include/drm/drm_fixed.h

   1 /*
   2  * Copyright 2009 Red Hat Inc.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * Authors: Dave Airlie
  23  *          Christian König
  24  */
  25 #ifndef DRM_FIXED_H
  26 #define DRM_FIXED_H
  27
  28 #include <linux/math64.h>
  29
  30 typedef union dfixed {
  31         u32 full;
  32 } fixed20_12;
  33
  34
  35 #define dfixed_const(A) (u32)(((A) << 12))/*  + ((B + 0.000122)*4096)) */
  36 #define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
  37 #define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
  38 #define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
  39 #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
  40 #define dfixed_init(A) { .full = dfixed_const((A)) }
  41 #define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
  42 #define dfixed_trunc(A) ((A).full >> 12)
  43 #define dfixed_frac(A) ((A).full & ((1 << 12) - 1))
  44
  45 static inline u32 dfixed_floor(fixed20_12 A)
  46 {
  47         u32 non_frac = dfixed_trunc(A);
  48
  49         return dfixed_const(non_frac);
  50 }
  51
  52 static inline u32 dfixed_ceil(fixed20_12 A)
  53 {
  54         u32 non_frac = dfixed_trunc(A);
  55
  56         if (A.full > dfixed_const(non_frac))
  57                 return dfixed_const(non_frac + 1);
  58         else
  59                 return dfixed_const(non_frac);
  60 }
  61
  62 static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
  63 {
  64         u64 tmp = ((u64)A.full << 13);
  65
  66         do_div(tmp, B.full);
  67         tmp += 1;
  68         tmp /= 2;
  69         return lower_32_bits(tmp);
  70 }
  71
  72 #define DRM_FIXED_POINT         32
  73 #define DRM_FIXED_ONE           (1ULL << DRM_FIXED_POINT)
  74 #define DRM_FIXED_DECIMAL_MASK  (DRM_FIXED_ONE - 1)
  75 #define DRM_FIXED_DIGITS_MASK   (~DRM_FIXED_DECIMAL_MASK)
  76
  77 static inline s64 drm_int2fixp(int a)
  78 {
  79         return ((s64)a) << DRM_FIXED_POINT;
  80 }
  81
  82 static inline int drm_fixp2int(int64_t a)
  83 {
  84         return ((s64)a) >> DRM_FIXED_POINT;
  85 }
  86
  87 static inline unsigned drm_fixp_msbset(int64_t a)
  88 {
  89         unsigned shift, sign = (a >> 63) & 1;
  90
  91         for (shift = 62; shift > 0; --shift)
  92                 if (((a >> shift) & 1) != sign)
  93                         return shift;
  94
  95         return 0;
  96 }
  97
  98 static inline s64 drm_fixp_mul(s64 a, s64 b)
  99 {
 100         unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
 101         s64 result;
 102
 103         if (shift > 61) {
 104                 shift = shift - 61;
 105                 a >>= (shift >> 1) + (shift & 1);
 106                 b >>= shift >> 1;
 107         } else
 108                 shift = 0;
 109
 110         result = a * b;
 111
 112         if (shift > DRM_FIXED_POINT)
 113                 return result << (shift - DRM_FIXED_POINT);
 114
 115         if (shift < DRM_FIXED_POINT)
 116                 return result >> (DRM_FIXED_POINT - shift);
 117
 118         return result;
 119 }
 120
 121 static inline s64 drm_fixp_div(s64 a, s64 b)
 122 {
 123         unsigned shift = 62 - drm_fixp_msbset(a);
 124         s64 result;
 125
 126         a <<= shift;
 127
 128         if (shift < DRM_FIXED_POINT)
 129                 b >>= (DRM_FIXED_POINT - shift);
 130
 131         result = div64_s64(a, b);
 132
 133         if (shift > DRM_FIXED_POINT)
 134                 return result >> (shift - DRM_FIXED_POINT);
 135
 136         return result;
 137 }
 138
 139 static inline s64 drm_fixp_exp(s64 x)
 140 {
 141         s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
 142         s64 sum = DRM_FIXED_ONE, term, y = x;
 143         u64 count = 1;
 144
 145         if (x < 0)
 146                 y = -1 * x;
 147
 148         term = y;
 149
 150         while (term >= tolerance) {
 151                 sum = sum + term;
 152                 count = count + 1;
 153                 term = drm_fixp_mul(term, div64_s64(y, count));
 154         }
 155
 156         if (x < 0)
 157                 sum = drm_fixp_div(DRM_FIXED_ONE, sum);
 158
 159         return sum;
 160 }
 161
 162 #endif