File: dtoa.rs

package info (click to toggle)
rust-dtoa 0.4.3-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 136 kB
  • sloc: makefile: 2
file content (501 lines) | stat: -rw-r--r-- 15,418 bytes parent folder | download | duplicates (3)
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
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
// Copyright 2016 Dtoa Developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// ---
//
// The C++ implementation preserved here in comments is licensed as follows:
//
// Tencent is pleased to support the open source community by making RapidJSON
// available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All
// rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License
// at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#[macro_export]
macro_rules! dtoa {(
    floating_type: $fty:ty,
    significand_type: $sigty:ty,
    exponent_type: $expty:ty,
    $($diyfp_param:ident: $diyfp_value:tt,)*
) => {

diyfp! {
    floating_type: $fty,
    significand_type: $sigty,
    exponent_type: $expty,
    $($diyfp_param: $diyfp_value,)*
};

/*
inline void GrisuRound(char* buffer, int len, uint64_t delta, uint64_t rest, uint64_t ten_kappa, uint64_t wp_w) {
    while (rest < wp_w && delta - rest >= ten_kappa &&
           (rest + ten_kappa < wp_w ||  /// closer
            wp_w - rest > rest + ten_kappa - wp_w)) {
        buffer[len - 1]--;
        rest += ten_kappa;
    }
}
*/

#[inline]
unsafe fn grisu_round(buffer: *mut u8, len: isize, delta: $sigty, mut rest: $sigty, ten_kappa: $sigty, wp_w: $sigty) {
    while rest < wp_w && delta - rest >= ten_kappa &&
           (rest + ten_kappa < wp_w || // closer
            wp_w - rest > rest + ten_kappa - wp_w) {
        *buffer.offset(len - 1) -= 1;
        rest += ten_kappa;
    }
}

/*
inline unsigned CountDecimalDigit32(uint32_t n) {
    // Simple pure C++ implementation was faster than __builtin_clz version in this situation.
    if (n < 10) return 1;
    if (n < 100) return 2;
    if (n < 1000) return 3;
    if (n < 10000) return 4;
    if (n < 100000) return 5;
    if (n < 1000000) return 6;
    if (n < 10000000) return 7;
    if (n < 100000000) return 8;
    // Will not reach 10 digits in DigitGen()
    //if (n < 1000000000) return 9;
    //return 10;
    return 9;
}
*/

#[inline]
fn count_decimal_digit32(n: u32) -> usize {
    if n < 10 { 1 }
    else if n < 100 { 2 }
    else if n < 1000 { 3 }
    else if n < 10000 { 4 }
    else if n < 100000 { 5 }
    else if n < 1000000 { 6 }
    else if n < 10000000 { 7 }
    else if n < 100000000 { 8 }
    // Will not reach 10 digits in digit_gen()
    else { 9 }
}

/*
inline void DigitGen(const DiyFp& W, const DiyFp& Mp, uint64_t delta, char* buffer, int* len, int* K) {
    static const uint32_t kPow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
    const DiyFp one(uint64_t(1) << -Mp.e, Mp.e);
    const DiyFp wp_w = Mp - W;
    uint32_t p1 = static_cast<uint32_t>(Mp.f >> -one.e);
    uint64_t p2 = Mp.f & (one.f - 1);
    unsigned kappa = CountDecimalDigit32(p1); // kappa in [0, 9]
    *len = 0;
*/

// Returns length and k.
#[inline]
unsafe fn digit_gen(w: DiyFp, mp: DiyFp, mut delta: $sigty, buffer: *mut u8, mut k: isize) -> (isize, isize) {
    static POW10: [$sigty; 10] = [ 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 ];
    let one = DiyFp::new(1 << -mp.e, mp.e);
    let wp_w = mp - w;
    let mut p1 = (mp.f >> -one.e) as u32;
    let mut p2 = mp.f & (one.f - 1);
    let mut kappa = count_decimal_digit32(p1); // kappa in [0, 9]
    let mut len = 0;

    /*
    while (kappa > 0) {
        uint32_t d = 0;
        switch (kappa) {
            case  9: d = p1 /  100000000; p1 %=  100000000; break;
            case  8: d = p1 /   10000000; p1 %=   10000000; break;
            case  7: d = p1 /    1000000; p1 %=    1000000; break;
            case  6: d = p1 /     100000; p1 %=     100000; break;
            case  5: d = p1 /      10000; p1 %=      10000; break;
            case  4: d = p1 /       1000; p1 %=       1000; break;
            case  3: d = p1 /        100; p1 %=        100; break;
            case  2: d = p1 /         10; p1 %=         10; break;
            case  1: d = p1;              p1 =           0; break;
            default:;
        }
        if (d || *len)
            buffer[(*len)++] = static_cast<char>('0' + static_cast<char>(d));
        kappa--;
        uint64_t tmp = (static_cast<uint64_t>(p1) << -one.e) + p2;
        if (tmp <= delta) {
            *K += kappa;
            GrisuRound(buffer, *len, delta, tmp, static_cast<uint64_t>(kPow10[kappa]) << -one.e, wp_w.f);
            return;
        }
    }
    */
    while kappa > 0 {
        let mut d = 0u32;
        match kappa {
            9 => { d = p1 /  100000000; p1 %=  100000000; }
            8 => { d = p1 /   10000000; p1 %=   10000000; }
            7 => { d = p1 /    1000000; p1 %=    1000000; }
            6 => { d = p1 /     100000; p1 %=     100000; }
            5 => { d = p1 /      10000; p1 %=      10000; }
            4 => { d = p1 /       1000; p1 %=       1000; }
            3 => { d = p1 /        100; p1 %=        100; }
            2 => { d = p1 /         10; p1 %=         10; }
            1 => { d = p1;              p1 =           0; }
            _ => {}
        }
        if d != 0 || len != 0 {
            *buffer.offset(len) = b'0' + d as u8;
            len += 1;
        }
        kappa -= 1;
        let tmp = (p1 as $sigty << -one.e) + p2;
        if tmp <= delta {
            k += kappa as isize;
            grisu_round(buffer, len, delta, tmp, POW10[kappa] << -one.e, wp_w.f);
            return (len, k);
        }
    }

    // kappa = 0
    /*
    for (;;) {
        p2 *= 10;
        delta *= 10;
        char d = static_cast<char>(p2 >> -one.e);
        if (d || *len)
            buffer[(*len)++] = static_cast<char>('0' + d);
        p2 &= one.f - 1;
        kappa--;
        if (p2 < delta) {
            *K += kappa;
            int index = -static_cast<int>(kappa);
            GrisuRound(buffer, *len, delta, p2, one.f, wp_w.f * (index < 9 ? kPow10[-static_cast<int>(kappa)] : 0));
            return;
        }
    }
    */
    loop {
        p2 *= 10;
        delta *= 10;
        let d = (p2 >> -one.e) as u8;
        if d != 0 || len != 0 {
            *buffer.offset(len) = b'0' + d;
            len += 1;
        }
        p2 &= one.f - 1;
        kappa = kappa.wrapping_sub(1);
        if p2 < delta {
            k += kappa as isize;
            let index = -(kappa as isize);
            grisu_round(buffer, len, delta, p2, one.f, wp_w.f * if index < 9 { POW10[-(kappa as isize) as usize] } else { 0 });
            return (len, k);
        }
    }
}

/*
inline void Grisu2(double value, char* buffer, int* length, int* K) {
    const DiyFp v(value);
    DiyFp w_m, w_p;
    v.NormalizedBoundaries(&w_m, &w_p);

    const DiyFp c_mk = GetCachedPower(w_p.e, K);
    const DiyFp W = v.Normalize() * c_mk;
    DiyFp Wp = w_p * c_mk;
    DiyFp Wm = w_m * c_mk;
    Wm.f++;
    Wp.f--;
    DigitGen(W, Wp, Wp.f - Wm.f, buffer, length, K);
}
*/

// Returns length and k.
#[inline]
unsafe fn grisu2(value: $fty, buffer: *mut u8) -> (isize, isize) {
    let v = DiyFp::from(value);
    let (w_m, w_p) = v.normalized_boundaries();

    let (c_mk, k) = get_cached_power(w_p.e);
    let w = v.normalize() * c_mk;
    let mut wp = w_p * c_mk;
    let mut wm = w_m * c_mk;
    wm.f += 1;
    wp.f -= 1;
    digit_gen(w, wp, wp.f - wm.f, buffer, k)
}

/*
inline char* WriteExponent(int K, char* buffer) {
    if (K < 0) {
        *buffer++ = '-';
        K = -K;
    }

    if (K >= 100) {
        *buffer++ = static_cast<char>('0' + static_cast<char>(K / 100));
        K %= 100;
        const char* d = GetDigitsLut() + K * 2;
        *buffer++ = d[0];
        *buffer++ = d[1];
    }
    else if (K >= 10) {
        const char* d = GetDigitsLut() + K * 2;
        *buffer++ = d[0];
        *buffer++ = d[1];
    }
    else
        *buffer++ = static_cast<char>('0' + static_cast<char>(K));

    return buffer;
}
*/

#[inline]
unsafe fn write_exponent(mut k: isize, mut buffer: *mut u8) -> *mut u8 {
    if k < 0 {
        *buffer = b'-';
        buffer = buffer.offset(1);
        k = -k;
    }

    if k >= 100 {
        *buffer = b'0' + (k / 100) as u8;
        k %= 100;
        let d = DEC_DIGITS_LUT.as_ptr().offset(k * 2);
        ptr::copy_nonoverlapping(d, buffer.offset(1), 2);
        buffer.offset(3)
    } else if k >= 10 {
        let d = DEC_DIGITS_LUT.as_ptr().offset(k * 2);
        ptr::copy_nonoverlapping(d, buffer, 2);
        buffer.offset(2)
    } else {
        *buffer = b'0' + k as u8;
        buffer.offset(1)
    }
}

/*
inline char* Prettify(char* buffer, int length, int k, int maxDecimalPlaces) {
    const int kk = length + k;  // 10^(kk-1) <= v < 10^kk
*/

#[inline]
unsafe fn prettify(buffer: *mut u8, length: isize, k: isize) -> *mut u8 {
    let kk = length + k; // 10^(kk-1) <= v < 10^kk

    /*
    if (0 <= k && kk <= 21) {
        // 1234e7 -> 12340000000
        for (int i = length; i < kk; i++)
            buffer[i] = '0';
        buffer[kk] = '.';
        buffer[kk + 1] = '0';
        return &buffer[kk + 2];
    }
    */
    if 0 <= k && kk <= 21 {
        // 1234e7 -> 12340000000
        for i in length..kk {
            *buffer.offset(i) = b'0';
        }
        *buffer.offset(kk) = b'.';
        *buffer.offset(kk + 1) = b'0';
        buffer.offset(kk + 2)
    }

    /*
    else if (0 < kk && kk <= 21) {
        // 1234e-2 -> 12.34
        std::memmove(&buffer[kk + 1], &buffer[kk], static_cast<size_t>(length - kk));
        buffer[kk] = '.';
        if (0 > k + maxDecimalPlaces) {
            // When maxDecimalPlaces = 2, 1.2345 -> 1.23, 1.102 -> 1.1
            // Remove extra trailing zeros (at least one) after truncation.
            for (int i = kk + maxDecimalPlaces; i > kk + 1; i--)
                if (buffer[i] != '0')
                    return &buffer[i + 1];
            return &buffer[kk + 2]; // Reserve one zero
        }
        else
            return &buffer[length + 1];
    }
    */
    else if 0 < kk && kk <= 21 {
        // 1234e-2 -> 12.34
        ptr::copy(buffer.offset(kk), buffer.offset(kk + 1), (length - kk) as usize);
        *buffer.offset(kk) = b'.';
        if 0 > k + MAX_DECIMAL_PLACES {
            // When MAX_DECIMAL_PLACES = 2, 1.2345 -> 1.23, 1.102 -> 1.1
            // Remove extra trailing zeros (at least one) after truncation.
            for i in (kk + 2 .. kk + MAX_DECIMAL_PLACES + 1).rev() {
                if *buffer.offset(i) != b'0' {
                    return buffer.offset(i + 1);
                }
            }
            buffer.offset(kk + 2) // Reserve one zero
        } else {
            buffer.offset(length + 1)
        }
    }

    /*
    else if (-6 < kk && kk <= 0) {
        // 1234e-6 -> 0.001234
        const int offset = 2 - kk;
        std::memmove(&buffer[offset], &buffer[0], static_cast<size_t>(length));
        buffer[0] = '0';
        buffer[1] = '.';
        for (int i = 2; i < offset; i++)
            buffer[i] = '0';
        if (length - kk > maxDecimalPlaces) {
            // When maxDecimalPlaces = 2, 0.123 -> 0.12, 0.102 -> 0.1
            // Remove extra trailing zeros (at least one) after truncation.
            for (int i = maxDecimalPlaces + 1; i > 2; i--)
                if (buffer[i] != '0')
                    return &buffer[i + 1];
            return &buffer[3]; // Reserve one zero
        }
        else
            return &buffer[length + offset];
    }
    */
    else if -6 < kk && kk <= 0 {
        // 1234e-6 -> 0.001234
        let offset = 2 - kk;
        ptr::copy(buffer, buffer.offset(offset), length as usize);
        *buffer = b'0';
        *buffer.offset(1) = b'.';
        for i in 2..offset {
            *buffer.offset(i) = b'0';
        }
        if length - kk > MAX_DECIMAL_PLACES {
            // When MAX_DECIMAL_PLACES = 2, 0.123 -> 0.12, 0.102 -> 0.1
            // Remove extra trailing zeros (at least one) after truncation.
            for i in (3 .. MAX_DECIMAL_PLACES + 2).rev() {
                if *buffer.offset(i) != b'0' {
                    return buffer.offset(i + 1);
                }
            }
            buffer.offset(3) // Reserve one zero
        } else {
            buffer.offset(length + offset)
        }
    }

    /*
    else if (kk < -maxDecimalPlaces) {
        // Truncate to zero
        buffer[0] = '0';
        buffer[1] = '.';
        buffer[2] = '0';
        return &buffer[3];
    }
    */
    else if kk < -MAX_DECIMAL_PLACES {
        *buffer = b'0';
        *buffer.offset(1) = b'.';
        *buffer.offset(2) = b'0';
        buffer.offset(3)
    }

    /*
    else if (length == 1) {
        // 1e30
        buffer[1] = 'e';
        return WriteExponent(kk - 1, &buffer[2]);
    }
    */
    else if length == 1 {
        // 1e30
        *buffer.offset(1) = b'e';
        write_exponent(kk - 1, buffer.offset(2))
    }

    /*
    else {
        // 1234e30 -> 1.234e33
        std::memmove(&buffer[2], &buffer[1], static_cast<size_t>(length - 1));
        buffer[1] = '.';
        buffer[length + 1] = 'e';
        return WriteExponent(kk - 1, &buffer[0 + length + 2]);
    }
    */
    else {
        // 1234e30 -> 1.234e33
        ptr::copy(buffer.offset(1), buffer.offset(2), (length - 1) as usize);
        *buffer.offset(1) = b'.';
        *buffer.offset(length + 1) = b'e';
        write_exponent(kk - 1, buffer.offset(length + 2))
    }
}

/*
inline char* dtoa(double value, char* buffer, int maxDecimalPlaces = 324) {
    RAPIDJSON_ASSERT(maxDecimalPlaces >= 1);
    Double d(value);
    if (d.IsZero()) {
        if (d.Sign())
            *buffer++ = '-';     // -0.0, Issue #289
        buffer[0] = '0';
        buffer[1] = '.';
        buffer[2] = '0';
        return &buffer[3];
    }
    else {
        if (value < 0) {
            *buffer++ = '-';
            value = -value;
        }
        int length, K;
        Grisu2(value, buffer, &length, &K);
        return Prettify(buffer, length, K, maxDecimalPlaces);
    }
}
*/

#[inline]
unsafe fn dtoa<W: io::Write>(mut wr: W, mut value: $fty) -> io::Result<usize> {
    if value == 0.0 {
        if value.is_sign_negative() {
            try!(wr.write_all(b"-0.0"));
            Ok(4)
        } else {
            try!(wr.write_all(b"0.0"));
            Ok(3)
        }
    } else {
        let negative = value < 0.0;
        if negative {
            try!(wr.write_all(b"-"));
            value = -value;
        }
        let mut buffer: [u8; 24] = mem::uninitialized();
        let buf_ptr = buffer.as_mut_ptr();
        let (length, k) = grisu2(value, buf_ptr);
        let end = prettify(buf_ptr, length, k);
        let len = end as usize - buf_ptr as usize;
        try!(wr.write_all(slice::from_raw_parts(buf_ptr, len)));
        if negative {
            Ok(len + 1)
        } else {
            Ok(len)
        }
    }
}

}}