arch/cris/lib/old_checksum.c

   1 /* $Id: old_checksum.c,v 1.1.1.1 2001/12/17 13:59:27 bjornw Exp $
   2  *
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              IP/TCP/UDP checksumming routines
   8  *
   9  * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
  10  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  11  *              Tom May, <ftom@netcom.com>
  12  *              Lots of code moved from tcp.c and ip.c; see those files
  13  *              for more names.
  14  *
  15  *              This program is free software; you can redistribute it and/or
  16  *              modify it under the terms of the GNU General Public License
  17  *              as published by the Free Software Foundation; either version
  18  *              2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <net/checksum.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 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
  50 {
  51   /*
  52    * Experiments with ethernet and slip connections show that buff
  53    * is aligned on either a 2-byte or 4-byte boundary.
  54    */
  55   const unsigned char *endMarker = buff + len;
  56   const unsigned char *marker = endMarker - (len % 16);
  57 #if 0
  58   if((int)buff & 0x3)
  59     printk("unaligned buff %p\n", buff);
  60   __delay(900); /* extra delay of 90 us to test performance hit */
  61 #endif
  62   BITON;
  63   while (buff < marker) {
  64     sum += *((unsigned short *)buff)++;
  65     sum += *((unsigned short *)buff)++;
  66     sum += *((unsigned short *)buff)++;
  67     sum += *((unsigned short *)buff)++;
  68     sum += *((unsigned short *)buff)++;
  69     sum += *((unsigned short *)buff)++;
  70     sum += *((unsigned short *)buff)++;
  71     sum += *((unsigned short *)buff)++;
  72   }
  73   marker = endMarker - (len % 2);
  74   while(buff < marker) {
  75     sum += *((unsigned short *)buff)++;
  76   }
  77   if(endMarker - buff > 0) {
  78     sum += *buff;                 /* add extra byte separately */
  79   }
  80   BITOFF;
  81   return(sum);
  82 }