FreeCalypso > hg > freecalypso-tools
view miscutil/imei-luhn.c @ 416:30f6d1c32c6f
doc/Flash-boot-defect article removed (no longer relevant)
This article is no longer relevant because the issue in question
only affected one (1) defective FCDEV3B board which was not
and never will be sold.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Fri, 26 Oct 2018 07:11:08 +0000 |
parents | e7502631a0f9 |
children |
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/* * This program computes the Luhn check digit for an IMEI number given * the first 14 digits, or verifies the correctness of this check digit * given a 15-digit number as input. * * The number given on the command line may optionally include punctuation, * which is skipped and ignored. */ #include <stdio.h> #include <ctype.h> #include <stdlib.h> char digits[15]; compute_cd() { int i, dig, sum; sum = 0; for (i = 0; i < 14; i++) { dig = digits[i]; if (i & 1) { dig *= 2; if (dig > 9) dig -= 9; } sum += dig; } dig = sum % 10; if (dig) dig = 10 - dig; return dig; } main(argc, argv) char **argv; { char *cp; int i; if (argc != 2) { usage: fprintf(stderr, "usage: %s number\n", argv[0]); exit(2); } cp = argv[1]; if (!isdigit(*cp)) goto usage; for (i = 0; *cp; ) { if (ispunct(*cp)) cp++; if (!isdigit(*cp)) goto usage; if (i >= 15) { wrong_len: fprintf(stderr, "error: argument must have 14 or 15 digits\n"); exit(2); } digits[i++] = *cp++ - '0'; } switch (i) { case 14: printf("%d\n", compute_cd()); exit(0); case 15: if (digits[14] == compute_cd()) { printf("IMEI OK\n"); exit(0); } else { printf("Check digit mismatch!\n"); exit(1); } default: goto wrong_len; } }