As an extension, GNU C supports additional floating
__float128 to support 80-bit
XFmode) and 128-bit (
TFmode) floating types.
Support for additional types includes the arithmetic operators:
add, subtract, multiply, divide; unary arithmetic operators;
relational operators; equality operators; and conversions to and from
integer and other floating types. Use a suffix ‘w’ or ‘W’
in a literal constant of type
__float80 or type
__ibm128. Use a suffix ‘q’ or ‘Q’ for
On the i386, x86_64, IA-64, and HP-UX targets, you can declare complex
types using the corresponding internal complex type,
__float80 type and
typedef _Complex float __attribute__((mode(TC))) _Complex128; typedef _Complex float __attribute__((mode(XC))) _Complex80;
On PowerPC 64-bit Linux systems there are currently problems in using
__float128 type. When these problems are fixed,
you would use:
typedef _Complex float __attribute__((mode(KC))) _Complex128;
Not all targets support additional floating-point types.
__float128 types are supported on x86 and
IA-64 targets. The
__float128 type is supported on hppa HP-UX.
__float128 type is supported on PowerPC 64-bit Linux
systems by default if the vector scalar instruction set (VSX) is
On the PowerPC,
__ibm128 provides access to the IBM extended
double format, and it is intended to be used by the library functions
that handle conversions if/when long double is changed to be IEEE
128-bit floating point.