mirror of https://gerrit.osmocom.org/asn1c
expanded step-by-step examples
git-svn-id: https://asn1c.svn.sourceforge.net/svnroot/asn1c/trunk@620 59561ff5-6e30-0410-9f3c-9617f08c8826
This commit is contained in:
vlm
parent
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commit
a1fd7f9a16
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@ -2320,45 +2320,6 @@ As with BER decoder, the DER encoder may be invoked either directly from
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which is somewhat simpler:
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\layout LyX-Code
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/*
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\layout LyX-Code
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* This is a custom function which writes the
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\layout LyX-Code
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* encoded output into some FILE stream.
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\layout LyX-Code
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*/
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\layout LyX-Code
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static int
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\layout LyX-Code
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write_stream(const void *buffer, size_t size, void *app_key) {
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\layout LyX-Code
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FILE *ostream = app_key;
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\layout LyX-Code
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size_t wrote;
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\layout LyX-Code
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\layout LyX-Code
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wrote = fwrite(buffer, 1, size, ostream);
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\layout LyX-Code
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\layout LyX-Code
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return (wrote == size) ? 0 : -1;
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\layout LyX-Code
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}
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\layout LyX-Code
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\layout LyX-Code
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@ -2777,9 +2738,542 @@ free_struct
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\layout Part
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Examples
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\layout Chapter*
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\layout Chapter
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Step-by-step: A
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Step by step examples
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\layout Section
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A
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\begin_inset Quotes sld
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\end_inset
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Rectangle
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\begin_inset Quotes srd
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\end_inset
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Encoder
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\layout Standard
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This chapter will help you to create a simple BER and XER encoder of a
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\begin_inset Quotes sld
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\end_inset
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Rectangle
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\begin_inset Quotes srd
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\end_inset
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type used throughout this document.
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\layout Enumerate
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Create a file named
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\series bold
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rectangle.asn1
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\series default
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with the following contents:
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\begin_deeper
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\layout LyX-Code
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RectangleModule1 DEFINITIONS ::=
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\layout LyX-Code
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BEGIN
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\layout LyX-Code
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\layout LyX-Code
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Rectangle ::= SEQUENCE {
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\layout LyX-Code
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height INTEGER,
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\layout LyX-Code
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width INTEGER
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\layout LyX-Code
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}
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\layout LyX-Code
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\layout LyX-Code
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END
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\end_deeper
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\layout Enumerate
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Compile it into the set of .c and .h files using asn1c compiler
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\begin_inset LatexCommand \cite{ASN1C}
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\end_inset
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:
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\begin_deeper
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\layout LyX-Code
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\emph on
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asn1c -fnative-types
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\series bold
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\emph default
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rectangle.asn1
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\end_deeper
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\layout Enumerate
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Alternatively, use the Online ASN.1 compiler
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\begin_inset LatexCommand \cite{AONL}
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\end_inset
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by uploading the
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\series bold
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rectangle.asn1
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\series default
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file into the Web form and unpacking the produced archive on your computer.
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\layout Enumerate
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By this time, you should have gotten multiple files in the current directory,
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including the
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\series bold
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Rectangle.c
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\series default
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and
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\series bold
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Rectangle.h
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\series default
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.
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\layout Enumerate
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Create a main() routine which creates the Rectangle_t structure in memory
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and encodes it using BER and XER encoding rules.
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Let's name the file
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\series bold
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main.c
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\series default
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:
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\begin_inset ERT
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status Open
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\layout Standard
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\backslash
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clearpage{}
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\end_inset
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\begin_deeper
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\layout LyX-Code
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\size small
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#include <stdio.h>
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\layout LyX-Code
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\size small
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#include <sys/types.h>
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\layout LyX-Code
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\size small
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#include <Rectangle.h> /* Rectangle ASN.1 type */
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\layout LyX-Code
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\layout LyX-Code
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\size small
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/*
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\layout LyX-Code
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\size small
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* This is a custom function which writes the
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\layout LyX-Code
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\size small
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* encoded output into some FILE stream.
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\layout LyX-Code
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\size small
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*/
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\layout LyX-Code
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\size small
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static int
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\layout LyX-Code
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\size small
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write_out(const void *buffer, size_t size, void *app_key) {
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\layout LyX-Code
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\size small
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FILE *out_fp = app_key;
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\layout LyX-Code
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\size small
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size_t wrote;
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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wrote = fwrite(buffer, 1, size, out_fp);
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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return (wrote == size) ? 0 : -1;
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\layout LyX-Code
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\size small
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}
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\layout LyX-Code
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\layout LyX-Code
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\size small
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int main(int ac, char *av) {
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\layout LyX-Code
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\size small
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Rectangle_t *rectangle; /* Type to encode */
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\layout LyX-Code
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\size small
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asn_enc_rval_t ec; /* Encoder return value */
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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/* Allocate the Rectangle_t */
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\layout LyX-Code
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\size small
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rectangle = calloc(1, sizeof(Rectangle_t); /* not malloc! */
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\layout LyX-Code
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\size small
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if(!rectangle) {
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\layout LyX-Code
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\size small
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perror(
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\begin_inset Quotes sld
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\end_inset
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calloc() failed
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\begin_inset Quotes srd
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\end_inset
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);
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\layout LyX-Code
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\size small
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exit(71); /* better, EX_OSERR */
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\layout LyX-Code
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\size small
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}
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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/* Initialize the Rectangle members */
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\layout LyX-Code
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\size small
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rectangle->height = 42; /* any random value */
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\layout LyX-Code
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\size small
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rectangle->width = 23; /* any random value */
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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/* BER encode the data if filename is given */
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\layout LyX-Code
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\size small
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if(ac < 2) {
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\layout LyX-Code
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\size small
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fprintf(stderr,
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\begin_inset Quotes sld
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\end_inset
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Specify filename for BER output
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\backslash
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n
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\begin_inset Quotes srd
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\end_inset
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);
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\layout LyX-Code
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\size small
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} else {
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\layout LyX-Code
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\size small
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const char *filename = av[1];
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\layout LyX-Code
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\size small
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FILE *fp = fopen(filename,
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\begin_inset Quotes sld
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\end_inset
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w
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\begin_inset Quotes srd
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\end_inset
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); /* for BER output */
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\layout LyX-Code
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\layout LyX-Code
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\size small
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if(!fp) {
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\layout LyX-Code
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\size small
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perror(filename);
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\layout LyX-Code
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\size small
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exit(71); /* better, EX_OSERR */
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\layout LyX-Code
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\size small
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}
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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/* Encode the Rectangle type as BER (DER) */
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\layout LyX-Code
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\size small
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ec = der_encode(&asn_DEF_Rectangle,
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\layout LyX-Code
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\size small
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rectangle, write_out, stream);
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\layout LyX-Code
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\size small
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fclose(fp);
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\layout LyX-Code
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\size small
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if(ec.encoded == -1) {
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\layout LyX-Code
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\size small
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fprintf(stderr,
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\layout LyX-Code
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\size small
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\begin_inset Quotes sld
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\end_inset
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Could not encode Rectangle (at %s)
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\backslash
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n
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\begin_inset Quotes srd
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\end_inset
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,
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\layout LyX-Code
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\size small
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ec.failed_type ? ec.failed_type->name :
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\begin_inset Quotes sld
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\end_inset
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unknown
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\begin_inset Quotes srd
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\end_inset
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);
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\layout LyX-Code
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\size small
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exit(65); /* better, EX_DATAERR */
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\layout LyX-Code
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\size small
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} else {
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\layout LyX-Code
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\size small
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fprintf(stderr,
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\begin_inset Quotes sld
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\end_inset
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Created %s with BER encoded Rectangle
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\backslash
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n
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\begin_inset Quotes srd
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\end_inset
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,
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\layout LyX-Code
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\size small
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filename);
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\layout LyX-Code
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\size small
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}
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\layout LyX-Code
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\size small
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}
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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/* Also print the constructed Rectangle XER encoded (XML) */
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\layout LyX-Code
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\size small
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xer_fprint(stdout, &asn_DEF_Rectangle, rectangle);
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\layout LyX-Code
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\size small
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\layout LyX-Code
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\size small
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return 0; /* Encoding finished successfully */
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\layout LyX-Code
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\size small
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}
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\end_deeper
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\layout Enumerate
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Compile all files together using C compiler (varies by platform):
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\begin_deeper
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\layout LyX-Code
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\emph on
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cc -I.
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-o
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\series bold
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rencode
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\series default
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*.c
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\end_deeper
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\layout Enumerate
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Voila! You have just created the BER and XER encoder of a Rectangle type,
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named
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\series bold
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rencode
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\series default
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!
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\layout Standard
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\begin_inset ERT
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status Collapsed
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\layout Standard
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\backslash
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clearpage{}
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\end_inset
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\layout Section
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A
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\begin_inset Quotes sld
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\end_inset
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@ -2790,7 +3284,7 @@ Rectangle
|
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Decoder
|
||||
\layout Standard
|
||||
|
||||
This chapter will help you to create a simple decoder of a simple
|
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This chapter will help you to create a simple BER decoder of a simple
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\begin_inset Quotes sld
|
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\end_inset
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|
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@ -3204,7 +3698,8 @@ rdecode
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\end_deeper
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||||
\layout Enumerate
|
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|
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Voila! You have just created the Rectangle type decoder named
|
||||
Voila! You have just created the BER decoder of a Rectangle type, named
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|
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\series bold
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rdecode
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\series default
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Binary file not shown.
Loading…
Reference in New Issue