101 lines
2.2 KiB
C
101 lines
2.2 KiB
C
#ifndef _BITS_BITOPS_H
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#define _BITS_BITOPS_H
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/** @file
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*
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* ARM bit operations
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdint.h>
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/**
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* Test and set bit atomically
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*
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* @v bit Bit to set
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* @v bits Bit field
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* @ret old Old value of bit (zero or non-zero)
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*/
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static inline __attribute__ (( always_inline )) int
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test_and_set_bit ( unsigned int bit, volatile void *bits ) {
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unsigned int index = ( bit / 64 );
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unsigned int offset = ( bit % 64 );
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volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
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uint64_t mask = ( 1UL << offset );
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uint64_t old;
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uint64_t new;
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uint32_t flag;
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__asm__ __volatile__ ( "\n1:\n\t"
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"ldxr %0, %3\n\t"
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"orr %1, %0, %4\n\t"
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"stxr %w2, %1, %3\n\t"
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"tst %w2, %w2\n\t"
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"bne 1b\n\t"
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: "=&r" ( old ), "=&r" ( new ), "=&r" ( flag ),
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"+Q" ( *qword )
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: "r" ( mask )
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: "cc" );
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return ( !! ( old & mask ) );
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}
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/**
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* Test and clear bit atomically
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*
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* @v bit Bit to set
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* @v bits Bit field
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* @ret old Old value of bit (zero or non-zero)
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*/
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static inline __attribute__ (( always_inline )) int
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test_and_clear_bit ( unsigned int bit, volatile void *bits ) {
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unsigned int index = ( bit / 64 );
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unsigned int offset = ( bit % 64 );
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volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
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uint64_t mask = ( 1UL << offset );
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uint64_t old;
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uint64_t new;
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uint32_t flag;
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__asm__ __volatile__ ( "\n1:\n\t"
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"ldxr %0, %3\n\t"
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"bic %1, %0, %4\n\t"
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"stxr %w2, %1, %3\n\t"
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"tst %w2, %w2\n\t"
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"bne 1b\n\t"
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: "=&r" ( old ), "=&r" ( new ), "=&r" ( flag ),
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"+Q" ( *qword )
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: "r" ( mask )
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: "cc" );
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return ( !! ( old & mask ) );
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}
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/**
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* Set bit atomically
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*
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* @v bit Bit to set
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* @v bits Bit field
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*/
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static inline __attribute__ (( always_inline )) void
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set_bit ( unsigned int bit, volatile void *bits ) {
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test_and_set_bit ( bit, bits );
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}
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/**
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* Clear bit atomically
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*
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* @v bit Bit to set
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* @v bits Bit field
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*/
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static inline __attribute__ (( always_inline )) void
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clear_bit ( unsigned int bit, volatile void *bits ) {
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test_and_clear_bit ( bit, bits );
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}
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#endif /* _BITS_BITOPS_H */
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