/*
 * upc.h - UPC-A barcode validation.
 *
 * Pure C, no SIBO/PLIB dependencies, so it can be unit-tested on any host
 * compiler as well as built for the Workabout.
 */
#ifndef UPC_H
#define UPC_H

#define UPC_A_LEN 12

/*
 * Returns 1 if s is a valid 12-digit UPC-A (all digits and a correct
 * check digit), 0 otherwise. s must be NUL-terminated.
 */
int upcIsValid(const char *s);

/*
 * Returns the UPC-A check digit (0-9) computed from the first 11 digits
 * of s, or -1 if those 11 characters are not all digits.
 */
int upcCheckDigit(const char *s);

#endif /* UPC_H */