1// Copyright 2018 Ulf Adams
2//
3// The contents of this file may be used under the terms of the Apache License,
4// Version 2.0.
5//
6//    (See accompanying file LICENSE-Apache or copy at
7//     http://www.apache.org/licenses/LICENSE-2.0)
8//
9// Alternatively, the contents of this file may be used under the terms of
10// the Boost Software License, Version 1.0.
11//    (See accompanying file LICENSE-Boost or copy at
12//     https://www.boost.org/LICENSE_1_0.txt)
13//
14// Unless required by applicable law or agreed to in writing, this software
15// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16// KIND, either express or implied.
17#ifndef RYU_COMMON_H
18#define RYU_COMMON_H
19
20
21#if defined(_M_IX86) || defined(_M_ARM)
22#define RYU_32_BIT_PLATFORM
23#endif
24
25// Returns the number of decimal digits in v, which must not contain more than 9 digits.
26static inline uint32_t decimalLength9(const uint32_t v) {
27  // Function precondition: v is not a 10-digit number.
28  // (f2s: 9 digits are sufficient for round-tripping.)
29  // (d2fixed: We print 9-digit blocks.)
30  assert(v < 1000000000);
31  if (v >= 100000000) { return 9; }
32  if (v >= 10000000) { return 8; }
33  if (v >= 1000000) { return 7; }
34  if (v >= 100000) { return 6; }
35  if (v >= 10000) { return 5; }
36  if (v >= 1000) { return 4; }
37  if (v >= 100) { return 3; }
38  if (v >= 10) { return 2; }
39  return 1;
40}
41
42// Returns e == 0 ? 1 : [log_2(5^e)]; requires 0 <= e <= 3528.
43static inline int32_t log2pow5(const int32_t e) {
44  // This approximation works up to the point that the multiplication overflows at e = 3529.
45  // If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
46  // than 2^9297.
47  assert(e >= 0);
48  assert(e <= 3528);
49  return (int32_t) ((((uint32_t) e) * 1217359) >> 19);
50}
51
52// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
53static inline int32_t pow5bits(const int32_t e) {
54  // This approximation works up to the point that the multiplication overflows at e = 3529.
55  // If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
56  // than 2^9297.
57  assert(e >= 0);
58  assert(e <= 3528);
59  return (int32_t) (((((uint32_t) e) * 1217359) >> 19) + 1);
60}
61
62// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
63static inline int32_t ceil_log2pow5(const int32_t e) {
64  return log2pow5(e) + 1;
65}
66
67// Returns floor(log_10(2^e)); requires 0 <= e <= 1650.
68static inline uint32_t log10Pow2(const int32_t e) {
69  // The first value this approximation fails for is 2^1651 which is just greater than 10^297.
70  assert(e >= 0);
71  assert(e <= 1650);
72  return (((uint32_t) e) * 78913) >> 18;
73}
74
75// Returns floor(log_10(5^e)); requires 0 <= e <= 2620.
76static inline uint32_t log10Pow5(const int32_t e) {
77  // The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
78  assert(e >= 0);
79  assert(e <= 2620);
80  return (((uint32_t) e) * 732923) >> 20;
81}
82
83static inline uint32_t float_to_bits(const float f) {
84  uint32_t bits = 0;
85  memcpy(&bits, &f, sizeof(float));
86  return bits;
87}
88
89static inline uint64_t double_to_bits(const double d) {
90  uint64_t bits = 0;
91  memcpy(&bits, &d, sizeof(double));
92  return bits;
93}
94
95#endif // RYU_COMMON_H
96