1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
/*
* Copyright 2008 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkMathPriv.h"
#include "SkFloatBits.h"
#include "SkFloatingPoint.h"
#include "SkScalar.h"
const uint32_t gIEEENotANumber = 0x7FFFFFFF;
const uint32_t gIEEEInfinity = 0x7F800000;
const uint32_t gIEEENegativeInfinity = 0xFF800000;
#define sub_shift(zeros, x, n) \
zeros -= n; \
x >>= n
int SkCLZ_portable(uint32_t x) {
if (x == 0) {
return 32;
}
int zeros = 31;
if (x & 0xFFFF0000) {
sub_shift(zeros, x, 16);
}
if (x & 0xFF00) {
sub_shift(zeros, x, 8);
}
if (x & 0xF0) {
sub_shift(zeros, x, 4);
}
if (x & 0xC) {
sub_shift(zeros, x, 2);
}
if (x & 0x2) {
sub_shift(zeros, x, 1);
}
return zeros;
}
///////////////////////////////////////////////////////////////////////////////
#define DIVBITS_ITER(n) \
case n: \
if ((numer = (numer << 1) - denom) >= 0) \
result |= 1 << (n - 1); else numer += denom
int32_t SkDivBits(int32_t numer, int32_t denom, int shift_bias) {
SkASSERT(denom != 0);
if (numer == 0) {
return 0;
}
// make numer and denom positive, and sign hold the resulting sign
int32_t sign = SkExtractSign(numer ^ denom);
numer = SkAbs32(numer);
denom = SkAbs32(denom);
int nbits = SkCLZ(numer) - 1;
int dbits = SkCLZ(denom) - 1;
int bits = shift_bias - nbits + dbits;
if (bits < 0) { // answer will underflow
return 0;
}
if (bits > 31) { // answer will overflow
return SkApplySign(SK_MaxS32, sign);
}
denom <<= dbits;
numer <<= nbits;
SkFixed result = 0;
// do the first one
if ((numer -= denom) >= 0) {
result = 1;
} else {
numer += denom;
}
// Now fall into our switch statement if there are more bits to compute
if (bits > 0) {
// make room for the rest of the answer bits
result <<= bits;
switch (bits) {
DIVBITS_ITER(31); DIVBITS_ITER(30); DIVBITS_ITER(29);
DIVBITS_ITER(28); DIVBITS_ITER(27); DIVBITS_ITER(26);
DIVBITS_ITER(25); DIVBITS_ITER(24); DIVBITS_ITER(23);
DIVBITS_ITER(22); DIVBITS_ITER(21); DIVBITS_ITER(20);
DIVBITS_ITER(19); DIVBITS_ITER(18); DIVBITS_ITER(17);
DIVBITS_ITER(16); DIVBITS_ITER(15); DIVBITS_ITER(14);
DIVBITS_ITER(13); DIVBITS_ITER(12); DIVBITS_ITER(11);
DIVBITS_ITER(10); DIVBITS_ITER( 9); DIVBITS_ITER( 8);
DIVBITS_ITER( 7); DIVBITS_ITER( 6); DIVBITS_ITER( 5);
DIVBITS_ITER( 4); DIVBITS_ITER( 3); DIVBITS_ITER( 2);
// we merge these last two together, makes GCC make better ARM
default:
DIVBITS_ITER( 1);
}
}
if (result < 0) {
result = SK_MaxS32;
}
return SkApplySign(result, sign);
}
/* www.worldserver.com/turk/computergraphics/FixedSqrt.pdf
*/
int32_t SkSqrtBits(int32_t x, int count) {
SkASSERT(x >= 0 && count > 0 && (unsigned)count <= 30);
uint32_t root = 0;
uint32_t remHi = 0;
uint32_t remLo = x;
do {
root <<= 1;
remHi = (remHi<<2) | (remLo>>30);
remLo <<= 2;
uint32_t testDiv = (root << 1) + 1;
if (remHi >= testDiv) {
remHi -= testDiv;
root++;
}
} while (--count >= 0);
return root;
}
///////////////////////////////////////////////////////////////////////////////
float SkScalarSinCos(float radians, float* cosValue) {
float sinValue = sk_float_sin(radians);
if (cosValue) {
*cosValue = sk_float_cos(radians);
if (SkScalarNearlyZero(*cosValue)) {
*cosValue = 0;
}
}
if (SkScalarNearlyZero(sinValue)) {
sinValue = 0;
}
return sinValue;
}
|
