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Diffstat (limited to 'linux/src/include/asm-i386/checksum.h')
| -rw-r--r-- | linux/src/include/asm-i386/checksum.h | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/linux/src/include/asm-i386/checksum.h b/linux/src/include/asm-i386/checksum.h new file mode 100644 index 0000000..ac49b14 --- /dev/null +++ b/linux/src/include/asm-i386/checksum.h @@ -0,0 +1,121 @@ +#ifndef _I386_CHECKSUM_H +#define _I386_CHECKSUM_H + +/* + * computes the checksum of a memory block at buff, length len, + * and adds in "sum" (32-bit) + * + * returns a 32-bit number suitable for feeding into itself + * or csum_tcpudp_magic + * + * this function must be called with even lengths, except + * for the last fragment, which may be odd + * + * it's best to have buff aligned on a 32-bit boundary + */ +unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum); + +/* + * the same as csum_partial, but copies from src while it + * checksums + * + * here even more important to align src and dst on a 32-bit (or even + * better 64-bit) boundary + */ + +unsigned int csum_partial_copy( const char *src, char *dst, int len, int sum); + + +/* + * the same as csum_partial_copy, but copies from user space. + * + * here even more important to align src and dst on a 32-bit (or even + * better 64-bit) boundary + */ + +unsigned int csum_partial_copy_fromuser(const char *src, char *dst, int len, int sum); + +/* + * This is a version of ip_compute_csum() optimized for IP headers, + * which always checksum on 4 octet boundaries. + * + * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by + * Arnt Gulbrandsen. + */ +static inline unsigned short ip_fast_csum(unsigned char * iph, + unsigned int ihl) { + unsigned int sum; + + __asm__ __volatile__(" + movl (%1), %0 + subl $4, %2 + jbe 2f + addl 4(%1), %0 + adcl 8(%1), %0 + adcl 12(%1), %0 +1: adcl 16(%1), %0 + lea 4(%1), %1 + decl %2 + jne 1b + adcl $0, %0 + movl %0, %2 + shrl $16, %0 + addw %w2, %w0 + adcl $0, %0 + notl %0 +2: + " + /* Since the input registers which are loaded with iph and ipl + are modified, we must also specify them as outputs, or gcc + will assume they contain their original values. */ + : "=r" (sum), "=r" (iph), "=r" (ihl) + : "1" (iph), "2" (ihl)); + return(sum); +} + +/* + * Fold a partial checksum + */ + +static inline unsigned int csum_fold(unsigned int sum) +{ + __asm__(" + addl %1, %0 + adcl $0xffff, %0 + " + : "=r" (sum) + : "r" (sum << 16), "0" (sum & 0xffff0000) + ); + return (~sum) >> 16; +} + +/* + * computes the checksum of the TCP/UDP pseudo-header + * returns a 16-bit checksum, already complemented + */ + +static inline unsigned short int csum_tcpudp_magic(unsigned long saddr, + unsigned long daddr, + unsigned short len, + unsigned short proto, + unsigned int sum) { + __asm__(" + addl %1, %0 + adcl %2, %0 + adcl %3, %0 + adcl $0, %0 + " + : "=r" (sum) + : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum)); + return csum_fold(sum); +} +/* + * this routine is used for miscellaneous IP-like checksums, mainly + * in icmp.c + */ + +static inline unsigned short ip_compute_csum(unsigned char * buff, int len) { + return csum_fold (csum_partial(buff, len, 0)); +} + +#endif |