157 строки
3.8 KiB
C
157 строки
3.8 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_CHECKSUM_H
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#define __ASM_AVR32_CHECKSUM_H
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/*
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* computes the checksum of a memory block at buff, length len,
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* and adds in "sum" (32-bit)
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*
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* returns a 32-bit number suitable for feeding into itself
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* or csum_tcpudp_magic
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*
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* this function must be called with even lengths, except
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* for the last fragment, which may be odd
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*
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* it's best to have buff aligned on a 32-bit boundary
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*/
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unsigned int csum_partial(const unsigned char * buff, int len,
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unsigned int sum);
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/*
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* the same as csum_partial, but copies from src while it
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* checksums, and handles user-space pointer exceptions correctly, when needed.
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*
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* here even more important to align src and dst on a 32-bit (or even
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* better 64-bit) boundary
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*/
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unsigned int csum_partial_copy_generic(const char *src, char *dst, int len,
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int sum, int *src_err_ptr,
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int *dst_err_ptr);
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/*
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* Note: when you get a NULL pointer exception here this means someone
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* passed in an incorrect kernel address to one of these functions.
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*
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* If you use these functions directly please don't forget the
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* verify_area().
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*/
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static inline
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unsigned int csum_partial_copy_nocheck(const char *src, char *dst,
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int len, int sum)
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{
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return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
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}
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static inline
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unsigned int csum_partial_copy_from_user (const char __user *src, char *dst,
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int len, int sum, int *err_ptr)
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{
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return csum_partial_copy_generic((const char __force *)src, dst, len,
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sum, err_ptr, NULL);
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}
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/*
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* This is a version of ip_compute_csum() optimized for IP headers,
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* which always checksum on 4 octet boundaries.
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*/
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static inline unsigned short ip_fast_csum(unsigned char *iph,
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unsigned int ihl)
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{
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unsigned int sum, tmp;
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__asm__ __volatile__(
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" ld.w %0, %1++\n"
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" ld.w %3, %1++\n"
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" sub %2, 4\n"
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" add %0, %3\n"
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" ld.w %3, %1++\n"
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" adc %0, %0, %3\n"
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" ld.w %3, %1++\n"
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" adc %0, %0, %3\n"
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" acr %0\n"
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"1: ld.w %3, %1++\n"
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" add %0, %3\n"
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" acr %0\n"
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" sub %2, 1\n"
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" brne 1b\n"
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" lsl %3, %0, 16\n"
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" andl %0, 0\n"
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" mov %2, 0xffff\n"
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" add %0, %3\n"
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" adc %0, %0, %2\n"
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" com %0\n"
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" lsr %0, 16\n"
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: "=r"(sum), "=r"(iph), "=r"(ihl), "=r"(tmp)
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: "1"(iph), "2"(ihl)
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: "memory", "cc");
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return sum;
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}
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/*
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* Fold a partial checksum
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*/
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static inline unsigned int csum_fold(unsigned int sum)
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{
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unsigned int tmp;
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asm(" bfextu %1, %0, 0, 16\n"
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" lsr %0, 16\n"
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" add %0, %1\n"
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" bfextu %1, %0, 16, 16\n"
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" add %0, %1"
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: "=&r"(sum), "=&r"(tmp)
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: "0"(sum));
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return ~sum;
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}
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static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
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unsigned long daddr,
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unsigned short len,
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unsigned short proto,
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unsigned int sum)
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{
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asm(" add %0, %1\n"
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" adc %0, %0, %2\n"
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" adc %0, %0, %3\n"
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" acr %0"
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: "=r"(sum)
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: "r"(daddr), "r"(saddr), "r"(ntohs(len) | (proto << 16)),
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"0"(sum)
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: "cc");
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return sum;
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}
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/*
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* computes the checksum of the TCP/UDP pseudo-header
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* returns a 16-bit checksum, already complemented
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*/
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static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
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unsigned long daddr,
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unsigned short len,
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unsigned short proto,
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unsigned int sum)
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{
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return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
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}
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/*
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* this routine is used for miscellaneous IP-like checksums, mainly
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* in icmp.c
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*/
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static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
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{
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return csum_fold(csum_partial(buff, len, 0));
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}
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#endif /* __ASM_AVR32_CHECKSUM_H */
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