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#ifndef _BITS_BITOPS_H
#define _BITS_BITOPS_H
/** @file
*
* loongArch bit operations
*
* We perform atomic bit set and bit clear operations using "ll"
* and "sc". We use the output constraint to inform the
* compiler that any memory from the start of the bit field up to and
* including the byte containing the bit may be modified. (This is
* overkill but shouldn't matter in practice since we're unlikely to
* subsequently read other bits from the same bit field.)
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
/**
* Test and set bit atomically
*
* @v bit Bit to set
* @v bits Bit field
* @ret old Old value of bit (zero or non-zero)
*/
static inline __attribute__ (( always_inline )) int
test_and_set_bit ( unsigned int bit, volatile void *bits ) {
unsigned int index = ( bit / 64 );
unsigned int offset = ( bit % 64 );
volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
uint64_t mask = ( 1UL << offset );
uint64_t old;
uint64_t new;
__asm__ __volatile__ ( "1: \n\t"
"ll.d %[old], %[qword] \n\t"
"or %[new], %[old], %[mask] \n\t"
"sc.d %[new], %[qword] \n\t"
"beqz %[new], 1b \n\t"
: [old] "=&r" ( old ),
[new] "=&r" ( new ),
[qword] "+m" ( *qword )
: [mask] "r" ( mask )
: "cc", "memory");
return ( !! ( old & mask ) );
}
/**
* Test and clear bit atomically
*
* @v bit Bit to set
* @v bits Bit field
* @ret old Old value of bit (zero or non-zero)
*/
static inline __attribute__ (( always_inline )) int
test_and_clear_bit ( unsigned int bit, volatile void *bits ) {
unsigned int index = ( bit / 64 );
unsigned int offset = ( bit % 64 );
volatile uint64_t *qword = ( ( ( volatile uint64_t * ) bits ) + index );
uint64_t mask = ( 1UL << offset );
uint64_t old;
uint64_t new;
__asm__ __volatile__ ( "1: \n\t"
"ll.d %[old], %[qword] \n\t"
"andn %[new], %[old], %[mask] \n\t"
"sc.d %[new], %[qword] \n\t"
"beqz %[new], 1b \n\t"
: [old] "=&r" ( old ),
[new] "=&r" ( new ),
[qword] "+m" ( *qword )
: [mask] "r" ( mask )
: "cc", "memory");
return ( !! ( old & mask ) );
}
/**
* Set bit atomically
*
* @v bit Bit to set
* @v bits Bit field
*/
static inline __attribute__ (( always_inline )) void
set_bit ( unsigned int bit, volatile void *bits ) {
test_and_set_bit ( bit, bits );
}
/**
* Clear bit atomically
*
* @v bit Bit to set
* @v bits Bit field
*/
static inline __attribute__ (( always_inline )) void
clear_bit ( unsigned int bit, volatile void *bits ) {
test_and_clear_bit ( bit, bits );
}
#endif /* _BITS_BITOPS_H */
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