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