hosted and freestanding implementations

[subramanian100in]

The ISO/IEC-14882:2003 document mentions the following in the section
"1.4 Implementation Compliance" paragraph 7:

"Two kinds of implementations of defined:hosted and freestanding. For
a hosted implementation, this International Standard defines the set
of available libraries. A freestanding implementation is one in which
the execution may take place without the benefit of an operating
system, and has an implementation-defined set of libraries that
includes certain language-support libraries(17.4.1.3)"

From the above definition, I am unable to understand what is a hosted
implementation and and what is a freestanding implementation. Kindly
explain these two kinds of implementations.

I am using g++3.4.3 under Redhat Enterprise Linux on an Intel-x86
based PC. Kindly let me know whether this implementation is a hosted
implementation or a freestanding implementation.

Thanks
V.Subramanian

 

[Victor Bazarov]

The ISO/IEC-14882:2003 document mentions the following in the section
"1.4 Implementation Compliance" paragraph 7:

"Two kinds of implementations of defined:hosted and freestanding. For
a hosted implementation, this International Standard defines the set
of available libraries. A freestanding implementation is one in which
the execution may take place without the benefit of an operating
system, and has an implementation-defined set of libraries that
includes certain language-support libraries(17.4.1.3)"

From the above definition, I am unable to understand what is a hosted
implementation and and what is a freestanding implementation. Kindly
explain these two kinds of implementations.

I am using g++3.4.3 under Redhat Enterprise Linux on an Intel-x86
based PC. Kindly let me know whether this implementation is a hosted
implementation or a freestanding implementation.

Hosted implementation: running on (or under) an operating system. Your
computer has an independent operating system, so the implementation is
indeed a hosted one. Also, the resulting executable is going to be
hosted as well since it's not capable of running on a computer without
an operating system.

V

 

[James Kanze]

Hosted implementation: running on (or under) an operating
system. Your computer has an independent operating system, so
the implementation is indeed a hosted one. Also, the
resulting executable is going to be hosted as well since it's
not capable of running on a computer without an operating
system.

That's certainly the intent: that a freestanding implementation
can run without the underlying support of an operating system,
say by being burned into a PROM. There are, however, some
differences between the two languages: a freestanding system
uses an implementation defined means of start-up, rather than
main; a freestanding system might require you to provide a
function called _tmain, for example, rather than main, and it
might provide the argument list in wchar_t rather than char.
And while the intent is to support systems without an OS, the
freestanding implementation can place pretty much any
requirements on the environment that it wants.