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/kernel.h> 29 #include <linux/math64.h> 30 31 typedef union dfixed { 32 u32 full; 33 } fixed20_12; 34 35 36 #define dfixed_const(A) (u32)(((A) << 12))/* + ((B + 0.000122)*4096)) */ 37 #define dfixed_const_half(A) (u32)(((A) << 12) + 2048) 38 #define dfixed_const_666(A) (u32)(((A) << 12) + 2731) 39 #define dfixed_const_8(A) (u32)(((A) << 12) + 3277) 40 #define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12) 41 #define dfixed_init(A) { .full = dfixed_const((A)) } 42 #define dfixed_init_half(A) { .full = dfixed_const_half((A)) } 43 #define dfixed_trunc(A) ((A).full >> 12) 44 #define dfixed_frac(A) ((A).full & ((1 << 12) - 1)) 45 46 static inline u32 dfixed_floor(fixed20_12 A) 47 { 48 u32 non_frac = dfixed_trunc(A); 49 50 return dfixed_const(non_frac); 51 } 52 53 static inline u32 dfixed_ceil(fixed20_12 A) 54 { 55 u32 non_frac = dfixed_trunc(A); 56 57 if (A.full > dfixed_const(non_frac)) 58 return dfixed_const(non_frac + 1); 59 else 60 return dfixed_const(non_frac); 61 } 62 63 static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B) 64 { 65 u64 tmp = ((u64)A.full << 13); 66 67 do_div(tmp, B.full); 68 tmp += 1; 69 tmp /= 2; 70 return lower_32_bits(tmp); 71 } 72 73 #define DRM_FIXED_POINT 32 74 #define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT) 75 #define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1) 76 #define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK) 77 #define DRM_FIXED_EPSILON 1LL 78 #define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON) 79 80 static inline s64 drm_int2fixp(int a) 81 { 82 return ((s64)a) << DRM_FIXED_POINT; 83 } 84 85 static inline int drm_fixp2int(s64 a) 86 { 87 return ((s64)a) >> DRM_FIXED_POINT; 88 } 89 90 static inline int drm_fixp2int_round(s64 a) 91 { 92 return drm_fixp2int(a + DRM_FIXED_ONE / 2); 93 } 94 95 static inline int drm_fixp2int_ceil(s64 a) 96 { 97 if (a >= 0) 98 return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE); 99 else 100 return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE); 101 } 102 103 static inline unsigned drm_fixp_msbset(s64 a) 104 { 105 unsigned shift, sign = (a >> 63) & 1; 106 107 for (shift = 62; shift > 0; --shift) 108 if (((a >> shift) & 1) != sign) 109 return shift; 110 111 return 0; 112 } 113 114 static inline s64 drm_fixp_mul(s64 a, s64 b) 115 { 116 unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b); 117 s64 result; 118 119 if (shift > 61) { 120 shift = shift - 61; 121 a >>= (shift >> 1) + (shift & 1); 122 b >>= shift >> 1; 123 } else 124 shift = 0; 125 126 result = a * b; 127 128 if (shift > DRM_FIXED_POINT) 129 return result << (shift - DRM_FIXED_POINT); 130 131 if (shift < DRM_FIXED_POINT) 132 return result >> (DRM_FIXED_POINT - shift); 133 134 return result; 135 } 136 137 static inline s64 drm_fixp_div(s64 a, s64 b) 138 { 139 unsigned shift = 62 - drm_fixp_msbset(a); 140 s64 result; 141 142 a <<= shift; 143 144 if (shift < DRM_FIXED_POINT) 145 b >>= (DRM_FIXED_POINT - shift); 146 147 result = div64_s64(a, b); 148 149 if (shift > DRM_FIXED_POINT) 150 return result >> (shift - DRM_FIXED_POINT); 151 152 return result; 153 } 154 155 static inline s64 drm_fixp_from_fraction(s64 a, s64 b) 156 { 157 s64 res; 158 bool a_neg = a < 0; 159 bool b_neg = b < 0; 160 u64 a_abs = a_neg ? -a : a; 161 u64 b_abs = b_neg ? -b : b; 162 u64 rem; 163 164 /* determine integer part */ 165 u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem); 166 167 /* determine fractional part */ 168 { 169 u32 i = DRM_FIXED_POINT; 170 171 do { 172 rem <<= 1; 173 res_abs <<= 1; 174 if (rem >= b_abs) { 175 res_abs |= 1; 176 rem -= b_abs; 177 } 178 } while (--i != 0); 179 } 180 181 /* round up LSB */ 182 { 183 u64 summand = (rem << 1) >= b_abs; 184 185 res_abs += summand; 186 } 187 188 res = (s64) res_abs; 189 if (a_neg ^ b_neg) 190 res = -res; 191 return res; 192 } 193 194 static inline s64 drm_fixp_exp(s64 x) 195 { 196 s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000); 197 s64 sum = DRM_FIXED_ONE, term, y = x; 198 u64 count = 1; 199 200 if (x < 0) 201 y = -1 * x; 202 203 term = y; 204 205 while (term >= tolerance) { 206 sum = sum + term; 207 count = count + 1; 208 term = drm_fixp_mul(term, div64_s64(y, count)); 209 } 210 211 if (x < 0) 212 sum = drm_fixp_div(DRM_FIXED_ONE, sum); 213 214 return sum; 215 } 216 217 #endif 218