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drm_fixed.h revision 1.1.1.1.6.1 
      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 Knig
     24  */
     25 #ifndef DRM_FIXED_H
     26 #define DRM_FIXED_H
     27 
     28 #include <linux/math64.h>
     29 
     30 typedef 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 
     45 static inline u32 dfixed_floor(fixed20_12 A)
     46 {
     47 	u32 non_frac = dfixed_trunc(A);
     48 
     49 	return dfixed_const(non_frac);
     50 }
     51 
     52 static 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 
     62 static 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 
     77 static inline s64 drm_int2fixp(int a)
     78 {
     79 	return ((s64)a) << DRM_FIXED_POINT;
     80 }
     81 
     82 static inline int drm_fixp2int(int64_t a)
     83 {
     84 	return ((s64)a) >> DRM_FIXED_POINT;
     85 }
     86 
     87 static inline unsigned drm_fixp_msbset(int64_t a)
     88 {
     89 	unsigned shift, sign = (a >> 63) & 1;
     90 
     91 	for (shift = 62; shift > 0; --shift)
     92 		if (((a >> shift) & 1) != sign)
     93 			return shift;
     94 
     95 	return 0;
     96 }
     97 
     98 static inline s64 drm_fixp_mul(s64 a, s64 b)
     99 {
    100 	unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);
    101 	s64 result;
    102 
    103 	if (shift > 61) {
    104 		shift = shift - 61;
    105 		a >>= (shift >> 1) + (shift & 1);
    106 		b >>= shift >> 1;
    107 	} else
    108 		shift = 0;
    109 
    110 	result = a * b;
    111 
    112 	if (shift > DRM_FIXED_POINT)
    113 		return result << (shift - DRM_FIXED_POINT);
    114 
    115 	if (shift < DRM_FIXED_POINT)
    116 		return result >> (DRM_FIXED_POINT - shift);
    117 
    118 	return result;
    119 }
    120 
    121 static inline s64 drm_fixp_div(s64 a, s64 b)
    122 {
    123 	unsigned shift = 62 - drm_fixp_msbset(a);
    124 	s64 result;
    125 
    126 	a <<= shift;
    127 
    128 	if (shift < DRM_FIXED_POINT)
    129 		b >>= (DRM_FIXED_POINT - shift);
    130 
    131 	result = div64_s64(a, b);
    132 
    133 	if (shift > DRM_FIXED_POINT)
    134 		return result >> (shift - DRM_FIXED_POINT);
    135 
    136 	return result;
    137 }
    138 
    139 static inline s64 drm_fixp_exp(s64 x)
    140 {
    141 	s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);
    142 	s64 sum = DRM_FIXED_ONE, term, y = x;
    143 	u64 count = 1;
    144 
    145 	if (x < 0)
    146 		y = -1 * x;
    147 
    148 	term = y;
    149 
    150 	while (term >= tolerance) {
    151 		sum = sum + term;
    152 		count = count + 1;
    153 		term = drm_fixp_mul(term, div64_s64(y, count));
    154 	}
    155 
    156 	if (x < 0)
    157 		sum = drm_fixp_div(DRM_FIXED_ONE, sum);
    158 
    159 	return sum;
    160 }
    161 
    162 #endif
    163