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
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