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Mark Rutland
118d777c4c
In some cases it's necessary to replicate a byte across a u32 value, for
which REPEAT_BYTE() would be helpful. Currently this requires explicit
masking of the result to avoid sparse warnings, as e.g.
(u32)REPEAT_BYTE(0xa0))
... will result in a warning:
cast truncates bits from constant value (a0a0a0a0a0a0a0a0 becomes a0a0a0a0)
Add a new REPEAT_BYTE_U32() which does the necessary masking internally,
so that we don't need to duplicate this for every usage.
Signed-off-by: Mark Rutland <[email protected]>
Cc: Alexandru Elisei <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
58 lines
1.5 KiB
C
58 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_WORDPART_H
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#define _LINUX_WORDPART_H
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/**
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* upper_32_bits - return bits 32-63 of a number
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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 bits 0-31 of a number
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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) & 0xffffffff))
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/**
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* upper_16_bits - return bits 16-31 of a number
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* @n: the number we're accessing
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*/
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#define upper_16_bits(n) ((u16)((n) >> 16))
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/**
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* lower_16_bits - return bits 0-15 of a number
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* @n: the number we're accessing
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*/
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#define lower_16_bits(n) ((u16)((n) & 0xffff))
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/**
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* REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value
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* @x: value to repeat
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*
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* NOTE: @x is not checked for > 0xff; larger values produce odd results.
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*/
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#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
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/**
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* REPEAT_BYTE_U32 - repeat the value @x multiple times as a u32 value
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* @x: value to repeat
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*
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* NOTE: @x is not checked for > 0xff; larger values produce odd results.
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*/
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#define REPEAT_BYTE_U32(x) lower_32_bits(REPEAT_BYTE(x))
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/* Set bits in the first 'n' bytes when loaded from memory */
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#ifdef __LITTLE_ENDIAN
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# define aligned_byte_mask(n) ((1UL << 8*(n))-1)
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#else
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# define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n)))
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#endif
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#endif // _LINUX_WORDPART_H
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