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kernel/linux-imx6_3.14.28/arch/tile/lib/checksum.c 2.04 KB
6b13f685e   김민수   BSP 최초 추가
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  /*
   * Copyright 2010 Tilera Corporation. All Rights Reserved.
   *
   *   This program is free software; you can redistribute it and/or
   *   modify it under the terms of the GNU General Public License
   *   as published by the Free Software Foundation, version 2.
   *
   *   This program is distributed in the hope that it will be useful, but
   *   WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
   *   NON INFRINGEMENT.  See the GNU General Public License for
   *   more details.
   * Support code for the main lib/checksum.c.
   */
  
  #include <net/checksum.h>
  #include <linux/module.h>
  
  __wsum 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 += *(const unsigned short *)buff;
  			count--;
  			len -= 2;
  			buff += 2;
  		}
  		count >>= 1;		/* nr of 32-bit words.. */
  		if (count) {
  #ifdef __tilegx__
  			if (4 & (unsigned long) buff) {
  				unsigned int w = *(const unsigned int *)buff;
  				result = __insn_v2sadau(result, w, 0);
  				count--;
  				len -= 4;
  				buff += 4;
  			}
  			count >>= 1;		/* nr of 64-bit words.. */
  #endif
  
  			/*
  			 * This algorithm could wrap around for very
  			 * large buffers, but those should be impossible.
  			 */
  			BUG_ON(count >= 65530);
  
  			while (count) {
  				unsigned long w = *(const unsigned long *)buff;
  				count--;
  				buff += sizeof(w);
  #ifdef __tilegx__
  				result = __insn_v2sadau(result, w, 0);
  #else
  				result = __insn_sadah_u(result, w, 0);
  #endif
  			}
  #ifdef __tilegx__
  			if (len & 4) {
  				unsigned int w = *(const unsigned int *)buff;
  				result = __insn_v2sadau(result, w, 0);
  				buff += 4;
  			}
  #endif
  		}
  		if (len & 2) {
  			result += *(const unsigned short *) buff;
  			buff += 2;
  		}
  	}
  	if (len & 1)
  		result += *buff;
  	result = csum_long(result);
  	if (odd)
  		result = swab16(result);
  out:
  	return result;
  }