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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.

*/

#define calculus_IO_ROUTINES

#include "config.h"

#include "calculus.h"

#include "error.h"

#include "extra.h"

#include "xalloc.h"

/*

    CHECK FOR CORRECT HEADERS

    The functions defined in this file give the implementations of various

    support functions used by the calculus implementation.  They should

    therefore be compiled with the calculus implementation rather than the

    specification.

*/

#if calculus_SPECIFICATION

!!!error Implementation specific functions compiled with token specifications

#endif

/*

    FREE OBJECTS

    These variables indicate the free calculi.  There is an array containing

    lists of small blocks, plus a single larger block.

*/

static calculus *free_calculi = NULL ;

static unsigned free_calculi_left = 0 ;

static calculus *free_calculus_array [] = {

    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,

    NULL, NULL, NULL

} ;

/*

    GENERATE A NEW OBJECT BLOCK

    This routine generates a new blcok of calculi of size sz.  Small blocks

    are allocated from the calculus array, others from the main calculus list.

*/

calculus *gen_calculus

    PROTO_N ( ( sz ) )

    PROTO_T ( unsigned sz )

{

    calculus *p ;

    unsigned n = sz ;

    ASSERT ( array_size ( free_calculus_array ) == calculus_GEN_MAX ) ;

    ASSERT ( n != 0 ) ;

    if ( n < calculus_GEN_MAX ) {

	/* Allocate from small block array */

	p = free_calculus_array [n] ;

	if ( p ) {

	    free_calculus_array [n] = TAIL_list ( p ) ;

	    return ( p ) ;

	}

    }

    /* Allocate from large block */

    if ( n > free_calculi_left ) {

	free_calculi_left = 1000 ;

	free_calculi = xmalloc_nof ( calculus, free_calculi_left ) ;

    }

    p = free_calculi ;

    free_calculi += sz ;

    free_calculi_left -= sz ;

    return ( p ) ;

}

/*

    DESTROY AN OBJECT BLOCK

    This routine destroys the block of calculi p of size sz.  Only small

    blocks are recycled.

*/

void destroy_calculus

    PROTO_N ( ( p, sz ) )

    PROTO_T ( calculus *p X unsigned sz )

{

    unsigned n = sz ;

    ASSERT ( n != 0 ) ;

    if ( p && n < calculus_GEN_MAX ) {

	TAIL_list ( p ) = free_calculus_array [n] ;

	free_calculus_array [n] = p ;

    }

    return ;

}

/*

    DUMMY OBJECT BLOCK DESTRUCTOR

    This routine is a dummy destructor which does nothing.

*/

void dummy_destroy_calculus

    PROTO_N ( ( p, sz ) )

    PROTO_T ( calculus *p X unsigned sz )

{

    UNUSED ( p ) ;

    UNUSED ( sz ) ;

    return ;

}

/*

    DESTROY A LIST OF OBJECT BLOCKS

    This routine destroys the list p of blocks of calculi of size sz.  The

    list is added to the appropriate entry of the free calculus array.

*/

void destroy_calculus_list

    PROTO_N ( ( p, sz ) )

    PROTO_T ( calculus *p X unsigned sz )

{

    unsigned n = sz + 1 ;

    if ( p && n < calculus_GEN_MAX ) {

	calculus *q = p ;

	while ( TAIL_list ( p ) ) p = TAIL_list ( p ) ;

	TAIL_list ( p ) = free_calculus_array [n] ;

	free_calculus_array [n] = q ;

    }

    return ;

}

/*

    FIND THE LENGTH OF A LIST

    This routine calculates the length of the list p.

*/

unsigned length_calculus_list

    PROTO_N ( ( p ) )

    PROTO_T ( calculus *p )

{

    calculus *q ;

    unsigned n = 0 ;

    for ( q = p ; q != NULL ; q = TAIL_list ( q ) ) n++ ;

    return ( n ) ;

}

/*

    REVERSE A LIST

    This routine reverses the order of the list p.

*/

calculus *reverse_calculus_list

    PROTO_N ( ( p ) )

    PROTO_T ( calculus *p )

{

    calculus *r = NULL ;

    calculus *q = p ;

    while ( q != NULL ) {

	calculus *nq = TAIL_list ( q ) ;

	TAIL_list ( q ) = r ;

	r = q ;

	q = nq ;

    }

    return ( r ) ;

}

/*

    APPEND TWO LISTS

    This routine appends the lists of calculus blocks p and q.

*/

calculus *append_calculus_list

    PROTO_N ( ( p, q ) )

    PROTO_T ( calculus *p X calculus *q )

{

    calculus *r = p ;

    if ( r == NULL ) return ( q ) ;

    while ( TAIL_list ( r ) ) r = TAIL_list ( r ) ;

    TAIL_list ( r ) = q ;

    return ( p ) ;

}

/*

    FIND THE LAST MEMBER OF A LIST

    This routine returns the last member of the list of calculus blocks p.

*/

calculus *end_calculus_list

    PROTO_N ( ( p ) )

    PROTO_T ( calculus *p )

{

    calculus *r = p ;

    if ( r == NULL ) return ( NULL ) ;

    while ( TAIL_list ( r ) ) r = TAIL_list ( r ) ;

    return ( r ) ;

}

/*

    EMPTY VECTOR

    This calculus represents the generic empty vector.  It is only defined

    if vector operations have been enabled.  Note that the element field

    of a vector is not be NULL, even if the vector is empty.

*/

#ifdef VEC

static calculus dummy_elem ;

calculus_VEC empty_calculus_vec = { 0, { &dummy_elem, &dummy_elem } } ;

#endif

/*

    ALIASING VARIABLES

    These variables give respectively the current alias number and the

    list of all aliases.

*/

unsigned crt_calculus_alias = 0 ;

static calculus *crt_alias_list = NULL ;

/*

    SET AN ALIAS

    This routine sets up an alias of p to n.

*/

void set_calculus_alias

    PROTO_N ( ( p, n ) )

    PROTO_T ( calculus *p X unsigned n )

{

    calculus *q ;

    ASSERT ( p != NULL ) ;

    q = gen_calculus ( ( unsigned ) 2 ) ;

    TAIL_list ( q ) = crt_alias_list ;

    HEAD_list ( q )->ag_ptr = p ;

    p->ag_tag = n ;

    crt_alias_list = q ;

    return ;

}

/*

    FIND AN ALIAS

    This routine searches for alias number n.

*/

calculus *find_calculus_alias

    PROTO_N ( ( n ) )

    PROTO_T ( unsigned n )

{

    calculus *p = crt_alias_list ;

    while ( p != NULL ) {

	calculus *q = HEAD_list ( p )->ag_ptr ;

	if ( q->ag_tag == n ) return ( q ) ;

	p = TAIL_list ( p ) ;

    }

    error ( ERROR_FATAL, "Can't find alias %u", n ) ;

    return ( NULL ) ;

}

/*

    CLEAR ALL ALIASES

    This routine clears all aliases.  Each alias in the list is reset to

    zero, and the list itself is freed.

*/

void clear_calculus_alias

    PROTO_Z ()

{

    calculus *p = crt_alias_list ;

    calculus *q = NULL ;

    while ( p != NULL ) {

	HEAD_list ( p )->ag_ptr->ag_tag = 0 ;

	q = p ;

	p = TAIL_list ( p ) ;

    }

    if ( q ) {

	TAIL_list ( q ) = free_calculus_array [2] ;

	free_calculus_array [2] = crt_alias_list ;

    }

    crt_calculus_alias = 0 ;

    crt_alias_list = NULL ;

    return ;

}

/*

    ADD TWO LISTS

    This routine copies the list of blocks of calculi p and adds the list

    q to the end.  sz gives the size of the blocks in the list.  This is

    used for the user defined tokens in extra.h.

*/

calculus *add_calculus_list

    PROTO_N ( ( p, q, sz ) )

    PROTO_T ( calculus *p X calculus *q X int sz )

{

    int i ;

    calculus *r ;

    if ( p == NULL ) return ( q ) ;

    r = gen_calculus ( ( unsigned ) ( sz + 1 ) ) ;

    for ( i = 1 ; i <= sz ; i++ ) r [i] = p [i] ;

    TAIL_list ( r ) = add_calculus_list ( TAIL_list ( p ), q, sz ) ;

    return ( r ) ;

}

/*

    ASSERTION ROUTINES

    These routine implement the assertion checks.

*/

#ifdef ASSERTS

#define assert_calculus assertion

#include "assert_def.h"

#endif