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JDBC Driver for the Firebird RDBMS
/*
* Copyright (c) 2018 Firebird development team and individual contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package org.firebirdsql.extern.decimal;
import java.math.BigInteger;
import java.util.Arrays;
/**
* Provides conversion between Densely Packed Decimal encoding and {@link BigInteger}.
*
* Densely packed decimals are encoded in groups of three digits, which are
* encoded in 10 bits per group.
*
*
* See: A Summary of
* Densely Packed Decimal encoding
*
*
* The implementation is tied to the needs of the IEEE-754 decimal encoding and
* decoding of this library, so it may be quirky for other purposes.
*
*
* This implementation can be made to behave as for {@code n * 3} digits by
* constructing it for {@code n * 3 + 1} digits and calling
* {@link #decodeValue(int, int, byte[])} with {@code 0} for the second
* parameter ({@code firstDigit}).
*
*
* @author Mark Rotteveel
*/
public final class DenselyPackedDecimalCodec {
static final int DIGITS_PER_GROUP = 3;
static final int BITS_PER_GROUP = 10;
private static final int BITS_PER_BYTE = 8;
private static final BigInteger ONE_THOUSAND = BigInteger.valueOf(1000);
//@formatter:off
// Generated using org.firebirdsql.decimal.generator.GenerateLookupTable
private static final char[] DPD_GROUP_BITS_2_DIGITS = (
"000" + "001" + "002" + "003" + "004" + "005" + "006" + "007" +
"008" + "009" + "080" + "081" + "800" + "801" + "880" + "881" +
"010" + "011" + "012" + "013" + "014" + "015" + "016" + "017" +
"018" + "019" + "090" + "091" + "810" + "811" + "890" + "891" +
"020" + "021" + "022" + "023" + "024" + "025" + "026" + "027" +
"028" + "029" + "082" + "083" + "820" + "821" + "808" + "809" +
"030" + "031" + "032" + "033" + "034" + "035" + "036" + "037" +
"038" + "039" + "092" + "093" + "830" + "831" + "818" + "819" +
"040" + "041" + "042" + "043" + "044" + "045" + "046" + "047" +
"048" + "049" + "084" + "085" + "840" + "841" + "088" + "089" +
"050" + "051" + "052" + "053" + "054" + "055" + "056" + "057" +
"058" + "059" + "094" + "095" + "850" + "851" + "098" + "099" +
"060" + "061" + "062" + "063" + "064" + "065" + "066" + "067" +
"068" + "069" + "086" + "087" + "860" + "861" + "888" + "889" +
"070" + "071" + "072" + "073" + "074" + "075" + "076" + "077" +
"078" + "079" + "096" + "097" + "870" + "871" + "898" + "899" +
"100" + "101" + "102" + "103" + "104" + "105" + "106" + "107" +
"108" + "109" + "180" + "181" + "900" + "901" + "980" + "981" +
"110" + "111" + "112" + "113" + "114" + "115" + "116" + "117" +
"118" + "119" + "190" + "191" + "910" + "911" + "990" + "991" +
"120" + "121" + "122" + "123" + "124" + "125" + "126" + "127" +
"128" + "129" + "182" + "183" + "920" + "921" + "908" + "909" +
"130" + "131" + "132" + "133" + "134" + "135" + "136" + "137" +
"138" + "139" + "192" + "193" + "930" + "931" + "918" + "919" +
"140" + "141" + "142" + "143" + "144" + "145" + "146" + "147" +
"148" + "149" + "184" + "185" + "940" + "941" + "188" + "189" +
"150" + "151" + "152" + "153" + "154" + "155" + "156" + "157" +
"158" + "159" + "194" + "195" + "950" + "951" + "198" + "199" +
"160" + "161" + "162" + "163" + "164" + "165" + "166" + "167" +
"168" + "169" + "186" + "187" + "960" + "961" + "988" + "989" +
"170" + "171" + "172" + "173" + "174" + "175" + "176" + "177" +
"178" + "179" + "196" + "197" + "970" + "971" + "998" + "999" +
"200" + "201" + "202" + "203" + "204" + "205" + "206" + "207" +
"208" + "209" + "280" + "281" + "802" + "803" + "882" + "883" +
"210" + "211" + "212" + "213" + "214" + "215" + "216" + "217" +
"218" + "219" + "290" + "291" + "812" + "813" + "892" + "893" +
"220" + "221" + "222" + "223" + "224" + "225" + "226" + "227" +
"228" + "229" + "282" + "283" + "822" + "823" + "828" + "829" +
"230" + "231" + "232" + "233" + "234" + "235" + "236" + "237" +
"238" + "239" + "292" + "293" + "832" + "833" + "838" + "839" +
"240" + "241" + "242" + "243" + "244" + "245" + "246" + "247" +
"248" + "249" + "284" + "285" + "842" + "843" + "288" + "289" +
"250" + "251" + "252" + "253" + "254" + "255" + "256" + "257" +
"258" + "259" + "294" + "295" + "852" + "853" + "298" + "299" +
"260" + "261" + "262" + "263" + "264" + "265" + "266" + "267" +
"268" + "269" + "286" + "287" + "862" + "863" + "888" + "889" +
"270" + "271" + "272" + "273" + "274" + "275" + "276" + "277" +
"278" + "279" + "296" + "297" + "872" + "873" + "898" + "899" +
"300" + "301" + "302" + "303" + "304" + "305" + "306" + "307" +
"308" + "309" + "380" + "381" + "902" + "903" + "982" + "983" +
"310" + "311" + "312" + "313" + "314" + "315" + "316" + "317" +
"318" + "319" + "390" + "391" + "912" + "913" + "992" + "993" +
"320" + "321" + "322" + "323" + "324" + "325" + "326" + "327" +
"328" + "329" + "382" + "383" + "922" + "923" + "928" + "929" +
"330" + "331" + "332" + "333" + "334" + "335" + "336" + "337" +
"338" + "339" + "392" + "393" + "932" + "933" + "938" + "939" +
"340" + "341" + "342" + "343" + "344" + "345" + "346" + "347" +
"348" + "349" + "384" + "385" + "942" + "943" + "388" + "389" +
"350" + "351" + "352" + "353" + "354" + "355" + "356" + "357" +
"358" + "359" + "394" + "395" + "952" + "953" + "398" + "399" +
"360" + "361" + "362" + "363" + "364" + "365" + "366" + "367" +
"368" + "369" + "386" + "387" + "962" + "963" + "988" + "989" +
"370" + "371" + "372" + "373" + "374" + "375" + "376" + "377" +
"378" + "379" + "396" + "397" + "972" + "973" + "998" + "999" +
"400" + "401" + "402" + "403" + "404" + "405" + "406" + "407" +
"408" + "409" + "480" + "481" + "804" + "805" + "884" + "885" +
"410" + "411" + "412" + "413" + "414" + "415" + "416" + "417" +
"418" + "419" + "490" + "491" + "814" + "815" + "894" + "895" +
"420" + "421" + "422" + "423" + "424" + "425" + "426" + "427" +
"428" + "429" + "482" + "483" + "824" + "825" + "848" + "849" +
"430" + "431" + "432" + "433" + "434" + "435" + "436" + "437" +
"438" + "439" + "492" + "493" + "834" + "835" + "858" + "859" +
"440" + "441" + "442" + "443" + "444" + "445" + "446" + "447" +
"448" + "449" + "484" + "485" + "844" + "845" + "488" + "489" +
"450" + "451" + "452" + "453" + "454" + "455" + "456" + "457" +
"458" + "459" + "494" + "495" + "854" + "855" + "498" + "499" +
"460" + "461" + "462" + "463" + "464" + "465" + "466" + "467" +
"468" + "469" + "486" + "487" + "864" + "865" + "888" + "889" +
"470" + "471" + "472" + "473" + "474" + "475" + "476" + "477" +
"478" + "479" + "496" + "497" + "874" + "875" + "898" + "899" +
"500" + "501" + "502" + "503" + "504" + "505" + "506" + "507" +
"508" + "509" + "580" + "581" + "904" + "905" + "984" + "985" +
"510" + "511" + "512" + "513" + "514" + "515" + "516" + "517" +
"518" + "519" + "590" + "591" + "914" + "915" + "994" + "995" +
"520" + "521" + "522" + "523" + "524" + "525" + "526" + "527" +
"528" + "529" + "582" + "583" + "924" + "925" + "948" + "949" +
"530" + "531" + "532" + "533" + "534" + "535" + "536" + "537" +
"538" + "539" + "592" + "593" + "934" + "935" + "958" + "959" +
"540" + "541" + "542" + "543" + "544" + "545" + "546" + "547" +
"548" + "549" + "584" + "585" + "944" + "945" + "588" + "589" +
"550" + "551" + "552" + "553" + "554" + "555" + "556" + "557" +
"558" + "559" + "594" + "595" + "954" + "955" + "598" + "599" +
"560" + "561" + "562" + "563" + "564" + "565" + "566" + "567" +
"568" + "569" + "586" + "587" + "964" + "965" + "988" + "989" +
"570" + "571" + "572" + "573" + "574" + "575" + "576" + "577" +
"578" + "579" + "596" + "597" + "974" + "975" + "998" + "999" +
"600" + "601" + "602" + "603" + "604" + "605" + "606" + "607" +
"608" + "609" + "680" + "681" + "806" + "807" + "886" + "887" +
"610" + "611" + "612" + "613" + "614" + "615" + "616" + "617" +
"618" + "619" + "690" + "691" + "816" + "817" + "896" + "897" +
"620" + "621" + "622" + "623" + "624" + "625" + "626" + "627" +
"628" + "629" + "682" + "683" + "826" + "827" + "868" + "869" +
"630" + "631" + "632" + "633" + "634" + "635" + "636" + "637" +
"638" + "639" + "692" + "693" + "836" + "837" + "878" + "879" +
"640" + "641" + "642" + "643" + "644" + "645" + "646" + "647" +
"648" + "649" + "684" + "685" + "846" + "847" + "688" + "689" +
"650" + "651" + "652" + "653" + "654" + "655" + "656" + "657" +
"658" + "659" + "694" + "695" + "856" + "857" + "698" + "699" +
"660" + "661" + "662" + "663" + "664" + "665" + "666" + "667" +
"668" + "669" + "686" + "687" + "866" + "867" + "888" + "889" +
"670" + "671" + "672" + "673" + "674" + "675" + "676" + "677" +
"678" + "679" + "696" + "697" + "876" + "877" + "898" + "899" +
"700" + "701" + "702" + "703" + "704" + "705" + "706" + "707" +
"708" + "709" + "780" + "781" + "906" + "907" + "986" + "987" +
"710" + "711" + "712" + "713" + "714" + "715" + "716" + "717" +
"718" + "719" + "790" + "791" + "916" + "917" + "996" + "997" +
"720" + "721" + "722" + "723" + "724" + "725" + "726" + "727" +
"728" + "729" + "782" + "783" + "926" + "927" + "968" + "969" +
"730" + "731" + "732" + "733" + "734" + "735" + "736" + "737" +
"738" + "739" + "792" + "793" + "936" + "937" + "978" + "979" +
"740" + "741" + "742" + "743" + "744" + "745" + "746" + "747" +
"748" + "749" + "784" + "785" + "946" + "947" + "788" + "789" +
"750" + "751" + "752" + "753" + "754" + "755" + "756" + "757" +
"758" + "759" + "794" + "795" + "956" + "957" + "798" + "799" +
"760" + "761" + "762" + "763" + "764" + "765" + "766" + "767" +
"768" + "769" + "786" + "787" + "966" + "967" + "988" + "989" +
"770" + "771" + "772" + "773" + "774" + "775" + "776" + "777" +
"778" + "779" + "796" + "797" + "976" + "977" + "998" + "999"
).toCharArray();
// from ICU decNumber decDPD.h
private static final int[] BIN_2_DPD = {0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 32,
33, 34, 35, 36, 37, 38, 39, 40, 41, 48, 49, 50, 51,
52, 53, 54, 55, 56, 57, 64, 65, 66, 67, 68, 69, 70,
71, 72, 73, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 112, 113, 114,
115, 116, 117, 118, 119, 120, 121, 10, 11, 42, 43, 74, 75,
106, 107, 78, 79, 26, 27, 58, 59, 90, 91, 122, 123, 94,
95, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 144, 145,
146, 147, 148, 149, 150, 151, 152, 153, 160, 161, 162, 163, 164,
165, 166, 167, 168, 169, 176, 177, 178, 179, 180, 181, 182, 183,
184, 185, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 208,
209, 210, 211, 212, 213, 214, 215, 216, 217, 224, 225, 226, 227,
228, 229, 230, 231, 232, 233, 240, 241, 242, 243, 244, 245, 246,
247, 248, 249, 138, 139, 170, 171, 202, 203, 234, 235, 206, 207,
154, 155, 186, 187, 218, 219, 250, 251, 222, 223, 256, 257, 258,
259, 260, 261, 262, 263, 264, 265, 272, 273, 274, 275, 276, 277,
278, 279, 280, 281, 288, 289, 290, 291, 292, 293, 294, 295, 296,
297, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 320, 321,
322, 323, 324, 325, 326, 327, 328, 329, 336, 337, 338, 339, 340,
341, 342, 343, 344, 345, 352, 353, 354, 355, 356, 357, 358, 359,
360, 361, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377, 266,
267, 298, 299, 330, 331, 362, 363, 334, 335, 282, 283, 314, 315,
346, 347, 378, 379, 350, 351, 384, 385, 386, 387, 388, 389, 390,
391, 392, 393, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409,
416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 432, 433, 434,
435, 436, 437, 438, 439, 440, 441, 448, 449, 450, 451, 452, 453,
454, 455, 456, 457, 464, 465, 466, 467, 468, 469, 470, 471, 472,
473, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 496, 497,
498, 499, 500, 501, 502, 503, 504, 505, 394, 395, 426, 427, 458,
459, 490, 491, 462, 463, 410, 411, 442, 443, 474, 475, 506, 507,
478, 479, 512, 513, 514, 515, 516, 517, 518, 519, 520, 521, 528,
529, 530, 531, 532, 533, 534, 535, 536, 537, 544, 545, 546, 547,
548, 549, 550, 551, 552, 553, 560, 561, 562, 563, 564, 565, 566,
567, 568, 569, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585,
592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 608, 609, 610,
611, 612, 613, 614, 615, 616, 617, 624, 625, 626, 627, 628, 629,
630, 631, 632, 633, 522, 523, 554, 555, 586, 587, 618, 619, 590,
591, 538, 539, 570, 571, 602, 603, 634, 635, 606, 607, 640, 641,
642, 643, 644, 645, 646, 647, 648, 649, 656, 657, 658, 659, 660,
661, 662, 663, 664, 665, 672, 673, 674, 675, 676, 677, 678, 679,
680, 681, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 704,
705, 706, 707, 708, 709, 710, 711, 712, 713, 720, 721, 722, 723,
724, 725, 726, 727, 728, 729, 736, 737, 738, 739, 740, 741, 742,
743, 744, 745, 752, 753, 754, 755, 756, 757, 758, 759, 760, 761,
650, 651, 682, 683, 714, 715, 746, 747, 718, 719, 666, 667, 698,
699, 730, 731, 762, 763, 734, 735, 768, 769, 770, 771, 772, 773,
774, 775, 776, 777, 784, 785, 786, 787, 788, 789, 790, 791, 792,
793, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 816, 817,
818, 819, 820, 821, 822, 823, 824, 825, 832, 833, 834, 835, 836,
837, 838, 839, 840, 841, 848, 849, 850, 851, 852, 853, 854, 855,
856, 857, 864, 865, 866, 867, 868, 869, 870, 871, 872, 873, 880,
881, 882, 883, 884, 885, 886, 887, 888, 889, 778, 779, 810, 811,
842, 843, 874, 875, 846, 847, 794, 795, 826, 827, 858, 859, 890,
891, 862, 863, 896, 897, 898, 899, 900, 901, 902, 903, 904, 905,
912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 928, 929, 930,
931, 932, 933, 934, 935, 936, 937, 944, 945, 946, 947, 948, 949,
950, 951, 952, 953, 960, 961, 962, 963, 964, 965, 966, 967, 968,
969, 976, 977, 978, 979, 980, 981, 982, 983, 984, 985, 992, 993,
994, 995, 996, 997, 998, 999, 1000, 1001, 1008, 1009, 1010, 1011, 1012,
1013, 1014, 1015, 1016, 1017, 906, 907, 938, 939, 970, 971, 1002, 1003,
974, 975, 922, 923, 954, 955, 986, 987, 1018, 1019, 990, 991, 12,
13, 268, 269, 524, 525, 780, 781, 46, 47, 28, 29, 284, 285,
540, 541, 796, 797, 62, 63, 44, 45, 300, 301, 556, 557, 812,
813, 302, 303, 60, 61, 316, 317, 572, 573, 828, 829, 318, 319,
76, 77, 332, 333, 588, 589, 844, 845, 558, 559, 92, 93, 348,
349, 604, 605, 860, 861, 574, 575, 108, 109, 364, 365, 620, 621,
876, 877, 814, 815, 124, 125, 380, 381, 636, 637, 892, 893, 830,
831, 14, 15, 270, 271, 526, 527, 782, 783, 110, 111, 30, 31,
286, 287, 542, 543, 798, 799, 126, 127, 140, 141, 396, 397, 652,
653, 908, 909, 174, 175, 156, 157, 412, 413, 668, 669, 924, 925,
190, 191, 172, 173, 428, 429, 684, 685, 940, 941, 430, 431, 188,
189, 444, 445, 700, 701, 956, 957, 446, 447, 204, 205, 460, 461,
716, 717, 972, 973, 686, 687, 220, 221, 476, 477, 732, 733, 988,
989, 702, 703, 236, 237, 492, 493, 748, 749, 1004, 1005, 942, 943,
252, 253, 508, 509, 764, 765, 1020, 1021, 958, 959, 142, 143, 398,
399, 654, 655, 910, 911, 238, 239, 158, 159, 414, 415, 670, 671,
926, 927, 254, 255};
//@formatter:on
private final int numberOfDigits;
private final int digitGroups;
/**
* Creates a densely packed decimal coder for the specified number of digits.
*
* Current implementation only supports decoding and encoding {@code n * 3 + 1} number of digits with
* {@code n > 0}, where the most significant digit is provided by the caller during decoding.
*
*
* @param numberOfDigits
* Number of digits that this coder will decode or encode
* @throws IllegalArgumentException
* When {@code numberOfDigits} is not {@code n * 3 + 1} with {@code n > 0}
*/
public DenselyPackedDecimalCodec(int numberOfDigits) {
if (numberOfDigits / DIGITS_PER_GROUP <= 0 || numberOfDigits % DIGITS_PER_GROUP != 1) {
throw new IllegalArgumentException(
"numberOfDigits must be of form n * 3 + 1 with n > 0, was " + numberOfDigits);
}
this.numberOfDigits = numberOfDigits;
digitGroups = numberOfDigits / DIGITS_PER_GROUP;
}
/**
* Decodes a densely packed decimal from a byte array to a {@link BigInteger}.
*
* Digits are read from the end of the array to the front.
*
*
* @param signum
* Signum value (values other than {@link Signum#NEGATIVE} are considered positive!)
* @param firstDigit
* First, most significant, digit ({@code 0 <= firstDigit <= 9})
* @param decBytes
* Byte array with the densely packed decimal, with the least significant byte at index {@code length - 1}
* @return A {@code BigInteger} with the decoded value
* @throws IllegalArgumentException
* When {@code firstDigit} is out of range, or {@code decBytes} is too small for
* the necessary number of bytes
* @see #decodeValue(int, int, byte[], int)
*/
public BigInteger decodeValue(final int signum, final int firstDigit, final byte[] decBytes) {
return decodeValue(signum, firstDigit, decBytes, decBytes.length - 1);
}
/**
* Decodes a densely packed decimal from a byte array to a {@link BigInteger}.
*
* Digits are read from {@code lsbIndex} of the array to the front.
*
*
* @param signum
* Signum value (values other than {@link Signum#NEGATIVE} are considered positive!)
* @param firstDigit
* First, most significant, digit ({@code 0 <= firstDigit <= 9})
* @param decBytes
* Byte array with the densely packed decimal, with the least significant byte at index {@code lsbIndex}
* @param lsbIndex
* Index of the least significant byte (or the last byte)
* @return A {@code BigInteger} with the decoded value
* @throws IndexOutOfBoundsException
* If {@code lsbIndex} is not valid for {@code decBytes}
* @throws IllegalArgumentException
* When {@code firstDigit} is out of range, or {@code lsbIndex} is too small for
* the necessary number of bytes
*/
public BigInteger decodeValue(final int signum, final int firstDigit, final byte[] decBytes, final int lsbIndex) {
if (firstDigit < 0 || firstDigit > 9) {
throw new IllegalArgumentException("firstDigit must be in range 0 <= firstDigit <= 9, was " + firstDigit);
}
validateLsbIndex(lsbIndex, decBytes.length);
return decodeValue0(signum, firstDigit, decBytes, lsbIndex);
}
/**
* Encodes a {@link BigInteger} to a densely packed decimal in a byte array.
*
* Digits are written from the end of the array to the front. The most significant digit is not encoded
* into the array, but instead returned to the caller.
*
*
* @param value
* {@code BigInteger} with the value to encode
* @param decBytes
* Target byte array for the densely packed decimal, with the least significant byte to be written at
* index {@code length - 1}. The implementation assumes the array is zero-filled for the bits to be
* populated by this method.
* @return First, most significant, digit ({@code 0 <= firstDigit <= 9}) to be encoded separately
* @throws IndexOutOfBoundsException
* If {@code lsbIndex} is not valid for {@code decBytes}
* @throws IllegalArgumentException
* When {@code lsbIndex} is too small for the necessary number of bytes
* @see #encodeValue(BigInteger, byte[], int)
*/
public int encodeValue(final BigInteger value, final byte[] decBytes) {
return encodeValue(value.abs(), decBytes, decBytes.length - 1);
}
/**
* Encodes a {@link BigInteger} to a densely packed decimal in a byte array.
*
* Digits are written from {@code lsbIndex} of the array to the front. The most significant digit is not encoded
* into the array, but instead returned to the caller.
*
*
* @param value
* {@code BigInteger} with the value to encode
* @param decBytes
* Target byte array for the densely packed decimal, with the least significant byte to be written at
* index {@code lsbIndex}. The implementation assumes the array is zero-filled for the bits to be populated
* by this method.
* @param lsbIndex
* Index for the least significant byte (or the last byte)
* @return First, most significant, digit ({@code 0 <= firstDigit <= 9}) to be encoded separately
* @throws IndexOutOfBoundsException
* If {@code lsbIndex} is not valid for {@code decBytes}
* @throws IllegalArgumentException
* When {@code lsbIndex} is too small for the necessary number of bytes
*/
public int encodeValue(final BigInteger value, final byte[] decBytes, final int lsbIndex) {
validateLsbIndex(lsbIndex, decBytes.length);
return encodeValue0(value.abs(), decBytes, lsbIndex);
}
private BigInteger decodeValue0(final int signum, final int firstDigit, final byte[] decBytes, final int lsbIndex) {
final char[] digitChars = createZeroedCharArray();
for (int digitGroup = 0; digitGroup < digitGroups; digitGroup++) {
// Each digit group is 10 bits in two bytes in the array as [.., second, first, ..],
// moving to the left for next digit groups. If there are unconsumed bits in the second byte,
// the second byte becomes the first byte of the next group.
final int digitBitsFromEnd = digitGroup * BITS_PER_GROUP;
final int firstByteBitOffset = digitBitsFromEnd % BITS_PER_BYTE;
final int firstByteIndex = lsbIndex - digitBitsFromEnd / BITS_PER_BYTE;
int dpdGroupBits = 0x3FF & (
(decBytes[firstByteIndex] & 0xFF) >>> firstByteBitOffset
| decBytes[firstByteIndex - 1] << BITS_PER_BYTE - firstByteBitOffset);
if (dpdGroupBits != 0) {
System.arraycopy(DPD_GROUP_BITS_2_DIGITS, dpdGroupBits * DIGITS_PER_GROUP,
digitChars, digitChars.length - (digitGroup + 1) * DIGITS_PER_GROUP, DIGITS_PER_GROUP);
}
}
if (firstDigit != 0) {
digitChars[1] = Character.forDigit(firstDigit, 10);
}
return toBigInteger(signum, digitChars);
}
private int encodeValue0(final BigInteger value, final byte[] decBytes, final int lsbIndex) {
BigInteger remainingValue = value;
for (int digitGroup = 0; digitGroup < digitGroups; digitGroup++) {
// Each digit group is 10 bits in two bytes in the array as [.., second, first, ..],
// moving to the left for next digit groups. If there are unconsumed bits in the second byte,
// the second byte becomes the first byte of the next group.
final int digitBitsFromEnd = digitGroup * BITS_PER_GROUP;
final int firstByteBitOffset = digitBitsFromEnd % BITS_PER_BYTE;
final int firstByteIndex = lsbIndex - digitBitsFromEnd / BITS_PER_BYTE;
final BigInteger[] valueAndRemainder = remainingValue.divideAndRemainder(ONE_THOUSAND);
remainingValue = valueAndRemainder[0];
final int currentGroup = BIN_2_DPD[valueAndRemainder[1].intValue()];
decBytes[firstByteIndex] =
(byte) (decBytes[firstByteIndex] | (currentGroup << firstByteBitOffset));
decBytes[firstByteIndex - 1] =
(byte) (decBytes[firstByteIndex - 1] | (currentGroup >>> BITS_PER_BYTE - firstByteBitOffset));
}
final int mostSignificantDigit = remainingValue.intValue();
assert 0 <= mostSignificantDigit && mostSignificantDigit <= 9
: "mostSignificantDigit out of range, was " + mostSignificantDigit;
return mostSignificantDigit;
}
/**
* @return a char array of the appropriate size filled with {@code '0'}.
*/
private char[] createZeroedCharArray() {
final char[] digitChars = new char[numberOfDigits + 1];
Arrays.fill(digitChars, '0');
return digitChars;
}
private void validateLsbIndex(final int lsbIndex, final int decBytesLength) {
if (lsbIndex < 0 || lsbIndex >= decBytesLength) {
throw new ArrayIndexOutOfBoundsException("lsbIndex must be within array decBytes with length of " +
decBytesLength + " , was " + lsbIndex);
}
if ((lsbIndex + 1) * BITS_PER_BYTE < BITS_PER_GROUP * digitGroups) {
throw new IllegalArgumentException(String.format("Need at least %d bytes for value, have %d (lsbIndex = %d)",
(BITS_PER_GROUP * digitGroups + 7) / BITS_PER_BYTE, lsbIndex + 1, lsbIndex));
}
}
private static BigInteger toBigInteger(final int signum, final char[] digitChars) {
int digitCharIndex = findFirstNonZero(digitChars);
if (digitCharIndex == -1) {
// All zeroes
return BigInteger.ZERO;
}
if (signum == Signum.NEGATIVE) {
digitChars[--digitCharIndex] = '-';
}
return new BigInteger(
new String(digitChars, digitCharIndex, digitChars.length - digitCharIndex));
}
/**
* Finds the first non-{@code '0'} in a character array.
*
* @param digitChars
* Character array
* @return Index of first non-{@code '0'} character in the array, {@code -1}
* if the entire array is populated with {@code '0'}
*/
private static int findFirstNonZero(final char[] digitChars) {
for (int index = 0; index < digitChars.length; index++) {
if (digitChars[index] != '0') {
return index;
}
}
return -1;
}
}