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
30void ToExponentAndMantissa(double val, double thresh, int precision,
31                           double one_k, std::string* mantissa,
32                           int64_t* exponent) {
33  std::stringstream mantissa_stream;
34
35  if (val < 0) {
36    mantissa_stream << "-";
37    val = -val;
38  }
39
40  // Adjust threshold so that it never excludes things which can't be rendered
41  // in 'precision' digits.
42  const double adjusted_threshold =
43      std::max(thresh, 1.0 / std::pow(10.0, precision));
44  const double big_threshold = adjusted_threshold * one_k;
45  const double small_threshold = adjusted_threshold;
46  // Values in ]simple_threshold,small_threshold[ will be printed as-is
47  const double simple_threshold = 0.01;
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    if (val < simple_threshold) {
66      double scaled = val;
67      for (size_t i = 0; i < arraysize(kSmallSIUnits); ++i) {
68        scaled *= one_k;
69        if (scaled >= small_threshold) {
70          mantissa_stream << scaled;
71          *exponent = -static_cast<int64_t>(i + 1);
72          *mantissa = mantissa_stream.str();
73          return;
74        }
75      }
76    }
77    mantissa_stream << val;
78    *exponent = 0;
79  } else {
80    mantissa_stream << val;
81    *exponent = 0;
82  }
83  *mantissa = mantissa_stream.str();
84}
85
86std::string ExponentToPrefix(int64_t exponent, bool iec) {
87  if (exponent == 0) return "";
88
89  const int64_t index = (exponent > 0 ? exponent - 1 : -exponent - 1);
90  if (index >= kUnitsSize) return "";
91
92  const char* array =
93      (exponent > 0 ? (iec ? kBigIECUnits : kBigSIUnits) : kSmallSIUnits);
94  if (iec)
95    return array[index] + std::string("i");
96  else
97    return std::string(1, array[index]);
98}
99
100std::string ToBinaryStringFullySpecified(double value, double threshold,
101                                         int precision, double one_k = 1024.0) {
102  std::string mantissa;
103  int64_t exponent;
104  ToExponentAndMantissa(value, threshold, precision, one_k, &mantissa,
105                        &exponent);
106  return mantissa + ExponentToPrefix(exponent, false);
107}
108
109}  // end namespace
110
111void AppendHumanReadable(int n, std::string* str) {
112  std::stringstream ss;
113  // Round down to the nearest SI prefix.
114  ss << ToBinaryStringFullySpecified(n, 1.0, 0);
115  *str += ss.str();
116}
117
118std::string HumanReadableNumber(double n, double one_k) {
119  // 1.1 means that figures up to 1.1k should be shown with the next unit down;
120  // this softens edge effects.
121  // 1 means that we should show one decimal place of precision.
122  return ToBinaryStringFullySpecified(n, 1.1, 1, one_k);
123}
124
125std::string StrFormatImp(const char* msg, va_list args) {
126  // we might need a second shot at this, so pre-emptivly make a copy
127  va_list args_cp;
128  va_copy(args_cp, args);
129
130  // TODO(ericwf): use std::array for first attempt to avoid one memory
131  // allocation guess what the size might be
132  std::array<char, 256> local_buff;
133  std::size_t size = local_buff.size();
134  // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
135  // in the android-ndk
136  auto ret = vsnprintf(local_buff.data(), size, msg, args_cp);
137
138  va_end(args_cp);
139
140  // handle empty expansion
141  if (ret == 0) return std::string{};
142  if (static_cast<std::size_t>(ret) < size)
143    return std::string(local_buff.data());
144
145  // we did not provide a long enough buffer on our first attempt.
146  // add 1 to size to account for null-byte in size cast to prevent overflow
147  size = static_cast<std::size_t>(ret) + 1;
148  auto buff_ptr = std::unique_ptr<char[]>(new char[size]);
149  // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
150  // in the android-ndk
151  ret = vsnprintf(buff_ptr.get(), size, msg, args);
152  return std::string(buff_ptr.get());
153}
154
155std::string StrFormat(const char* format, ...) {
156  va_list args;
157  va_start(args, format);
158  std::string tmp = StrFormatImp(format, args);
159  va_end(args);
160  return tmp;
161}
162
163void ReplaceAll(std::string* str, const std::string& from,
164                const std::string& to) {
165  std::size_t start = 0;
166  while ((start = str->find(from, start)) != std::string::npos) {
167    str->replace(start, from.length(), to);
168    start += to.length();
169  }
170}
171
172}  // end namespace benchmark
173