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98 lines
2.0 KiB
98 lines
2.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Network Checksum & Copy routine |
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* |
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* Copyright (C) 1999, 2003-2004 Hewlett-Packard Co |
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* Stephane Eranian <[email protected]> |
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* |
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* Most of the code has been imported from Linux/Alpha |
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*/ |
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#include <linux/module.h> |
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#include <linux/types.h> |
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#include <linux/string.h> |
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#include <net/checksum.h> |
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/* |
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* XXX Fixme: those 2 inlines are meant for debugging and will go away |
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*/ |
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static inline unsigned |
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short from64to16(unsigned long x) |
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{ |
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/* add up 32-bit words for 33 bits */ |
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x = (x & 0xffffffff) + (x >> 32); |
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/* add up 16-bit and 17-bit words for 17+c bits */ |
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x = (x & 0xffff) + (x >> 16); |
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/* add up 16-bit and 2-bit for 16+c bit */ |
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x = (x & 0xffff) + (x >> 16); |
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/* add up carry.. */ |
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x = (x & 0xffff) + (x >> 16); |
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return x; |
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} |
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static inline |
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unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum) |
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{ |
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int odd, count; |
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unsigned long result = (unsigned long)psum; |
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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 += *(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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if (4 & (unsigned long) buff) { |
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result += *(unsigned int *) buff; |
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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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if (count) { |
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unsigned long carry = 0; |
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do { |
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unsigned long w = *(unsigned long *) buff; |
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count--; |
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buff += 8; |
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result += carry; |
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result += w; |
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carry = (w > result); |
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} while (count); |
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result += carry; |
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result = (result & 0xffffffff) + (result >> 32); |
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} |
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if (len & 4) { |
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result += *(unsigned int *) buff; |
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buff += 4; |
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} |
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} |
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if (len & 2) { |
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result += *(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 = from64to16(result); |
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if (odd) |
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
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out: |
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return result; |
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}
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