arch/cris/arch-v10/lib/old_checksum.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IP/TCP/UDP checksumming routines
   7  *
   8  * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
   9  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  10  *              Tom May, <ftom@netcom.com>
  11  *              Lots of code moved from tcp.c and ip.c; see those files
  12  *              for more names.
  13  *
  14  *              This program is free software; you can redistribute it and/or
  15  *              modify it under the terms of the GNU General Public License
  16  *              as published by the Free Software Foundation; either version
  17  *              2 of the License, or (at your option) any later version.
  18  */
  19
  20 #include <net/checksum.h>
  21 #include <net/module.h>
  22
  23 #undef PROFILE_CHECKSUM
  24
  25 #ifdef PROFILE_CHECKSUM
  26 /* these are just for profiling the checksum code with an oscillioscope.. uh */
  27 #if 0
  28 #define BITOFF *((unsigned char *)0xb0000030) = 0xff
  29 #define BITON *((unsigned char *)0xb0000030) = 0x0
  30 #endif
  31 #include <asm/io.h>
  32 #define CBITON LED_ACTIVE_SET(1)
  33 #define CBITOFF LED_ACTIVE_SET(0)
  34 #define BITOFF
  35 #define BITON
  36 #else
  37 #define BITOFF
  38 #define BITON
  39 #define CBITOFF
  40 #define CBITON
  41 #endif
  42
  43 /*
  44  * computes a partial checksum, e.g. for TCP/UDP fragments
  45  */
  46
  47 #include <asm/delay.h>
  48
  49 __wsum csum_partial(const void *p, int len, __wsum __sum)
  50 {
  51         u32 sum = (__force u32)__sum;
  52         const u16 *buff = p;
  53         /*
  54         * Experiments with ethernet and slip connections show that buff
  55         * is aligned on either a 2-byte or 4-byte boundary.
  56         */
  57         const void *endMarker = p + len;
  58         const void *marker = endMarker - (len % 16);
  59 #if 0
  60         if((int)buff & 0x3)
  61                 printk("unaligned buff %p\n", buff);
  62         __delay(900); /* extra delay of 90 us to test performance hit */
  63 #endif
  64         BITON;
  65         while (buff < marker) {
  66                 sum += *buff++;
  67                 sum += *buff++;
  68                 sum += *buff++;
  69                 sum += *buff++;
  70                 sum += *buff++;
  71                 sum += *buff++;
  72                 sum += *buff++;
  73                 sum += *buff++;
  74         }
  75         marker = endMarker - (len % 2);
  76         while (buff < marker)
  77                 sum += *buff++;
  78
  79         if (endMarker > buff)
  80                 sum += *(const u8 *)buff;       /* add extra byte separately */
  81
  82         BITOFF;
  83         return (__force __wsum)sum;
  84 }
  85
  86 EXPORT_SYMBOL(csum_partial);