Signed-off-by: Leah Rowe <leah@libreboot.org>

the loop in main() already checks EOF, and errno is
properly handled at the end of main()

we only need to call ferror(), to check error state

this fixes a bogus error message when pressing ctrl+D
to terminate the program, *which is the intended way
to terminate this program* (that, or EOF is reached
in any other another way)

do not treat intended behaviour as an error condition!

Signed-off-by: Leah Rowe <leah@libreboot.org>

i've build-tested this code with clang and that also
works. in practise, a user is going to have clang or gcc

Signed-off-by: Leah Rowe <leah@libreboot.org>

Signed-off-by: Leah Rowe <leah@libreboot.org>

Signed-off-by: Leah Rowe <leah@libreboot.org>

Signed-off-by: Leah Rowe <leah@libreboot.org>

make it more obvious that this *is* a ring buffer being
handled, and make it more obvious when checking a pulse
in the next frame

Signed-off-by: Leah Rowe <leah@libreboot.org>

Signed-off-by: Leah Rowe <leah@libreboot.org>

i forked spkmodem-recv from coreboot, who forked it from
gnu grub. gnu grub's version has the full header, with
copyright declared as belonging to the fsf

coreboot made changes after forking it, and later replaced
the license declaration with an equivalent SPDX header, but
they also removed the FSF's copyright declaration, which by
itself does not void the declaration

anyway, i just feel better re-adding the full declaration.
make it so!

Signed-off-by: Leah Rowe <leah@libreboot.org>

The last bit wasn't being handled, *and* ascii_bit
wasn't being reduced at all.

Signed-off-by: Leah Rowe <leah@libreboot.org>