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1.1 ! root 1: /* ! 2: * Copyright (c) 1994 The University of Utah and ! 3: * the Center for Software Science (CSS). All rights reserved. ! 4: * ! 5: * Permission to use, copy, modify and distribute this software and its ! 6: * documentation is hereby granted, provided that both the copyright ! 7: * notice and this permission notice appear in all copies of the ! 8: * software, derivative works or modified versions, and any portions ! 9: * thereof, and that both notices appear in supporting documentation. ! 10: * ! 11: * THE UNIVERSITY OF UTAH AND CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS ! 12: * IS" CONDITION. THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF ! 13: * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. ! 14: * ! 15: * CSS requests users of this software to return to [email protected] any ! 16: * improvements that they make and grant CSS redistribution rights. ! 17: * ! 18: * Author: Bryan Ford, University of Utah CSS ! 19: */ ! 20: #ifndef _MACH_I386_PROC_OPS_H_ ! 21: #define _MACH_I386_PROC_OPS_H_ ! 22: ! 23: #include <mach/machine/vm_types.h> ! 24: #include <mach/inline.h> ! 25: ! 26: /* Returns the bit number of the most-significant set bit in `val', ! 27: e.g. 0 for 1, 1 for 2-3, 2 for 4-7, etc. ! 28: If `val' is 0 (i.e. no bits are set), the behavior is undefined. */ ! 29: MACH_INLINE int find_msb_set(natural_t val) ! 30: { ! 31: int msb; ! 32: ! 33: asm(" ! 34: bsr %0,%0 ! 35: " : "=r" (msb) : "0" (val)); ! 36: ! 37: return msb; ! 38: } ! 39: ! 40: #endif _MACH_I386_PROC_OPS_H_
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