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 | |