view ccd/README @ 11:bf52986ae7f2

L1/cfile/l1_isr_glue.c: applying changes discovered in TCS211 L1 reconstruction
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 09 Jun 2016 06:37:40 +0000
parents 75a11d740a02
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CCD (Condat Coder and Decoder) is yet another component needed in order to
produce a functional GSM/GPRS MS (mobile station) firmware image based on the
TI/Condat architecture.  We got the C source for this component from the
LoCosto find.

CCD code that went into TI's firmware builds (as opposed to TI/Condat's
Windows-based tools etc) has two subdivisions:

1. The main CCD library - ccd_na7_db.lib in the case of our Leonardo reference
   firmware.  The C modules compiled into this library must be very independent,
   as it's one of the "frozen" GPF libs - it appears that GPF was maintained by
   a separate group inside TI, and the builders of actual GSM/GPRS firmwares
   used that group's GPF (and CCD) binary lib deliverables as untouched blobs.

2. The ccddata component is meant to be compiled as part of the product firmware
   build process, in both TCS211 and LoCosto versions.  Our Leonardo reference
   version has it in a binary lib too, but it's one of those "unprivileged
   customer" libs, and one can see from the makefiles that it was meant to be
   compiled the same way as L1 and L23 etc.  The LoCosto version came with the
   full source for all of CCD, but the build system is set up to only compile
   ccddata, whereas the rest of CCD is used in the form of an imported GPF
   binary lib, just like GPF proper, just like in TCS211.

It appears, however, that the C source for both above-listed parts of CCD has
always been maintained in a single directory, and that is how it appears in the
LoCosto find.

The true reason for the subdivision became apparent when we went through the
process of integrating CCD into FreeCalypso.  The C modules that comprise
ccddata include cdginc headers (see ../cdg/README to learn what a nightmare
that is), require these headers to be present in order to pass compilation, and
depend on any changes in these headers, whereas the "base" part of CCD (the one
that was maintained as a GPF stable lib inside TI) has no dependency on cdginc.

For our use in FreeCalypso we shall compile all of CCD (both subdivisions) into
a single library in this directory - in this project we always compile
everything from source anyway, so we may as well simplify the build process in
this regard.