Function zipTryEncoding

app/redis-6.2.6/src/ziplist.c:522–546

Check if string pointed to by 'entry' can be encoded as an integer. * Stores the integer value in 'v' and its encoding in 'encoding'. */

/* Check if string pointed to by 'entry' can be encoded as an integer.
 * Stores the integer value in 'v' and its encoding in 'encoding'. */
int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) {
    long long value;

    if (entrylen >= 32 || entrylen == 0) return 0;
    if (string2ll((char*)entry,entrylen,&value)) {
        /* Great, the string can be encoded. Check what's the smallest
         * of our encoding types that can hold this value. */
        if (value >= 0 && value <= 12) {
            *encoding = ZIP_INT_IMM_MIN+value;
        } else if (value >= INT8_MIN && value <= INT8_MAX) {
            *encoding = ZIP_INT_8B;
        } else if (value >= INT16_MIN && value <= INT16_MAX) {
            *encoding = ZIP_INT_16B;
        } else if (value >= INT24_MIN && value <= INT24_MAX) {
            *encoding = ZIP_INT_24B;
        } else if (value >= INT32_MIN && value <= INT32_MAX) {
            *encoding = ZIP_INT_32B;
        } else {
            *encoding = ZIP_INT_64B;
        }
        *v = value;
        return 1;
    }
    return 0;
}

/* Store integer 'value' at 'p', encoded as 'encoding' */
void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encoding) {