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 12 namespace benchmark { 13 namespace { 14 15 // kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta. 16 const char kBigSIUnits[] = "kMGTPEZY"; 17 // Kibi, Mebi, Gibi, Tebi, Pebi, Exbi, Zebi, Yobi. 18 const char kBigIECUnits[] = "KMGTPEZY"; 19 // milli, micro, nano, pico, femto, atto, zepto, yocto. 20 const char kSmallSIUnits[] = "munpfazy"; 21 22 // We require that all three arrays have the same size. 23 static_assert(arraysize(kBigSIUnits) == arraysize(kBigIECUnits), 24 "SI and IEC unit arrays must be the same size"); 25 static_assert(arraysize(kSmallSIUnits) == arraysize(kBigSIUnits), 26 "Small SI and Big SI unit arrays must be the same size"); 27 28 static const int64_t kUnitsSize = arraysize(kBigSIUnits); 29 30 } // end anonymous namespace 31 32 void 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 84 std::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 98 std::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 } 106 107 void 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 } 113 114 std::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 } 120 121 std::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 } 150 151 std::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 } 158 159 void 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
