Hi Marc, > Gnulib > offers strtod replacements, but these refer to conversion routines of the > host systems and may lack the accuracy described in Clinger's well-known > paper [1] IIUC. > > Wouldn't it make sense to include an accurate conversion algorithm in > Gnulib like [2] with the small improvement from [3]?
If you have time to do so, and would like to contribute decent unit tests accompanying the code, please do so! > Maybe code from glibc can be reused. The problem with the glibc code is that they have specialized code for each format: - IEEE 754 single-precision, - IEEE 754 double-precision, - 'long double' with LDBL_MANT_DIG == 106 (a.k.a. "double double"), - 'long double' with LDBL_MANT_DIG == 113 (a.k.a. "quad precision"). That makes for a lot of code and a lot of required testing, and is not future-proof (regarding new floating-point types). If possible, in Gnulib, we would prefer a single implementation, even if it is a bit slow. > Let me also mention what I feel is an inconvenience of the standard C > library functions: they mix parsing/composing the strings with the actual > conversion routines. That's because the "actual conversion routines" have a big-integer type as input or output, and standard C does not have these types. > Routines that take the sign, the (integer) mantissa, > and the exponent separately (or return them separately) are more > fundamental. Yes, and you find such routines in GMP or possibly in minigmp. For the "composing" part, Gnulib has such routines in vasnprintf.c, lines 443..1650. Bruno
