Add initial copy-pasted code

11 files changed, 1128 insertions, 0 deletions

diff --git a/src/fec/LICENSE b/src/fec/LICENSE
new file mode 100644
index 0000000..5a883d3
--- /dev/null
+++ b/src/fec/LICENSE
@@ -0,0 +1,502 @@
+GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+(This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.)
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+Licenses are intended to guarantee your freedom to share and change
+free software--to make sure the software is free for all its users.
+
+  This license, the Lesser General Public License, applies to some
+specially designated software packages--typically libraries--of the
+Free Software Foundation and other authors who decide to use it.  You
+can use it too, but we suggest you first think carefully about whether
+this license or the ordinary General Public License is the better
+strategy to use in any particular case, based on the explanations below.
+
+  When we speak of free software, we are referring to freedom of use,
+not price.  Our General Public Licenses are designed to make sure that
+you have the freedom to distribute copies of free software (and charge
+for this service if you wish); that you receive source code or can get
+it if you want it; that you can change the software and use pieces of
+it in new free programs; and that you are informed that you can do
+these things.
+
+  To protect your rights, we need to make restrictions that forbid
+distributors to deny you these rights or to ask you to surrender these
+rights.  These restrictions translate to certain responsibilities for
+you if you distribute copies of the library or if you modify it.
+
+  For example, if you distribute copies of the library, whether gratis
+or for a fee, you must give the recipients all the rights that we gave
+you.  You must make sure that they, too, receive or can get the source
+code.  If you link other code with the library, you must provide
+complete object files to the recipients, so that they can relink them
+with the library after making changes to the library and recompiling
+it.  And you must show them these terms so they know their rights.
+
+  We protect your rights with a two-step method: (1) we copyright the
+library, and (2) we offer you this license, which gives you legal
+permission to copy, distribute and/or modify the library.
+
+  To protect each distributor, we want to make it very clear that
+there is no warranty for the free library.  Also, if the library is
+modified by someone else and passed on, the recipients should know
+that what they have is not the original version, so that the original
+author's reputation will not be affected by problems that might be
+introduced by others.
+
+  Finally, software patents pose a constant threat to the existence of
+any free program.  We wish to make sure that a company cannot
+effectively restrict the users of a free program by obtaining a
+restrictive license from a patent holder.  Therefore, we insist that
+any patent license obtained for a version of the library must be
+consistent with the full freedom of use specified in this license.
+
+  Most GNU software, including some libraries, is covered by the
+ordinary GNU General Public License.  This license, the GNU Lesser
+General Public License, applies to certain designated libraries, and
+is quite different from the ordinary General Public License.  We use
+this license for certain libraries in order to permit linking those
+libraries into non-free programs.
+
+  When a program is linked with a library, whether statically or using
+a shared library, the combination of the two is legally speaking a
+combined work, a derivative of the original library.  The ordinary
+General Public License therefore permits such linking only if the
+entire combination fits its criteria of freedom.  The Lesser General
+Public License permits more lax criteria for linking other code with
+the library.
+
+  We call this license the "Lesser" General Public License because it
+does Less to protect the user's freedom than the ordinary General
+Public License.  It also provides other free software developers Less
+of an advantage over competing non-free programs.  These disadvantages
+are the reason we use the ordinary General Public License for many
+libraries.  However, the Lesser license provides advantages in certain
+special circumstances.
+
+  For example, on rare occasions, there may be a special need to
+encourage the widest possible use of a certain library, so that it becomes
+a de-facto standard.  To achieve this, non-free programs must be
+allowed to use the library.  A more frequent case is that a free
+library does the same job as widely used non-free libraries.  In this
+case, there is little to gain by limiting the free library to free
+software only, so we use the Lesser General Public License.
+
+  In other cases, permission to use a particular library in non-free
+programs enables a greater number of people to use a large body of
+free software.  For example, permission to use the GNU C Library in
+non-free programs enables many more people to use the whole GNU
+operating system, as well as its variant, the GNU/Linux operating
+system.
+
+  Although the Lesser General Public License is Less protective of the
+users' freedom, it does ensure that the user of a program that is
+linked with the Library has the freedom and the wherewithal to run
+that program using a modified version of the Library.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.  Pay close attention to the difference between a
+"work based on the library" and a "work that uses the library".  The
+former contains code derived from the library, whereas the latter must
+be combined with the library in order to run.
+
+                  GNU LESSER GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License Agreement applies to any software library or other
+program which contains a notice placed by the copyright holder or
+other authorized party saying it may be distributed under the terms of
+this Lesser General Public License (also called "this License").
+Each licensee is addressed as "you".
+
+  A "library" means a collection of software functions and/or data
+prepared so as to be conveniently linked with application programs
+(which use some of those functions and data) to form executables.
+
+  The "Library", below, refers to any such software library or work
+which has been distributed under these terms.  A "work based on the
+Library" means either the Library or any derivative work under
+copyright law: that is to say, a work containing the Library or a
+portion of it, either verbatim or with modifications and/or translated
+straightforwardly into another language.  (Hereinafter, translation is
+included without limitation in the term "modification".)
+
+  "Source code" for a work means the preferred form of the work for
+making modifications to it.  For a library, complete source code means
+all the source code for all modules it contains, plus any associated
+interface definition files, plus the scripts used to control compilation
+and installation of the library.
+
+  Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running a program using the Library is not restricted, and output from
+such a program is covered only if its contents constitute a work based
+on the Library (independent of the use of the Library in a tool for
+writing it).  Whether that is true depends on what the Library does
+and what the program that uses the Library does.
+
+  1. You may copy and distribute verbatim copies of the Library's
+complete source code as you receive it, in any medium, provided that
+you conspicuously and appropriately publish on each copy an
+appropriate copyright notice and disclaimer of warranty; keep intact
+all the notices that refer to this License and to the absence of any
+warranty; and distribute a copy of this License along with the
+Library.
+
+  You may charge a fee for the physical act of transferring a copy,
+and you may at your option offer warranty protection in exchange for a
+fee.
+
+  2. You may modify your copy or copies of the Library or any portion
+of it, thus forming a work based on the Library, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) The modified work must itself be a software library.
+
+    b) You must cause the files modified to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    c) You must cause the whole of the work to be licensed at no
+    charge to all third parties under the terms of this License.
+
+    d) If a facility in the modified Library refers to a function or a
+    table of data to be supplied by an application program that uses
+    the facility, other than as an argument passed when the facility
+    is invoked, then you must make a good faith effort to ensure that,
+    in the event an application does not supply such function or
+    table, the facility still operates, and performs whatever part of
+    its purpose remains meaningful.
+
+    (For example, a function in a library to compute square roots has
+    a purpose that is entirely well-defined independent of the
+    application.  Therefore, Subsection 2d requires that any
+    application-supplied function or table used by this function must
+    be optional: if the application does not supply it, the square
+    root function must still compute square roots.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Library,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Library, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote
+it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Library.
+
+In addition, mere aggregation of another work not based on the Library
+with the Library (or with a work based on the Library) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may opt to apply the terms of the ordinary GNU General Public
+License instead of this License to a given copy of the Library.  To do
+this, you must alter all the notices that refer to this License, so
+that they refer to the ordinary GNU General Public License, version 2,
+instead of to this License.  (If a newer version than version 2 of the
+ordinary GNU General Public License has appeared, then you can specify
+that version instead if you wish.)  Do not make any other change in
+these notices.
+
+  Once this change is made in a given copy, it is irreversible for
+that copy, so the ordinary GNU General Public License applies to all
+subsequent copies and derivative works made from that copy.
+
+  This option is useful when you wish to copy part of the code of
+the Library into a program that is not a library.
+
+  4. You may copy and distribute the Library (or a portion or
+derivative of it, under Section 2) in object code or executable form
+under the terms of Sections 1 and 2 above provided that you accompany
+it with the complete corresponding machine-readable source code, which
+must be distributed under the terms of Sections 1 and 2 above on a
+medium customarily used for software interchange.
+
+  If distribution of object code is made by offering access to copy
+from a designated place, then offering equivalent access to copy the
+source code from the same place satisfies the requirement to
+distribute the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  5. A program that contains no derivative of any portion of the
+Library, but is designed to work with the Library by being compiled or
+linked with it, is called a "work that uses the Library".  Such a
+work, in isolation, is not a derivative work of the Library, and
+therefore falls outside the scope of this License.
+
+  However, linking a "work that uses the Library" with the Library
+creates an executable that is a derivative of the Library (because it
+contains portions of the Library), rather than a "work that uses the
+library".  The executable is therefore covered by this License.
+Section 6 states terms for distribution of such executables.
+
+  When a "work that uses the Library" uses material from a header file
+that is part of the Library, the object code for the work may be a
+derivative work of the Library even though the source code is not.
+Whether this is true is especially significant if the work can be
+linked without the Library, or if the work is itself a library.  The
+threshold for this to be true is not precisely defined by law.
+
+  If such an object file uses only numerical parameters, data
+structure layouts and accessors, and small macros and small inline
+functions (ten lines or less in length), then the use of the object
+file is unrestricted, regardless of whether it is legally a derivative
+work.  (Executables containing this object code plus portions of the
+Library will still fall under Section 6.)
+
+  Otherwise, if the work is a derivative of the Library, you may
+distribute the object code for the work under the terms of Section 6.
+Any executables containing that work also fall under Section 6,
+whether or not they are linked directly with the Library itself.
+
+  6. As an exception to the Sections above, you may also combine or
+link a "work that uses the Library" with the Library to produce a
+work containing portions of the Library, and distribute that work
+under terms of your choice, provided that the terms permit
+modification of the work for the customer's own use and reverse
+engineering for debugging such modifications.
+
+  You must give prominent notice with each copy of the work that the
+Library is used in it and that the Library and its use are covered by
+this License.  You must supply a copy of this License.  If the work
+during execution displays copyright notices, you must include the
+copyright notice for the Library among them, as well as a reference
+directing the user to the copy of this License.  Also, you must do one
+of these things:
+
+    a) Accompany the work with the complete corresponding
+    machine-readable source code for the Library including whatever
+    changes were used in the work (which must be distributed under
+    Sections 1 and 2 above); and, if the work is an executable linked
+    with the Library, with the complete machine-readable "work that
+    uses the Library", as object code and/or source code, so that the
+    user can modify the Library and then relink to produce a modified
+    executable containing the modified Library.  (It is understood
+    that the user who changes the contents of definitions files in the
+    Library will not necessarily be able to recompile the application
+    to use the modified definitions.)
+
+    b) Use a suitable shared library mechanism for linking with the
+    Library.  A suitable mechanism is one that (1) uses at run time a
+    copy of the library already present on the user's computer system,
+    rather than copying library functions into the executable, and (2)
+    will operate properly with a modified version of the library, if
+    the user installs one, as long as the modified version is
+    interface-compatible with the version that the work was made with.
+
+    c) Accompany the work with a written offer, valid for at
+    least three years, to give the same user the materials
+    specified in Subsection 6a, above, for a charge no more
+    than the cost of performing this distribution.
+
+    d) If distribution of the work is made by offering access to copy
+    from a designated place, offer equivalent access to copy the above
+    specified materials from the same place.
+
+    e) Verify that the user has already received a copy of these
+    materials or that you have already sent this user a copy.
+
+  For an executable, the required form of the "work that uses the
+Library" must include any data and utility programs needed for
+reproducing the executable from it.  However, as a special exception,
+the materials to be distributed need not include anything that is
+normally distributed (in either source or binary form) with the major
+components (compiler, kernel, and so on) of the operating system on
+which the executable runs, unless that component itself accompanies
+the executable.
+
+  It may happen that this requirement contradicts the license
+restrictions of other proprietary libraries that do not normally
+accompany the operating system.  Such a contradiction means you cannot
+use both them and the Library together in an executable that you
+distribute.
+
+  7. You may place library facilities that are a work based on the
+Library side-by-side in a single library together with other library
+facilities not covered by this License, and distribute such a combined
+library, provided that the separate distribution of the work based on
+the Library and of the other library facilities is otherwise
+permitted, and provided that you do these two things:
+
+    a) Accompany the combined library with a copy of the same work
+    based on the Library, uncombined with any other library
+    facilities.  This must be distributed under the terms of the
+    Sections above.
+
+    b) Give prominent notice with the combined library of the fact
+    that part of it is a work based on the Library, and explaining
+    where to find the accompanying uncombined form of the same work.
+
+  8. You may not copy, modify, sublicense, link with, or distribute
+the Library except as expressly provided under this License.  Any
+attempt otherwise to copy, modify, sublicense, link with, or
+distribute the Library is void, and will automatically terminate your
+rights under this License.  However, parties who have received copies,
+or rights, from you under this License will not have their licenses
+terminated so long as such parties remain in full compliance.
+
+  9. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Library or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Library (or any work based on the
+Library), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Library or works based on it.
+
+  10. Each time you redistribute the Library (or any work based on the
+Library), the recipient automatically receives a license from the
+original licensor to copy, distribute, link with or modify the Library
+subject to these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties with
+this License.
+
+  11. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Library at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Library by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Library.
+
+If any portion of this section is held invalid or unenforceable under any
+particular circumstance, the balance of the section is intended to apply,
+and the section as a whole is intended to apply in other circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  12. If the distribution and/or use of the Library is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Library under this License may add
+an explicit geographical distribution limitation excluding those countries,
+so that distribution is permitted only in or among countries not thus
+excluded.  In such case, this License incorporates the limitation as if
+written in the body of this License.
+
+  13. The Free Software Foundation may publish revised and/or new
+versions of the Lesser General Public License from time to time.
+Such new versions will be similar in spirit to the present version,
+but may differ in detail to address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Library
+specifies a version number of this License which applies to it and
+"any later version", you have the option of following the terms and
+conditions either of that version or of any later version published by
+the Free Software Foundation.  If the Library does not specify a
+license version number, you may choose any version ever published by
+the Free Software Foundation.
+
+  14. If you wish to incorporate parts of the Library into other free
+programs whose distribution conditions are incompatible with these,
+write to the author to ask for permission.  For software which is
+copyrighted by the Free Software Foundation, write to the Free
+Software Foundation; we sometimes make exceptions for this.  Our
+decision will be guided by the two goals of preserving the free status
+of all derivatives of our free software and of promoting the sharing
+and reuse of software generally.
+
+                            NO WARRANTY
+
+  15. BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO
+WARRANTY FOR THE LIBRARY, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
+EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
+OTHER PARTIES PROVIDE THE LIBRARY "AS IS" WITHOUT WARRANTY OF ANY
+KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
+LIBRARY IS WITH YOU.  SHOULD THE LIBRARY PROVE DEFECTIVE, YOU ASSUME
+THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
+WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY
+AND/OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE LIABLE TO YOU
+FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
+CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
+LIBRARY (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
+RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
+FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
+SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+           How to Apply These Terms to Your New Libraries
+
+  If you develop a new library, and you want it to be of the greatest
+possible use to the public, we recommend making it free software that
+everyone can redistribute and change.  You can do so by permitting
+redistribution under these terms (or, alternatively, under the terms of the
+ordinary General Public License).
+
+  To apply these terms, attach the following notices to the library.  It is
+safest to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least the
+"copyright" line and a pointer to where the full notice is found.
+
+    {description}
+    Copyright (C) {year} {fullname}
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+Also add information on how to contact you by electronic and paper mail.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the library, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the
+  library `Frob' (a library for tweaking knobs) written by James Random Hacker.
+
+  {signature of Ty Coon}, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!
diff --git a/src/fec/README.md b/src/fec/README.md
new file mode 100644
index 0000000..a44d28d
--- /dev/null
+++ b/src/fec/README.md
@@ -0,0 +1,12 @@
+FEC routines from KA9Q's libfec
+===============================
+
+This folder contains part of the libfec library by KA9Q. Only the
+char-sized Reed-Solomon encoder and decoder is here.
+
+The files have been copied from the libfec fork at
+https://github.com/Opendigitalradio/ka9q-fec
+
+Original code is at http://www.ka9q.net/code/fec/
+
+All files in this folder are licenced under the LGPL v2.1, please see LICENCE
diff --git a/src/fec/char.h b/src/fec/char.h
new file mode 100644
index 0000000..25efd65
--- /dev/null
+++ b/src/fec/char.h
@@ -0,0 +1,24 @@
+/* Stuff specific to the 8-bit symbol version of the general purpose RS codecs
+ *
+ * Copyright 2003, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+typedef unsigned char data_t;
+
+#define MODNN(x) modnn(rs,x)
+
+#define MM (rs->mm)
+#define NN (rs->nn)
+#define ALPHA_TO (rs->alpha_to) 
+#define INDEX_OF (rs->index_of)
+#define GENPOLY (rs->genpoly)
+#define NROOTS (rs->nroots)
+#define FCR (rs->fcr)
+#define PRIM (rs->prim)
+#define IPRIM (rs->iprim)
+#define PAD (rs->pad)
+#define A0 (NN)
+
+
+
+
diff --git a/src/fec/decode_rs.h b/src/fec/decode_rs.h
new file mode 100644
index 0000000..c165cf3
--- /dev/null
+++ b/src/fec/decode_rs.h
@@ -0,0 +1,298 @@
+/* The guts of the Reed-Solomon decoder, meant to be #included
+ * into a function body with the following typedefs, macros and variables supplied
+ * according to the code parameters:
+
+ * data_t - a typedef for the data symbol
+ * data_t data[] - array of NN data and parity symbols to be corrected in place
+ * retval - an integer lvalue into which the decoder's return code is written
+ * NROOTS - the number of roots in the RS code generator polynomial,
+ *          which is the same as the number of parity symbols in a block.
+            Integer variable or literal.
+ * NN - the total number of symbols in a RS block. Integer variable or literal.
+ * PAD - the number of pad symbols in a block. Integer variable or literal.
+ * ALPHA_TO - The address of an array of NN elements to convert Galois field
+ *            elements in index (log) form to polynomial form. Read only.
+ * INDEX_OF - The address of an array of NN elements to convert Galois field
+ *            elements in polynomial form to index (log) form. Read only.
+ * MODNN - a function to reduce its argument modulo NN. May be inline or a macro.
+ * FCR - An integer literal or variable specifying the first consecutive root of the
+ *       Reed-Solomon generator polynomial. Integer variable or literal.
+ * PRIM - The primitive root of the generator poly. Integer variable or literal.
+ * DEBUG - If set to 1 or more, do various internal consistency checking. Leave this
+ *         undefined for production code
+
+ * The memset(), memmove(), and memcpy() functions are used. The appropriate header
+ * file declaring these functions (usually <string.h>) must be included by the calling
+ * program.
+ */
+
+
+#if !defined(NROOTS)
+#error "NROOTS not defined"
+#endif
+
+#if !defined(NN)
+#error "NN not defined"
+#endif
+
+#if !defined(PAD)
+#error "PAD not defined"
+#endif
+
+#if !defined(ALPHA_TO)
+#error "ALPHA_TO not defined"
+#endif
+
+#if !defined(INDEX_OF)
+#error "INDEX_OF not defined"
+#endif
+
+#if !defined(MODNN)
+#error "MODNN not defined"
+#endif
+
+#if !defined(FCR)
+#error "FCR not defined"
+#endif
+
+#if !defined(PRIM)
+#error "PRIM not defined"
+#endif
+
+#if !defined(NULL)
+#define NULL ((void *)0)
+#endif
+
+#undef MIN
+#define	MIN(a,b)	((a) < (b) ? (a) : (b))
+#undef A0
+#define A0 (NN)
+
+{
+  int deg_lambda, el, deg_omega;
+  int i, j, r,k;
+  data_t u,q,tmp,num1,num2,den,discr_r;
+  data_t lambda[NROOTS+1], s[NROOTS];	/* Err+Eras Locator poly
+					 * and syndrome poly */
+  data_t b[NROOTS+1], t[NROOTS+1], omega[NROOTS+1];
+  data_t root[NROOTS], reg[NROOTS+1], loc[NROOTS];
+  int syn_error, count;
+
+  /* form the syndromes; i.e., evaluate data(x) at roots of g(x) */
+  for(i=0;i<NROOTS;i++)
+    s[i] = data[0];
+
+  for(j=1;j<NN-PAD;j++){
+    for(i=0;i<NROOTS;i++){
+      if(s[i] == 0){
+	s[i] = data[j];
+      } else {
+	s[i] = data[j] ^ ALPHA_TO[MODNN(INDEX_OF[s[i]] + (FCR+i)*PRIM)];
+      }
+    }
+  }
+
+  /* Convert syndromes to index form, checking for nonzero condition */
+  syn_error = 0;
+  for(i=0;i<NROOTS;i++){
+    syn_error |= s[i];
+    s[i] = INDEX_OF[s[i]];
+  }
+
+  if (!syn_error) {
+    /* if syndrome is zero, data[] is a codeword and there are no
+     * errors to correct. So return data[] unmodified
+     */
+    count = 0;
+    goto finish;
+  }
+  memset(&lambda[1],0,NROOTS*sizeof(lambda[0]));
+  lambda[0] = 1;
+
+  if (no_eras > 0) {
+    /* Init lambda to be the erasure locator polynomial */
+    lambda[1] = ALPHA_TO[MODNN(PRIM*(NN-1-eras_pos[0]))];
+    for (i = 1; i < no_eras; i++) {
+      u = MODNN(PRIM*(NN-1-eras_pos[i]));
+      for (j = i+1; j > 0; j--) {
+	tmp = INDEX_OF[lambda[j - 1]];
+	if(tmp != A0)
+	  lambda[j] ^= ALPHA_TO[MODNN(u + tmp)];
+      }
+    }
+
+#if DEBUG >= 1
+    /* Test code that verifies the erasure locator polynomial just constructed
+       Needed only for decoder debugging. */
+    
+    /* find roots of the erasure location polynomial */
+    for(i=1;i<=no_eras;i++)
+      reg[i] = INDEX_OF[lambda[i]];
+
+    count = 0;
+    for (i = 1,k=IPRIM-1; i <= NN; i++,k = MODNN(k+IPRIM)) {
+      q = 1;
+      for (j = 1; j <= no_eras; j++)
+	if (reg[j] != A0) {
+	  reg[j] = MODNN(reg[j] + j);
+	  q ^= ALPHA_TO[reg[j]];
+	}
+      if (q != 0)
+	continue;
+      /* store root and error location number indices */
+      root[count] = i;
+      loc[count] = k;
+      count++;
+    }
+    if (count != no_eras) {
+      printf("count = %d no_eras = %d\n lambda(x) is WRONG\n",count,no_eras);
+      count = -1;
+      goto finish;
+    }
+#if DEBUG >= 2
+    printf("\n Erasure positions as determined by roots of Eras Loc Poly:\n");
+    for (i = 0; i < count; i++)
+      printf("%d ", loc[i]);
+    printf("\n");
+#endif
+#endif
+  }
+  for(i=0;i<NROOTS+1;i++)
+    b[i] = INDEX_OF[lambda[i]];
+  
+  /*
+   * Begin Berlekamp-Massey algorithm to determine error+erasure
+   * locator polynomial
+   */
+  r = no_eras;
+  el = no_eras;
+  while (++r <= NROOTS) {	/* r is the step number */
+    /* Compute discrepancy at the r-th step in poly-form */
+    discr_r = 0;
+    for (i = 0; i < r; i++){
+      if ((lambda[i] != 0) && (s[r-i-1] != A0)) {
+	discr_r ^= ALPHA_TO[MODNN(INDEX_OF[lambda[i]] + s[r-i-1])];
+      }
+    }
+    discr_r = INDEX_OF[discr_r];	/* Index form */
+    if (discr_r == A0) {
+      /* 2 lines below: B(x) <-- x*B(x) */
+      memmove(&b[1],b,NROOTS*sizeof(b[0]));
+      b[0] = A0;
+    } else {
+      /* 7 lines below: T(x) <-- lambda(x) - discr_r*x*b(x) */
+      t[0] = lambda[0];
+      for (i = 0 ; i < NROOTS; i++) {
+	if(b[i] != A0)
+	  t[i+1] = lambda[i+1] ^ ALPHA_TO[MODNN(discr_r + b[i])];
+	else
+	  t[i+1] = lambda[i+1];
+      }
+      if (2 * el <= r + no_eras - 1) {
+	el = r + no_eras - el;
+	/*
+	 * 2 lines below: B(x) <-- inv(discr_r) *
+	 * lambda(x)
+	 */
+	for (i = 0; i <= NROOTS; i++)
+	  b[i] = (lambda[i] == 0) ? A0 : MODNN(INDEX_OF[lambda[i]] - discr_r + NN);
+      } else {
+	/* 2 lines below: B(x) <-- x*B(x) */
+	memmove(&b[1],b,NROOTS*sizeof(b[0]));
+	b[0] = A0;
+      }
+      memcpy(lambda,t,(NROOTS+1)*sizeof(t[0]));
+    }
+  }
+
+  /* Convert lambda to index form and compute deg(lambda(x)) */
+  deg_lambda = 0;
+  for(i=0;i<NROOTS+1;i++){
+    lambda[i] = INDEX_OF[lambda[i]];
+    if(lambda[i] != A0)
+      deg_lambda = i;
+  }
+  /* Find roots of the error+erasure locator polynomial by Chien search */
+  memcpy(&reg[1],&lambda[1],NROOTS*sizeof(reg[0]));
+  count = 0;		/* Number of roots of lambda(x) */
+  for (i = 1,k=IPRIM-1; i <= NN; i++,k = MODNN(k+IPRIM)) {
+    q = 1; /* lambda[0] is always 0 */
+    for (j = deg_lambda; j > 0; j--){
+      if (reg[j] != A0) {
+	reg[j] = MODNN(reg[j] + j);
+	q ^= ALPHA_TO[reg[j]];
+      }
+    }
+    if (q != 0)
+      continue; /* Not a root */
+    /* store root (index-form) and error location number */
+#if DEBUG>=2
+    printf("count %d root %d loc %d\n",count,i,k);
+#endif
+    root[count] = i;
+    loc[count] = k;
+    /* If we've already found max possible roots,
+     * abort the search to save time
+     */
+    if(++count == deg_lambda)
+      break;
+  }
+  if (deg_lambda != count) {
+    /*
+     * deg(lambda) unequal to number of roots => uncorrectable
+     * error detected
+     */
+    count = -1;
+    goto finish;
+  }
+  /*
+   * Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo
+   * x**NROOTS). in index form. Also find deg(omega).
+   */
+  deg_omega = deg_lambda-1;
+  for (i = 0; i <= deg_omega;i++){
+    tmp = 0;
+    for(j=i;j >= 0; j--){
+      if ((s[i - j] != A0) && (lambda[j] != A0))
+	tmp ^= ALPHA_TO[MODNN(s[i - j] + lambda[j])];
+    }
+    omega[i] = INDEX_OF[tmp];
+  }
+
+  /*
+   * Compute error values in poly-form. num1 = omega(inv(X(l))), num2 =
+   * inv(X(l))**(FCR-1) and den = lambda_pr(inv(X(l))) all in poly-form
+   */
+  for (j = count-1; j >=0; j--) {
+    num1 = 0;
+    for (i = deg_omega; i >= 0; i--) {
+      if (omega[i] != A0)
+	num1  ^= ALPHA_TO[MODNN(omega[i] + i * root[j])];
+    }
+    num2 = ALPHA_TO[MODNN(root[j] * (FCR - 1) + NN)];
+    den = 0;
+    
+    /* lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i] */
+    for (i = MIN(deg_lambda,NROOTS-1) & ~1; i >= 0; i -=2) {
+      if(lambda[i+1] != A0)
+	den ^= ALPHA_TO[MODNN(lambda[i+1] + i * root[j])];
+    }
+#if DEBUG >= 1
+    if (den == 0) {
+      printf("\n ERROR: denominator = 0\n");
+      count = -1;
+      goto finish;
+    }
+#endif
+    /* Apply error to data */
+    if (num1 != 0 && loc[j] >= PAD) {
+      data[loc[j]-PAD] ^= ALPHA_TO[MODNN(INDEX_OF[num1] + INDEX_OF[num2] + NN - INDEX_OF[den])];
+    }
+  }
+ finish:
+  if(eras_pos != NULL){
+    for(i=0;i<count;i++)
+      eras_pos[i] = loc[i];
+  }
+  retval = count;
+}
diff --git a/src/fec/decode_rs_char.c b/src/fec/decode_rs_char.c
new file mode 100644
index 0000000..7105233
--- /dev/null
+++ b/src/fec/decode_rs_char.c
@@ -0,0 +1,22 @@
+/* General purpose Reed-Solomon decoder for 8-bit symbols or less
+ * Copyright 2003 Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+#include <string.h>
+
+#include "char.h"
+#include "rs-common.h"
+
+int decode_rs_char(void *p, data_t *data, int *eras_pos, int no_eras){
+  int retval;
+  struct rs *rs = (struct rs *)p;
+ 
+#include "decode_rs.h"
+  
+  return retval;
+}
diff --git a/src/fec/encode_rs.h b/src/fec/encode_rs.h
new file mode 100644
index 0000000..2c157f9
--- /dev/null
+++ b/src/fec/encode_rs.h
@@ -0,0 +1,58 @@
+/* The guts of the Reed-Solomon encoder, meant to be #included
+ * into a function body with the following typedefs, macros and variables supplied
+ * according to the code parameters:
+
+ * data_t - a typedef for the data symbol
+ * data_t data[] - array of NN-NROOTS-PAD and type data_t to be encoded
+ * data_t parity[] - an array of NROOTS and type data_t to be written with parity symbols
+ * NROOTS - the number of roots in the RS code generator polynomial,
+ *          which is the same as the number of parity symbols in a block.
+            Integer variable or literal.
+	    * 
+ * NN - the total number of symbols in a RS block. Integer variable or literal.
+ * PAD - the number of pad symbols in a block. Integer variable or literal.
+ * ALPHA_TO - The address of an array of NN elements to convert Galois field
+ *            elements in index (log) form to polynomial form. Read only.
+ * INDEX_OF - The address of an array of NN elements to convert Galois field
+ *            elements in polynomial form to index (log) form. Read only.
+ * MODNN - a function to reduce its argument modulo NN. May be inline or a macro.
+ * GENPOLY - an array of NROOTS+1 elements containing the generator polynomial in index form
+
+ * The memset() and memmove() functions are used. The appropriate header
+ * file declaring these functions (usually <string.h>) must be included by the calling
+ * program.
+
+ * Copyright 2004, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+
+
+#undef A0
+#define A0 (NN) /* Special reserved value encoding zero in index form */
+
+{
+  int i, j;
+  data_t feedback;
+
+  memset(parity,0,NROOTS*sizeof(data_t));
+
+  for(i=0;i<NN-NROOTS-PAD;i++){
+    feedback = INDEX_OF[data[i] ^ parity[0]];
+    if(feedback != A0){      /* feedback term is non-zero */
+#ifdef UNNORMALIZED
+      /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must
+       * always be for the polynomials constructed by init_rs()
+       */
+      feedback = MODNN(NN - GENPOLY[NROOTS] + feedback);
+#endif
+      for(j=1;j<NROOTS;j++)
+	parity[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])];
+    }
+    /* Shift */
+    memmove(&parity[0],&parity[1],sizeof(data_t)*(NROOTS-1));
+    if(feedback != A0)
+      parity[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];
+    else
+      parity[NROOTS-1] = 0;
+  }
+}
diff --git a/src/fec/encode_rs_char.c b/src/fec/encode_rs_char.c
new file mode 100644
index 0000000..a9bf2b8
--- /dev/null
+++ b/src/fec/encode_rs_char.c
@@ -0,0 +1,15 @@
+/* Reed-Solomon encoder
+ * Copyright 2002, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#include <string.h>
+
+#include "char.h"
+#include "rs-common.h"
+
+void encode_rs_char(void *p,data_t *data, data_t *parity){
+  struct rs *rs = (struct rs *)p;
+
+#include "encode_rs.h"
+
+}
diff --git a/src/fec/fec.h b/src/fec/fec.h
new file mode 100644
index 0000000..0d1bae1
--- /dev/null
+++ b/src/fec/fec.h
@@ -0,0 +1,30 @@
+/* Main header for reduced libfec.
+ *
+ * The FEC code in this folder is
+ * Copyright 2003 Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+
+#pragma once
+
+#include <stdlib.h>
+
+#include "char.h"
+#include "rs-common.h"
+
+/* Initialize a Reed-Solomon codec
+ * symsize = symbol size, bits
+ * gfpoly = Field generator polynomial coefficients
+ * fcr = first root of RS code generator polynomial, index form
+ * prim = primitive element to generate polynomial roots
+ * nroots = RS code generator polynomial degree (number of roots)
+ * pad = padding bytes at front of shortened block
+ */
+void *init_rs_char(int symsize,int gfpoly,int fcr,int prim,int nroots,int pad);
+
+int decode_rs_char(void *p, data_t *data, int *eras_pos, int no_eras);
+
+void encode_rs_char(void *p,data_t *data, data_t *parity);
+
+void free_rs_char(void *p);
+
diff --git a/src/fec/init_rs.h b/src/fec/init_rs.h
new file mode 100644
index 0000000..2b2ae98
--- /dev/null
+++ b/src/fec/init_rs.h
@@ -0,0 +1,106 @@
+/* Common code for intializing a Reed-Solomon control block (char or int symbols)
+ * Copyright 2004 Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#undef NULL
+#define NULL ((void *)0)
+
+{
+  int i, j, sr,root,iprim;
+
+  rs = NULL;
+  /* Check parameter ranges */
+  if(symsize < 0 || symsize > 8*sizeof(data_t)){
+    goto done;
+  }
+
+  if(fcr < 0 || fcr >= (1<<symsize))
+    goto done;
+  if(prim <= 0 || prim >= (1<<symsize))
+    goto done;
+  if(nroots < 0 || nroots >= (1<<symsize))
+    goto done; /* Can't have more roots than symbol values! */
+  if(pad < 0 || pad >= ((1<<symsize) -1 - nroots))
+    goto done; /* Too much padding */
+
+  rs = (struct rs *)calloc(1,sizeof(struct rs));
+  if(rs == NULL)
+    goto done;
+
+  rs->mm = symsize;
+  rs->nn = (1<<symsize)-1;
+  rs->pad = pad;
+
+  rs->alpha_to = (data_t *)malloc(sizeof(data_t)*(rs->nn+1));
+  if(rs->alpha_to == NULL){
+    free(rs);
+    rs = NULL;
+    goto done;
+  }
+  rs->index_of = (data_t *)malloc(sizeof(data_t)*(rs->nn+1));
+  if(rs->index_of == NULL){
+    free(rs->alpha_to);
+    free(rs);
+    rs = NULL;
+    goto done;
+  }
+
+  /* Generate Galois field lookup tables */
+  rs->index_of[0] = A0; /* log(zero) = -inf */
+  rs->alpha_to[A0] = 0; /* alpha**-inf = 0 */
+  sr = 1;
+  for(i=0;i<rs->nn;i++){
+    rs->index_of[sr] = i;
+    rs->alpha_to[i] = sr;
+    sr <<= 1;
+    if(sr & (1<<symsize))
+      sr ^= gfpoly;
+    sr &= rs->nn;
+  }
+  if(sr != 1){
+    /* field generator polynomial is not primitive! */
+    free(rs->alpha_to);
+    free(rs->index_of);
+    free(rs);
+    rs = NULL;
+    goto done;
+  }
+
+  /* Form RS code generator polynomial from its roots */
+  rs->genpoly = (data_t *)malloc(sizeof(data_t)*(nroots+1));
+  if(rs->genpoly == NULL){
+    free(rs->alpha_to);
+    free(rs->index_of);
+    free(rs);
+    rs = NULL;
+    goto done;
+  }
+  rs->fcr = fcr;
+  rs->prim = prim;
+  rs->nroots = nroots;
+
+  /* Find prim-th root of 1, used in decoding */
+  for(iprim=1;(iprim % prim) != 0;iprim += rs->nn)
+    ;
+  rs->iprim = iprim / prim;
+
+  rs->genpoly[0] = 1;
+  for (i = 0,root=fcr*prim; i < nroots; i++,root += prim) {
+    rs->genpoly[i+1] = 1;
+
+    /* Multiply rs->genpoly[] by  @**(root + x) */
+    for (j = i; j > 0; j--){
+      if (rs->genpoly[j] != 0)
+	rs->genpoly[j] = rs->genpoly[j-1] ^ rs->alpha_to[modnn(rs,rs->index_of[rs->genpoly[j]] + root)];
+      else
+	rs->genpoly[j] = rs->genpoly[j-1];
+    }
+    /* rs->genpoly[0] can never be zero */
+    rs->genpoly[0] = rs->alpha_to[modnn(rs,rs->index_of[rs->genpoly[0]] + root)];
+  }
+  /* convert rs->genpoly[] to index form for quicker encoding */
+  for (i = 0; i <= nroots; i++)
+    rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
+ done:;
+
+}
diff --git a/src/fec/init_rs_char.c b/src/fec/init_rs_char.c
new file mode 100644
index 0000000..a51099a
--- /dev/null
+++ b/src/fec/init_rs_char.c
@@ -0,0 +1,35 @@
+/* Initialize a RS codec
+ *
+ * Copyright 2002 Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#include <stdlib.h>
+
+#include "char.h"
+#include "rs-common.h"
+
+void free_rs_char(void *p){
+  struct rs *rs = (struct rs *)p;
+
+  free(rs->alpha_to);
+  free(rs->index_of);
+  free(rs->genpoly);
+  free(rs);
+}
+
+/* Initialize a Reed-Solomon codec
+ * symsize = symbol size, bits
+ * gfpoly = Field generator polynomial coefficients
+ * fcr = first root of RS code generator polynomial, index form
+ * prim = primitive element to generate polynomial roots
+ * nroots = RS code generator polynomial degree (number of roots)
+ * pad = padding bytes at front of shortened block
+ */
+void *init_rs_char(int symsize,int gfpoly,int fcr,int prim,
+	int nroots,int pad){
+  struct rs *rs;
+
+#include "init_rs.h"
+
+  return rs;
+}
diff --git a/src/fec/rs-common.h b/src/fec/rs-common.h
new file mode 100644
index 0000000..e64eb39
--- /dev/null
+++ b/src/fec/rs-common.h
@@ -0,0 +1,26 @@
+/* Stuff common to all the general-purpose Reed-Solomon codecs
+ * Copyright 2004 Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+
+/* Reed-Solomon codec control block */
+struct rs {
+  int mm;              /* Bits per symbol */
+  int nn;              /* Symbols per block (= (1<<mm)-1) */
+  data_t *alpha_to;     /* log lookup table */
+  data_t *index_of;     /* Antilog lookup table */
+  data_t *genpoly;      /* Generator polynomial */
+  int nroots;     /* Number of generator roots = number of parity symbols */
+  int fcr;        /* First consecutive root, index form */
+  int prim;       /* Primitive element, index form */
+  int iprim;      /* prim-th root of 1, index form */
+  int pad;        /* Padding bytes in shortened block */
+};
+
+static inline int modnn(struct rs *rs,int x){
+  while (x >= rs->nn) {
+    x -= rs->nn;
+    x = (x >> rs->mm) + (x & rs->nn);
+  }
+  return x;
+}