/*
 *  hbytes raw2h BINARY                          => hex
 *  hbytes h2raw HEX                             => binary
 *
 *  hbytes length VALUE                          => count
 *  hbytes prepend VAR [VALUE ...]         = set VAR [concat VALUE ... $VAR]
 *  hbytes append VAR [VALUE ...]          = set VAR [concat $VAR VALUE ...]
 *  hbytes concat VAR [VALUE ...]          = set VAR [concat VALUE ...]
 *  hbytes unprepend VAR PREFIXLENGTH            => prefix (removed from VAR)
 *  hbytes unappend VAR SUFFIXLENGTH             => suffix (removed from VAR)
 *  hbytes chopto VAR NEWVARLENGTH               => suffix (removed from VAR)
 *                                                  (too short? error)
 *
 *  hbytes range VALUE START SIZE                => substring (or error)
 *  hbytes overwrite VAR START VALUE
 *  hbytes trimleft VAR                         removes any leading 0 octets
 *  hbytes repeat VALUE COUNT                    => COUNT copies of VALUE
 *  hbytes zeroes COUNT                          => COUNT zero bytes
 *  hbytes random COUNT                          => COUNT random bytes
 *  hbytes xor VAR VALUE                         $VAR (+)= VALUE
 *
 *  hbytes ushort2h LONG           => LONG must be <2^16, returns as hex
 *  hbytes h2ushort HEX            => |HEX| must be 2 bytes, returns as ulong
 *
 *  hbytes compare A B
 *      =>  -2   A is lexically earlier than B and not a prefix of B  (A<B)
 *          -1   A is prefix of B but not equal                       (A<B)
 *           0   A == B
 *          +1   A is B plus a nonempty suffix (ie, A has B as a prefix)
 *          +2   A is lexically later than B and does not have B as a prefix
 *
 *  hbytes pad pa|ua VAR ALG METH [METHARGS]       => worked? (always 1 for p)
 *  hbytes pad pn|un VAR BS METH [METHARGS]        => worked? (always 1 for p)
 *  hbytes pad pa|pn VAR ALG|BS pkcs5              => 1
 *  hbytes pad ua|un VAR ALG|BS pkcs5              => worked?
 *  hbytes pad pa|pn VAR ALG|BS rfc2406 NXTHDR     => 1
 *  hbytes pad ua|un VAR ALG|BS rfc2406 NXTHDRVAR  => worked?
 *
 *  hbytes blockcipher d|e VAR ALG KEY MODE [IV] => IV
 *  hbytes blockcipher mac MSG ALG KEY MODE IV   => final block
 *  hbytes blockcipher prop PROPERTY ALG         => property value
 *
 *  hbytes hash ALG MESSAGE                      => hash
 *  hbytes hmac ALG MESSAGE KEY [MACLENGTH]      => mac
 *  hbytes hash-prop PROPERTY ALG                => property value
 *
 *  ulong ul2int ULONG    => INT           can fail if >INT_MAX
 *  ulong int2ul INT      => ULONG         can fail if <0
 *  ulong mask A B                         => A & B
 *  ulong add A B                          => A + B  (mod 2^32)
 *  ulong subtract A B                     => A - B  (mod 2^32)
 *  ulong compare A B                      => 0  -1 (A<B)  +1 (A>B)
 *  ulong shift l|r ULONG BITS             fails if BITS >32
 *
 *  ulong ul2bitfields VALUE [SIZE TYPE [TYPE-ARG...] ...]  => 0/1
 *  ulong bitfields2ul BASE  [SIZE TYPE [TYPE-ARG...] ...]  => ULONG
 *      goes from left (MSbit) to right (LSbit) where
 *            SIZE is size in bits
 *            TYPE [TYPE-ARGS...] is as below
 *               zero
 *               ignore
 *               fixed ULONG-VALUE
 *               uint VARNAME/VALUE         (VARNAME if ul2bitfields;
 *               ulong VARNAME/VALUE         VALUE if bitfields2ul)
 *
 * Address ranges (addrmap.c):
 *
 *  An address range is a slightly efficient partial mapping from
 *  addresses to arbitrary data values.  An address is a number of
 *  octets expressed as an hbytes.  All the addresses covered by the
 *  same addrmap should have the same length.
 *
 *  hbytes addr-map lookup MAP-VAR ADDRESS [DEFAULT]   => DATA
 *     Error on missing default or if any prefix longer than ADDRESS.
 *
 *  hbytes addr-map amend-range MAP-VAR START END DATA
 *  hbytes addr-map amend-mask MAP-VAR PREFIX PREFIX-LENGTH DATA
 *     Sets all of the addresses in PREFIX/PREFIX-LENGTH to the
 *     relevant value.
 *
 *  Representation:
 *     An address map MAP is
 *           [list BIT-LENGTH                           \
 *                 [list START END DATA-VALUE]          \
 *                 [list START' END' DATA-VALUE']       \
 *                 ...
 *            ]
 *     The list is sorted by ascending START and entries do not overlap.
 *     START and END are both inclusive.  BIT-LENGTH is in usual Tcl
 *     integer notation and must be a multiple of 8.
 *
 * Error codes
 *
 * HBYTES BLOCKCIPHER CRYPTFAIL CRYPT  block cipher mode failed somehow (!)
 * HBYTES BLOCKCIPHER CRYPTFAIL MAC    HMAC failed somehow (!)
 * HBYTES BLOCKCIPHER LENGTH           block cipher input has unsuitable length
 * HBYTES BLOCKCIPHER PARAMS           key or iv not suitable
 * HBYTES HMAC PARAMS                  key, input or output size not suitable
 * HBYTES LENGTH OVERRUN               block too long
 * HBYTES LENGTH RANGE                 input length or offset is -ve or silly
 * HBYTES LENGTH UNDERRUN              block too short (or offset too big)
 * HBYTES LENGTH MISMATCH              when blocks must be exactly same length
 * HBYTES SYNTAX                       supposed hex block had wrong syntax
 * HBYTES VALUE OVERFLOW               value to be conv'd to hex too big/long
 * HBYTES ADDRMAP NOMATCH              no addr/mask matches address for lookup
 * HBYTES ADDRMAP UNDERRUN             addr for lookup or amend is too short
 * HBYTES ADDRMAP OVERRUN              addr for lookup or amend is too long
 * HBYTES ADDRMAP EXCLBITS             amend-mask 1-bits outside prefix len
 * HBYTES ADDRMAP BADRANGE             amend-range start > end
 * HBYTES ADDRMAP VALUE                addr-map string value is erroneous
 * SOCKADDR AFUNIX LENGTH              path for AF_UNIX socket too long
 * SOCKADDR SYNTAX IPV4                bad IPv4 socket address &/or port
 * SOCKADDR SYNTAX OTHER               bad socket addr, couldn't tell what kind
 * ULONG BITCOUNT NEGATIVE             -ve bitcount specified where not allowed
 * ULONG BITCOUNT OVERRUN              attempt to use more than 32 bits
 * ULONG BITCOUNT UNDERRUN             bitfields add up to less than 32
 * ULONG VALUE NEGATIVE                attempt convert -ve integers to ulong
 * ULONG VALUE OVERFLOW                converted value does not fit in result
 * TUNTAP IFNAME LENGTH                tun/tap interface name too long
 * TUNTAP MTU OVERRUN                  tun/tap mtu limited to 2^16 bytes
 *
 * Refs: HMAC: RFC2104
 */
/* ---8<--- end of documentation comment --8<-- */