gdb: Decimal Floating Point
15.4.1.8 Decimal Floating Point format
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GDB can examine, set and perform computations with numbers in decimal
floating point format, which in the C language correspond to the
'_Decimal32', '_Decimal64' and '_Decimal128' types as specified by the
extension to support decimal floating-point arithmetic.
There are two encodings in use, depending on the architecture: BID
(Binary Integer Decimal) for x86 and x86-64, and DPD (Densely Packed
Decimal) for PowerPC and S/390. GDB will use the appropriate encoding
for the configured target.
Because of a limitation in 'libdecnumber', the library used by GDB to
manipulate decimal floating point numbers, it is not possible to convert
(using a cast, for example) integers wider than 32-bit to decimal float.
In addition, in order to imitate GDB's behaviour with binary floating
point computations, error checking in decimal float operations ignores
underflow, overflow and divide by zero exceptions.
In the PowerPC architecture, GDB provides a set of pseudo-registers
to inspect '_Decimal128' values stored in floating point registers. See
PowerPC PowerPC. for more details.
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