% -*- texinfo -*- % @deftypefn {Function File} {@var{code} =} encode (@var{msg},@var{n},@var{k}) % @deftypefnx {Function File} {@var{code} =} encode (@var{msg},@var{n},@var{k},@var{typ}) % @deftypefnx {Function File} {@var{code} =} encode (@var{msg},@var{n},@var{k},@var{typ},@var{opt}) % @deftypefnx {Function File} {[@var{code}, @var{added}] =} encode (@var{...}) % % Top level block encoder. This function makes use of the lower level % functions such as @dfn{cyclpoly}, @dfn{cyclgen}, @dfn{hammgen}, and % @dfn{bchenco}. The message to code is pass in @var{msg}, the % codeword length is @var{n} and the message length is @var{k}. This % function is used to encode messages using either: % % @table @asis % @item A [n,k] linear block code defined by a generator matrix % @item A [n,k] cyclic code defined by a generator polynomial % @item A [n,k] Hamming code defined by a primitive polynomial % @item A [n,k] BCH code code defined by a generator polynomial % @end table % % The type of coding to use is defined by the variable @var{typ}. This % variable is a string taking one of the values % % @table @code % @item 'linear' or 'linear/binary' % A linear block code is assumed with the coded message @var{code} being in % a binary format. In this case the argument @var{opt} is the generator % matrix, and is required. % @item 'cyclic' or 'cyclic/binary' % A cyclic code is assumed with the coded message @var{code} being in a % binary format. The generator polynomial to use can be defined in @var{opt}. % The default generator polynomial to use will be % @dfn{cyclpoly(@var{n},@var{k})} % @item 'hamming' or 'hamming/binary' % A Hamming code is assumed with the coded message @var{code} being in a % binary format. In this case @var{n} must be of an integer of the form % @code{2^@var{m}-1}, where @var{m} is an integer. In addition @var{k} % must be @code{@var{n}-@var{m}}. The primitive polynomial to use can % be defined in @var{opt}. The default primitive polynomial to use is % the same as defined by @dfn{hammgen}. % @item 'bch' or 'bch/binary' % A BCH code is assumed with the coded message @var{code} being in a binary % format. The generator polynomial to use can be defined in @var{opt}. % The default generator polynomial to use will be % @dfn{bchpoly(@var{n},@var{k})} % @end table % % In addition the argument 'binary' above can be replaced with 'decimal', % in which case the message is assumed to be a decimal vector, with each % value representing a symbol to be coded. The binary format can be in two % forms % % @table @code % @item An @var{x}-by-@var{k} matrix % Each row of this matrix represents a symbol to be coded % @item A vector % The symbols are created from groups of @var{k} elements of this vector. % If the vector length is not divisble by @var{k}, then zeros are added % and the number of zeros added is returned in @var{added}. % @end table % % It should be noted that all internal calculations are performed in the % binary format. Therefore for large values of @var{n}, it is preferable % to use the binary format to pass the messages to avoid possible rounding % errors. Additionally, if repeated calls to @dfn{encode} will be performed, % it is often faster to create a generator matrix externally with the % functions @dfn{hammgen} or @dfn{cyclgen}, rather than let @dfn{encode} % recalculate this matrix at each iteration. In this case @var{typ} should % be 'linear'. The exception to this case is BCH codes, whose encoder % is implemented directly from the polynomial and is significantly faster. % % @end deftypefn % @seealso{decode,cyclgen,cyclpoly,hammgen,bchenco,bchpoly}

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