#ifndef _BITS_STRINGS_H
#define _BITS_STRINGS_H
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/**
+ * Find first (i.e. least significant) set bit
+ *
+ * @v value Value
+ * @ret lsb Least significant bit set in value (LSB=1), or zero
+ */
+static inline __attribute__ (( always_inline )) int __ffsll ( long long value ){
+ long long lsb_minus_one;
+
+ /* If the input value is zero, the BSF instruction returns
+ * ZF=0 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__ ( "bsfq %1, %0"
+ : "=r" ( lsb_minus_one )
+ : "rm" ( value ) );
+ return ( lsb_minus_one + 1 );
+ } else {
+ return 0;
+ }
+}
+
+/**
+ * Find first (i.e. least significant) set bit
+ *
+ * @v value Value
+ * @ret lsb Least significant bit set in value (LSB=1), or zero
+ */
+static inline __attribute__ (( always_inline )) int __ffsl ( long value ) {
+
+ return __ffsll ( value );
+}
/**
* Find last (i.e. most significant) set bit
long 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.
+ * ZF=0 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.