projects/linux·blob master · refs

259 lines · 5.6 KiB

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#include <linux/types.h>
30#include <linux/wordpart.h>
31
32typedef union dfixed {
33 u32 full;
34} fixed20_12;
35
36
37#define dfixed_const(A) (u32)(((A) << 12))/* + ((B + 0.000122)*4096)) */
38#define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
39#define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
40#define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
41#define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
42#define dfixed_init(A) { .full = dfixed_const((A)) }
43#define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
44#define dfixed_trunc(A) ((A).full >> 12)
45#define dfixed_frac(A) ((A).full & ((1 << 12) - 1))
46
47static inline u32 dfixed_floor(fixed20_12 A)
48{
49 u32 non_frac = dfixed_trunc(A);
50
51 return dfixed_const(non_frac);
52}
53
54static inline u32 dfixed_ceil(fixed20_12 A)
55{
56 u32 non_frac = dfixed_trunc(A);
57
58 if (A.full > dfixed_const(non_frac))
59 return dfixed_const(non_frac + 1);
60 else
61 return dfixed_const(non_frac);
62}
63
64static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
65{
66 u64 tmp = ((u64)A.full << 13);
67
68 do_div(tmp, B.full);
69 tmp += 1;
70 tmp /= 2;
71 return lower_32_bits(tmp);
72}
73
74#define DRM_FIXED_POINT 32
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
81/**
82 * drm_sm2fixp() - convert signed-magnitude to fixed point
83 * @a: 1.31.32 signed-magnitude fixed point
84 *
85 * Convert a 1.31.32 signed-magnitude fixed point to 32.32
86 * 2s-complement fixed point
87 *
88 * @return s64 2s-complement fixed point
89 */
90static inline s64 drm_sm2fixp(__u64 a)
91{
92 if ((a & (1LL << 63))) {
93 return -(a & 0x7fffffffffffffffll);
94 } else {
95 return a;
96 }
97}
98
99static inline s64 drm_int2fixp(int a)
100{
101 return ((s64)a) << DRM_FIXED_POINT;
102}
103
104static inline int drm_fixp2int(s64 a)
105{
106 return ((s64)a) >> DRM_FIXED_POINT;
107}
108
109static inline int drm_fixp2int_round(s64 a)
110{
111 return drm_fixp2int(a + DRM_FIXED_ONE / 2);
112}
113
114static inline int drm_fixp2int_ceil(s64 a)
115{
116 if (a >= 0)
117 return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
118 else
119 return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
120}
121
122static inline unsigned drm_fixp_msbset(s64 a)
123{
124 unsigned shift, sign = (a >> 63) & 1;
125
126 for (shift = 62; shift > 0; --shift)
127 if (((a >> shift) & 1) != sign)
128 return shift;
129
130 return 0;
131}
132
133static inline s64 drm_fixp_mul(s64 a, s64 b)
134{
135 unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
136 s64 result;
137
138 if (shift > 61) {
139 shift = shift - 61;
140 a >>= (shift >> 1) + (shift & 1);
141 b >>= shift >> 1;
142 } else
143 shift = 0;
144
145 result = a * b;
146
147 if (shift > DRM_FIXED_POINT)
148 return result << (shift - DRM_FIXED_POINT);
149
150 if (shift < DRM_FIXED_POINT)
151 return result >> (DRM_FIXED_POINT - shift);
152
153 return result;
154}
155
156static inline s64 drm_fixp_div(s64 a, s64 b)
157{
158 unsigned shift = 62 - drm_fixp_msbset(a);
159 s64 result;
160
161 a <<= shift;
162
163 if (shift < DRM_FIXED_POINT)
164 b >>= (DRM_FIXED_POINT - shift);
165
166 result = div64_s64(a, b);
167
168 if (shift > DRM_FIXED_POINT)
169 return result >> (shift - DRM_FIXED_POINT);
170
171 return result;
172}
173
174static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
175{
176 s64 res;
177 bool a_neg = a < 0;
178 bool b_neg = b < 0;
179 u64 a_abs = a_neg ? -a : a;
180 u64 b_abs = b_neg ? -b : b;
181 u64 rem;
182
183 /* determine integer part */
184 u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem);
185
186 /* determine fractional part */
187 {
188 u32 i = DRM_FIXED_POINT;
189
190 do {
191 rem <<= 1;
192 res_abs <<= 1;
193 if (rem >= b_abs) {
194 res_abs |= 1;
195 rem -= b_abs;
196 }
197 } while (--i != 0);
198 }
199
200 /* round up LSB */
201 {
202 u64 summand = (rem << 1) >= b_abs;
203
204 res_abs += summand;
205 }
206
207 res = (s64) res_abs;
208 if (a_neg ^ b_neg)
209 res = -res;
210 return res;
211}
212
213static inline s64 drm_fixp_exp(s64 x)
214{
215 s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
216 s64 sum = DRM_FIXED_ONE, term, y = x;
217 u64 count = 1;
218
219 if (x < 0)
220 y = -1 * x;
221
222 term = y;
223
224 while (term >= tolerance) {
225 sum = sum + term;
226 count = count + 1;
227 term = drm_fixp_mul(term, div64_s64(y, count));
228 }
229
230 if (x < 0)
231 sum = drm_fixp_div(DRM_FIXED_ONE, sum);
232
233 return sum;
234}
235
236static inline int fxp_q4_from_int(int val_int)
237{
238 return val_int << 4;
239}
240
241static inline int fxp_q4_to_int(int val_q4)
242{
243 return val_q4 >> 4;
244}
245
246static inline int fxp_q4_to_int_roundup(int val_q4)
247{
248 return (val_q4 + 0xf) >> 4;
249}
250
251static inline int fxp_q4_to_frac(int val_q4)
252{
253 return val_q4 & 0xf;
254}
255
256#define FXP_Q4_FMT "%d.%04d"
257#define FXP_Q4_ARGS(val_q4) fxp_q4_to_int(val_q4), (fxp_q4_to_frac(val_q4) * 625)
258
259#endif