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 void 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 86 std::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 } 99 100 std::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 110 111 void 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 } 117 118 std::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 } 124 125 std::string StringPrintFImp(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 } 154 155 std::string StringPrintF(const char* format, ...) { 156 va_list args; 157 va_start(args, format); 158 std::string tmp = StringPrintFImp(format, args); 159 va_end(args); 160 return tmp; 161 } 162 163 void 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
