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  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 Konig
  24.  */
  25. #ifndef DRM_FIXED_H
  26. #define DRM_FIXED_H
  27.  
  28. typedef union dfixed {
  29.         u32 full;
  30. } fixed20_12;
  31.  
  32.  
  33. #define dfixed_const(A) (u32)(((A) << 12))/*  + ((B + 0.000122)*4096)) */
  34. #define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
  35. #define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
  36. #define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
  37. #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
  38. #define dfixed_init(A) { .full = dfixed_const((A)) }
  39. #define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
  40. #define dfixed_trunc(A) ((A).full >> 12)
  41. #define dfixed_frac(A) ((A).full & ((1 << 12) - 1))
  42.  
  43. static inline u32 dfixed_floor(fixed20_12 A)
  44. {
  45.         u32 non_frac = dfixed_trunc(A);
  46.  
  47.         return dfixed_const(non_frac);
  48. }
  49.  
  50. static inline u32 dfixed_ceil(fixed20_12 A)
  51. {
  52.         u32 non_frac = dfixed_trunc(A);
  53.  
  54.         if (A.full > dfixed_const(non_frac))
  55.                 return dfixed_const(non_frac + 1);
  56.         else
  57.                 return dfixed_const(non_frac);
  58. }
  59.  
  60. static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
  61. {
  62.         u64 tmp = ((u64)A.full << 13);
  63.  
  64.         do_div(tmp, B.full);
  65.         tmp += 1;
  66.         tmp /= 2;
  67.         return lower_32_bits(tmp);
  68. }
  69.  
  70. #define DRM_FIXED_POINT         32
  71. #define DRM_FIXED_ONE           (1ULL << DRM_FIXED_POINT)
  72. #define DRM_FIXED_DECIMAL_MASK  (DRM_FIXED_ONE - 1)
  73. #define DRM_FIXED_DIGITS_MASK   (~DRM_FIXED_DECIMAL_MASK)
  74.  
  75. static inline s64 drm_int2fixp(int a)
  76. {
  77.         return ((s64)a) << DRM_FIXED_POINT;
  78. }
  79.  
  80. static inline int drm_fixp2int(int64_t a)
  81. {
  82.         return ((s64)a) >> DRM_FIXED_POINT;
  83. }
  84.  
  85. static inline unsigned drm_fixp_msbset(int64_t a)
  86. {
  87.         unsigned shift, sign = (a >> 63) & 1;
  88.  
  89.         for (shift = 62; shift > 0; --shift)
  90.                 if (((a >> shift) & 1) != sign)
  91.                         return shift;
  92.  
  93.         return 0;
  94. }
  95.  
  96. static inline s64 drm_fixp_mul(s64 a, s64 b)
  97. {
  98.         unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
  99.         s64 result;
  100.  
  101.         if (shift > 61) {
  102.                 shift = shift - 61;
  103.                 a >>= (shift >> 1) + (shift & 1);
  104.                 b >>= shift >> 1;
  105.         } else
  106.                 shift = 0;
  107.  
  108.         result = a * b;
  109.  
  110.         if (shift > DRM_FIXED_POINT)
  111.                 return result << (shift - DRM_FIXED_POINT);
  112.  
  113.         if (shift < DRM_FIXED_POINT)
  114.                 return result >> (DRM_FIXED_POINT - shift);
  115.  
  116.         return result;
  117. }
  118.  
  119. static inline s64 drm_fixp_div(s64 a, s64 b)
  120. {
  121.         unsigned shift = 62 - drm_fixp_msbset(a);
  122.         s64 result;
  123.  
  124.         a <<= shift;
  125.  
  126.         if (shift < DRM_FIXED_POINT)
  127.                 b >>= (DRM_FIXED_POINT - shift);
  128.  
  129.         result = div64_s64(a, b);
  130.  
  131.         if (shift > DRM_FIXED_POINT)
  132.                 return result >> (shift - DRM_FIXED_POINT);
  133.  
  134.         return result;
  135. }
  136.  
  137. static inline s64 drm_fixp_exp(s64 x)
  138. {
  139.         s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
  140.         s64 sum = DRM_FIXED_ONE, term, y = x;
  141.         u64 count = 1;
  142.  
  143.         if (x < 0)
  144.                 y = -1 * x;
  145.  
  146.         term = y;
  147.  
  148.         while (term >= tolerance) {
  149.                 sum = sum + term;
  150.                 count = count + 1;
  151.                 term = drm_fixp_mul(term, div64_s64(y, count));
  152.         }
  153.  
  154.         if (x < 0)
  155.                 sum = drm_fixp_div(DRM_FIXED_ONE, sum);
  156.  
  157.         return sum;
  158. }
  159.  
  160. #endif
  161.