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/*

 * Copyright (c) 2002-2005 The TenDRA Project <http://www.tendra.org/>.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * 1. Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

 * 3. Neither the name of The TenDRA Project nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific, prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS

 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * $Id$

 */

/*

    		 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 "read.h"

#include "calculus.h"

#include "common.h"

#include "error.h"

#include "output.h"

#include "xalloc.h"

/*

 * BITMASKS

 *

 * This array gives the masks for each bit value.

 */

unsigned long bitmask[CHAR_BIT];

/*

 * INITIALISE MASKS

 *

 * This routine initialises the array of bitmasks.  This is done

 * dynamically rather than statically in case CHAR_BIT is not 8.

 */

void

init_bitmask(void)

{

    int i;

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

	    bitmask[i] = MASK(i);

    }

    return;

}

/*

 * INPUT FILE

 *

 * These variables describe the input file.  There is a one byte input

 * buffer.

 */

static FILE *input_file;

static unsigned long input_buff = 0;

static int input_bits = 0;

/*

 * READ A NUMBER OF BITS

 *

 * This routine reads the next n bits from the input file.

 */

static unsigned long

read_bits(int n)

{

    int b = input_bits;

    unsigned long m = input_buff;

    unsigned long r = 0;

    while (n) {

	if (b == 0) {

	    /* Read next byte */

	    int c = getc(input_file);

	    if (c == EOF) {

		error(ERROR_FATAL, "Premature end of file");

	    } else {

		m = (((unsigned long)c) & MASK(CHAR_BIT));

	    }

	    b = CHAR_BIT;

	}

	if (n >= b) {

	    r = (r << b) | m;

	    n -= b;

	    b = 0;

	} else {

	    int c = b - n;

	    r = (r << n) | (m >> c);

	    m &= bitmask[c];

	    n = 0;

	    b = c;

	}

    }

    input_bits = b;

    input_buff = m;

    return(r);

}

/*

 * READ AN INTEGER

 *

 * This routine reads an integer from the input file.  This is encoded

 * as a sequence of octal digits with a marker bit for the end of the

 * number.

 */

static unsigned long

read_int(void)

{

    unsigned long r = 0, d;

    while (d = read_bits(4), (d & 0x08) == 0) {

	r = (r << 3) | d;

    }

    r = (r << 3) | (d & 0x07);

    return(r);

}

/*

 * READ A STRING

 *

 * This routine reads an integer from the input file.  This is encoded

 * as the string length followed by the characters comprising the

 * string (8 bits each).

 */

static char *

read_string(void)

{

    unsigned long i, n = read_int();

    char *s = xstr((long)(n + 1));

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

	s[i] = (char)read_bits(8);

    }

    s[n] = 0;

    return(s);

}

/*

 * READ A FILENAME

 *

 * File names are just strings, however they are buffered to save

 * space.

 */

static char *

read_filename(void)

{

    char *s;

    static char *last_filename = "????";

    if (read_bits(1)) {

	s = last_filename;

    } else {

	s = read_string();

	last_filename = s;

    }

    return(s);

}

/*

 * AUTOMATICALLY GENERATED DISK READING ROUTINES

 *

 * The main disk reading routines are automatically generated.  The

 * various macros are used to customise these routines.

 */

#define READ_BITS(N)		((unsigned)read_bits(N))

#define READ_ALIAS()		((unsigned)read_int())

#define READ_DIM()		((unsigned)read_int())

#define READ_int()		((int)read_int())

#define READ_number()		((number)read_int())

#define READ_string()		read_string()

#define READ_name_string()	read_filename()

#define READ_zero_int()		0

#include "read_def.h"

/*

 * READ AN INPUT FILE

 *

 * This routine reads an algebra from the input file nm.

 */

void

read_file(char *nm)

{

    char *s;

    /* Open file */

    crt_line_no = -1;

    crt_file_name = nm;

    input_file = fopen(nm, "rb");

    if (input_file == NULL) {

	error(ERROR_SERIOUS, "Can't open input file, '%s'", nm);

	return;

    }

    init_bitmask();

    input_buff = 0;

    input_bits = 0;

    /* Confirm file header */

    s = READ_string();

    if (!streq(s, calculus_NAME)) {

	error(ERROR_FATAL, "Invalid file header identifier");

    }

    s = READ_string();

    if (!streq(s, calculus_VERSION)) {

	error(ERROR_FATAL, "Invalid file header version, '%s'", s);

    }

    /* Read the algebra */

    algebra->name = READ_string();

    algebra->major_no = READ_int();

    algebra->minor_no = READ_int();

    algebra->types = READ_list_ptr_type();

    clear_calculus_alias();

    /* Extract lists of primitives etc */

    LOOP_TYPE {

	TYPE_P t = CRT_TYPE;

	TYPE t0 = DEREF_type(t);

	switch (TAG_type(t0)) {

	    case type_primitive_tag: {

		PRIMITIVE_P p = DEREF_ptr(type_primitive_prim(t0));

		CONS_ptr(p, algebra->primitives, algebra->primitives);

		break;

	    }

	    case type_ident_tag: {

		IDENTITY_P p = DEREF_ptr(type_ident_id(t0));

		CONS_ptr(p, algebra->identities, algebra->identities);

		break;

	    }

	    case type_enumeration_tag: {

		ENUM_P p = DEREF_ptr(type_enumeration_en(t0));

		CONS_ptr(p, algebra->enumerations, algebra->enumerations);

		break;

	    }

	    case type_structure_tag: {

		STRUCTURE_P p = DEREF_ptr(type_structure_struc(t0));

		CONS_ptr(p, algebra->structures, algebra->structures);

		break;

	    }

	    case type_onion_tag: {

		UNION_P p = DEREF_ptr(type_onion_un(t0));

		CONS_ptr(p, algebra->unions, algebra->unions);

		break;

	    }

	}

    }

    /* Close file */

    fclose_v(input_file);

    return;

}