diff options
Diffstat (limited to 'absl/strings/internal/str_format/float_conversion.cc')
| -rw-r--r-- | absl/strings/internal/str_format/float_conversion.cc | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc index 2aa41aa7..2b1fd8cb 100644 --- a/absl/strings/internal/str_format/float_conversion.cc +++ b/absl/strings/internal/str_format/float_conversion.cc @@ -112,12 +112,22 @@ inline uint64_t DivideBy10WithCarry(uint64_t *v, uint64_t carry) { return next_carry % divisor; } +constexpr bool IsDoubleDouble() { + // This is the `double-double` representation of `long double`. + // We do not handle it natively. Fallback to snprintf. + return std::numeric_limits<long double>::digits == + 2 * std::numeric_limits<double>::digits; +} + +using MaxFloatType = + typename std::conditional<IsDoubleDouble(), double, long double>::type; + // Generates the decimal representation for an integer of the form `v * 2^exp`, // where `v` and `exp` are both positive integers. // It generates the digits from the left (ie the most significant digit first) // to allow for direct printing into the sink. // -// Requires `0 <= exp` and `exp <= numeric_limits<long double>::max_exponent`. +// Requires `0 <= exp` and `exp <= numeric_limits<MaxFloatType>::max_exponent`. class BinaryToDecimal { static constexpr int ChunksNeeded(int exp) { // We will left shift a uint128 by `exp` bits, so we need `128+exp` total @@ -132,10 +142,10 @@ class BinaryToDecimal { static void RunConversion(uint128 v, int exp, absl::FunctionRef<void(BinaryToDecimal)> f) { assert(exp > 0); - assert(exp <= std::numeric_limits<long double>::max_exponent); + assert(exp <= std::numeric_limits<MaxFloatType>::max_exponent); static_assert( static_cast<int>(StackArray::kMaxCapacity) >= - ChunksNeeded(std::numeric_limits<long double>::max_exponent), + ChunksNeeded(std::numeric_limits<MaxFloatType>::max_exponent), ""); StackArray::RunWithCapacity( @@ -232,14 +242,14 @@ class BinaryToDecimal { // Converts a value of the form `x * 2^-exp` into a sequence of decimal digits. // Requires `-exp < 0` and -// `-exp >= limits<long double>::min_exponent - limits<long double>::digits`. +// `-exp >= limits<MaxFloatType>::min_exponent - limits<MaxFloatType>::digits`. class FractionalDigitGenerator { public: // Run the conversion for `v * 2^exp` and call `f(generator)`. // This function will allocate enough stack space to perform the conversion. static void RunConversion( uint128 v, int exp, absl::FunctionRef<void(FractionalDigitGenerator)> f) { - using Limits = std::numeric_limits<long double>; + using Limits = std::numeric_limits<MaxFloatType>; assert(-exp < 0); assert(-exp >= Limits::min_exponent - 128); static_assert(StackArray::kMaxCapacity >= @@ -871,10 +881,10 @@ void FormatA(const HexFloatTypeParams float_traits, Int mantissa, int exp, // This buffer holds the "0x1.ab1de3" portion of "0x1.ab1de3pe+2". Compute the // size with long double which is the largest of the floats. constexpr size_t kBufSizeForHexFloatRepr = - 2 // 0x - + std::numeric_limits<long double>::digits / 4 // number of hex digits - + 1 // round up - + 1; // "." (dot) + 2 // 0x + + std::numeric_limits<MaxFloatType>::digits / 4 // number of hex digits + + 1 // round up + + 1; // "." (dot) char digits_buffer[kBufSizeForHexFloatRepr]; char *digits_iter = digits_buffer; const char *const digits = @@ -1393,10 +1403,7 @@ bool FloatToSink(const Float v, const FormatConversionSpecImpl &conv, bool ConvertFloatImpl(long double v, const FormatConversionSpecImpl &conv, FormatSinkImpl *sink) { - if (std::numeric_limits<long double>::digits == - 2 * std::numeric_limits<double>::digits) { - // This is the `double-double` representation of `long double`. - // We do not handle it natively. Fallback to snprintf. + if (IsDoubleDouble()) { return FallbackToSnprintf(v, conv, sink); } |