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2f9267ec23
implementations can provide a base zero ffs function if they wish. This changes #define RQB_FFS(mask) (ffs64(mask)) foo = RQB_FFS(mask) - 1; to #define RQB_FFS(mask) (ffs64(mask) - 1) foo = RQB_FFS(mask); On some platforms we can get the "- 1" for free, eg: those that use the C code for ffs64(). Reviewed by: jake (in principle)
59 lines
2.0 KiB
C
59 lines
2.0 KiB
C
/*
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* Copyright (c) 2001 Jake Burkholder <jake@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _MACHINE_RUNQ_H_
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#define _MACHINE_RUNQ_H_
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#define RQB_LEN (1UL) /* Number of priority status words. */
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#define RQB_L2BPW (6UL) /* Log2(sizeof(rqb_word_t) * NBBY)). */
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#define RQB_BPW (1UL<<RQB_L2BPW) /* Bits in an rqb_word_t. */
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#define RQB_BIT(pri) (1UL << ((pri) & (RQB_BPW - 1)))
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#define RQB_WORD(pri) ((pri) >> RQB_L2BPW)
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#define RQB_FFS(word) (ffs64(word) - 1)
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/*
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* Type of run queue status word.
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*/
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typedef u_int64_t rqb_word_t;
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static __inline u_long
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ffs64(u_long mask)
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{
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u_long bit;
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if (mask == 0)
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return (0);
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for (bit = 1; (mask & 1UL) == 0; bit++)
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mask >>= 1UL;
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return (bit);
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}
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#endif
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