About ===== _decimal.c is a wrapper for the libmpdec library. libmpdec is a fast C library for correctly-rounded arbitrary precision decimal floating point arithmetic. It is a complete implementation of Mike Cowlishaw/IBM's General Decimal Arithmetic Specification. Build process for the module ============================ As usual, the build process for _decimal.so is driven by setup.py in the top level directory. setup.py autodetects the following build configurations: 1) x64 - 64-bit Python, x86_64 processor (AMD, Intel) 2) uint128 - 64-bit Python, compiler provides __uint128_t (gcc) 3) ansi64 - 64-bit Python, ANSI C 4) ppro - 32-bit Python, x86 CPU, PentiumPro or later 5) ansi32 - 32-bit Python, ANSI C 6) ansi-legacy - 32-bit Python, compiler without uint64_t 7) universal - Mac OS only (multi-arch) It is possible to override autodetection by exporting: PYTHON_DECIMAL_WITH_MACHINE=value, where value is one of the above options. NOTE ==== decimal.so is not built from a static libmpdec.a since doing so led to failures on AIX (user report) and Windows (mixing static and dynamic CRTs causes locale problems and more).