1#include "string_util.h"
2
3#include <array>
4#include <cmath>
5#include <cstdarg>
6#include <cstdio>
7#include <memory>
8#include <sstream>
9
10#include "arraysize.h"
11
12namespace benchmark {
13namespace {
14
15// kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta.
16const char kBigSIUnits[] = "kMGTPEZY";
17// Kibi, Mebi, Gibi, Tebi, Pebi, Exbi, Zebi, Yobi.
18const char kBigIECUnits[] = "KMGTPEZY";
19// milli, micro, nano, pico, femto, atto, zepto, yocto.
20const char kSmallSIUnits[] = "munpfazy";
21
22// We require that all three arrays have the same size.
23static_assert(arraysize(kBigSIUnits) == arraysize(kBigIECUnits),
24 "SI and IEC unit arrays must be the same size");
25static_assert(arraysize(kSmallSIUnits) == arraysize(kBigSIUnits),
26 "Small SI and Big SI unit arrays must be the same size");
27
28static const int64_t kUnitsSize = arraysize(kBigSIUnits);
29
30} // end anonymous namespace
31
32void ToExponentAndMantissa(double val, double thresh, int precision,
33 double one_k, std::string* mantissa,
34 int64_t* exponent) {
35 std::stringstream mantissa_stream;
36
37 if (val < 0) {
38 mantissa_stream << "-";
39 val = -val;
40 }
41
42 // Adjust threshold so that it never excludes things which can't be rendered
43 // in 'precision' digits.
44 const double adjusted_threshold =
45 std::max(thresh, 1.0 / std::pow(10.0, precision));
46 const double big_threshold = adjusted_threshold * one_k;
47 const double small_threshold = adjusted_threshold;
48
49 if (val > big_threshold) {
50 // Positive powers
51 double scaled = val;
52 for (size_t i = 0; i < arraysize(kBigSIUnits); ++i) {
53 scaled /= one_k;
54 if (scaled <= big_threshold) {
55 mantissa_stream << scaled;
56 *exponent = i + 1;
57 *mantissa = mantissa_stream.str();
58 return;
59 }
60 }
61 mantissa_stream << val;
62 *exponent = 0;
63 } else if (val < small_threshold) {
64 // Negative powers
65 double scaled = val;
66 for (size_t i = 0; i < arraysize(kSmallSIUnits); ++i) {
67 scaled *= one_k;
68 if (scaled >= small_threshold) {
69 mantissa_stream << scaled;
70 *exponent = -static_cast<int64_t>(i + 1);
71 *mantissa = mantissa_stream.str();
72 return;
73 }
74 }
75 mantissa_stream << val;
76 *exponent = 0;
77 } else {
78 mantissa_stream << val;
79 *exponent = 0;
80 }
81 *mantissa = mantissa_stream.str();
82}
83
84std::string ExponentToPrefix(int64_t exponent, bool iec) {
85 if (exponent == 0) return "";
86
87 const int64_t index = (exponent > 0 ? exponent - 1 : -exponent - 1);
88 if (index >= kUnitsSize) return "";
89
90 const char* array =
91 (exponent > 0 ? (iec ? kBigIECUnits : kBigSIUnits) : kSmallSIUnits);
92 if (iec)
93 return array[index] + std::string("i");
94 else
95 return std::string(1, array[index]);
96}
97
98std::string ToBinaryStringFullySpecified(double value, double threshold,
99 int precision) {
100 std::string mantissa;
101 int64_t exponent;
102 ToExponentAndMantissa(value, threshold, precision, 1024.0, &mantissa,
103 &exponent);
104 return mantissa + ExponentToPrefix(exponent, false);
105}
106
107void AppendHumanReadable(int n, std::string* str) {
108 std::stringstream ss;
109 // Round down to the nearest SI prefix.
110 ss << ToBinaryStringFullySpecified(n, 1.0, 0);
111 *str += ss.str();
112}
113
114std::string HumanReadableNumber(double n) {
115 // 1.1 means that figures up to 1.1k should be shown with the next unit down;
116 // this softens edge effects.
117 // 1 means that we should show one decimal place of precision.
118 return ToBinaryStringFullySpecified(n, 1.1, 1);
119}
120
121std::string StringPrintFImp(const char* msg, va_list args) {
122 // we might need a second shot at this, so pre-emptivly make a copy
123 va_list args_cp;
124 va_copy(args_cp, args);
125
126 // TODO(ericwf): use std::array for first attempt to avoid one memory
127 // allocation guess what the size might be
128 std::array<char, 256> local_buff;
129 std::size_t size = local_buff.size();
130 // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
131 // in the android-ndk
132 auto ret = vsnprintf(local_buff.data(), size, msg, args_cp);
133
134 va_end(args_cp);
135
136 // handle empty expansion
137 if (ret == 0) return std::string{};
138 if (static_cast<std::size_t>(ret) < size)
139 return std::string(local_buff.data());
140
141 // we did not provide a long enough buffer on our first attempt.
142 // add 1 to size to account for null-byte in size cast to prevent overflow
143 size = static_cast<std::size_t>(ret) + 1;
144 auto buff_ptr = std::unique_ptr<char[]>(new char[size]);
145 // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
146 // in the android-ndk
147 ret = vsnprintf(buff_ptr.get(), size, msg, args);
148 return std::string(buff_ptr.get());
149}
150
151std::string StringPrintF(const char* format, ...) {
152 va_list args;
153 va_start(args, format);
154 std::string tmp = StringPrintFImp(format, args);
155 va_end(args);
156 return tmp;
157}
158
159void ReplaceAll(std::string* str, const std::string& from,
160 const std::string& to) {
161 std::size_t start = 0;
162 while ((start = str->find(from, start)) != std::string::npos) {
163 str->replace(start, from.length(), to);
164 start += to.length();
165 }
166}
167
168} // end namespace benchmark
169