drm_fixed.h 4.7 KB

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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. #include <linux/math64.h>
  28. typedef union dfixed {
  29. u32 full;
  30. } fixed20_12;
  31. #define dfixed_const(A) (u32)(((A) << 12))/* + ((B + 0.000122)*4096)) */
  32. #define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
  33. #define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
  34. #define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
  35. #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
  36. #define dfixed_init(A) { .full = dfixed_const((A)) }
  37. #define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
  38. #define dfixed_trunc(A) ((A).full >> 12)
  39. #define dfixed_frac(A) ((A).full & ((1 << 12) - 1))
  40. static inline u32 dfixed_floor(fixed20_12 A)
  41. {
  42. u32 non_frac = dfixed_trunc(A);
  43. return dfixed_const(non_frac);
  44. }
  45. static inline u32 dfixed_ceil(fixed20_12 A)
  46. {
  47. u32 non_frac = dfixed_trunc(A);
  48. if (A.full > dfixed_const(non_frac))
  49. return dfixed_const(non_frac + 1);
  50. else
  51. return dfixed_const(non_frac);
  52. }
  53. static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
  54. {
  55. u64 tmp = ((u64)A.full << 13);
  56. do_div(tmp, B.full);
  57. tmp += 1;
  58. tmp /= 2;
  59. return lower_32_bits(tmp);
  60. }
  61. #define DRM_FIXED_POINT 32
  62. #define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT)
  63. #define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1)
  64. #define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK)
  65. #define DRM_FIXED_EPSILON 1LL
  66. #define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON)
  67. static inline s64 drm_int2fixp(int a)
  68. {
  69. return ((s64)a) << DRM_FIXED_POINT;
  70. }
  71. static inline int drm_fixp2int(s64 a)
  72. {
  73. return ((s64)a) >> DRM_FIXED_POINT;
  74. }
  75. static inline int drm_fixp2int_ceil(s64 a)
  76. {
  77. if (a > 0)
  78. return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
  79. else
  80. return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
  81. }
  82. static inline unsigned drm_fixp_msbset(s64 a)
  83. {
  84. unsigned shift, sign = (a >> 63) & 1;
  85. for (shift = 62; shift > 0; --shift)
  86. if (((a >> shift) & 1) != sign)
  87. return shift;
  88. return 0;
  89. }
  90. static inline s64 drm_fixp_mul(s64 a, s64 b)
  91. {
  92. unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
  93. s64 result;
  94. if (shift > 61) {
  95. shift = shift - 61;
  96. a >>= (shift >> 1) + (shift & 1);
  97. b >>= shift >> 1;
  98. } else
  99. shift = 0;
  100. result = a * b;
  101. if (shift > DRM_FIXED_POINT)
  102. return result << (shift - DRM_FIXED_POINT);
  103. if (shift < DRM_FIXED_POINT)
  104. return result >> (DRM_FIXED_POINT - shift);
  105. return result;
  106. }
  107. static inline s64 drm_fixp_div(s64 a, s64 b)
  108. {
  109. unsigned shift = 62 - drm_fixp_msbset(a);
  110. s64 result;
  111. a <<= shift;
  112. if (shift < DRM_FIXED_POINT)
  113. b >>= (DRM_FIXED_POINT - shift);
  114. result = div64_s64(a, b);
  115. if (shift > DRM_FIXED_POINT)
  116. return result >> (shift - DRM_FIXED_POINT);
  117. return result;
  118. }
  119. static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
  120. {
  121. s64 res;
  122. bool a_neg = a < 0;
  123. bool b_neg = b < 0;
  124. u64 a_abs = a_neg ? -a : a;
  125. u64 b_abs = b_neg ? -b : b;
  126. u64 rem;
  127. /* determine integer part */
  128. u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem);
  129. /* determine fractional part */
  130. {
  131. u32 i = DRM_FIXED_POINT;
  132. do {
  133. rem <<= 1;
  134. res_abs <<= 1;
  135. if (rem >= b_abs) {
  136. res_abs |= 1;
  137. rem -= b_abs;
  138. }
  139. } while (--i != 0);
  140. }
  141. /* round up LSB */
  142. {
  143. u64 summand = (rem << 1) >= b_abs;
  144. res_abs += summand;
  145. }
  146. res = (s64) res_abs;
  147. if (a_neg ^ b_neg)
  148. res = -res;
  149. return res;
  150. }
  151. static inline s64 drm_fixp_exp(s64 x)
  152. {
  153. s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
  154. s64 sum = DRM_FIXED_ONE, term, y = x;
  155. u64 count = 1;
  156. if (x < 0)
  157. y = -1 * x;
  158. term = y;
  159. while (term >= tolerance) {
  160. sum = sum + term;
  161. count = count + 1;
  162. term = drm_fixp_mul(term, div64_s64(y, count));
  163. }
  164. if (x < 0)
  165. sum = drm_fixp_div(DRM_FIXED_ONE, sum);
  166. return sum;
  167. }
  168. #endif