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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 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. #define DRM_FIXED_EPSILON       1LL
  77. #define DRM_FIXED_ALMOST_ONE    (DRM_FIXED_ONE - DRM_FIXED_EPSILON)
  78.  
  79. static inline s64 drm_int2fixp(int a)
  80. {
  81.         return ((s64)a) << DRM_FIXED_POINT;
  82. }
  83.  
  84. static inline int drm_fixp2int(s64 a)
  85. {
  86.         return ((s64)a) >> DRM_FIXED_POINT;
  87. }
  88.  
  89. static inline int drm_fixp2int_ceil(s64 a)
  90. {
  91.         if (a > 0)
  92.                 return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
  93.         else
  94.                 return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
  95. }
  96.  
  97. static inline unsigned drm_fixp_msbset(s64 a)
  98. {
  99.         unsigned shift, sign = (a >> 63) & 1;
  100.  
  101.         for (shift = 62; shift > 0; --shift)
  102.                 if (((a >> shift) & 1) != sign)
  103.                         return shift;
  104.  
  105.         return 0;
  106. }
  107.  
  108. static inline s64 drm_fixp_mul(s64 a, s64 b)
  109. {
  110.         unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
  111.         s64 result;
  112.  
  113.         if (shift > 61) {
  114.                 shift = shift - 61;
  115.                 a >>= (shift >> 1) + (shift & 1);
  116.                 b >>= shift >> 1;
  117.         } else
  118.                 shift = 0;
  119.  
  120.         result = a * b;
  121.  
  122.         if (shift > DRM_FIXED_POINT)
  123.                 return result << (shift - DRM_FIXED_POINT);
  124.  
  125.         if (shift < DRM_FIXED_POINT)
  126.                 return result >> (DRM_FIXED_POINT - shift);
  127.  
  128.         return result;
  129. }
  130.  
  131. static inline s64 drm_fixp_div(s64 a, s64 b)
  132. {
  133.         unsigned shift = 62 - drm_fixp_msbset(a);
  134.         s64 result;
  135.  
  136.         a <<= shift;
  137.  
  138.         if (shift < DRM_FIXED_POINT)
  139.                 b >>= (DRM_FIXED_POINT - shift);
  140.  
  141.         result = div64_s64(a, b);
  142.  
  143.         if (shift > DRM_FIXED_POINT)
  144.                 return result >> (shift - DRM_FIXED_POINT);
  145.  
  146.         return result;
  147. }
  148.  
  149. static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
  150. {
  151.         s64 res;
  152.         bool a_neg = a < 0;
  153.         bool b_neg = b < 0;
  154.         u64 a_abs = a_neg ? -a : a;
  155.         u64 b_abs = b_neg ? -b : b;
  156.         u64 rem;
  157.  
  158.         /* determine integer part */
  159.         u64 res_abs  = div64_u64_rem(a_abs, b_abs, &rem);
  160.  
  161.         /* determine fractional part */
  162.         {
  163.                 u32 i = DRM_FIXED_POINT;
  164.  
  165.                 do {
  166.                         rem <<= 1;
  167.                         res_abs <<= 1;
  168.                         if (rem >= b_abs) {
  169.                                 res_abs |= 1;
  170.                                 rem -= b_abs;
  171.                         }
  172.                 } while (--i != 0);
  173.         }
  174.  
  175.         /* round up LSB */
  176.         {
  177.                 u64 summand = (rem << 1) >= b_abs;
  178.  
  179.                 res_abs += summand;
  180.         }
  181.  
  182.         res = (s64) res_abs;
  183.         if (a_neg ^ b_neg)
  184.                 res = -res;
  185.         return res;
  186. }
  187.  
  188. static inline s64 drm_fixp_exp(s64 x)
  189. {
  190.         s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
  191.         s64 sum = DRM_FIXED_ONE, term, y = x;
  192.         u64 count = 1;
  193.  
  194.         if (x < 0)
  195.                 y = -1 * x;
  196.  
  197.         term = y;
  198.  
  199.         while (term >= tolerance) {
  200.                 sum = sum + term;
  201.                 count = count + 1;
  202.                 term = drm_fixp_mul(term, div64_s64(y, count));
  203.         }
  204.  
  205.         if (x < 0)
  206.                 sum = drm_fixp_div(DRM_FIXED_ONE, sum);
  207.  
  208.         return sum;
  209. }
  210.  
  211. #endif
  212.