# Macros¶

## Flint Macros¶

The file flint.h contains various useful macros.

The macro constant FLINT_BITS is set at compile time to be the number of bits per limb on the machine. FLINT requires it to be either 32 or 64 bits. Other architectures are not currently supported.

The macro constant FLINT_D_BITS is set at compile time to be the number of bits per double on the machine or one less than the number of bits per limb, whichever is smaller. This will have the value $$53$$ or $$31$$ on currently supported architectures. Numerous internal functions using precomputed inverses only support operands up to FLINT_D_BITS bits, hence the macro.

The macro FLINT_ABS(x) returns the absolute value of $$x$$ for primitive signed numerical types. It might fail for least negative values such as INT_MIN and WORD_MIN.

The macro FLINT_MIN(x, y) returns the minimum of $$x$$ and $$y$$ for primitive signed or unsigned numerical types. This macro is only safe to use when $$x$$ and $$y$$ are of the same type, to avoid problems with integer promotion.

Similar to the previous macro, FLINT_MAX(x, y) returns the maximum of $$x$$ and $$y$$.

The function FLINT_BIT_COUNT(x) returns the number of binary bits required to represent an ulong x. If $$x$$ is zero, returns $$0$$.

Derived from this there are the two macros FLINT_FLOG2(x) and FLINT_CLOG2(x) which, for any $$x \geq 1$$, compute $$\lfloor \log_2 x \rfloor$$ and $$\lceil \log_2 x \rceil$$.

To determine the current FLINT version a number of macros are available. For example, if the current FLINT version is 2.4.0 then __FLINT_VERSION will have the value $$2$$, __FLINT_MINOR will have the value $$4$$ and __FLINT_PATCHLEVEL will have the value $$0$$.

The __FLINT_RELEASE macro gives a single number representing the FLINT version. For example, it will have the value 20400 for version 2.4.0.

The FLINT_VERSION macro is a static text string giving the version number, e.g. “2.4” or “2.4.1”. Note that if the final digit is a zero it is suppressed.