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lib/checksum.c: fix endianess bug
The new generic checksum code has a small dependency on endianess and worked only on big-endian systems. I could not find a nice efficient way to express this, so I added an #ifdef. Using 'result += le16_to_cpu(*buff);' would have worked as well, but would be slightly less efficient on big-endian systems and IMHO would not be clearer. Also fix a bug that prevents this from working on 64-bit machines. If you have a 64-bit CPU and want to use the generic checksum code, you should probably do some more optimizations anyway, but at least the code should not break. Reported-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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@ -55,7 +55,11 @@ static unsigned int do_csum(const unsigned char *buff, int len)
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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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#ifdef __LITTLE_ENDIAN
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result = *buff;
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#else
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result += (*buff << 8);
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#endif
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len--;
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buff++;
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}
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@ -71,7 +75,7 @@ static unsigned int do_csum(const unsigned char *buff, int len)
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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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unsigned long w = *(unsigned int *) buff;
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count--;
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buff += 4;
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result += carry;
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@ -87,7 +91,11 @@ static unsigned int do_csum(const unsigned char *buff, int len)
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}
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}
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if (len & 1)
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#ifdef __LITTLE_ENDIAN
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result += *buff;
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#else
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result += (*buff << 8);
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#endif
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result = from32to16(result);
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if (odd)
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
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