Line data Source code
1 :
2 : /*
3 : * Copyright 2006 The Android Open Source Project
4 : *
5 : * Use of this source code is governed by a BSD-style license that can be
6 : * found in the LICENSE file.
7 : */
8 :
9 :
10 : #ifndef SkFloatingPoint_DEFINED
11 : #define SkFloatingPoint_DEFINED
12 :
13 : #include "SkTypes.h"
14 : #include "SkSafe_math.h"
15 : #include <float.h>
16 :
17 : #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
18 : #include <xmmintrin.h>
19 : #elif defined(SK_ARM_HAS_NEON)
20 : #include <arm_neon.h>
21 : #endif
22 :
23 : // For _POSIX_VERSION
24 : #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
25 : #include <unistd.h>
26 : #endif
27 :
28 : #include "SkFloatBits.h"
29 :
30 : // C++98 cmath std::pow seems to be the earliest portable way to get float pow.
31 : // However, on Linux including cmath undefines isfinite.
32 : // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14608
33 0 : static inline float sk_float_pow(float base, float exp) {
34 0 : return powf(base, exp);
35 : }
36 :
37 : #define sk_float_sqrt(x) sqrtf(x)
38 : #define sk_float_sin(x) sinf(x)
39 : #define sk_float_cos(x) cosf(x)
40 : #define sk_float_tan(x) tanf(x)
41 : #define sk_float_floor(x) floorf(x)
42 : #define sk_float_ceil(x) ceilf(x)
43 : #define sk_float_trunc(x) truncf(x)
44 : #ifdef SK_BUILD_FOR_MAC
45 : # define sk_float_acos(x) static_cast<float>(acos(x))
46 : # define sk_float_asin(x) static_cast<float>(asin(x))
47 : #else
48 : # define sk_float_acos(x) acosf(x)
49 : # define sk_float_asin(x) asinf(x)
50 : #endif
51 : #define sk_float_atan2(y,x) atan2f(y,x)
52 : #define sk_float_abs(x) fabsf(x)
53 : #define sk_float_copysign(x, y) copysignf(x, y)
54 : #define sk_float_mod(x,y) fmodf(x,y)
55 : #define sk_float_exp(x) expf(x)
56 : #define sk_float_log(x) logf(x)
57 :
58 : #define sk_float_round(x) sk_float_floor((x) + 0.5f)
59 :
60 : // can't find log2f on android, but maybe that just a tool bug?
61 : #ifdef SK_BUILD_FOR_ANDROID
62 : static inline float sk_float_log2(float x) {
63 : const double inv_ln_2 = 1.44269504088896;
64 : return (float)(log(x) * inv_ln_2);
65 : }
66 : #else
67 : #define sk_float_log2(x) log2f(x)
68 : #endif
69 :
70 : #ifdef SK_BUILD_FOR_WIN
71 : #define sk_float_isfinite(x) _finite(x)
72 : #define sk_float_isnan(x) _isnan(x)
73 : static inline int sk_float_isinf(float x) {
74 : int32_t bits = SkFloat2Bits(x);
75 : return (bits << 1) == (0xFF << 24);
76 : }
77 : #else
78 : #define sk_float_isfinite(x) isfinite(x)
79 : #define sk_float_isnan(x) isnan(x)
80 : #define sk_float_isinf(x) isinf(x)
81 : #endif
82 :
83 : #define sk_double_isnan(a) sk_float_isnan(a)
84 :
85 : #ifdef SK_USE_FLOATBITS
86 : #define sk_float_floor2int(x) SkFloatToIntFloor(x)
87 : #define sk_float_round2int(x) SkFloatToIntRound(x)
88 : #define sk_float_ceil2int(x) SkFloatToIntCeil(x)
89 : #else
90 : #define sk_float_floor2int(x) (int)sk_float_floor(x)
91 : #define sk_float_round2int(x) (int)sk_float_floor((x) + 0.5f)
92 : #define sk_float_ceil2int(x) (int)sk_float_ceil(x)
93 : #endif
94 :
95 : #define sk_double_floor(x) floor(x)
96 : #define sk_double_round(x) floor((x) + 0.5)
97 : #define sk_double_ceil(x) ceil(x)
98 : #define sk_double_floor2int(x) (int)floor(x)
99 : #define sk_double_round2int(x) (int)floor((x) + 0.5f)
100 : #define sk_double_ceil2int(x) (int)ceil(x)
101 :
102 : static const uint32_t kIEEENotANumber = 0x7fffffff;
103 : #define SK_FloatNaN (*SkTCast<const float*>(&kIEEENotANumber))
104 : #define SK_FloatInfinity (+(float)INFINITY)
105 : #define SK_FloatNegativeInfinity (-(float)INFINITY)
106 :
107 : static inline float sk_float_rsqrt_portable(float x) {
108 : // Get initial estimate.
109 : int i;
110 : memcpy(&i, &x, 4);
111 : i = 0x5F1FFFF9 - (i>>1);
112 : float estimate;
113 : memcpy(&estimate, &i, 4);
114 :
115 : // One step of Newton's method to refine.
116 : const float estimate_sq = estimate*estimate;
117 : estimate *= 0.703952253f*(2.38924456f-x*estimate_sq);
118 : return estimate;
119 : }
120 :
121 : // Fast, approximate inverse square root.
122 : // Compare to name-brand "1.0f / sk_float_sqrt(x)". Should be around 10x faster on SSE, 2x on NEON.
123 0 : static inline float sk_float_rsqrt(float x) {
124 : // We want all this inlined, so we'll inline SIMD and just take the hit when we don't know we've got
125 : // it at compile time. This is going to be too fast to productively hide behind a function pointer.
126 : //
127 : // We do one step of Newton's method to refine the estimates in the NEON and portable paths. No
128 : // refinement is faster, but very innacurate. Two steps is more accurate, but slower than 1/sqrt.
129 : //
130 : // Optimized constants in the portable path courtesy of http://rrrola.wz.cz/inv_sqrt.html
131 : #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
132 0 : return _mm_cvtss_f32(_mm_rsqrt_ss(_mm_set_ss(x)));
133 : #elif defined(SK_ARM_HAS_NEON)
134 : // Get initial estimate.
135 : const float32x2_t xx = vdup_n_f32(x); // Clever readers will note we're doing everything 2x.
136 : float32x2_t estimate = vrsqrte_f32(xx);
137 :
138 : // One step of Newton's method to refine.
139 : const float32x2_t estimate_sq = vmul_f32(estimate, estimate);
140 : estimate = vmul_f32(estimate, vrsqrts_f32(xx, estimate_sq));
141 : return vget_lane_f32(estimate, 0); // 1 will work fine too; the answer's in both places.
142 : #else
143 : return sk_float_rsqrt_portable(x);
144 : #endif
145 : }
146 :
147 : // This is the number of significant digits we can print in a string such that when we read that
148 : // string back we get the floating point number we expect. The minimum value C requires is 6, but
149 : // most compilers support 9
150 : #ifdef FLT_DECIMAL_DIG
151 : #define SK_FLT_DECIMAL_DIG FLT_DECIMAL_DIG
152 : #else
153 : #define SK_FLT_DECIMAL_DIG 9
154 : #endif
155 :
156 : #endif
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