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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
|
// The contents of this file is based on contents of:
//
// https://github.com/ulfjack/ryu/blob/master/ryu/common.h,
// https://github.com/ulfjack/ryu/blob/master/ryu/d2s.c, and
// https://github.com/ulfjack/ryu/blob/master/ryu/f2s.c,
//
// which are distributed under the following terms:
//--------------------------------------------------------------------------------
// Copyright 2018 Ulf Adams
//
// The contents of this file may be used under the terms of the Apache License,
// Version 2.0.
//
// (See accompanying file LICENSE-Apache or copy at
// http://www.apache.org/licenses/LICENSE-2.0)
//
// Alternatively, the contents of this file may be used under the terms of
// the Boost Software License, Version 1.0.
// (See accompanying file LICENSE-Boost or copy at
// https://www.boost.org/LICENSE_1_0.txt)
//
// Unless required by applicable law or agreed to in writing, this software
// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.
//--------------------------------------------------------------------------------
// Modifications Copyright 2020 Junekey Jeon
//
// Following modifications were made to the original contents:
// - Put everything inside the namespace jkj::dragonbox::to_chars_detail
// - Combined decimalLength9 (from common.h) and decimalLength17 (from d2s.c)
// into a single template function decimal_length
// - Combined to_chars (from f2s.c) and to_chars (from d2s.c) into a
// single template function fp_to_chars_impl
// - Removed index counting statements; replaced them with pointer increments
// - Removed usages of DIGIT_TABLE; replaced them with radix_100_table
//
// These modifications, together with other contents of this file may be used
// under the same terms as the original contents.
#include "dragonbox/dragonbox_to_chars.h"
namespace jkj::dragonbox {
namespace to_chars_detail {
static constexpr char radix_100_table[] = {
'0', '0', '0', '1', '0', '2', '0', '3', '0', '4',
'0', '5', '0', '6', '0', '7', '0', '8', '0', '9',
'1', '0', '1', '1', '1', '2', '1', '3', '1', '4',
'1', '5', '1', '6', '1', '7', '1', '8', '1', '9',
'2', '0', '2', '1', '2', '2', '2', '3', '2', '4',
'2', '5', '2', '6', '2', '7', '2', '8', '2', '9',
'3', '0', '3', '1', '3', '2', '3', '3', '3', '4',
'3', '5', '3', '6', '3', '7', '3', '8', '3', '9',
'4', '0', '4', '1', '4', '2', '4', '3', '4', '4',
'4', '5', '4', '6', '4', '7', '4', '8', '4', '9',
'5', '0', '5', '1', '5', '2', '5', '3', '5', '4',
'5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
'6', '0', '6', '1', '6', '2', '6', '3', '6', '4',
'6', '5', '6', '6', '6', '7', '6', '8', '6', '9',
'7', '0', '7', '1', '7', '2', '7', '3', '7', '4',
'7', '5', '7', '6', '7', '7', '7', '8', '7', '9',
'8', '0', '8', '1', '8', '2', '8', '3', '8', '4',
'8', '5', '8', '6', '8', '7', '8', '8', '8', '9',
'9', '0', '9', '1', '9', '2', '9', '3', '9', '4',
'9', '5', '9', '6', '9', '7', '9', '8', '9', '9'
};
template <class UInt>
static constexpr std::uint32_t decimal_length(UInt const v) {
if constexpr (std::is_same_v<UInt, std::uint32_t>) {
// Function precondition: v is not a 10-digit number.
// (f2s: 9 digits are sufficient for round-tripping.)
// (d2fixed: We print 9-digit blocks.)
assert(v < 1000000000);
if (v >= 100000000) { return 9; }
if (v >= 10000000) { return 8; }
if (v >= 1000000) { return 7; }
if (v >= 100000) { return 6; }
if (v >= 10000) { return 5; }
if (v >= 1000) { return 4; }
if (v >= 100) { return 3; }
if (v >= 10) { return 2; }
return 1;
}
else {
static_assert(std::is_same_v<UInt, std::uint64_t>);
// This is slightly faster than a loop.
// The average output length is 16.38 digits, so we check high-to-low.
// Function precondition: v is not an 18, 19, or 20-digit number.
// (17 digits are sufficient for round-tripping.)
assert(v < 100000000000000000L);
if (v >= 10000000000000000L) { return 17; }
if (v >= 1000000000000000L) { return 16; }
if (v >= 100000000000000L) { return 15; }
if (v >= 10000000000000L) { return 14; }
if (v >= 1000000000000L) { return 13; }
if (v >= 100000000000L) { return 12; }
if (v >= 10000000000L) { return 11; }
if (v >= 1000000000L) { return 10; }
if (v >= 100000000L) { return 9; }
if (v >= 10000000L) { return 8; }
if (v >= 1000000L) { return 7; }
if (v >= 100000L) { return 6; }
if (v >= 10000L) { return 5; }
if (v >= 1000L) { return 4; }
if (v >= 100L) { return 3; }
if (v >= 10L) { return 2; }
return 1;
}
}
template <class Float>
static char* to_chars_impl(unsigned_fp_t<Float> v, char* buffer)
{
auto output = v.significand;
auto const olength = decimal_length(output);
int32_t exp = v.exponent + (int32_t)olength - 1;
if (exp >= -6 && exp <= 20)
{
int index = 0;
if (exp < 0)
{
buffer[index++] = '0';
buffer[index++] = '.';
while (++exp)
buffer[index++] = '0';
for (int32_t i = olength - 1; i >= 0; --i)
{
const uint32_t c = output % 10;
output /= 10;
buffer[index + i] = '0' + c;
}
index += olength;
}
else if (exp + 1 >= olength)
{
for (int32_t i = olength - 1; i >= 0; --i)
{
const uint32_t c = output % 10;
output /= 10;
buffer[index + i] = '0' + c;
}
index += olength;
while (exp >= olength)
{
buffer[index++] = '0';
--exp;
}
}
else
{
for (int32_t i = olength; i > exp + 1; --i)
{
const uint32_t c = output % 10;
output /= 10;
buffer[index + i] = '0' + c;
}
buffer[index + exp + 1] = '.';
for (int32_t i = exp; i >= 0; --i)
{
const uint32_t c = output % 10;
output /= 10;
buffer[index + i] = '0' + c;
}
index += olength + 1;
}
return buffer + index;
}
// Print the decimal digits.
// The following code is equivalent to:
// for (uint32_t i = 0; i < olength - 1; ++i) {
// const uint32_t c = output % 10; output /= 10;
// result[index + olength - i] = (char) ('0' + c);
// }
// result[index] = '0' + output % 10;
uint32_t i = 0;
if constexpr (sizeof(Float) == 8) {
// We prefer 32-bit operations, even on 64-bit platforms.
// We have at most 17 digits, and uint32_t can store 9 digits.
// If output doesn't fit into uint32_t, we cut off 8 digits,
// so the rest will fit into uint32_t.
if ((output >> 32) != 0) {
// Expensive 64-bit division.
const uint64_t q = output / 100000000;
uint32_t output2 = ((uint32_t)output) - 100000000 * ((uint32_t)q);
output = q;
const uint32_t c = output2 % 10000;
output2 /= 10000;
const uint32_t d = output2 % 10000;
const uint32_t c0 = (c % 100) << 1;
const uint32_t c1 = (c / 100) << 1;
const uint32_t d0 = (d % 100) << 1;
const uint32_t d1 = (d / 100) << 1;
memcpy(buffer + olength - i - 1, radix_100_table + c0, 2);
memcpy(buffer + olength - i - 3, radix_100_table + c1, 2);
memcpy(buffer + olength - i - 5, radix_100_table + d0, 2);
memcpy(buffer + olength - i - 7, radix_100_table + d1, 2);
i += 8;
}
}
auto output2 = (uint32_t)output;
while (output2 >= 10000) {
#ifdef __clang__ // https://bugs.llvm.org/show_bug.cgi?id=38217
const uint32_t c = output2 - 10000 * (output2 / 10000);
#else
const uint32_t c = output2 % 10000;
#endif
output2 /= 10000;
const uint32_t c0 = (c % 100) << 1;
const uint32_t c1 = (c / 100) << 1;
memcpy(buffer + olength - i - 1, radix_100_table + c0, 2);
memcpy(buffer + olength - i - 3, radix_100_table + c1, 2);
i += 4;
}
if (output2 >= 100) {
const uint32_t c = (output2 % 100) << 1;
output2 /= 100;
memcpy(buffer + olength - i - 1, radix_100_table + c, 2);
i += 2;
}
if (output2 >= 10) {
const uint32_t c = output2 << 1;
// We can't use memcpy here: the decimal dot goes between these two digits.
buffer[olength - i] = radix_100_table[c + 1];
buffer[0] = radix_100_table[c];
}
else {
buffer[0] = (char)('0' + output2);
}
// Print decimal point if needed.
if (olength > 1) {
buffer[1] = '.';
buffer += olength + 1;
}
else {
++buffer;
}
// Print the exponent.
*buffer = 'e';
++buffer;
if (exp < 0) {
*buffer = '-';
++buffer;
exp = -exp;
}
if constexpr (sizeof(Float) == 8) {
if (exp >= 100) {
const int32_t c = exp % 10;
memcpy(buffer, radix_100_table + 2 * (exp / 10), 2);
buffer[2] = (char)('0' + c);
buffer += 3;
}
else if (exp >= 10) {
memcpy(buffer, radix_100_table + 2 * exp, 2);
buffer += 2;
}
else {
*buffer = (char)('0' + exp);
++buffer;
}
}
else {
if (exp >= 10) {
memcpy(buffer, radix_100_table + 2 * exp, 2);
buffer += 2;
}
else {
*buffer = (char)('0' + exp);
++buffer;
}
}
return buffer;
}
char* to_chars(unsigned_fp_t<float> v, char* buffer) {
return to_chars_impl(v, buffer);
}
char* to_chars(unsigned_fp_t<double> v, char* buffer) {
return to_chars_impl(v, buffer);
}
}
}
|
