FreeBSD/Linux Kernel Cross Reference
sys/dev/drm2/drm_fixed.h

     /*
      * Copyright 2009 Red Hat Inc.
      *
      * Permission is hereby granted, free of charge, to any person obtaining a
      * copy of this software and associated documentation files (the "Software"),
      * to deal in the Software without restriction, including without limitation
      * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      * and/or sell copies of the Software, and to permit persons to whom the
      * Software is furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
     * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     * OTHER DEALINGS IN THE SOFTWARE.
     *
     * Authors: Dave Airlie
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #ifndef DRM_FIXED_H
    #define DRM_FIXED_H
    
    typedef union dfixed {
            u32 full;
    } fixed20_12;
    
    
    #define dfixed_const(A) (u32)(((A) << 12))/*  + ((B + 0.000122)*4096)) */
    #define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
    #define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
    #define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
    #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
    #define dfixed_init(A) { .full = dfixed_const((A)) }
    #define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
    #define dfixed_trunc(A) ((A).full >> 12)
    #define dfixed_frac(A) ((A).full & ((1 << 12) - 1))
    
    static inline u32 dfixed_floor(fixed20_12 A)
    {
            u32 non_frac = dfixed_trunc(A);
    
            return dfixed_const(non_frac);
    }
    
    static inline u32 dfixed_ceil(fixed20_12 A)
    {
            u32 non_frac = dfixed_trunc(A);
    
            if (A.full > dfixed_const(non_frac))
                    return dfixed_const(non_frac + 1);
            else
                    return dfixed_const(non_frac);
    }
    
    static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
    {
            u64 tmp = ((u64)A.full << 13);
    
            do_div(tmp, B.full);
            tmp += 1;
            tmp /= 2;
            return lower_32_bits(tmp);
    }
    #endif

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