90 lines
2 KiB
C
90 lines
2 KiB
C
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/*
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* Copyright 2010 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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* Support code for the main lib/checksum.c.
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*/
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#include <net/checksum.h>
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#include <linux/module.h>
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__wsum do_csum(const unsigned char *buff, int len)
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{
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int odd, count;
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unsigned long result = 0;
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if (len <= 0)
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goto out;
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odd = 1 & (unsigned long) buff;
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if (odd) {
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result = (*buff << 8);
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len--;
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buff++;
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}
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count = len >> 1; /* nr of 16-bit words.. */
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if (count) {
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if (2 & (unsigned long) buff) {
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result += *(const unsigned short *)buff;
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count--;
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len -= 2;
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buff += 2;
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}
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count >>= 1; /* nr of 32-bit words.. */
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if (count) {
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#ifdef __tilegx__
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if (4 & (unsigned long) buff) {
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unsigned int w = *(const unsigned int *)buff;
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result = __insn_v2sadau(result, w, 0);
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count--;
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len -= 4;
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buff += 4;
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}
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count >>= 1; /* nr of 64-bit words.. */
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#endif
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/*
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* This algorithm could wrap around for very
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* large buffers, but those should be impossible.
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*/
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BUG_ON(count >= 65530);
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while (count) {
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unsigned long w = *(const unsigned long *)buff;
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count--;
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buff += sizeof(w);
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#ifdef __tilegx__
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result = __insn_v2sadau(result, w, 0);
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#else
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result = __insn_sadah_u(result, w, 0);
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#endif
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}
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#ifdef __tilegx__
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if (len & 4) {
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unsigned int w = *(const unsigned int *)buff;
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result = __insn_v2sadau(result, w, 0);
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buff += 4;
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}
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#endif
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}
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if (len & 2) {
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result += *(const unsigned short *) buff;
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buff += 2;
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}
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}
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if (len & 1)
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result += *buff;
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result = csum_long(result);
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if (odd)
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result = swab16(result);
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out:
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return result;
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}
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