By default, the library is only guaranteed to be compatible with other Erlang/OTP components from the same release as the library itself. For example, from the OTP R10 release is not compatible with an Erlang emulator from the OTP R9 release by default.

A call to sets the library in compatibility mode of release . Valid range of is [7, current release]. This makes it possible to communicate with Erlang/OTP components from earlier releases.

Encodes a version magic number for the binary format. Must be the first token in a binary term.

Encodes a long integer in the binary format. Note that if the code is 64 bits the function ei_encode_long() is exactly the same as ei_encode_longlong().

Encodes an unsigned long integer in the binary format. Note that if the code is 64 bits the function ei_encode_ulong() is exactly the same as ei_encode_ulonglong().

Encodes a GCC or Visual C++ (64 bit) integer in the binary format. Note that this function is missing in the VxWorks port.

Encodes a GCC or Visual C++ (64 bit) integer in the binary format. Note that this function is missing in the VxWorks port.

Encodes a GMP integer to binary format. To use this function the ei library needs to be configured and compiled to use the GMP library.

Encodes a double-precision (64 bit) floating point number in the binary format.

Encodes a boolean value, as the atom if p is not zero or if p is zero.

Encodes a char (8-bit) as an integer between 0-255 in the binary format. Note that for historical reasons the integer argument is of type . Your C code should consider the given argument to be of type even if the C compilers and system may define to be signed.

Encodes a string in the binary format. (A string in erlang is a list, but is encoded as a character array in the binary format.) The string should be zero-terminated, except for the function.

Encodes an atom in the binary format. The parameter is the name of the atom in latin1 encoding. Only upto MAXATOMLEN-1 bytes are encoded. The name should be zero-terminated, except for the function.

Encodes an atom in the binary format with character encoding to_enc (latin1 or utf8). The p parameter is the name of the atom with character encoding from_enc. The name must either be zero-terminated or a function variant with a len parameter must be used.

The encoding will fail if the atom is too long or if it can not be represented with character encoding to_enc.

These functions were introduced in R16 release of Erlang/OTP as part of a first step to support UTF8 atoms. Atoms encoded with ERLANG_UTF8 can not be decoded by earlier releases than R16.

Encodes a binary in the binary format. The data is at , of bytes length.

Encodes an erlang process identifier, pid, in the binary format. The parameter points to an structure (which should have been obtained earlier with ).

Encodes a fun in the binary format. The parameter points to an structure. The is not freed automatically, the should be called if the fun is not needed after encoding.

Encodes an erlang port in the binary format. The parameter points to a structure (which should have been obtained earlier with .

Encodes an erlang reference in the binary format. The parameter points to a structure (which should have been obtained earlier with .

This function encodes an , as obtained from . The parameter is actually an pointer. This function doesn't free the .

This function encodes an erlang trace token in the binary format. The parameter points to a structure (which should have been obtained earlier with .

This function encodes a tuple header, with a specified arity. The next terms encoded will be the elements of the tuple. Tuples and lists are encoded recursively, so that a tuple may contain another tuple or list.

E.g. to encode the tuple :

ei_encode_tuple_header(buf, &i, 2);
ei_encode_atom(buf, &i, "a");
ei_encode_tuple_header(buf, &i, 2);
ei_encode_atom(buf, &i, "b");
ei_encode_tuple_header(buf, &i, 0);
        

This function encodes a list header, with a specified arity. The next terms are the elements (actually its cons cells) and the tail of the list. Lists and tuples are encoded recursively, so that a list may contain another list or tuple.

E.g. to encode the list :

ei_encode_list_header(buf, &i, 3);
ei_encode_atom(buf, &i, "c");
ei_encode_atom(buf, &i, "d");
ei_encode_list_header(buf, &i, 1);
ei_encode_atom(buf, &i, "e");
ei_encode_atom(buf, &i, "f");
ei_encode_empty_list(buf, &i);
        

To encode a list, without knowing the arity in advance:

while (something()) {
    ei_x_encode_list_header(&x, 1);
    ei_x_encode_ulong(&x, i); /* just an example */
}
ei_x_encode_empty_list(&x);
        

This function encodes an empty list. It's often used at the tail of a list.

This function returns the type in and size in of the encoded term. For strings and atoms, size is the number of characters not including the terminating 0. For binaries, is the number of bytes. For lists and tuples, is the arity of the object. For other types, is 0. In all cases, is left unchanged.

This function decodes the version magic number for the erlang binary term format. It must be the first token in a binary term.

This function decodes a long integer from the binary format. Note that if the code is 64 bits the function ei_decode_long() is exactly the same as ei_decode_longlong().

This function decodes an unsigned long integer from the binary format. Note that if the code is 64 bits the function ei_decode_ulong() is exactly the same as ei_decode_ulonglong().

This function decodes a GCC or Visual C++ (64 bit) integer from the binary format. Note that this function is missing in the VxWorks port.

This function decodes a GCC or Visual C++ (64 bit) integer from the binary format. Note that this function is missing in the VxWorks port.

This function decodes an integer in the binary format to a GMP integer. To use this function the ei library needs to be configured and compiled to use the GMP library.

This function decodes an double-precision (64 bit) floating point number from the binary format.

This function decodes a boolean value from the binary format. A boolean is actually an atom, decodes 1 and decodes 0.

This function decodes a char (8-bit) integer between 0-255 from the binary format. Note that for historical reasons the returned integer is of type . Your C code should consider the returned value to be of type even if the C compilers and system may define to be signed.

This function decodes a string from the binary format. A string in erlang is a list of integers between 0 and 255. Note that since the string is just a list, sometimes lists are encoded as strings by , even if it was not intended.

The string is copied to , and enough space must be allocated. The returned string is null terminated so you need to add an extra byte to the memory requirement.

This function decodes an atom from the binary format. The null terminated name of the atom is placed at . There can be at most bytes placed in the buffer.

This function decodes an atom from the binary format. The null terminated name of the atom is placed in buffer at p of length plen bytes.

The wanted string encoding is specified by want. The original encoding used in the binary format (latin1 or utf8) can be obtained from *was. The actual encoding of the resulting string (7-bit ascii, latin1 or utf8) can be obtained from *result. Both was and result can be NULL. *result may differ from want if want is ERLANG_WHATEVER or if *result turn out to be pure 7-bit ascii (compatible with both latin1 and utf8).

This function fails if the atom is too long for the buffer or if it can not be represented with encoding want.

This functions was introduced in R16 release of Erlang/OTP as part of a first step to support UTF8 atoms.

This function decodes a binary from the binary format. The parameter is set to the actual size of the binary. Note that assumes that there are enough room for the binary. The size required can be fetched by .

This function decodes a fun from the binary format. The parameter should be NULL or point to an structure. This is the only decode function that allocates memory; when the is no longer needed, it should be freed with . (This has to do with the arbitrary size of the environment for a fun.)

Decodes a pid, process identifier, from the binary format.

This function decodes a port identifier from the binary format.

This function decodes a reference from the binary format.

Decodes an erlang trace token from the binary format.

This function decodes a tuple header, the number of elements is returned in . The tuple elements follows in order in the buffer.

This function decodes a list header from the binary format. The number of elements is returned in . The elements follows (the last one is the tail of the list, normally an empty list.) If is , it's an empty list.

Note that lists are encoded as strings, if they consist entirely of integers in the range 0..255. This function will not decode such strings, use instead.

This function decodes any term, or at least tries to. If the term pointed at by in fits in the union, it is decoded, and the appropriate field in value]]> is set, and is incremented by the term size.

The function returns 1 on successful decoding, -1 on error, and 0 if the term seems alright, but does not fit in the structure. If it returns 1, the will be incremented, and the contains the decoded term.

The structure will contain the arity for a tuple or list, size for a binary, string or atom. It will contains a term if it's any of the following: integer, float, atom, pid, port or ref.

This function decodes a term from the binary format. The term is return in as a , so is actually an (see . The term should later be deallocated.

Note that this function is located in the erl_interface library.

This function prints a term, in clear text, to the file given by , or the buffer pointed to by . It tries to resemble the term printing in the erlang shell.

In , the parameter should point to a dynamically (malloc) allocated string of bytes or a NULL pointer. The string may be reallocated (and may be updated) by this function if the result is more than characters. The string returned is zero-terminated.

The return value is the number of characters written to the file or string, or -1 if doesn't contain a valid term. Unfortunately, I/O errors on is not checked.

The argument is updated, i.e. this function can be viewed as en decode function that decodes a term into a human readable format.

Format a term, given as a string, to a buffer. This functions works like a sprintf for erlang terms. The contains a format string, with arguments like , to insert terms from variables. The following formats are supported (with the C types given):

~a - an atom, char*
~c - a character, char
~s - a string, char*
~i - an integer, int
~l - a long integer, long int
~u - a unsigned long integer, unsigned long int
~f - a float, float
~d - a double float, double float
~p - an Erlang PID, erlang_pid*
        

For instance, to encode a tuple with some stuff:

ei_x_format("{~a,~i,~d}", "numbers", 12, 3.14159)
encodes the tuple {numbers,12,3.14159}
        

The formats into a buffer, without the initial version byte.

This function allocates a new buffer. The fields of the structure pointed to by parameter is filled in, and a default buffer is allocated. The also puts an initial version byte, that is used in the binary format. (So that won't be needed.)

This function frees an buffer. The memory used by the buffer is returned to the OS.

These functions appends data at the end of the buffer .

This function skips a term in the given buffer, it recursively skips elements of lists and tuples, so that a full term is skipped. This is a way to get the size of an erlang term.

is the buffer.

is updated to point right after the term in the buffer.

The function returns on success and on failure.