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
dfixed_floor(fixed20_12 A)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
dfixed_ceil(fixed20_12 A)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
dfixed_div(fixed20_12 A,fixed20_12 B)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_POINT_HALF 16
75 #define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT)
76 #define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1)
77 #define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK)
78 #define DRM_FIXED_EPSILON 1LL
79 #define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON)
80
drm_int2fixp(int a)81 static inline s64 drm_int2fixp(int a)
82 {
83 return ((s64)a) << DRM_FIXED_POINT;
84 }
85
drm_fixp2int(s64 a)86 static inline int drm_fixp2int(s64 a)
87 {
88 return ((s64)a) >> DRM_FIXED_POINT;
89 }
90
drm_fixp2int_round(s64 a)91 static inline int drm_fixp2int_round(s64 a)
92 {
93 return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
94 }
95
drm_fixp2int_ceil(s64 a)96 static inline int drm_fixp2int_ceil(s64 a)
97 {
98 if (a > 0)
99 return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
100 else
101 return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
102 }
103
drm_fixp_msbset(s64 a)104 static inline unsigned drm_fixp_msbset(s64 a)
105 {
106 unsigned shift, sign = (a >> 63) & 1;
107
108 for (shift = 62; shift > 0; --shift)
109 if (((a >> shift) & 1) != sign)
110 return shift;
111
112 return 0;
113 }
114
drm_fixp_mul(s64 a,s64 b)115 static inline s64 drm_fixp_mul(s64 a, s64 b)
116 {
117 unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
118 s64 result;
119
120 if (shift > 61) {
121 shift = shift - 61;
122 a >>= (shift >> 1) + (shift & 1);
123 b >>= shift >> 1;
124 } else
125 shift = 0;
126
127 result = a * b;
128
129 if (shift > DRM_FIXED_POINT)
130 return result << (shift - DRM_FIXED_POINT);
131
132 if (shift < DRM_FIXED_POINT)
133 return result >> (DRM_FIXED_POINT - shift);
134
135 return result;
136 }
137
drm_fixp_div(s64 a,s64 b)138 static inline s64 drm_fixp_div(s64 a, s64 b)
139 {
140 unsigned shift = 62 - drm_fixp_msbset(a);
141 s64 result;
142
143 a <<= shift;
144
145 if (shift < DRM_FIXED_POINT)
146 b >>= (DRM_FIXED_POINT - shift);
147
148 result = div64_s64(a, b);
149
150 if (shift > DRM_FIXED_POINT)
151 return result >> (shift - DRM_FIXED_POINT);
152
153 return result;
154 }
155
drm_fixp_from_fraction(s64 a,s64 b)156 static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
157 {
158 s64 res;
159 bool a_neg = a < 0;
160 bool b_neg = b < 0;
161 u64 a_abs = a_neg ? -a : a;
162 u64 b_abs = b_neg ? -b : b;
163 u64 rem;
164
165 /* determine integer part */
166 u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem);
167
168 /* determine fractional part */
169 {
170 u32 i = DRM_FIXED_POINT;
171
172 do {
173 rem <<= 1;
174 res_abs <<= 1;
175 if (rem >= b_abs) {
176 res_abs |= 1;
177 rem -= b_abs;
178 }
179 } while (--i != 0);
180 }
181
182 /* round up LSB */
183 {
184 u64 summand = (rem << 1) >= b_abs;
185
186 res_abs += summand;
187 }
188
189 res = (s64) res_abs;
190 if (a_neg ^ b_neg)
191 res = -res;
192 return res;
193 }
194
drm_fixp_exp(s64 x)195 static inline s64 drm_fixp_exp(s64 x)
196 {
197 s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
198 s64 sum = DRM_FIXED_ONE, term, y = x;
199 u64 count = 1;
200
201 if (x < 0)
202 y = -1 * x;
203
204 term = y;
205
206 while (term >= tolerance) {
207 sum = sum + term;
208 count = count + 1;
209 term = drm_fixp_mul(term, div64_s64(y, count));
210 }
211
212 if (x < 0)
213 sum = drm_fixp_div(DRM_FIXED_ONE, sum);
214
215 return sum;
216 }
217
218 #endif
219
