include/asm-arm26/checksum.h

   1 /*
   2  *  linux/include/asm-arm/checksum.h
   3  *
   4  * IP checksum routines
   5  *
   6  * Copyright (C) Original authors of ../asm-i386/checksum.h
   7  * Copyright (C) 1996-1999 Russell King
   8  */
   9 #ifndef __ASM_ARM_CHECKSUM_H
  10 #define __ASM_ARM_CHECKSUM_H
  11
  12 /*
  13  * computes the checksum of a memory block at buff, length len,
  14  * and adds in "sum" (32-bit)
  15  *
  16  * returns a 32-bit number suitable for feeding into itself
  17  * or csum_tcpudp_magic
  18  *
  19  * this function must be called with even lengths, except
  20  * for the last fragment, which may be odd
  21  *
  22  * it's best to have buff aligned on a 32-bit boundary
  23  */
  24 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  25
  26 /*
  27  * the same as csum_partial, but copies from src while it
  28  * checksums, and handles user-space pointer exceptions correctly, when needed.
  29  *
  30  * here even more important to align src and dst on a 32-bit (or even
  31  * better 64-bit) boundary
  32  */
  33
  34 unsigned int
  35 csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum);
  36
  37 unsigned int
  38 csum_partial_copy_from_user(const char *src, char *dst, int len, int sum, int *err_ptr);
  39
  40 /*
  41  * These are the old (and unsafe) way of doing checksums, a warning message will be
  42  * printed if they are used and an exception occurs.
  43  *
  44  * these functions should go away after some time.
  45  */
  46 #define csum_partial_copy(src,dst,len,sum)      csum_partial_copy_nocheck(src,dst,len,sum)
  47
  48 /*
  49  *      This is a version of ip_compute_csum() optimized for IP headers,
  50  *      which always checksum on 4 octet boundaries.
  51  */
  52 static inline unsigned short
  53 ip_fast_csum(unsigned char * iph, unsigned int ihl)
  54 {
  55         unsigned int sum, tmp1;
  56
  57         __asm__ __volatile__(
  58         "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
  59         ldr     %3, [%1], #4                                    \n\
  60         sub     %2, %2, #5                                      \n\
  61         adds    %0, %0, %3                                      \n\
  62         ldr     %3, [%1], #4                                    \n\
  63         adcs    %0, %0, %3                                      \n\
  64         ldr     %3, [%1], #4                                    \n\
  65 1:      adcs    %0, %0, %3                                      \n\
  66         ldr     %3, [%1], #4                                    \n\
  67         tst     %2, #15                 @ do this carefully     \n\
  68         subne   %2, %2, #1              @ without destroying    \n\
  69         bne     1b                      @ the carry flag        \n\
  70         adcs    %0, %0, %3                                      \n\
  71         adc     %0, %0, #0                                      \n\
  72         adds    %0, %0, %0, lsl #16                             \n\
  73         addcs   %0, %0, #0x10000                                \n\
  74         mvn     %0, %0                                          \n\
  75         mov     %0, %0, lsr #16"
  76         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  77         : "1" (iph), "2" (ihl)
  78         : "cc");
  79         return sum;
  80 }
  81
  82 /*
  83  *      Fold a partial checksum without adding pseudo headers
  84  */
  85 static inline unsigned int
  86 csum_fold(unsigned int sum)
  87 {
  88         __asm__(
  89         "adds   %0, %1, %1, lsl #16     @ csum_fold             \n\
  90         addcs   %0, %0, #0x10000"
  91         : "=r" (sum)
  92         : "r" (sum)
  93         : "cc");
  94         return (~sum) >> 16;
  95 }
  96
  97 static inline unsigned int
  98 csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
  99                    unsigned int proto, unsigned int sum)
 100 {
 101         __asm__(
 102         "adds   %0, %1, %2              @ csum_tcpudp_nofold    \n\
 103         adcs    %0, %0, %3                                      \n\
 104         adcs    %0, %0, %4                                      \n\
 105         adcs    %0, %0, %5                                      \n\
 106         adc     %0, %0, #0"
 107         : "=&r"(sum)
 108         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len) << 16), "Ir" (proto << 8)
 109         : "cc");
 110         return sum;
 111 }
 112 /*
 113  * computes the checksum of the TCP/UDP pseudo-header
 114  * returns a 16-bit checksum, already complemented
 115  */
 116 static inline unsigned short int
 117 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
 118                   unsigned int proto, unsigned int sum)
 119 {
 120         __asm__(
 121         "adds   %0, %1, %2              @ csum_tcpudp_magic     \n\
 122         adcs    %0, %0, %3                                      \n\
 123         adcs    %0, %0, %4                                      \n\
 124         adcs    %0, %0, %5                                      \n\
 125         adc     %0, %0, #0                                      \n\
 126         adds    %0, %0, %0, lsl #16                             \n\
 127         addcs   %0, %0, #0x10000                                \n\
 128         mvn     %0, %0"
 129         : "=&r"(sum)
 130         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (proto << 8)
 131         : "cc");
 132         return sum >> 16;
 133 }
 134
 135
 136 /*
 137  * this routine is used for miscellaneous IP-like checksums, mainly
 138  * in icmp.c
 139  */
 140 static inline unsigned short
 141 ip_compute_csum(unsigned char * buff, int len)
 142 {
 143         return csum_fold(csum_partial(buff, len, 0));
 144 }
 145
 146 #define _HAVE_ARCH_IPV6_CSUM
 147 extern unsigned long
 148 __csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 149                 __u32 proto, unsigned int sum);
 150
 151 static inline unsigned short int
 152 csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 153                 unsigned short proto, unsigned int sum)
 154 {
 155         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 156                                            htonl(proto), sum));
 157 }
 158 #endif