**diff options**

Diffstat (limited to 'arch/alpha/lib/checksum.c')

-rw-r--r-- | arch/alpha/lib/checksum.c | 186 |

1 files changed, 186 insertions, 0 deletions

diff --git a/arch/alpha/lib/checksum.c b/arch/alpha/lib/checksum.c new file mode 100644 index 00000000000..89044e6385f --- /dev/null +++ b/arch/alpha/lib/checksum.c @@ -0,0 +1,186 @@ +/* + * arch/alpha/lib/checksum.c + * + * This file contains network checksum routines that are better done + * in an architecture-specific manner due to speed.. + * Comments in other versions indicate that the algorithms are from RFC1071 + * + * accellerated versions (and 21264 assembly versions ) contributed by + * Rick Gorton <rick.gorton@alpha-processor.com> + */ + +#include <linux/module.h> +#include <linux/string.h> + +#include <asm/byteorder.h> + +static inline unsigned short from64to16(unsigned long x) +{ + /* Using extract instructions is a bit more efficient + than the original shift/bitmask version. */ + + union { + unsigned long ul; + unsigned int ui[2]; + unsigned short us[4]; + } in_v, tmp_v, out_v; + + in_v.ul = x; + tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1]; + + /* Since the bits of tmp_v.sh[3] are going to always be zero, + we don't have to bother to add that in. */ + out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1] + + (unsigned long) tmp_v.us[2]; + + /* Similarly, out_v.us[2] is always zero for the final add. */ + return out_v.us[0] + out_v.us[1]; +} + +/* + * computes the checksum of the TCP/UDP pseudo-header + * returns a 16-bit checksum, already complemented. + */ +unsigned short int csum_tcpudp_magic(unsigned long saddr, + unsigned long daddr, + unsigned short len, + unsigned short proto, + unsigned int sum) +{ + return ~from64to16(saddr + daddr + sum + + ((unsigned long) ntohs(len) << 16) + + ((unsigned long) proto << 8)); +} + +unsigned int csum_tcpudp_nofold(unsigned long saddr, + unsigned long daddr, + unsigned short len, + unsigned short proto, + unsigned int sum) +{ + unsigned long result; + + result = (saddr + daddr + sum + + ((unsigned long) ntohs(len) << 16) + + ((unsigned long) proto << 8)); + + /* Fold down to 32-bits so we don't lose in the typedef-less + network stack. */ + /* 64 to 33 */ + result = (result & 0xffffffff) + (result >> 32); + /* 33 to 32 */ + result = (result & 0xffffffff) + (result >> 32); + return result; +} + +/* + * Do a 64-bit checksum on an arbitrary memory area.. + * + * This isn't a great routine, but it's not _horrible_ either. The + * inner loop could be unrolled a bit further, and there are better + * ways to do the carry, but this is reasonable. + */ +static inline unsigned long do_csum(const unsigned char * buff, int len) +{ + int odd, count; + unsigned long result = 0; + + if (len <= 0) + goto out; + odd = 1 & (unsigned long) buff; + if (odd) { + result = *buff << 8; + len--; + buff++; + } + count = len >> 1; /* nr of 16-bit words.. */ + if (count) { + if (2 & (unsigned long) buff) { + result += *(unsigned short *) buff; + count--; + len -= 2; + buff += 2; + } + count >>= 1; /* nr of 32-bit words.. */ + if (count) { + if (4 & (unsigned long) buff) { + result += *(unsigned int *) buff; + count--; + len -= 4; + buff += 4; + } + count >>= 1; /* nr of 64-bit words.. */ + if (count) { + unsigned long carry = 0; + do { + unsigned long w = *(unsigned long *) buff; + count--; + buff += 8; + result += carry; + result += w; + carry = (w > result); + } while (count); + result += carry; + result = (result & 0xffffffff) + (result >> 32); + } + if (len & 4) { + result += *(unsigned int *) buff; + buff += 4; + } + } + if (len & 2) { + result += *(unsigned short *) buff; + buff += 2; + } + } + if (len & 1) + result += *buff; + result = from64to16(result); + if (odd) + result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); +out: + return result; +} + +/* + * This is a version of ip_compute_csum() optimized for IP headers, + * which always checksum on 4 octet boundaries. + */ +unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl) +{ + return ~do_csum(iph,ihl*4); +} + +/* + * 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) +{ + unsigned long result = do_csum(buff, len); + + /* add in old sum, and carry.. */ + result += sum; + /* 32+c bits -> 32 bits */ + result = (result & 0xffffffff) + (result >> 32); + return result; +} + +EXPORT_SYMBOL(csum_partial); + +/* + * this routine is used for miscellaneous IP-like checksums, mainly + * in icmp.c + */ +unsigned short ip_compute_csum(unsigned char * buff, int len) +{ + return ~from64to16(do_csum(buff,len)); +} |