summaryrefslogtreecommitdiffstats
path: root/include/drm/drm_fixed.h
blob: 255645c1f9a89c28304317783f348baa8fe9e15f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/*
 * Copyright 2009 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Dave Airlie
 *          Christian König
 */
#ifndef DRM_FIXED_H
#define DRM_FIXED_H

#include <linux/kernel.h>
#include <linux/math64.h>

typedef union dfixed {
	u32 full;
} fixed20_12;


#define dfixed_const(A) (u32)(((A) << 12))/*  + ((B + 0.000122)*4096)) */
#define dfixed_const_half(A) (u32)(((A) << 12) + 2048)
#define dfixed_const_666(A) (u32)(((A) << 12) + 2731)
#define dfixed_const_8(A) (u32)(((A) << 12) + 3277)
#define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)
#define dfixed_init(A) { .full = dfixed_const((A)) }
#define dfixed_init_half(A) { .full = dfixed_const_half((A)) }
#define dfixed_trunc(A) ((A).full >> 12)
#define dfixed_frac(A) ((A).full & ((1 << 12) - 1))

static inline u32 dfixed_floor(fixed20_12 A)
{
	u32 non_frac = dfixed_trunc(A);

	return dfixed_const(non_frac);
}

static inline u32 dfixed_ceil(fixed20_12 A)
{
	u32 non_frac = dfixed_trunc(A);

	if (A.full > dfixed_const(non_frac))
		return dfixed_const(non_frac + 1);
	else
		return dfixed_const(non_frac);
}

static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
{
	u64 tmp = ((u64)A.full << 13);

	do_div(tmp, B.full);
	tmp += 1;
	tmp /= 2;
	return lower_32_bits(tmp);
}

#define DRM_FIXED_POINT		32
#define DRM_FIXED_ONE		(1ULL << DRM_FIXED_POINT)
#define DRM_FIXED_DECIMAL_MASK	(DRM_FIXED_ONE - 1)
#define DRM_FIXED_DIGITS_MASK	(~DRM_FIXED_DECIMAL_MASK)
#define DRM_FIXED_EPSILON	1LL
#define DRM_FIXED_ALMOST_ONE	(DRM_FIXED_ONE - DRM_FIXED_EPSILON)

static inline s64 drm_int2fixp(int a)
{
	return ((s64)a) << DRM_FIXED_POINT;
}

static inline int drm_fixp2int(s64 a)
{
	return ((s64)a) >> DRM_FIXED_POINT;
}

static inline int drm_fixp2int_ceil(s64 a)
{
	if (a > 0)
		return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
	else
		return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
}

static inline unsigned drm_fixp_msbset(s64 a)
{
	unsigned shift, sign = (a >> 63) & 1;

	for (shift = 62; shift > 0; --shift)
		if (((a >> shift) & 1) != sign)
			return shift;

	return 0;
}

static inline s64 drm_fixp_mul(s64 a, s64 b)
{
	unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
	s64 result;

	if (shift > 61) {
		shift = shift - 61;
		a >>= (shift >> 1) + (shift & 1);
		b >>= shift >> 1;
	} else
		shift = 0;

	result = a * b;

	if (shift > DRM_FIXED_POINT)
		return result << (shift - DRM_FIXED_POINT);

	if (shift < DRM_FIXED_POINT)
		return result >> (DRM_FIXED_POINT - shift);

	return result;
}

static inline s64 drm_fixp_div(s64 a, s64 b)
{
	unsigned shift = 62 - drm_fixp_msbset(a);
	s64 result;

	a <<= shift;

	if (shift < DRM_FIXED_POINT)
		b >>= (DRM_FIXED_POINT - shift);

	result = div64_s64(a, b);

	if (shift > DRM_FIXED_POINT)
		return result >> (shift - DRM_FIXED_POINT);

	return result;
}

static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
{
	s64 res;
	bool a_neg = a < 0;
	bool b_neg = b < 0;
	u64 a_abs = a_neg ? -a : a;
	u64 b_abs = b_neg ? -b : b;
	u64 rem;

	/* determine integer part */
	u64 res_abs  = div64_u64_rem(a_abs, b_abs, &rem);

	/* determine fractional part */
	{
		u32 i = DRM_FIXED_POINT;

		do {
			rem <<= 1;
			res_abs <<= 1;
			if (rem >= b_abs) {
				res_abs |= 1;
				rem -= b_abs;
			}
		} while (--i != 0);
	}

	/* round up LSB */
	{
		u64 summand = (rem << 1) >= b_abs;

		res_abs += summand;
	}

	res = (s64) res_abs;
	if (a_neg ^ b_neg)
		res = -res;
	return res;
}

static inline s64 drm_fixp_exp(s64 x)
{
	s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
	s64 sum = DRM_FIXED_ONE, term, y = x;
	u64 count = 1;

	if (x < 0)
		y = -1 * x;

	term = y;

	while (term >= tolerance) {
		sum = sum + term;
		count = count + 1;
		term = drm_fixp_mul(term, div64_s64(y, count));
	}

	if (x < 0)
		sum = drm_fixp_div(DRM_FIXED_ONE, sum);

	return sum;
}

#endif