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As an extension, the GNU C compiler supports additional floating
types, __float80 and __float128 to support 80bit
(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 and ‘q’ or ‘Q’
for _float128. You can declare complex types using the
corresponding internal complex type, XCmode for __float80
type and TCmode for __float128 type:
typedef _Complex float __attribute__((mode(TC))) _Complex128;
typedef _Complex float __attribute__((mode(XC))) _Complex80;
Not all targets support additional floating point types. __float80
is supported on i386, x86_64 and ia64 targets and target __float128
is supported on x86_64 and ia64 targets.