Subversion Repositories tendra.SVN

/*

    		 Crown Copyright (c) 1997

    This TenDRA(r) Computer Program is subject to Copyright

    owned by the United Kingdom Secretary of State for Defence

    acting through the Defence Evaluation and Research Agency

    (DERA).  It is made available to Recipients with a

    royalty-free licence for its use, reproduction, transfer

    to other parties and amendment for any purpose not excluding

    product development provided that any such use et cetera

    shall be deemed to be acceptance of the following conditions:-

        (1) Its Recipients shall ensure that this Notice is

        reproduced upon any copies or amended versions of it;

        (2) Any amended version of it shall be clearly marked to

        show both the nature of and the organisation responsible

        for the relevant amendment or amendments;

        (3) Its onward transfer from a recipient to another

        party shall be deemed to be that party's acceptance of

        these conditions;

        (4) DERA gives no warranty or assurance as to its

        quality or suitability for any purpose and DERA accepts

        no liability whatsoever in relation to any use to which

        it may be put.

*/

#include "config.h"

#include "types.h"

#include "check.h"

#include "de_types.h"

#include "de_capsule.h"

#include "de_unit.h"

#include "decode.h"

#include "eval.h"

#include "fetch.h"

#include "high.h"

#include "node.h"

#include "shape.h"

#include "table.h"

#include "tdf.h"

#include "utility.h"

/*

    DECODE AN EXTENDED VALUE

    An extended n bit encoding is decoded.

*/

long fetch_extn

    PROTO_N ( ( n ) )

    PROTO_T ( int n )

{

    long r = 0, s ;

    while ( s = fetch ( n ), s == 0 ) r += ( ( 1 << n ) - 1 ) ;

    return ( r + s ) ;

}

/*

    DECODE A TDF INTEGER

    A TDF integer is decoded and returned as a long (no overflow checks).

*/

long tdf_int

    PROTO_Z ()

{

    long d, n = 0 ;

    do {

	d = fetch ( 4 ) ;

	n = 8 * n + ( d & 7 ) ;

    } while ( !( d & 8 ) ) ;

    return ( n ) ;

}

/*

    DECODE A TOKEN APPLICATION

    A token application returning sort s is appended to p.  If s is

    SORT_unknown a simple token (rather than a token application) is

    read.

*/

construct *de_token

    PROTO_N ( ( p, s ) )

    PROTO_T ( node *p X sortname s )

{

    long bits ;

    construct *t ;

    tok_info *info ;

    construct dummy ;

    /* Find token type */

    long n = de_token_bits () ;

    if ( n == ENC_make_tok ) {

	long m = tdf_int () ;

	t = find_binding ( crt_binding, tok_var, m ) ;

	info = get_tok_info ( t ) ;

	p->son = new_node () ;

	p->son->cons = t ;

    } else if ( n == ENC_use_tokdef ) {

	char *nm ;

	t = make_construct ( SORT_token ) ;

	nm = alloc_nof ( char, 32 ) ;

	IGNORE sprintf ( nm, "~~token_%ld", t->encoding ) ;

	t->name = nm ;

	if ( add_to_var_hash ( t, SORT_token ) ) {

	    input_error ( "%s has already been defined", nm ) ;

	}

	de_token_defn ( t, ( node * ) null ) ;

	info = get_tok_info ( t ) ;

	p->son = new_node () ;

	p->son->cons = t ;

    } else {

	high_sort *h ;

	construct *tt ;

	tt = de_token ( p, SORT_token ) ;

	info = get_tok_info ( tt ) ;

	h = high_sorts + high_no ( info->res ) ;

	dummy.name = "high level token" ;

	dummy.u.tok_u.res = h->res ;

	dummy.u.tok_u.args = find_decode_string ( h ) ;

	t = &dummy ;

	info = &dummy.u.tok_u ;

    }

    /* Quit here if only reading token */

    if ( s == SORT_unknown ) {

	if ( !text_output ) {

	    p->son->son = new_node () ;

	    p->son->son->cons = &token_cons ;

	}

	return ( null ) ;

    }

    /* Find the length of the arguments */

    bits = tdf_int () ;

    if ( info->res == SORT_unknown ) {

	/* Unknown token */

	if ( bits ) {

	    /* Step over arguments */

	    char *args ;

	    if ( streq ( t->name, "~dg_exp" ) ) {

		args = "xFF" ;

	    } else if ( streq ( t->name, "~exp_to_source" ) ) {

		args = "xFF" ;

	    } else if ( streq ( t->name, "~diag_id_scope" ) ) {

		args = "x$xF" ;

	    } else if ( streq ( t->name, "~diag_type_scope" ) ) {

		args = "x$F" ;

	    } else if ( streq ( t->name, "~diag_tag_scope" ) ) {

		args = "x$F" ;

	    } else {

		warning ( "Token %s undeclared", t->name ) ;

		args = "F" ;

	    }

	    bits += input_posn () ;

	    p->son->son = de_node ( args ) ;

	    bits -= input_posn () ;

	    if ( bits < 0 ) {

		input_error ( "Token %s, arguments length wrong", t->name ) ;

		return ( t ) ;

	    }

	    input_skip ( bits ) ;

	} else {

	    /* No argument - can deduce token sort */

	    info->res = s ;

	    info->dec = 1 ;

	}

    } else {

	/* Known token */

	if ( s == SORT_token ) {

	    /* Must be high level */

	    if ( !is_high ( info->res ) ) {

		input_error ( "Sort error in token %s", t->name ) ;

	    }

	} else if ( info->res != s ) {

	    /* Result sort must match */

	    input_error ( "Sort error in token %s", t->name ) ;

	}

	if ( info->args ) {

	    /* Decode arguments */

	    long end_posn = input_posn () + bits ;

	    p->son->son = de_node ( info->args ) ;

	    if ( input_posn () != end_posn ) {

		input_error ( "Token %s, arguments length wrong", t->name ) ;

		return ( t ) ;

	    }

	} else {

	    /* No arguments */

	    if ( bits ) {

		input_error ( "Token %s, arguments length wrong", t->name ) ;

		return ( t ) ;

	    }

	}

	info->dec = 1 ;

    }

    /* Mark used tokens */

    if ( info->dec ) adjust_token ( t ) ;

    return ( t ) ;

}

/*

    DECODE A VARIABLE SORT

    A construct of the vth variable sort is decoded.

*/

node *de_var_sort

    PROTO_N ( ( v ) )

    PROTO_T ( long v )

{

    long n = tdf_int () ;

    node *p = new_node () ;

    p->cons = find_binding ( crt_binding, v, n ) ;

    return ( p ) ;

}

/*

    DECODE A LABEL

    A label construct is decoded.

*/

void de_make_label

    PROTO_N ( ( p ) )

    PROTO_T ( node *p )

{

    long n = tdf_int () ;

    p->son = new_node () ;

    p->son->cons = find_label ( n ) ;

    return ;

}

/*

    DECODE A STRING OF DECODE CHARACTERS

    The string of decode character str is decoded.

*/

node *de_node

    PROTO_N ( ( str ) )

    PROTO_T ( char *str )

{

    char c ;

    node *p, *q = null, *qe = null ;

    while ( c = *str, c != 0 && c != ']' ) {

	switch ( c ) {

	    case '[' :

	    case '{' :

	    case '}' :

	    case '&' :

	    case '^' : {

		/* Ignore these cases */

		p = null ;

		break ;

	    }

	    case '|' : {

		/* Align input stream */

		byte_align () ;

		p = null ;

		break ;

	    }

	    case 'i' : {

		/* Decode an integer as a string of octal digits */

		long d, n = 0 ;

		char buff [1000] ;

		do {

		    d = fetch ( 4 ) ;

		    buff [n] = ( char ) ( '0' + ( d & 7 ) ) ;

		    n++ ;

		} while ( !( d & 8 ) ) ;

		buff [n] = 0 ;

		p = new_node () ;

		p->cons = new_construct () ;

		if ( fits_ulong ( buff, 1 ) ) {

		    p->cons->sortnum = SORT_small_tdfint ;

		    p->cons->encoding = ( long ) octal_to_ulong ( buff ) ;

		} else {

		    p->cons->sortnum = SORT_tdfint ;

		    p->cons->name = string_copy_aux ( buff ) ;

		}

		break ;

	    }

	    case 'j' : {

		/* Decode a bit */

		p = new_node () ;

		p->cons = ( tdf_bool () ? &true_cons : &false_cons ) ;

		break ;

	    }

	    case '$' : {

		/* Decode a string */

		long i, n = tdf_int () ;

		if ( n == 8 ) {

		    char *s ;

		    n = tdf_int () ;

		    s = alloc_nof ( char, n + 1 ) ;

		    p = new_node () ;

		    p->cons = new_construct () ;

		    p->cons->sortnum = SORT_tdfstring ;

		    p->cons->encoding = n ;

		    p->cons->name = s ;

		    p->cons->next = null ;

		    for ( i = 0 ; i < n ; i++ ) {

			s [i] = ( char ) fetch ( 8 ) ; /* LINT */

		    }

		    s [n] = 0 ;

		} else {

		    long m ;

		    node *px ;

		    p = new_node () ;

		    p->cons = &string_cons ;

		    p->son = make_int ( n ) ;

		    m = tdf_int () ;

		    px = new_node () ;

		    px->cons = new_construct () ;

		    px->cons->sortnum = SORT_repeat ;

		    px->cons->encoding = m ;

		    p->son->bro->bro = px ;

		    for ( i = 0 ; i < m ; i++ ) {

			long v = fetch ( ( int ) n ) ;

			if ( i == 0 ) {

			    px->son = make_int ( v ) ;

			    px = px->son ;

			} else {

			    px->bro->bro = make_int ( v ) ;

			    px = px->bro->bro ;

			}

		    }

		}

		break ;

	    }

	    case '=' : {

		/* Decode an aligned string */

		char *s ;

		long i, n = tdf_int () ;

		if ( n != 8 ) input_error ( "Only 8-bit strings allowed" ) ;

		n = tdf_int () ;

		byte_align () ;

		s = alloc_nof ( char, n + 1 ) ;

		p = new_node () ;

		p->cons = new_construct () ;

		p->cons->sortnum = SORT_tdfstring ;

		p->cons->encoding = n ;

		p->cons->name = s ;

		p->cons->next = null ;

		for ( i = 0 ; i < n ; i++ ) {

		    s [i] = ( char ) fetch ( 8 ) ; /* LINT */

		}

		s [n] = 0 ;

		byte_align () ;

		break ;

	    }

	    case '*' : {

		/* The following text is repeated n times */

		de_list_start () ;

		goto percent_case ;

	    }

	    case '%' :

	    percent_case : {

		/* The following text is repeated n times */

		node *pe = null ;

		long i, n = tdf_int () ;

		p = new_node () ;

		p->cons = new_construct () ;

		p->cons->sortnum = SORT_repeat ;

		p->cons->encoding = n ;

		str += 2 ;

		for ( i = 0 ; i < n ; i++ ) {

		    node *pi = de_node ( str ) ;

		    if ( pe == null ) {

			p->son = pi ;

		    } else {

			pe->bro = pi ;

		    }

		    pe = pi ;

		    while ( pe->bro ) pe = pe->bro ;

		}

		str = skip_text ( str ) ;

		break ;

	    }

	    case '?' : {

		/* The following text is optional */

		p = new_node () ;

		p->cons = &optional_cons ;

		str += 2 ;

		if ( tdf_bool () ) {

		    p->son = de_node ( str ) ;

		    if ( *str == '*' && p->son->cons->encoding == 0 ) {

			/* Get rid of optional empty lists */

			p->son = null ;

		    }

		}

		str = skip_text ( str ) ;

		break ;

	    }

	    case '@' : {

		/* The following text is a bitstream */

		long len, pos ;

		str += 2 ;

		len = tdf_int () ;

		pos = input_posn () ;

		p = new_node () ;

		p->cons = &bytestream_cons ;

		p->son = de_node ( str ) ;

		if ( len + pos != input_posn () ) {

		    input_error ( "Conditional length wrong" ) ;

		}

		str = skip_text ( str ) ;

		break ;

	    }

	    case 'T' : {

		node dummy ;

		str = find_sortname ( str, ( sortname * ) null ) ;

		IGNORE de_token ( &dummy, SORT_unknown ) ;

		p = dummy.son ;

		break ;

	    }

	    case 'F' : {

		/* Unknown sort */

		p = new_node () ;

		p->cons = &unknown_cons ;

		break ;

	    }

	    default : {

		/* Basic sorts */

		sortname s = find_sort ( c ) ;

		p = ( sort_decode [s] ) () ;

		break ;

	    }

	}

	if ( p ) {

	    if ( qe == null ) {

		q = p ;

	    } else {

		qe->bro = p ;

	    }

	    qe = p ;

	    while ( qe->bro ) qe = qe->bro ;

	}

	str++ ;

    }

    return ( q ) ;

}