1 /*
2 * Copyright (C) Alexander Borisov
3 *
4 * Based on nxt_diyfp.c from NGINX NJS project
5 *
6 * Copyright (C) Dmitry Volyntsev
7 * Copyright (C) NGINX, Inc.
8 *
9 * An internal diy_fp implementation.
10 * For details, see Loitsch, Florian. "Printing floating-point numbers quickly
11 * and accurately with integers." ACM Sigplan Notices 45.6 (2010): 233-243.
12 */
13
14 #include "lexbor/core/diyfp.h"
15
16
17 typedef struct {
18 uint64_t significand;
19 int16_t bin_exp;
20 int16_t dec_exp;
21 }
22 lexbor_diyfp_cpe_t;
23
24
25 static const lexbor_diyfp_cpe_t lexbor_cached_powers[] = {
26 { lexbor_uint64_hl(0xfa8fd5a0, 0x081c0288), -1220, -348 },
27 { lexbor_uint64_hl(0xbaaee17f, 0xa23ebf76), -1193, -340 },
28 { lexbor_uint64_hl(0x8b16fb20, 0x3055ac76), -1166, -332 },
29 { lexbor_uint64_hl(0xcf42894a, 0x5dce35ea), -1140, -324 },
30 { lexbor_uint64_hl(0x9a6bb0aa, 0x55653b2d), -1113, -316 },
31 { lexbor_uint64_hl(0xe61acf03, 0x3d1a45df), -1087, -308 },
32 { lexbor_uint64_hl(0xab70fe17, 0xc79ac6ca), -1060, -300 },
33 { lexbor_uint64_hl(0xff77b1fc, 0xbebcdc4f), -1034, -292 },
34 { lexbor_uint64_hl(0xbe5691ef, 0x416bd60c), -1007, -284 },
35 { lexbor_uint64_hl(0x8dd01fad, 0x907ffc3c), -980, -276 },
36 { lexbor_uint64_hl(0xd3515c28, 0x31559a83), -954, -268 },
37 { lexbor_uint64_hl(0x9d71ac8f, 0xada6c9b5), -927, -260 },
38 { lexbor_uint64_hl(0xea9c2277, 0x23ee8bcb), -901, -252 },
39 { lexbor_uint64_hl(0xaecc4991, 0x4078536d), -874, -244 },
40 { lexbor_uint64_hl(0x823c1279, 0x5db6ce57), -847, -236 },
41 { lexbor_uint64_hl(0xc2109436, 0x4dfb5637), -821, -228 },
42 { lexbor_uint64_hl(0x9096ea6f, 0x3848984f), -794, -220 },
43 { lexbor_uint64_hl(0xd77485cb, 0x25823ac7), -768, -212 },
44 { lexbor_uint64_hl(0xa086cfcd, 0x97bf97f4), -741, -204 },
45 { lexbor_uint64_hl(0xef340a98, 0x172aace5), -715, -196 },
46 { lexbor_uint64_hl(0xb23867fb, 0x2a35b28e), -688, -188 },
47 { lexbor_uint64_hl(0x84c8d4df, 0xd2c63f3b), -661, -180 },
48 { lexbor_uint64_hl(0xc5dd4427, 0x1ad3cdba), -635, -172 },
49 { lexbor_uint64_hl(0x936b9fce, 0xbb25c996), -608, -164 },
50 { lexbor_uint64_hl(0xdbac6c24, 0x7d62a584), -582, -156 },
51 { lexbor_uint64_hl(0xa3ab6658, 0x0d5fdaf6), -555, -148 },
52 { lexbor_uint64_hl(0xf3e2f893, 0xdec3f126), -529, -140 },
53 { lexbor_uint64_hl(0xb5b5ada8, 0xaaff80b8), -502, -132 },
54 { lexbor_uint64_hl(0x87625f05, 0x6c7c4a8b), -475, -124 },
55 { lexbor_uint64_hl(0xc9bcff60, 0x34c13053), -449, -116 },
56 { lexbor_uint64_hl(0x964e858c, 0x91ba2655), -422, -108 },
57 { lexbor_uint64_hl(0xdff97724, 0x70297ebd), -396, -100 },
58 { lexbor_uint64_hl(0xa6dfbd9f, 0xb8e5b88f), -369, -92 },
59 { lexbor_uint64_hl(0xf8a95fcf, 0x88747d94), -343, -84 },
60 { lexbor_uint64_hl(0xb9447093, 0x8fa89bcf), -316, -76 },
61 { lexbor_uint64_hl(0x8a08f0f8, 0xbf0f156b), -289, -68 },
62 { lexbor_uint64_hl(0xcdb02555, 0x653131b6), -263, -60 },
63 { lexbor_uint64_hl(0x993fe2c6, 0xd07b7fac), -236, -52 },
64 { lexbor_uint64_hl(0xe45c10c4, 0x2a2b3b06), -210, -44 },
65 { lexbor_uint64_hl(0xaa242499, 0x697392d3), -183, -36 },
66 { lexbor_uint64_hl(0xfd87b5f2, 0x8300ca0e), -157, -28 },
67 { lexbor_uint64_hl(0xbce50864, 0x92111aeb), -130, -20 },
68 { lexbor_uint64_hl(0x8cbccc09, 0x6f5088cc), -103, -12 },
69 { lexbor_uint64_hl(0xd1b71758, 0xe219652c), -77, -4 },
70 { lexbor_uint64_hl(0x9c400000, 0x00000000), -50, 4 },
71 { lexbor_uint64_hl(0xe8d4a510, 0x00000000), -24, 12 },
72 { lexbor_uint64_hl(0xad78ebc5, 0xac620000), 3, 20 },
73 { lexbor_uint64_hl(0x813f3978, 0xf8940984), 30, 28 },
74 { lexbor_uint64_hl(0xc097ce7b, 0xc90715b3), 56, 36 },
75 { lexbor_uint64_hl(0x8f7e32ce, 0x7bea5c70), 83, 44 },
76 { lexbor_uint64_hl(0xd5d238a4, 0xabe98068), 109, 52 },
77 { lexbor_uint64_hl(0x9f4f2726, 0x179a2245), 136, 60 },
78 { lexbor_uint64_hl(0xed63a231, 0xd4c4fb27), 162, 68 },
79 { lexbor_uint64_hl(0xb0de6538, 0x8cc8ada8), 189, 76 },
80 { lexbor_uint64_hl(0x83c7088e, 0x1aab65db), 216, 84 },
81 { lexbor_uint64_hl(0xc45d1df9, 0x42711d9a), 242, 92 },
82 { lexbor_uint64_hl(0x924d692c, 0xa61be758), 269, 100 },
83 { lexbor_uint64_hl(0xda01ee64, 0x1a708dea), 295, 108 },
84 { lexbor_uint64_hl(0xa26da399, 0x9aef774a), 322, 116 },
85 { lexbor_uint64_hl(0xf209787b, 0xb47d6b85), 348, 124 },
86 { lexbor_uint64_hl(0xb454e4a1, 0x79dd1877), 375, 132 },
87 { lexbor_uint64_hl(0x865b8692, 0x5b9bc5c2), 402, 140 },
88 { lexbor_uint64_hl(0xc83553c5, 0xc8965d3d), 428, 148 },
89 { lexbor_uint64_hl(0x952ab45c, 0xfa97a0b3), 455, 156 },
90 { lexbor_uint64_hl(0xde469fbd, 0x99a05fe3), 481, 164 },
91 { lexbor_uint64_hl(0xa59bc234, 0xdb398c25), 508, 172 },
92 { lexbor_uint64_hl(0xf6c69a72, 0xa3989f5c), 534, 180 },
93 { lexbor_uint64_hl(0xb7dcbf53, 0x54e9bece), 561, 188 },
94 { lexbor_uint64_hl(0x88fcf317, 0xf22241e2), 588, 196 },
95 { lexbor_uint64_hl(0xcc20ce9b, 0xd35c78a5), 614, 204 },
96 { lexbor_uint64_hl(0x98165af3, 0x7b2153df), 641, 212 },
97 { lexbor_uint64_hl(0xe2a0b5dc, 0x971f303a), 667, 220 },
98 { lexbor_uint64_hl(0xa8d9d153, 0x5ce3b396), 694, 228 },
99 { lexbor_uint64_hl(0xfb9b7cd9, 0xa4a7443c), 720, 236 },
100 { lexbor_uint64_hl(0xbb764c4c, 0xa7a44410), 747, 244 },
101 { lexbor_uint64_hl(0x8bab8eef, 0xb6409c1a), 774, 252 },
102 { lexbor_uint64_hl(0xd01fef10, 0xa657842c), 800, 260 },
103 { lexbor_uint64_hl(0x9b10a4e5, 0xe9913129), 827, 268 },
104 { lexbor_uint64_hl(0xe7109bfb, 0xa19c0c9d), 853, 276 },
105 { lexbor_uint64_hl(0xac2820d9, 0x623bf429), 880, 284 },
106 { lexbor_uint64_hl(0x80444b5e, 0x7aa7cf85), 907, 292 },
107 { lexbor_uint64_hl(0xbf21e440, 0x03acdd2d), 933, 300 },
108 { lexbor_uint64_hl(0x8e679c2f, 0x5e44ff8f), 960, 308 },
109 { lexbor_uint64_hl(0xd433179d, 0x9c8cb841), 986, 316 },
110 { lexbor_uint64_hl(0x9e19db92, 0xb4e31ba9), 1013, 324 },
111 { lexbor_uint64_hl(0xeb96bf6e, 0xbadf77d9), 1039, 332 },
112 { lexbor_uint64_hl(0xaf87023b, 0x9bf0ee6b), 1066, 340 },
113 };
114
115
116 #define LEXBOR_DIYFP_D_1_LOG2_10 0.30102999566398114 /* 1 / log2(10). */
117
118
119 lexbor_diyfp_t
lexbor_cached_power_dec(int exp,int * dec_exp)120 lexbor_cached_power_dec(int exp, int *dec_exp)
121 {
122 unsigned int index;
123 const lexbor_diyfp_cpe_t *cp;
124
125 index = (exp + LEXBOR_DECIMAL_EXPONENT_OFF) / LEXBOR_DECIMAL_EXPONENT_DIST;
126 cp = &lexbor_cached_powers[index];
127
128 *dec_exp = cp->dec_exp;
129
130 return lexbor_diyfp(cp->significand, cp->bin_exp);
131 }
132
133 lexbor_diyfp_t
lexbor_cached_power_bin(int exp,int * dec_exp)134 lexbor_cached_power_bin(int exp, int *dec_exp)
135 {
136 int k;
137 unsigned int index;
138 const lexbor_diyfp_cpe_t *cp;
139
140 k = (int) ceil((-61 - exp) * LEXBOR_DIYFP_D_1_LOG2_10)
141 + LEXBOR_DECIMAL_EXPONENT_OFF - 1;
142
143 index = (unsigned) (k >> 3) + 1;
144
145 cp = &lexbor_cached_powers[index];
146
147 *dec_exp = -(LEXBOR_DECIMAL_EXPONENT_MIN + (int) (index << 3));
148
149 return lexbor_diyfp(cp->significand, cp->bin_exp);
150 }
151
152
153 #undef LEXBOR_DIYFP_D_1_LOG2_10
154
