diff options
Diffstat (limited to 'usr.sbin/pim6sd/crc.c')
| -rw-r--r-- | usr.sbin/pim6sd/crc.c | 54 |
1 files changed, 30 insertions, 24 deletions
diff --git a/usr.sbin/pim6sd/crc.c b/usr.sbin/pim6sd/crc.c index 917371e..ca16b63 100644 --- a/usr.sbin/pim6sd/crc.c +++ b/usr.sbin/pim6sd/crc.c @@ -40,58 +40,64 @@ */ /* CRC implantation : stolen from RFC 2083 section 15.*/ +#include <sys/cdefs.h> +#include "crc.h" + /* Table of CRCs of all 8-bit messages. */ unsigned long crc_table[256]; - + /* Flag: has the table been computed? Initially false. */ int crc_table_computed = 0; + +/* Make the table for a fast CRC. */ -/* Make the table for a fast CRC. */ +static void make_crc_table __P((void)); +static unsigned long update_crc __P((unsigned long, unsigned char *, int)); -void make_crc_table(void) +static void make_crc_table(void) { - unsigned long c; + unsigned long c; int n, k; - for (n = 0; n < 256; n++) + for (n = 0; n < 256; n++) { c = (unsigned long) n; - for (k = 0; k < 8; k++) + for (k = 0; k < 8; k++) { - if (c & 1) + if (c & 1) c = 0xedb88320L ^ (c >> 1); - else - c = c >> 1; - } + else + c = c >> 1; + } crc_table[n] = c; - } + } crc_table_computed = 1; -} - +} + /* Update a running CRC with the bytes buf[0..len-1]--the CRC should be initialized to all 1's, and the transmitted value is the 1's complement of the final running CRC (see the crc() routine below)). */ - -unsigned long update_crc(unsigned long crc, unsigned char *buf, + +static unsigned long update_crc(unsigned long crc, unsigned char *buf, int len) -{ +{ unsigned long c = crc; - int n; - + int n; + if (!crc_table_computed) make_crc_table(); - for (n = 0; n < len; n++) + for (n = 0; n < len; n++) { c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8); - } + } return c; -} - +} + /* Return the CRC of the bytes buf[0..len-1]. */ unsigned long crc(unsigned char *buf, int len) -{ +{ return update_crc(0xffffffffL, buf, len) ^ 0xffffffffL; -} +} |
