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57
58 package jdk.nashorn.internal.runtime.doubleconv;
59
60 public class CachedPowers {
61
62 static class CachedPower {
63 final private long significand;
64 final private int binaryExponent;
65 final private int decimalExponent;
66
67 CachedPower(final long significand, final int binaryExponent, final int decimalExponent) {
68 this.significand = significand;
69 this.binaryExponent = binaryExponent;
70 this.decimalExponent = decimalExponent;
71 }
72 }
73
74 static private final CachedPower[] kCachedPowers = {
75 new CachedPower(0xfa8fd5a0081c0288L, -1220, -348),
76 new CachedPower(0xbaaee17fa23ebf76L, -1193, -340),
77 new CachedPower(0x8b16fb203055ac76L, -1166, -332),
78 new CachedPower(0xcf42894a5dce35eaL, -1140, -324),
79 new CachedPower(0x9a6bb0aa55653b2dL, -1113, -316),
80 new CachedPower(0xe61acf033d1a45dfL, -1087, -308),
81 new CachedPower(0xab70fe17c79ac6caL, -1060, -300),
82 new CachedPower(0xff77b1fcbebcdc4fL, -1034, -292),
83 new CachedPower(0xbe5691ef416bd60cL, -1007, -284),
84 new CachedPower(0x8dd01fad907ffc3cL, -980, -276),
85 new CachedPower(0xd3515c2831559a83L, -954, -268),
86 new CachedPower(0x9d71ac8fada6c9b5L, -927, -260),
87 new CachedPower(0xea9c227723ee8bcbL, -901, -252),
88 new CachedPower(0xaecc49914078536dL, -874, -244),
89 new CachedPower(0x823c12795db6ce57L, -847, -236),
90 new CachedPower(0xc21094364dfb5637L, -821, -228),
91 new CachedPower(0x9096ea6f3848984fL, -794, -220),
92 new CachedPower(0xd77485cb25823ac7L, -768, -212),
93 new CachedPower(0xa086cfcd97bf97f4L, -741, -204),
94 new CachedPower(0xef340a98172aace5L, -715, -196),
95 new CachedPower(0xb23867fb2a35b28eL, -688, -188),
96 new CachedPower(0x84c8d4dfd2c63f3bL, -661, -180),
97 new CachedPower(0xc5dd44271ad3cdbaL, -635, -172),
98 new CachedPower(0x936b9fcebb25c996L, -608, -164),
99 new CachedPower(0xdbac6c247d62a584L, -582, -156),
100 new CachedPower(0xa3ab66580d5fdaf6L, -555, -148),
101 new CachedPower(0xf3e2f893dec3f126L, -529, -140),
102 new CachedPower(0xb5b5ada8aaff80b8L, -502, -132),
103 new CachedPower(0x87625f056c7c4a8bL, -475, -124),
104 new CachedPower(0xc9bcff6034c13053L, -449, -116),
105 new CachedPower(0x964e858c91ba2655L, -422, -108),
106 new CachedPower(0xdff9772470297ebdL, -396, -100),
107 new CachedPower(0xa6dfbd9fb8e5b88fL, -369, -92),
108 new CachedPower(0xf8a95fcf88747d94L, -343, -84),
109 new CachedPower(0xb94470938fa89bcfL, -316, -76),
110 new CachedPower(0x8a08f0f8bf0f156bL, -289, -68),
111 new CachedPower(0xcdb02555653131b6L, -263, -60),
112 new CachedPower(0x993fe2c6d07b7facL, -236, -52),
113 new CachedPower(0xe45c10c42a2b3b06L, -210, -44),
114 new CachedPower(0xaa242499697392d3L, -183, -36),
115 new CachedPower(0xfd87b5f28300ca0eL, -157, -28),
116 new CachedPower(0xbce5086492111aebL, -130, -20),
117 new CachedPower(0x8cbccc096f5088ccL, -103, -12),
118 new CachedPower(0xd1b71758e219652cL, -77, -4),
119 new CachedPower(0x9c40000000000000L, -50, 4),
120 new CachedPower(0xe8d4a51000000000L, -24, 12),
121 new CachedPower(0xad78ebc5ac620000L, 3, 20),
122 new CachedPower(0x813f3978f8940984L, 30, 28),
123 new CachedPower(0xc097ce7bc90715b3L, 56, 36),
124 new CachedPower(0x8f7e32ce7bea5c70L, 83, 44),
125 new CachedPower(0xd5d238a4abe98068L, 109, 52),
126 new CachedPower(0x9f4f2726179a2245L, 136, 60),
127 new CachedPower(0xed63a231d4c4fb27L, 162, 68),
128 new CachedPower(0xb0de65388cc8ada8L, 189, 76),
129 new CachedPower(0x83c7088e1aab65dbL, 216, 84),
130 new CachedPower(0xc45d1df942711d9aL, 242, 92),
131 new CachedPower(0x924d692ca61be758L, 269, 100),
132 new CachedPower(0xda01ee641a708deaL, 295, 108),
133 new CachedPower(0xa26da3999aef774aL, 322, 116),
134 new CachedPower(0xf209787bb47d6b85L, 348, 124),
135 new CachedPower(0xb454e4a179dd1877L, 375, 132),
136 new CachedPower(0x865b86925b9bc5c2L, 402, 140),
137 new CachedPower(0xc83553c5c8965d3dL, 428, 148),
138 new CachedPower(0x952ab45cfa97a0b3L, 455, 156),
139 new CachedPower(0xde469fbd99a05fe3L, 481, 164),
140 new CachedPower(0xa59bc234db398c25L, 508, 172),
141 new CachedPower(0xf6c69a72a3989f5cL, 534, 180),
142 new CachedPower(0xb7dcbf5354e9beceL, 561, 188),
143 new CachedPower(0x88fcf317f22241e2L, 588, 196),
144 new CachedPower(0xcc20ce9bd35c78a5L, 614, 204),
145 new CachedPower(0x98165af37b2153dfL, 641, 212),
146 new CachedPower(0xe2a0b5dc971f303aL, 667, 220),
147 new CachedPower(0xa8d9d1535ce3b396L, 694, 228),
148 new CachedPower(0xfb9b7cd9a4a7443cL, 720, 236),
149 new CachedPower(0xbb764c4ca7a44410L, 747, 244),
150 new CachedPower(0x8bab8eefb6409c1aL, 774, 252),
151 new CachedPower(0xd01fef10a657842cL, 800, 260),
152 new CachedPower(0x9b10a4e5e9913129L, 827, 268),
153 new CachedPower(0xe7109bfba19c0c9dL, 853, 276),
154 new CachedPower(0xac2820d9623bf429L, 880, 284),
155 new CachedPower(0x80444b5e7aa7cf85L, 907, 292),
156 new CachedPower(0xbf21e44003acdd2dL, 933, 300),
157 new CachedPower(0x8e679c2f5e44ff8fL, 960, 308),
158 new CachedPower(0xd433179d9c8cb841L, 986, 316),
159 new CachedPower(0x9e19db92b4e31ba9L, 1013, 324),
160 new CachedPower(0xeb96bf6ebadf77d9L, 1039, 332),
161 new CachedPower(0xaf87023b9bf0ee6bL, 1066, 340)
162 };
163
164 static final int kCachedPowersOffset = 348; // -1 * the first decimal_exponent.
165 static final double kD_1_LOG2_10 = 0.30102999566398114; // 1 / lg(10)
166 // Difference between the decimal exponents in the table above.
167 static final int kDecimalExponentDistance = 8;
168 static final int kMinDecimalExponent = -348;
169 static final int kMaxDecimalExponent = 340;
170
171 static int getCachedPowerForBinaryExponentRange(
172 final int min_exponent,
173 final int max_exponent,
174 final DiyFp power) {
175 final int kQ = DiyFp.kSignificandSize;
176 final double k = Math.ceil((min_exponent + kQ - 1) * kD_1_LOG2_10);
177 final int index =
178 (kCachedPowersOffset + (int) k - 1) / kDecimalExponentDistance + 1;
179 assert (0 <= index && index < kCachedPowers.length);
180 final CachedPower cached_power = kCachedPowers[index];
181 assert (min_exponent <= cached_power.binaryExponent);
182 assert (cached_power.binaryExponent <= max_exponent);
183 power.setF(cached_power.significand);
184 power.setE(cached_power.binaryExponent);
185 return cached_power.decimalExponent;
186 }
187
188
189 static int getCachedPowerForDecimalExponent(final int requested_exponent,
190 final DiyFp power) {
191 assert (kMinDecimalExponent <= requested_exponent);
192 assert (requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance);
193 final int index =
194 (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance;
195 final CachedPower cached_power = kCachedPowers[index];
196 power.setF(cached_power.significand);
197 power.setE(cached_power.binaryExponent);
198 final int found_exponent = cached_power.decimalExponent;
199 assert (found_exponent <= requested_exponent);
200 assert (requested_exponent < found_exponent + kDecimalExponentDistance);
201 return cached_power.decimalExponent;
202 }
203
204 }