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#ifndef _BITS_BITOPS_H
#define _BITS_BITOPS_H
/** @file
*
* ARM bit operations
*
*/
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 / 32 );
unsigned int offset = ( bit % 32 );
volatile uint32_t *dword = ( ( ( volatile uint32_t * ) bits ) + index );
uint32_t mask = ( 1UL << offset );
uint32_t old;
uint32_t new;
uint32_t flag;
__asm__ __volatile__ ( "\n1:\n\t"
"ldrex %0, %3\n\t"
"orr %1, %0, %4\n\t"
"strex %2, %1, %3\n\t"
"tst %2, %2\n\t"
"bne 1b\n\t"
: "=&r" ( old ), "=&r" ( new ), "=&l" ( flag ),
"+Q" ( *dword )
: "r" ( mask )
: "cc" );
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 / 32 );
unsigned int offset = ( bit % 32 );
volatile uint32_t *dword = ( ( ( volatile uint32_t * ) bits ) + index );
uint32_t mask = ( 1UL << offset );
uint32_t old;
uint32_t new;
uint32_t flag;
__asm__ __volatile__ ( "\n1:\n\t"
"ldrex %0, %3\n\t"
"bic %1, %0, %4\n\t"
"strex %2, %1, %3\n\t"
"tst %2, %2\n\t"
"bne 1b\n\t"
: "=&r" ( old ), "=&r" ( new ), "=&l" ( flag ),
"+Q" ( *dword )
: "r" ( mask )
: "cc" );
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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