drm_fixed.h

  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
 83 *
 84 * Convert a 1.31.32 signed-magnitude fixed point to 32.32
 85 * 2s-complement fixed point
 86 *
 87 * @return s64 2s-complement fixed point
 88 */
 89static inline s64 drm_sm2fixp(__u64 a)
 90{
 91	if ((a & (1LL << 63))) {
 92		return -(a & 0x7fffffffffffffffll);
 93	} else {
 94		return a;
 95	}
 96}
 97
 98static inline s64 drm_int2fixp(int a)
 99{
100	return ((s64)a) << DRM_FIXED_POINT;
101}
102
103static inline int drm_fixp2int(s64 a)
104{
105	return ((s64)a) >> DRM_FIXED_POINT;
106}
107
108static inline int drm_fixp2int_round(s64 a)
109{
110	return drm_fixp2int(a + DRM_FIXED_ONE / 2);
111}
112
113static inline int drm_fixp2int_ceil(s64 a)
114{
115	if (a >= 0)
116		return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);
117	else
118		return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);
119}
120
121static inline unsigned drm_fixp_msbset(s64 a)
122{
123	unsigned shift, sign = (a >> 63) & 1;
124
125	for (shift = 62; shift > 0; --shift)
126		if (((a >> shift) & 1) != sign)
127			return shift;
128
129	return 0;
130}
131
132static inline s64 drm_fixp_mul(s64 a, s64 b)
133{
134	unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
135	s64 result;
136
137	if (shift > 61) {
138		shift = shift - 61;
139		a >>= (shift >> 1) + (shift & 1);
140		b >>= shift >> 1;
141	} else
142		shift = 0;
143
144	result = a * b;
145
146	if (shift > DRM_FIXED_POINT)
147		return result << (shift - DRM_FIXED_POINT);
148
149	if (shift < DRM_FIXED_POINT)
150		return result >> (DRM_FIXED_POINT - shift);
151
152	return result;
153}
154
155static inline s64 drm_fixp_div(s64 a, s64 b)
156{
157	unsigned shift = 62 - drm_fixp_msbset(a);
158	s64 result;
159
160	a <<= shift;
161
162	if (shift < DRM_FIXED_POINT)
163		b >>= (DRM_FIXED_POINT - shift);
164
165	result = div64_s64(a, b);
166
167	if (shift > DRM_FIXED_POINT)
168		return result >> (shift - DRM_FIXED_POINT);
169
170	return result;
171}
172
173static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
174{
175	s64 res;
176	bool a_neg = a < 0;
177	bool b_neg = b < 0;
178	u64 a_abs = a_neg ? -a : a;
179	u64 b_abs = b_neg ? -b : b;
180	u64 rem;
181
182	/* determine integer part */
183	u64 res_abs  = div64_u64_rem(a_abs, b_abs, &rem);
184
185	/* determine fractional part */
186	{
187		u32 i = DRM_FIXED_POINT;
188
189		do {
190			rem <<= 1;
191			res_abs <<= 1;
192			if (rem >= b_abs) {
193				res_abs |= 1;
194				rem -= b_abs;
195			}
196		} while (--i != 0);
197	}
198
199	/* round up LSB */
200	{
201		u64 summand = (rem << 1) >= b_abs;
202
203		res_abs += summand;
204	}
205
206	res = (s64) res_abs;
207	if (a_neg ^ b_neg)
208		res = -res;
209	return res;
210}
211
212static inline s64 drm_fixp_exp(s64 x)
213{
214	s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
215	s64 sum = DRM_FIXED_ONE, term, y = x;
216	u64 count = 1;
217
218	if (x < 0)
219		y = -1 * x;
220
221	term = y;
222
223	while (term >= tolerance) {
224		sum = sum + term;
225		count = count + 1;
226		term = drm_fixp_mul(term, div64_s64(y, count));
227	}
228
229	if (x < 0)
230		sum = drm_fixp_div(DRM_FIXED_ONE, sum);
231
232	return sum;
233}
234
235static inline int fxp_q4_from_int(int val_int)
236{
237	return val_int << 4;
238}
239
240static inline int fxp_q4_to_int(int val_q4)
241{
242	return val_q4 >> 4;
243}
244
245static inline int fxp_q4_to_int_roundup(int val_q4)
246{
247	return (val_q4 + 0xf) >> 4;
248}
249
250static inline int fxp_q4_to_frac(int val_q4)
251{
252	return val_q4 & 0xf;
253}
254
255#define FXP_Q4_FMT		"%d.%04d"
256#define FXP_Q4_ARGS(val_q4)	fxp_q4_to_int(val_q4), (fxp_q4_to_frac(val_q4) * 625)
257
258#endif