👤
Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:
Select Section of Man Page:
Select Man Page Repository:

Linux 2.6 - man page for erl_marshal (linux section 3erl)

erl_marshal(3erl)		       C Library Functions			erl_marshal(3erl)

NAME
       erl_marshal - Encoding and Decoding of Erlang terms

DESCRIPTION
       This module contains functions for encoding Erlang terms into a sequence of bytes, and for
       decoding Erlang terms from a sequence of bytes.

EXPORTS
       int erl_compare_ext(bufp1, bufp2)

	      Types  unsigned char *bufp1,*bufp2;

	      This function compares two encoded terms.

	      bufp1 is a buffer containing an encoded Erlang term term1.

	      bufp2 is a buffer containing an encoded Erlang term term2.

	      The function returns 0 if the terms are equal, -1 if term1 is less than term2, or 1
	      if term2 is less than term1.

       ETERM * erl_decode(bufp)
       ETERM * erl_decode_buf(bufpp)

	      Types  unsigned char *bufp;
		     unsigned char **bufpp;

	      erl_decode()  and  erl_decode_buf()  decode the contents of a buffer and return the
	      corresponding Erlang term. erl_decode_buf() provides a simple mechanism for dealing
	      with several encoded terms stored consecutively in the buffer.

	      bufp is a pointer to a buffer containing one or more encoded Erlang terms.

	      bufpp  is the address of a buffer pointer. The buffer contains one or more consecu-
	      tively encoded Erlang terms. Following a	successful  call  to  erl_decode_buf()	,
	      bufpp will be updated so that it points to the next encoded term.

	      erl_decode()  returns  an Erlang term corresponding to the contents of bufp on suc-
	      cess, or NULL on failure. erl_decode_buf() returns an Erlang term corresponding  to
	      the first of the consecutive terms in bufpp and moves bufpp forward to point to the
	      next term in the buffer. On failure, each of the functions returns NULL.

       int erl_encode(term, bufp)
       int erl_encode_buf(term, bufpp)

	      Types  ETERM *term;
		     unsigned char *bufp;
		     unsigned char **bufpp;

	      erl_encode() and erl_encode_buf() encode Erlang  terms  into  external  format  for
	      storage  or transmission. erl_encode_buf() provides a simple mechanism for encoding
	      several terms consecutively in the same buffer.

	      term is an Erlang term to be encoded.

	      bufp is a pointer to a buffer containing one or more encoded Erlang terms.

	      bufpp is a pointer to a pointer to a buffer containing one  or  more  consecutively
	      encoded  Erlang terms. Following a successful call to erl_encode_buf() , bufpp will
	      be updated so that it points to the position for the next encoded term.

	      These functions returns the number of bytes written to buffer if successful, other-
	      wise returns 0.

	      Note that no bounds checking is done on the buffer. It is the caller's responsibil-
	      ity to make sure that the buffer is large enough to hold the encoded terms. You can
	      either  use  a  static  buffer that is large enough to hold the terms you expect to
	      need in your program, or use erl_term_len() to determine the exact requirements for
	      a given term.

	      The  following  can help you estimate the buffer requirements for a term. Note that
	      this information is implementation specific, and may change in future versions.  If
	      you are unsure, use erl_term_len() .

	      Erlang terms are encoded with a 1 byte tag that identifies the type of object, a 2-
	      or 4-byte length field, and then the data itself. Specifically:

		Tuples :
		  need 5 bytes, plus the space for each element.

		Lists :
		  need 5 bytes, plus the space for each element, and 1 additional  byte  for  the
		  empty list at the end.

		Strings and atoms :
		  need	3  bytes,  plus  1  byte  for  each  character	(the terminating 0 is not
		  encoded). Really long strings (more than 64k characters) are encoded as  lists.
		  Atoms cannot contain more than 256 characters.

		Integers :
		  need 5 bytes.

		Characters :
		  (integers < 256) need 2 bytes.

		Floating point numbers :
		  need 32 bytes.

		Pids :
		  need 10 bytes, plus the space for the node name, which is an atom.

		Ports and Refs :
		  need 6 bytes, plus the space for the node name, which is an atom.

	      The  total space required will be the result calculated from the information above,
	      plus 1 additional byte for a version identifier.

       int erl_ext_size(bufp)

	      Types  unsigned char *bufp;

	      This function returns the number of elements in an encoded term.

       unsigned char erl_ext_type(bufp)

	      Types  unsigned char *bufp;

	      This function identifies and returns the type of Erlang term encoded in  a  buffer.
	      It will skip a trailing magic identifier. Returns 0 if the type can't be determined
	      or one of

		* ERL_INTEGER

		* ERL_ATOM

		* ERL_PID /* Erlang process identifier */

		* ERL_PORT

		* ERL_REF /* Erlang reference */

		* ERL_EMPTY_LIST

		* ERL_LIST

		* ERL_TUPLE

		* ERL_FLOAT

		* ERL_BINARY

		* ERL_FUNCTION

       unsigned char * erl_peek_ext(bufp, pos)

	      Types  unsigned char *bufp;
		     int pos;

	      This function is used for stepping over one or more encoded terms in a  buffer,  in
	      order to directly access a later term.

	      bufp is a pointer to a buffer containing one or more encoded Erlang terms.

	      pos indicates how many terms to step over in the buffer.

	      The  function returns a pointer to a sub-term that can be used in a subsequent call
	      to erl_decode() in order to retrieve the term at that  position.	If  there  is  no
	      term, or pos would exceed the size of the terms in the buffer, NULL is returned.

       int erl_term_len(t)

	      Types  ETERM *t;

	      This  function  determines  the  buffer  space that would be needed by t if it were
	      encoded into Erlang external format by erl_encode() .

	      The size in bytes is returned.

Ericsson AB			       erl_interface 3.7.3			erl_marshal(3erl)


All times are GMT -4. The time now is 07:51 AM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
×
UNIX.COM Login
Username:
Password:  
Show Password