zephyr settings part 3: persistence of multiple key-values at once (handler)
July 30, 2022•213 words
LOAD MULTIPLE VARIABLES AT ONCE EXAMPLE:
direct_length_data: your structure variable that will be set:
struct direct_length_data {
uint64_t length;
uint16_t length_1;
uint32_t length_2;
};
the handler: direct_loader
static int direct_loader(const char *name, size_t len, settings_read_cb read_cb,
void *cb_arg, void *param)
{
const char *next;
size_t name_len;
int rc;
struct direct_length_data *dest = (struct direct_length_data *)param;
printk("direct load: ");
name_len = settings_name_next(name, &next);
if (name_len == 0) {
rc = read_cb(cb_arg, &(dest->length), sizeof(dest->length));
printk("<alpha/length>\n");
return 0;
}
name_len = settings_name_next(name, &next);
if (next) {
printk("nothing\n");
return -ENOENT;
}
if (!strncmp(name, "1", name_len)) {
rc = read_cb(cb_arg, &(dest->length_1), sizeof(dest->length_1));
printk("<alpha/length/1>\n");
return 0;
}
if (!strncmp(name, "2", name_len)) {
rc = read_cb(cb_arg, &(dest->length_2), sizeof(dest->length_2));
printk("<alpha/length/2>\n");
return 0;
}
printk("nothing\n");
return -ENOENT;
}
example using the handler direct_loader and structure variable struct direct_length_data:
static void example_direct_load_subtree(void)
{
struct direct_length_data dld;
int rc;
/* load subtree directly using call-specific handler `direct_loader'
* This handder loads subtree values to call-speciffic structure of type
* 'direct_length_data`.
*/
printk(SECTION_BEGIN_LINE);
printk("loading subtree to destination provided by the caller\n\n");
rc = settings_load_subtree_direct("alpha/length", direct_loader,
(void *)&dld);
if (rc == 0) {
printk(" direct.length = %" PRId64 "\n", dld.length);
printk(" direct.length_1 = %d\n", dld.length_1);
printk(" direct.length_2 = %d\n", dld.length_2);
} else {
printk(" direct load fails unexpectedly\n");
}
}