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
81static inline s64 drm_int2fixp(int a)
82{
83 return ((s64)a) << DRM_FIXED_POINT;
84}
85
86static inline int drm_fixp2int(s64 a)
87{
88 return ((s64)a) >> DRM_FIXED_POINT;
89}
90
91static inline int drm_fixp2int_round(s64 a)
92{
93 return drm_fixp2int(a: a + DRM_FIXED_ONE / 2);
94}
95
96static inline int drm_fixp2int_ceil(s64 a)
97{
98 if (a >= 0)
99 return drm_fixp2int(a: a + DRM_FIXED_ALMOST_ONE);
100 else
101 return drm_fixp2int(a: a - DRM_FIXED_ALMOST_ONE);
102}
103
104static 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
115static inline s64 drm_fixp_mul(s64 a, s64 b)
116{
117 unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(a: 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
138static 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(dividend: a, divisor: b);
149
150 if (shift > DRM_FIXED_POINT)
151 return result >> (shift - DRM_FIXED_POINT);
152
153 return result;
154}
155
156static 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(dividend: a_abs, divisor: b_abs, remainder: &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
195static inline s64 drm_fixp_exp(s64 x)
196{
197 s64 tolerance = div64_s64(DRM_FIXED_ONE, divisor: 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(a: term, b: div64_s64(dividend: y, divisor: count));
210 }
211
212 if (x < 0)
213 sum = drm_fixp_div(DRM_FIXED_ONE, b: sum);
214
215 return sum;
216}
217
218static inline int fxp_q4_from_int(int val_int)
219{
220 return val_int << 4;
221}
222
223static inline int fxp_q4_to_int(int val_q4)
224{
225 return val_q4 >> 4;
226}
227
228static inline int fxp_q4_to_int_roundup(int val_q4)
229{
230 return (val_q4 + 0xf) >> 4;
231}
232
233static inline int fxp_q4_to_frac(int val_q4)
234{
235 return val_q4 & 0xf;
236}
237
238#define FXP_Q4_FMT "%d.%04d"
239#define FXP_Q4_ARGS(val_q4) fxp_q4_to_int(val_q4), (fxp_q4_to_frac(val_q4) * 625)
240
241#endif
242

source code of linux/include/drm/drm_fixed.h