linux/compat.h: port lower_32_bits and upper_32_bits from Linux
[backport from linux commit 204b885e and 218e180e7] 64 bit processors are becomming more and more popular. lower_32_bits and upper_32_bits save our labor doing shifts/manipulations like (u32)(n) and (u32)((n) >> 32). They are good helpers in both little and big endian cases. Port these two functions here from Linux:include/linux/kernel.h, cater the comment message to little/big endian cases. Later on, developers could include linux/compat.h if they want to use these two functions. Signed-off-by: Lijun Pan <Lijun.Pan@freescale.com>
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#define PAGE_SIZE 4096
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#define PAGE_SIZE 4096
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/**
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* upper_32_bits - return MSB bits 32-63 of a number if little endian, or
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* return MSB bits 0-31 of a number if big endian.
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* @n: the number we're accessing
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*
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* A basic shift-right of a 64- or 32-bit quantity. Use this to suppress
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* the "right shift count >= width of type" warning when that quantity is
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* 32-bits.
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*/
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#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
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/**
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* lower_32_bits - return LSB bits 0-31 of a number if little endian, or
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* return LSB bits 32-63 of a number if big endian.
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* @n: the number we're accessing
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*/
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#define lower_32_bits(n) ((u32)(n))
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#endif
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#endif
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