LXR linux/include/drm/drm

   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
  30typedef 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
  45static inline u32 dfixed_floor(fixed20_12 A)
  46{
  47        u32 non_frac = dfixed_trunc(A);
  48
  49        return dfixed_const(non_frac);
  50}
  51
  52static 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
  62static 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
  77static inline s64 drm_int2fixp(int a)
  78{
  79        return ((s64)a) << DRM_FIXED_POINT;
  80}
  81
  82static inline int drm_fixp2int(int64_t a)
  83{
  84        return ((s64)a) >> DRM_FIXED_POINT;
  85}
  86
  87static 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
  98static 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
 121static 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
 139static 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
 163