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- #ifndef _BITS_STRINGS_H
- #define _BITS_STRINGS_H
-
- FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
- /**
- * Find last (i.e. most significant) set bit
- *
- * @v value Value
- * @ret msb Most significant bit set in value (LSB=1), or zero
- */
- static inline __attribute__ (( always_inline )) int __flsl ( long value ) {
- long msb_minus_one;
-
- /* If the input value is zero, the BSR instruction returns
- * ZF=1 and leaves an undefined value in the output register.
- * Perform this check in C rather than asm so that it can be
- * omitted in cases where the compiler is able to prove that
- * the input is non-zero.
- */
- if ( value ) {
- __asm__ ( "bsrl %1, %0"
- : "=r" ( msb_minus_one )
- : "rm" ( value ) );
- return ( msb_minus_one + 1 );
- } else {
- return 0;
- }
- }
-
- /**
- * Find last (i.e. most significant) set bit
- *
- * @v value Value
- * @ret msb Most significant bit set in value (LSB=1), or zero
- */
- static inline __attribute__ (( always_inline )) int __flsll ( long long value ){
- unsigned long high = ( value >> 32 );
- unsigned long low = ( value >> 0 );
-
- if ( high ) {
- return ( 32 + __flsl ( high ) );
- } else if ( low ) {
- return ( __flsl ( low ) );
- } else {
- return 0;
- }
- }
-
- #endif /* _BITS_STRINGS_H */
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