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 K├Ânig
24 */
25#ifndef DRM_FIXED_H
26#define DRM_FIXED_H
27
28#include <linux/math64.h>
29
30typedef 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
45static inline u32 dfixed_floor(fixed20_12 A)
46{
47 u32 non_frac = dfixed_trunc(A);
48
49 return dfixed_const(non_frac);
50}
51
52static 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
62static 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
79static inline s64 drm_int2fixp(int a)
80{
81 return ((s64)a) << DRM_FIXED_POINT;
82}
83
84static inline int drm_fixp2int(s64 a)
85{
86 return ((s64)a) >> DRM_FIXED_POINT;
87}
88
89static 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
97static 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
108static 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
131static 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
149static 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
188static 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