I've been playing around with Microchip's free dsPIC30F Math
Library, making assembly language calls to various functions, and
I've noticed some behavior that seems a bit odd to me.

These math functions are in a Microchip-supplied object archive
file, libm-coff.a, and I am calling them from my assembly code in
a .s file.  I expected to have to use an .extern statement to
declare each of the library functions I call; yet my program
assembles, links, and runs just fine whether I include the
.extern statements or omit them.

I've looked in the ASM30 help file, the dsPIC30F Math Library
documentation, the dsPIC Language Tools Libraries document, and
find nothing to indicate that the .extern directive is optional
in this circumstance.

Questions:

1) Am I being clueless here about some basic principle in the
Grand Unified Theory of Assemblers And Linkers-- i.e., is this
perfectly normal to not need .extern directives when calling
library functions? or

2) Is this some kind of "undocumented behavior" that I shouldn't
rely on in my coding, and to be safe I should declare each called
function with an .extern directive, whether they're apparently
needed here or not?

All suggestions welcome; thanks.

Dave D.

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