mirror of https://github.com/ipxe/ipxe.git
103 lines
2.6 KiB
C
103 lines
2.6 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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* loongArch bit operations
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*
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* We perform atomic bit set and bit clear operations using "ll"
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* and "sc". We use the output constraint to inform the
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* compiler that any memory from the start of the bit field up to and
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* including the byte containing the bit may be modified. (This is
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* overkill but shouldn't matter in practice since we're unlikely to
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* subsequently read other bits from the same bit field.)
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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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__asm__ __volatile__ ( "1: \n\t"
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"ll.d %[old], %[qword] \n\t"
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"or %[new], %[old], %[mask] \n\t"
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"sc.d %[new], %[qword] \n\t"
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"beqz %[new], 1b \n\t"
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: [old] "=&r" ( old ),
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[new] "=&r" ( new ),
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[qword] "+m" ( *qword )
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: [mask] "r" ( mask )
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: "cc", "memory");
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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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__asm__ __volatile__ ( "1: \n\t"
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"ll.d %[old], %[qword] \n\t"
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"andn %[new], %[old], %[mask] \n\t"
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"sc.d %[new], %[qword] \n\t"
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"beqz %[new], 1b \n\t"
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: [old] "=&r" ( old ),
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[new] "=&r" ( new ),
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[qword] "+m" ( *qword )
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: [mask] "r" ( mask )
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: "cc", "memory");
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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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