer 1: 8/8; buffer 2: 7/8 <-- See here -->