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/*

    		 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 "de_types.h"

#include "de_unit.h"

#include "decode.h"

#include "fetch.h"

#include "names.h"

#include "node.h"

#include "table.h"

#include "tdf.h"

#include "utility.h"

/*

    FLAG : DECODE STATUS

    A value of 0 indicates that we are decoding the names at the start

    of the capsule, 1 that we are decoding the linkage information, and

    2 that we are decoding a main equation body.

*/

int decode_status = -1 ;

/*

    FLAG : ONLY DECODE TOKEN DECLARATIONS

    This flag is true if we are only interested in the token

    declarations in a capsule.

*/

boolean extract_tokdecs = 0 ;

/*

    THE ARRAY OF ALL VARIABLE SORTS

    The array vars of size no_var gives all variable sorts.  The

    indexes in this array of the alignment tags, tags and tokens are

    given by al_tag_var, tag_var, tok_var respectively.

*/

static long no_var ;

static var_sort *vars ;

long al_tag_var, tag_var, tok_var ;

/*

    LIST OF UNUSED CONSTRUCTS

    All unused constructs in a capsule are formed into a list for

    later reuse.

*/

static construct *garbage = null ;

/*

    CURRENT BINDINGS

    The current bindings are held in crt_binding.  spare_binding, if not

    null, contains a binding suitable for reuse.

*/

binding *crt_binding ;

static binding *spare_binding = null ;

/*

    CREATE A NEW BINDING

    A new binding with space for no_var variable sorts is created and

    cleared.

*/

static binding *new_binding

    PROTO_Z ()

{

    binding *b ;

    long i, n = no_var ;

    if ( n == 0 ) return ( null ) ;

    if ( spare_binding ) {

	b = spare_binding ;

	spare_binding = null ;

	for ( i = 0 ; i < n ; i++ ) b [i].max_no = 0 ;

	return ( b ) ;

    }

    b = alloc_nof ( binding, n ) ;

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

	b [i].max_no = 0 ;

	b [i].sz = 0 ;

	b [i].table = null ;

    }

    return ( b ) ;

}

/*

    FREE A BINDING

    The binding b is returned to free.

*/

static void free_binding

    PROTO_N ( ( b ) )

    PROTO_T ( binding *b )

{

    spare_binding = b ;

    return ;

}

/*

    SET THE SIZE OF AN ENTRY IN A BINDING

    The size of the table of the vth variable sort in the binding bt

    is set to n.

*/

static void set_binding_size

    PROTO_N ( ( bt, v, n ) )

    PROTO_T ( binding *bt X long v X long n )

{

    binding *b ;

    construct **p ;

    long i, m = n + 10 ;

    if ( v < 0 || v >= no_var ) {

	input_error ( "Illegal binding sort" ) ;

	return ;

    }

    b = bt + v ;

    b->max_no = n ;

    if ( b->sz < m ) {

	p = realloc_nof ( b->table, construct *, m ) ;

	b->sz = m ;

	b->table = p ;

    } else {

	p = b->table ;

    }

    for ( i = 0 ; i < b->sz ; i++ ) p [i] = null ;

    return ;

}

/*

    COMPLETE A BINDING

    The unused entries in the binding b are filled in.

*/

static void complete_binding

    PROTO_N ( ( b ) )

    PROTO_T ( binding *b )

{

    long v ;

    for ( v = 0 ; v < no_var ; v++ ) {

	long i ;

	binding *bv = b + v ;

	sortname s = vars [v].sortnum ;

	for ( i = 0 ; i < bv->max_no ; i++ ) {

	    if ( bv->table [i] == null ) {

		construct *p = make_construct ( s ) ;

		if ( extract_tokdecs ) {

		    /* This construct is unused - free it */

		    ( sort_count [s] )-- ;

		    p->next = garbage ;

		    garbage = p ;

		} else {

		    /* Make up an internal name */

		    long n = p->encoding ;

		    char *nm = alloc_nof ( char, 32 ) ;

		    IGNORE sprintf ( nm, "~~%s_%ld", vars [v].name, n ) ;

		    p->name = nm ;

		    if ( add_to_var_hash ( p, s ) ) {

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

		    }

		}

		bv->table [i] = p ;

	    }

	}

    }

    return ;

}

/*

    SET AN ENTRY IN A BINDING

    The nth entry of the vth variable sort of the binding bt is set to

    the construct p.

*/

static void set_binding

    PROTO_N ( ( bt, v, n, p ) )

    PROTO_T ( binding *bt X long v X long n X construct *p )

{

    binding *b ;

    if ( v < 0 || v >= no_var ) {

	input_error ( "Illegal binding sort" ) ;

	return ;

    }

    b = bt + v ;

    if ( n >= b->max_no || n < 0 ) {

	input_error ( "Object number %ld (%s) too big", n, vars [v].name ) ;

	return ;

    }

    if ( b->table [n] ) {

	input_error ( "Object %ld (%s) already bound", n, vars [v].name ) ;

	return ;

    }

    b->table [n] = p ;

    return ;

}

/*

    FIND AN ENTRY IN A BINDING

    The nth entry of the vth variable sort of the binding bt is returned.

*/

construct *find_binding

    PROTO_N ( ( bt, v, n ) )

    PROTO_T ( binding *bt X long v X long n )

{

    binding *b ;

    if ( v < 0 || v >= no_var ) {

	input_error ( "Illegal binding sort" ) ;

	return ( null ) ;

    }

    b = bt + v ;

    if ( n >= b->max_no || n < 0 ) {

	input_error ( "Object number %ld (%s) too big", n, vars [v].name ) ;

	return ( null ) ;

    }

    return ( b->table [n] ) ;

}

/*

    DECODE AN ALIGNED STRING

    An aligned string (in an external name) is decoded and returned

    as an array of characters.

*/

char *de_aligned_string

    PROTO_Z ()

{

    char *p ;

    long i, n = tdf_int () ;

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

    n = tdf_int () ;

    byte_align () ;

    p = alloc_nof ( char, n + 1 ) ;

    for ( i = 0 ; i < n ; i++ ) p [i] = ( char ) fetch ( 8 ) /* LINT */ ;

    p [n] = 0 ;

    byte_align () ;

    return ( p ) ;

}

/*

    FLAG INDICATING SKIP PASS

    This flag is true if we are in the skip pass of a set of equations

    (primarily token definitions).

*/

boolean in_skip_pass = 0 ;

/*

    DECODE A SET OF EQUATIONS

    A set of equations with decoding routine f is decoded.  If f is null

    the equations are stepped over, otherwise they are decoded.

*/

typedef void ( *equation_func ) PROTO_S ( ( void ) ) ;

static void de_equation

    PROTO_N ( ( f ) )

    PROTO_T ( equation_func f )

{

    long i, n ;

    binding *old_binding = null ;

    /* Read new bindings */

    n = tdf_int () ;

    if ( n ) {

	if ( n != no_var ) input_error ( "Number of local variables wrong" ) ;

	old_binding = crt_binding ;

	crt_binding = new_binding () ;

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

	    long sz = tdf_int () ;

	    set_binding_size ( crt_binding, i, sz ) ;

	}

	n = tdf_int () ;

	if ( n != no_var ) input_error ( "Number of linkage units wrong" ) ;

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

	    long j, no_links = tdf_int () ;

	    for ( j = 0 ; j < no_links ; j++ ) {

		long inner = tdf_int () ;

		long outer = tdf_int () ;

		construct *p = find_binding ( old_binding, i, outer ) ;

		set_binding ( crt_binding, i, inner, p ) ;

	    }

	}

	complete_binding ( crt_binding ) ;

    } else {

	n = tdf_int () ;

	if ( n ) input_error ( "Number of linkage units wrong" ) ;

    }

    /* Read the actual equation */

    n = BYTESIZE * tdf_int () ;

    byte_align () ;

    if ( f == null ) {

	input_skip ( n ) ;

    } else {

	long end_posn = input_posn () + n ;

	decode_status = 2 ;

	( *f ) () ;

	byte_align () ;

	decode_status = 1 ;

	if ( input_posn () != end_posn ) input_error ( "Unit length wrong" ) ;

    }

    /* Restore the old bindings */

    if ( old_binding ) {

	free_binding ( crt_binding ) ;

	crt_binding = old_binding ;

    }

    return ;

}

/*

    DECODE A CAPSULE

    An entire TDF capsule is decoded.

*/

void de_capsule

    PROTO_Z ()

{

    long i, n ;

    long no_eqn ;

    char **eqns ;

    /* Reset variables */

    al_tag_var = -1 ;

    tag_var = -2 ;

    tok_var = -3 ;

    spare_binding = null ;

    have_version = 0 ;

    decode_status = 0 ;

    /* Read magic number */

    de_magic ( MAGIC_NUMBER ) ;

    /* Read equation names */

    no_eqn = tdf_int () ;

    eqns = alloc_nof ( char *, no_eqn ) ;

    for ( i = 0 ; i < no_eqn ; i++ ) eqns [i] = de_aligned_string () ;

    /* Read variable sort names */

    no_var = tdf_int () ;

    vars = alloc_nof ( var_sort, no_var ) ;

    crt_binding = new_binding () ;

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

	char *s = de_aligned_string () ;

	long sz = tdf_int () ;

	vars [i].name = s ;

	if ( streq ( s, LINK_al_tag ) ) {

	    vars [i].sortnum = SORT_al_tag ;

	    al_tag_var = i ;

	} else if ( streq ( s, LINK_tag ) ) {

	    vars [i].sortnum = SORT_tag ;

	    tag_var = i ;

	} else if ( streq ( s, LINK_token ) ) {

	    vars [i].sortnum = SORT_token ;

	    tok_var = i ;

	} else {

	    vars [i].sortnum = SORT_unknown ;

	}

	set_binding_size ( crt_binding, i, sz ) ;

    }

    /* Read external names */

    decode_status = 1 ;

    n = tdf_int () ;

    if ( n != no_var ) input_error ( "Number of variable sorts wrong" ) ;

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

	static int un = 0 ;

	sortname si = vars [i].sortnum ;

	long j, no_links = tdf_int () ;

	boolean reject = 0 ;

	if ( extract_tokdecs && i != tok_var ) reject = 1 ;

	for ( j = 0 ; j < no_links ; j++ ) {

	    construct *p, *q ;

	    long id = tdf_int () ;

	    n = de_external_bits () ;

	    byte_align () ;

	    p = make_construct ( si ) ;

	    if ( extract_tokdecs ) {

		( sort_count [ si ] )-- ;

		p->encoding = -1 ;

	    }

	    if ( n == ENC_string_extern ) {

		/* Simple external name */

		boolean name_ok = 1 ;

		node *ns = de_node ( "=" ) ;

		if ( reject ) {

		    free_node ( ns ) ;

		} else {

		    /* Check that name is a valid identifier */

		    char *nm = ns->cons->name ;

		    if ( alpha ( *nm ) ) {

			long k ;

			for ( k = 1 ; k < ns->cons->encoding ; k++ ) {

			    char c = nm [k] ;

			    if ( !alphanum ( c ) ) name_ok = 0 ;

			}

		    } else {

			name_ok = 0 ;

		    }

		    if ( name_ok ) {

			/* Use external name as internal name */

			p->name = nm ;

			if ( !is_local_name ( nm ) ) {

			    p->ename = new_node () ;

			    p->ename->cons = &false_cons ;

			}

		    } else {

			/* Make up internal name */

			p->name = alloc_nof ( char, 32 ) ;

			IGNORE sprintf ( p->name, "~~extern_%d", un++ ) ;

			if ( !is_local_name ( nm ) ) {

			    p->ename = new_node () ;

			    p->ename->cons = &true_cons ;

			    p->ename->son = ns ;

			}

		    }

		}

	    } else if ( n == ENC_unique_extern ) {

		/* Unique external name */

		node *nu = de_node ( "%[=]" ) ;

		if ( reject ) {

		    free_node ( nu ) ;

		} else {

		    /* Make up internal name */

		    p->name = alloc_nof ( char, 32 ) ;

		    IGNORE sprintf ( p->name, "~~extern_%d", un++ ) ;

		    p->ename = new_node () ;

		    p->ename->cons = &true_cons ;

		    p->ename->son = nu ;

		}

	    } else if ( n == ENC_chain_extern ) {

		/* Chain external name */

		node *nc = de_node ( "=i" ) ;

		if ( reject ) {

		    free_node ( nc ) ;

		} else {

		    /* Make up internal name */

		    p->name = alloc_nof ( char, 32 ) ;

		    IGNORE sprintf ( p->name, "~~extern_%d", un++ ) ;

		    p->ename = new_node () ;

		    p->ename->cons = &true_cons ;

		    p->ename->son = nc ;

		}

	    } else {

		input_error ( "Illegal EXTERN value, %ld", n ) ;

	    }

	    /* Add construct to tables */

	    if ( reject ) {

		set_binding ( crt_binding, i, id, p ) ;

		p->next = garbage ;

		garbage = p ;

	    } else {

		q = add_to_var_hash ( p, si ) ;

		if ( q ) {

		    if ( !extract_tokdecs ) {

			( sort_count [ si ] )-- ;

			if ( q->encoding == -1 ) {

			    q->encoding = ( sort_count [ si ] )++ ;

			}

		    }

		    set_binding ( crt_binding, i, id, q ) ;

		    p->next = garbage ;

		    garbage = p ;

		} else {

		    set_binding ( crt_binding, i, id, p ) ;

		}

	    }

	}

    }

    /* Complete the bindings */

    complete_binding ( crt_binding ) ;

    /* Read the equations */

    n = tdf_int () ;

    if ( n != no_eqn ) input_error ( "Number of equations wrong" ) ;

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

	char *eq = eqns [i] ;

	long j, no_units = tdf_int () ;

	if ( no_units ) {

	    boolean skip_pass = 0 ;

	    equation_func f = null ;

	    /* Find equation decoding routine */

	    if ( extract_tokdecs ) {

		if ( streq ( eq, LINK_tokdec_props ) ) {

		    f = de_tokdec ;

		} else if ( streq ( eq, LINK_tokdef_props ) ) {

		    f = de_tokdef ;

		    in_skip_pass = 1 ;

		}

	    } else {

		if ( streq ( eq, LINK_al_tagdef_props ) ) {

		    f = de_aldef ;

		} else if ( streq ( eq, LINK_tagdec_props ) ) {

		    f = de_tagdec ;

		} else if ( streq ( eq, LINK_tagdef_props ) ) {

		    f = de_tagdef ;

		} else if ( streq ( eq, LINK_tokdec_props ) ) {

		    f = de_tokdec ;

		} else if ( streq ( eq, LINK_tokdef_props ) ) {

		    f = de_tokdef ;

		    skip_pass = 1 ;

		} else if ( streq ( eq, LINK_version_props ) ) {

		    f = de_version ;

		}

	    }

	    /* Skip pass */

	    if ( skip_pass ) {

		long old_posn = input_posn () ;

		in_skip_pass = 1 ;

		for ( j = 0 ; j < no_units ; j++ ) de_equation ( f ) ;

		in_skip_pass = 0 ;

		input_goto ( old_posn ) ;

	    }

	    /* Main pass */

	    for ( j = 0 ; j < no_units ; j++ ) de_equation ( f ) ;

	    in_skip_pass = 0 ;

	}

    }

    /* Free unused constructs */

    free_construct ( &garbage ) ;

    return ;

}

/*

    NAME OF CURRENT CAPSULE

    The current capsule of a library is recorded to use in error messages.

*/

char *capname = null ;

/*

    DECODE A TDF LIBRARY

*/

void de_library

    PROTO_Z ()

{

    long old_posn ;

    long i, no_cap ;

    boolean old_extract = extract_tokdecs ;

    de_magic ( MAGIC_LINK_NUMBER ) ;

    IGNORE tdf_int () ;

    no_cap = tdf_int () ;

    old_posn = input_posn () ;

    /* First pass - extract all token declaration */

    extract_tokdecs = 1 ;

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

	long end_posn ;

	long j, n ;

	decode_status = 0 ;

	n = tdf_int () ;

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

	n = tdf_int () ;

	byte_align () ;

	capname = alloc_nof ( char, n + 1 ) ;

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

	    capname [j] = ( char ) fetch ( 8 ) ; /* LINT */

	}

	capname [n] = 0 ;

	n = BYTESIZE * tdf_int () ;

	byte_align () ;

	end_posn = input_posn () + n ;

	de_capsule () ;

	byte_align () ;

	if ( input_posn () != end_posn ) {

	    input_error ( "Capsule length wrong" ) ;

	}

	capname = null ;

    }

    /* Second pass - if the first pass didn't do everything */

    extract_tokdecs = old_extract ;

    if ( extract_tokdecs ) return ;

    input_goto ( old_posn ) ;

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

	long end_posn ;

	long j, n ;

	decode_status = 0 ;

	n = tdf_int () ;

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

	n = tdf_int () ;

	byte_align () ;

	capname = alloc_nof ( char, n + 1 ) ;

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

	    capname [j] = ( char ) fetch ( 8 ) ; /* LINT */

	}

	capname [n] = 0 ;

	n = BYTESIZE * tdf_int () ;

	byte_align () ;

	end_posn = input_posn () + n ;

	de_capsule () ;

	byte_align () ;

	if ( input_posn () != end_posn ) {

	    input_error ( "Capsule length wrong" ) ;

	}

	capname = null ;

    }

    return ;

}