On 06/18/2012 10:51 PM, Franz Fehringer wrote: > Hi, > > I am investigating the possibilities of using decimal floating point > arithmetic with gcc (on Linux / x86_64 to be explicit).
I'm a little rusty on this and my information might be out of date, but this should be a good start. If I say something horribly wrong I hope to be corrected. > Are _Decimal32/_Decimal64/_Decimal128 available as builtin types without > further action or do i as a DFP consumer have to issue the correspondent > typedef/float/attributeS by myself (as is done in the testcases and the > std::decimal headerS)? > How do i convert _Decimal32/_Decimal64/_Decimal128/std::decimal from/to > string/char* (and do cout/stdout I/O)? > Can the (internal?) std::decimal method __getval (giving one of > _Decimal32/_Decimal64/_Decimal128) be used by me as a user? The types _Decimal32, _Decimal64, and _Decimal128 are builtin types for C with "gcc --std=gnu99". Those types are not in the C++ language extension for decimal float. With G++ you can use typedefs with modes SD/DD/TD to use those types for source code shared with C. G++ treats the decimal classes as the underlying scalars for passing arguments, returning function values, and assignments between the classes and the scalar types; there's no need to use __getval. > Are there plans to add DFP support to glibc? I don't know about the current status of decimal floating-point support in the C library (glibc in particular). For status of GCC's C++ support see <http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.tr24733>. > Are there good examples out there showing the superiority of DFP > arithmetic over ordinary (binary) FP arithmetic in the domain of > monetary calculations? For general information about decimal floating-point arithmetic see <http://speleotrove.com/decimal/>. From what I understand, serious monetary calculations are never done with binary floating-point arithmetic and most business applications use some sort of software emulation of decimal floating-point or decimal fixed-point arithmetic. Janis
