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view src/fixed_point.h @ 25:5ff8ce78059a

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first pass at converting the rasterizer to fixed point
author John Tsiombikas <nuclear@member.fsf.org>
date Sun, 22 Sep 2013 02:21:30 +0300
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1 #ifndef FIXED_POINT_H_
2 #define FIXED_POINT_H_
3
4 #include "inttypes.h"
5
6 #ifdef DBG_USE_FLOAT
7 typedef float fixed;
8 #else
9 typedef int32_t fixed;
10 #endif
11
12 /* valid choices for DECIMAL_BITS
13 * 8: for fixed point 24:8
14 * 16: for fixed point 16:16
15 */
16 #define DECIMAL_BITS 16
17
18 #if DECIMAL_BITS == 8
19 #define FIXED_SHIFT 8
20 #define FLT_SCALE 256.0f
21 #define FRAC_MASK 0xff
22 #else /* DECIMAL_BITS == 16 */
23 #define FIXED_SHIFT 16
24 #define FLT_SCALE 65536.0f
25 #define FRAC_MASK 0xffff
26 #endif /* DECIMAL_BITS */
27
28 /*extern const fixed fixed_zero;
29 extern const fixed fixed_one;
30 extern const fixed fixed_half;
31 extern const fixed fixed_tenth;
32 extern const fixed fixed_255;*/
33
34 #ifdef DBG_USE_FLOAT
35 /* ------- debug mode, use floating point -------- */
36 #define FIXED_INT_PART(n) ((int)(n))
37 #define FIXED_FRAC_PART(n) ((n) > 0.0f ? (FIXED_INT_PART(n) - (n)) : (FIXED_INT_PART(n) + (n)))
38 #define FIXED_ROUND(n) FIXED_INT_PART((n) >= 0.0 ? (n) + 0.5f : (n) - 0.5f)
39
40 #define FIXED_TO_FLOAT(n) (n)
41 #define FLOAT_TO_FIXED(n) (n)
42 #define INT_TO_FIXED(n) ((float)(n))
43
44 #define FIXED_EPSILON (1e-6)
45
46 #else /* ---- really fixed point ---- */
47
48 #define FIXED_INT_PART(n) ((n) >> FIXED_SHIFT)
49 #define FIXED_FRAC_PART(n) ((n) & FRAC_MASK)
50 #define FIXED_ROUND(n) FIXED_INT_PART((n) >= 0 ? (n) + fixedf(0.5) : (n) - fixedf(0.5))
51 /*#define FIXED_ROUND(n) FIXED_INT_PART(n)*/
52
53 #define FIXED_TO_FLOAT(n) (float)((n) / FLT_SCALE)
54 #define FLOAT_TO_FIXED(n) (fixed)((n) * FLT_SCALE)
55 #define INT_TO_FIXED(n) (fixed)((n) << FIXED_SHIFT)
56
57 #define FIXED_EPSILON (1)
58
59 #endif
60
61
62 #define fixed_int(n) FIXED_INT_PART(n)
63 #define fixed_frac(n) FIXED_FRAC_PART(n)
64 #define fixed_float(n) FIXED_TO_FLOAT(n)
65 #define fixed_round(n) FIXED_ROUND(n)
66
67 #define fixedf(n) FLOAT_TO_FIXED(n)
68 #define fixedi(n) INT_TO_FIXED(n)
69
70 #define fixed_add(n1, n2) ((n1) + (n2))
71 #define fixed_sub(n1, n2) ((n1) - (n2))
72
73
74
75 #ifdef DBG_USE_FLOAT
76
77 #define fixed_mul(n1, n2) ((n1) * (n2))
78 #define fixed_div(n1, n2) ((n1) / (n2))
79
80 #define fixed_sin(x) (fixed)sin(x)
81 #define fixed_cos(x) (fixed)cos(x)
82
83 #else
84
85 #if DECIMAL_BITS == 8
86 #define fixed_mul(n1, n2) (fixed)((n1) * (n2) >> FIXED_SHIFT)
87 #define fixed_div(n1, n2) (((n1) << FIXED_SHIFT) / (n2))
88 #else
89 #define fixed_div(n1, n2) (((int64_t)(n1) << FIXED_SHIFT) / (int64_t)(n2))
90 #define fixed_mul(n1, n2) (((n1) >> 8) * ((n2) >> 8))
91 #endif /* DECIMAL_BITS */
92
93 #ifdef __cplusplus
94 extern "C" {
95 #endif
96
97 fixed fixed_sin(fixed angle);
98 fixed fixed_cos(fixed angle);
99
100 #ifdef __cplusplus
101 }
102 #endif
103
104 #endif
105
106 #endif /* FIXED_POINT_H_ */