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34 #include "cached-powers.h"
39 namespace double_conversion
{
43 int16_t binary_exponent
;
44 int16_t decimal_exponent
;
47 static const double kD_1_LOG2_10
= 0.30102999566398114; // 1 / lg(10)
48 static const CachedPower kCachedPowers
[] = {
49 {UINT64_2PART_C(0xfa8fd5a0, 081c0288
), -1220, -348},
50 {UINT64_2PART_C(0xbaaee17f, a23ebf76
), -1193, -340},
51 {UINT64_2PART_C(0x8b16fb20, 3055ac76
), -1166, -332},
52 {UINT64_2PART_C(0xcf42894a, 5dce35ea
), -1140, -324},
53 {UINT64_2PART_C(0x9a6bb0aa, 55653b2d
), -1113, -316},
54 {UINT64_2PART_C(0xe61acf03, 3d1a45df
), -1087, -308},
55 {UINT64_2PART_C(0xab70fe17, c79ac6ca
), -1060, -300},
56 {UINT64_2PART_C(0xff77b1fc, bebcdc4f
), -1034, -292},
57 {UINT64_2PART_C(0xbe5691ef, 416bd60c
), -1007, -284},
58 {UINT64_2PART_C(0x8dd01fad, 907ffc3c
), -980, -276},
59 {UINT64_2PART_C(0xd3515c28, 31559a83
), -954, -268},
60 {UINT64_2PART_C(0x9d71ac8f, ada6c9b5
), -927, -260},
61 {UINT64_2PART_C(0xea9c2277, 23ee8bcb
), -901, -252},
62 {UINT64_2PART_C(0xaecc4991, 4078536d
), -874, -244},
63 {UINT64_2PART_C(0x823c1279, 5db6ce57
), -847, -236},
64 {UINT64_2PART_C(0xc2109436, 4dfb5637
), -821, -228},
65 {UINT64_2PART_C(0x9096ea6f, 3848984f
), -794, -220},
66 {UINT64_2PART_C(0xd77485cb, 25823ac7
), -768, -212},
67 {UINT64_2PART_C(0xa086cfcd, 97bf97f4
), -741, -204},
68 {UINT64_2PART_C(0xef340a98, 172aace5
), -715, -196},
69 {UINT64_2PART_C(0xb23867fb, 2a35b28e
), -688, -188},
70 {UINT64_2PART_C(0x84c8d4df, d2c63f3b
), -661, -180},
71 {UINT64_2PART_C(0xc5dd4427, 1ad3cdba
), -635, -172},
72 {UINT64_2PART_C(0x936b9fce, bb25c996
), -608, -164},
73 {UINT64_2PART_C(0xdbac6c24, 7d62a584
), -582, -156},
74 {UINT64_2PART_C(0xa3ab6658, 0d5fdaf6
), -555, -148},
75 {UINT64_2PART_C(0xf3e2f893, dec3f126
), -529, -140},
76 {UINT64_2PART_C(0xb5b5ada8, aaff80b8
), -502, -132},
77 {UINT64_2PART_C(0x87625f05, 6c7c4a8b
), -475, -124},
78 {UINT64_2PART_C(0xc9bcff60, 34c13053
), -449, -116},
79 {UINT64_2PART_C(0x964e858c, 91ba2655
), -422, -108},
80 {UINT64_2PART_C(0xdff97724, 70297ebd
), -396, -100},
81 {UINT64_2PART_C(0xa6dfbd9f, b8e5b88f
), -369, -92},
82 {UINT64_2PART_C(0xf8a95fcf, 88747d94
), -343, -84},
83 {UINT64_2PART_C(0xb9447093, 8fa89bcf
), -316, -76},
84 {UINT64_2PART_C(0x8a08f0f8, bf0f156b
), -289, -68},
85 {UINT64_2PART_C(0xcdb02555, 653131b6
), -263, -60},
86 {UINT64_2PART_C(0x993fe2c6, d07b7fac
), -236, -52},
87 {UINT64_2PART_C(0xe45c10c4, 2a2b3b06
), -210, -44},
88 {UINT64_2PART_C(0xaa242499, 697392d3
), -183, -36},
89 {UINT64_2PART_C(0xfd87b5f2, 8300ca0e
), -157, -28},
90 {UINT64_2PART_C(0xbce50864, 92111aeb
), -130, -20},
91 {UINT64_2PART_C(0x8cbccc09, 6f5088cc
), -103, -12},
92 {UINT64_2PART_C(0xd1b71758, e219652c
), -77, -4},
93 {UINT64_2PART_C(0x9c400000, 00000000), -50, 4},
94 {UINT64_2PART_C(0xe8d4a510, 00000000), -24, 12},
95 {UINT64_2PART_C(0xad78ebc5, ac620000
), 3, 20},
96 {UINT64_2PART_C(0x813f3978, f8940984
), 30, 28},
97 {UINT64_2PART_C(0xc097ce7b, c90715b3
), 56, 36},
98 {UINT64_2PART_C(0x8f7e32ce, 7bea5c70
), 83, 44},
99 {UINT64_2PART_C(0xd5d238a4, abe98068
), 109, 52},
100 {UINT64_2PART_C(0x9f4f2726, 179a2245
), 136, 60},
101 {UINT64_2PART_C(0xed63a231, d4c4fb27
), 162, 68},
102 {UINT64_2PART_C(0xb0de6538, 8cc8ada8
), 189, 76},
103 {UINT64_2PART_C(0x83c7088e, 1aab65db
), 216, 84},
104 {UINT64_2PART_C(0xc45d1df9, 42711d9a
), 242, 92},
105 {UINT64_2PART_C(0x924d692c, a61be758
), 269, 100},
106 {UINT64_2PART_C(0xda01ee64, 1a708dea
), 295, 108},
107 {UINT64_2PART_C(0xa26da399, 9aef774a
), 322, 116},
108 {UINT64_2PART_C(0xf209787b, b47d6b85
), 348, 124},
109 {UINT64_2PART_C(0xb454e4a1, 79dd1877
), 375, 132},
110 {UINT64_2PART_C(0x865b8692, 5b9bc5c2
), 402, 140},
111 {UINT64_2PART_C(0xc83553c5, c8965d3d
), 428, 148},
112 {UINT64_2PART_C(0x952ab45c, fa97a0b3
), 455, 156},
113 {UINT64_2PART_C(0xde469fbd, 99a05fe3
), 481, 164},
114 {UINT64_2PART_C(0xa59bc234, db398c25
), 508, 172},
115 {UINT64_2PART_C(0xf6c69a72, a3989f5c
), 534, 180},
116 {UINT64_2PART_C(0xb7dcbf53, 54e9bece
), 561, 188},
117 {UINT64_2PART_C(0x88fcf317, f22241e2
), 588, 196},
118 {UINT64_2PART_C(0xcc20ce9b, d35c78a5
), 614, 204},
119 {UINT64_2PART_C(0x98165af3, 7b2153df
), 641, 212},
120 {UINT64_2PART_C(0xe2a0b5dc, 971f303a
), 667, 220},
121 {UINT64_2PART_C(0xa8d9d153, 5ce3b396
), 694, 228},
122 {UINT64_2PART_C(0xfb9b7cd9, a4a7443c
), 720, 236},
123 {UINT64_2PART_C(0xbb764c4c, a7a44410
), 747, 244},
124 {UINT64_2PART_C(0x8bab8eef, b6409c1a
), 774, 252},
125 {UINT64_2PART_C(0xd01fef10, a657842c
), 800, 260},
126 {UINT64_2PART_C(0x9b10a4e5, e9913129
), 827, 268},
127 {UINT64_2PART_C(0xe7109bfb, a19c0c9d
), 853, 276},
128 {UINT64_2PART_C(0xac2820d9, 623bf429
), 880, 284},
129 {UINT64_2PART_C(0x80444b5e, 7aa7cf85
), 907, 292},
130 {UINT64_2PART_C(0xbf21e440, 03acdd2d
), 933, 300},
131 {UINT64_2PART_C(0x8e679c2f, 5e44ff8f
), 960, 308},
132 {UINT64_2PART_C(0xd433179d, 9c8cb841
), 986, 316},
133 {UINT64_2PART_C(0x9e19db92, b4e31ba9
), 1013, 324},
134 {UINT64_2PART_C(0xeb96bf6e, badf77d9
), 1039, 332},
135 {UINT64_2PART_C(0xaf87023b, 9bf0ee6b
), 1066, 340},
137 static const int kCachedPowersOffset
= 348; // -kCachedPowers[0].decimal_exponent
139 const int PowersOfTenCache::kDecimalExponentDistance
= 8; // kCachedPowers[1].decimal_exponent - kCachedPowers[0].decimal_exponent
140 const int PowersOfTenCache::kMinDecimalExponent
= -348; // kCachedPowers[0].decimal_exponent
141 const int PowersOfTenCache::kMaxDecimalExponent
= 340; // kCachedPowers[kCachedPowersLength - 1].decimal_exponent
144 static const int kCachedPowersLength
= ARRAY_SIZE(kCachedPowers
);
146 // Check that the static constants match the values in kCachedPowers.
147 static void validateStaticConstants() {
148 ASSERT(kCachedPowersOffset
== -kCachedPowers
[0].decimal_exponent
);
149 ASSERT(PowersOfTenCache::kDecimalExponentDistance
== (kCachedPowers
[1].decimal_exponent
- kCachedPowers
[0].decimal_exponent
));
150 ASSERT(PowersOfTenCache::kMinDecimalExponent
== kCachedPowers
[0].decimal_exponent
);
151 ASSERT(PowersOfTenCache::kMaxDecimalExponent
== kCachedPowers
[kCachedPowersLength
- 1].decimal_exponent
);
155 void PowersOfTenCache::GetCachedPowerForBinaryExponentRange(
159 int* decimal_exponent
) {
161 validateStaticConstants();
163 int kQ
= DiyFp::kSignificandSize
;
164 double k
= ceil((min_exponent
+ kQ
- 1) * kD_1_LOG2_10
);
165 int foo
= kCachedPowersOffset
;
167 (foo
+ static_cast<int>(k
) - 1) / kDecimalExponentDistance
+ 1;
168 ASSERT(0 <= index
&& index
< kCachedPowersLength
);
169 CachedPower cached_power
= kCachedPowers
[index
];
170 ASSERT(min_exponent
<= cached_power
.binary_exponent
);
171 ASSERT(cached_power
.binary_exponent
<= max_exponent
);
172 *decimal_exponent
= cached_power
.decimal_exponent
;
173 *power
= DiyFp(cached_power
.significand
, cached_power
.binary_exponent
);
177 void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent
,
179 int* found_exponent
) {
180 ASSERT(kMinDecimalExponent
<= requested_exponent
);
181 ASSERT(requested_exponent
< kMaxDecimalExponent
+ kDecimalExponentDistance
);
183 validateStaticConstants();
186 (requested_exponent
+ kCachedPowersOffset
) / kDecimalExponentDistance
;
187 CachedPower cached_power
= kCachedPowers
[index
];
188 *power
= DiyFp(cached_power
.significand
, cached_power
.binary_exponent
);
189 *found_exponent
= cached_power
.decimal_exponent
;
190 ASSERT(*found_exponent
<= requested_exponent
);
191 ASSERT(requested_exponent
< *found_exponent
+ kDecimalExponentDistance
);
194 } // namespace double_conversion
