FreeCalypso > hg > freecalypso-tools
view miscutil/imei-luhn.c @ 995:74024eb17e04
fc-loadtool help: improve language regarding 16 MiB flash chips
In FC project history, 16 MiB flash originally meant Pirelli DP-L10.
Then we got FCDEV3B with the same flash (our own design), but now we are
discovering more Calypso devices that used such large flash, both late
Calypso era (Sony Ericsson K2x0) as well as much earlier ones (FIC FLUID
devices.txt file with 2004 dates, Leonardo+ rev 5). Hence we need to
migrate to more generic or neutral language in associated documentation,
without giving elevated status to specific examples that drove our
early project history.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sun, 03 Dec 2023 21:11:12 +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; } }