1/*
2Copyright (c) 2012, Broadcom Europe Ltd
3All rights reserved.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are met:
7 * Redistributions of source code must retain the above copyright
8 notice, this list of conditions and the following disclaimer.
9 * Redistributions in binary form must reproduce the above copyright
10 notice, this list of conditions and the following disclaimer in the
11 documentation and/or other materials provided with the distribution.
12 * Neither the name of the copyright holder nor the
13 names of its contributors may be used to endorse or promote products
14 derived from this software without specific prior written permission.
15
16THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
20DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*/
27
28#include <limits.h>
29#include "interface/mmal/util/mmal_util_rational.h"
30
31#define Q16_ONE (1 << 16)
32
33#define ABS(v) (((v) < 0) ? -(v) : (v))
34
35/** Calculate the greatest common denominator between 2 integers.
36 * Avoids division. */
37static int32_t gcd(int32_t a, int32_t b)
38{
39 int shift;
40
41 if (a == 0 || b == 0)
42 return 1;
43
44 a = ABS(a);
45 b = ABS(b);
46 for (shift = 0; !((a | b) & 0x01); shift++)
47 a >>= 1, b >>= 1;
48
49 while (a > 0)
50 {
51 while (!(a & 0x01))
52 a >>= 1;
53 while (!(b & 0x01))
54 b >>= 1;
55 if (a >= b)
56 a = (a - b) >> 1;
57 else
58 b = (b - a) >> 1;
59 }
60 return b << shift;
61}
62
63/** Calculate a + b. */
64MMAL_RATIONAL_T mmal_rational_add(MMAL_RATIONAL_T a, MMAL_RATIONAL_T b)
65{
66 MMAL_RATIONAL_T result;
67 int32_t g = gcd(a.den, b.den);
68 a.den /= g;
69 a.num = a.num * (b.den / g) + b.num * a.den;
70 g = gcd(a.num, g);
71 a.num /= g;
72 a.den *= b.den / g;
73
74 result.num = a.num;
75 result.den = a.den;
76 return result;
77}
78
79/** Calculate a - b. */
80MMAL_RATIONAL_T mmal_rational_subtract(MMAL_RATIONAL_T a, MMAL_RATIONAL_T b)
81{
82 b.num = -b.num;
83 return mmal_rational_add(a, b);
84}
85
86/** Calculate a * b */
87MMAL_RATIONAL_T mmal_rational_multiply(MMAL_RATIONAL_T a, MMAL_RATIONAL_T b)
88{
89 MMAL_RATIONAL_T result;
90 int32_t gcd1 = gcd(a.num, b.den);
91 int32_t gcd2 = gcd(b.num, a.den);
92 result.num = (a.num / gcd1) * (b.num / gcd2);
93 result.den = (a.den / gcd2) * (b.den / gcd1);
94
95 return result;
96}
97
98/** Calculate a / b */
99MMAL_RATIONAL_T mmal_rational_divide(MMAL_RATIONAL_T a, MMAL_RATIONAL_T b)
100{
101 MMAL_RATIONAL_T result;
102 int32_t gcd1, gcd2;
103
104 if (b.num == 0)
105 {
106 vcos_assert(0);
107 return a;
108 }
109
110 if (a.num == 0)
111 return a;
112
113 gcd1 = gcd(a.num, b.num);
114 gcd2 = gcd(b.den, a.den);
115 result.num = (a.num / gcd1) * (b.den / gcd2);
116 result.den = (a.den / gcd2) * (b.num / gcd1);
117
118 return result;
119}
120
121/** Convert a rational number to a signed 32-bit Q16 number. */
122int32_t mmal_rational_to_fixed_16_16(MMAL_RATIONAL_T rational)
123{
124 int64_t result = (int64_t)rational.num << 16;
125 if (rational.den)
126 result /= rational.den;
127
128 if (result > INT_MAX)
129 result = INT_MAX;
130 else if (result < INT_MIN)
131 result = INT_MIN;
132
133 return (int32_t)result;
134}
135
136/** Convert a rational number to a signed 32-bit Q16 number. */
137MMAL_RATIONAL_T mmal_rational_from_fixed_16_16(int32_t fixed)
138{
139 MMAL_RATIONAL_T result = { fixed, Q16_ONE };
140 mmal_rational_simplify(&result);
141 return result;
142}
143
144/** Reduce a rational number to it's simplest form. */
145void mmal_rational_simplify(MMAL_RATIONAL_T *rational)
146{
147 int g = gcd(rational->num, rational->den);
148 rational->num /= g;
149 rational->den /= g;
150}
151
152/** Tests for equality */
153MMAL_BOOL_T mmal_rational_equal(MMAL_RATIONAL_T a, MMAL_RATIONAL_T b)
154{
155 if (a.num != b.num && a.num * (int64_t)b.num == 0)
156 return MMAL_FALSE;
157 return a.num * (int64_t)b.den == b.num * (int64_t)a.den;
158}
159