/* object.c - Object manipulation opcodes
 * Copyright (c) 1995-1997 Stefan Jokisch
 *
 * This file is part of Frotz.
 *
 * Frotz is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Frotz is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include "frotz.h"

#define MAX_OBJECT 2000

#define O1_PARENT 4
#define O1_SIBLING 5
#define O1_CHILD 6
#define O1_PROPERTY_OFFSET 7
#define O1_SIZE 9

#define O4_PARENT 6
#define O4_SIBLING 8
#define O4_CHILD 10
#define O4_PROPERTY_OFFSET 12
#define O4_SIZE 14

/*
 * object_address
 *
 * Calculate the address of an object.
 *
 */

static zword object_address (zword obj)
{
    /* Check object number */

    if (obj > ((h_version <= V3) ? 255 : MAX_OBJECT)) {
        print_string("@Attempt to address illegal object ");
        print_num(obj);
        print_string(".  This is normally fatal.");
        new_line();
        runtime_error (ERR_ILL_OBJ);
    }

    /* Return object address */

    if (h_version <= V3)
        return h_objects + ((obj - 1) * O1_SIZE + 62);
    else
        return h_objects + ((obj - 1) * O4_SIZE + 126);

}/* object_address */

/*
 * object_name
 *
 * Return the address of the given object's name.
 *
 */

zword object_name (zword object)
{
    zword obj_addr;
    zword name_addr;

    obj_addr = object_address (object);

    /* The object name address is found at the start of the properties */

    if (h_version <= V3)
        obj_addr += O1_PROPERTY_OFFSET;
    else
        obj_addr += O4_PROPERTY_OFFSET;

    LOW_WORD (obj_addr, name_addr)

    return name_addr;

}/* object_name */

/*
 * first_property
 *
 * Calculate the start address of the property list associated with
 * an object.
 *
 */

static zword first_property (zword obj)
{
    zword prop_addr;
    zbyte size;

    /* Fetch address of object name */

    prop_addr = object_name (obj);

    /* Get length of object name */

    LOW_BYTE (prop_addr, size)

    /* Add name length to pointer */

    return prop_addr + 1 + 2 * size;

}/* first_property */

/*
 * next_property
 *
 * Calculate the address of the next property in a property list.
 *
 */

static zword next_property (zword prop_addr)
{
    zbyte value;

    /* Load the current property id */

    LOW_BYTE (prop_addr, value)
    prop_addr++;

    /* Calculate the length of this property */

    if (h_version <= V3)
        value >>= 5;
    else if (!(value & 0x80))
        value >>= 6;
    else {

        LOW_BYTE (prop_addr, value)
        value &= 0x3f;

        if (value == 0) value = 64;        /* demanded by Spec 1.0 */

    }

    /* Add property length to current property pointer */

    return prop_addr + value + 1;

}/* next_property */

/*
 * unlink_object
 *
 * Unlink an object from its parent and siblings.
 *
 */

static void unlink_object (zword object)
{
    zword obj_addr;
    zword parent_addr;
    zword sibling_addr;

    if (object == 0) {
        runtime_error (ERR_REMOVE_OBJECT_0);
        return;
    }

    obj_addr = object_address (object);

    if (h_version <= V3) {

        zbyte parent;
        zbyte younger_sibling;
        zbyte older_sibling;
        zbyte zero = 0;

        /* Get parent of object, and return if no parent */

        obj_addr += O1_PARENT;
        LOW_BYTE (obj_addr, parent)
        if (!parent)
            return;

        /* Get (older) sibling of object and set both parent and sibling
           pointers to 0 */

        SET_BYTE (obj_addr, zero)
        obj_addr += O1_SIBLING - O1_PARENT;
        LOW_BYTE (obj_addr, older_sibling)
        SET_BYTE (obj_addr, zero)

        /* Get first child of parent (the youngest sibling of the object) */

        parent_addr = object_address (parent) + O1_CHILD;
        LOW_BYTE (parent_addr, younger_sibling)

        /* Remove object from the list of siblings */

        if (younger_sibling == object)
            SET_BYTE (parent_addr, older_sibling)
        else {
            do {
                sibling_addr = object_address (younger_sibling) + O1_SIBLING;
                LOW_BYTE (sibling_addr, younger_sibling)
            } while (younger_sibling != object);
            SET_BYTE (sibling_addr, older_sibling)
        }

    } else {

        zword parent;
        zword younger_sibling;
        zword older_sibling;
        zword zero = 0;

        /* Get parent of object, and return if no parent */

        obj_addr += O4_PARENT;
        LOW_WORD (obj_addr, parent)
        if (!parent)
            return;

        /* Get (older) sibling of object and set both parent and sibling
           pointers to 0 */

        SET_WORD (obj_addr, zero)
        obj_addr += O4_SIBLING - O4_PARENT;
        LOW_WORD (obj_addr, older_sibling)
        SET_WORD (obj_addr, zero)

        /* Get first child of parent (the youngest sibling of the object) */

        parent_addr = object_address (parent) + O4_CHILD;
        LOW_WORD (parent_addr, younger_sibling)

        /* Remove object from the list of siblings */

        if (younger_sibling == object)
            SET_WORD (parent_addr, older_sibling)
        else {
            do {
                sibling_addr = object_address (younger_sibling) + O4_SIBLING;
                LOW_WORD (sibling_addr, younger_sibling)
            } while (younger_sibling != object);
            SET_WORD (sibling_addr, older_sibling)
        }

    }

}/* unlink_object */

/*
 * z_clear_attr, clear an object attribute.
 *
 *        zargs[0] = object
 *        zargs[1] = number of attribute to be cleared
 *
 */

void z_clear_attr (void)
{
    zword obj_addr;
    zbyte value;

    if (story_id == SHERLOCK)
        if (zargs[1] == 48)
            return;

    if (zargs[1] > ((h_version <= V3) ? 31 : 47))
        runtime_error (ERR_ILL_ATTR);

    /* If we are monitoring attribute assignment display a short note */

    if (option_attribute_assignment) {
        stream_mssg_on ();
        print_string ("@clear_attr ");
        print_object (zargs[0]);
        print_string (" ");
        print_num (zargs[1]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_CLEAR_ATTR_0);
        return;
    }

    /* Get attribute address */

    obj_addr = object_address (zargs[0]) + zargs[1] / 8;

    /* Clear attribute bit */

    LOW_BYTE (obj_addr, value)
    value &= ~(0x80 >> (zargs[1] & 7));
    SET_BYTE (obj_addr, value)

}/* z_clear_attr */

/*
 * z_jin, branch if the first object is inside the second.
 *
 *        zargs[0] = first object
 *        zargs[1] = second object
 *
 */

void z_jin (void)
{
    zword obj_addr;

    /* If we are monitoring object locating display a short note */

    if (option_object_locating) {
        stream_mssg_on ();
        print_string ("@jin ");
        print_object (zargs[0]);
        print_string (" ");
        print_object (zargs[1]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_JIN_0);
        branch (0 == zargs[1]);
        return;
    }

    obj_addr = object_address (zargs[0]);

    if (h_version <= V3) {

        zbyte parent;

        /* Get parent id from object */

        obj_addr += O1_PARENT;
        LOW_BYTE (obj_addr, parent)

        /* Branch if the parent is obj2 */

        branch (parent == zargs[1]);

    } else {

        zword parent;

        /* Get parent id from object */

        obj_addr += O4_PARENT;
        LOW_WORD (obj_addr, parent)

        /* Branch if the parent is obj2 */

        branch (parent == zargs[1]);

    }

}/* z_jin */

/*
 * z_get_child, store the child of an object.
 *
 *        zargs[0] = object
 *
 */

void z_get_child (void)
{
    zword obj_addr;

    /* If we are monitoring object locating display a short note */

    if (option_object_locating) {
        stream_mssg_on ();
        print_string ("@get_child ");
        print_object (zargs[0]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_CHILD_0);
        store (0);
        branch (FALSE);
        return;
    }

    obj_addr = object_address (zargs[0]);

    if (h_version <= V3) {

        zbyte child;

        /* Get child id from object */

        obj_addr += O1_CHILD;
        LOW_BYTE (obj_addr, child)

        /* Store child id and branch */

        store (child);
        branch (child);

    } else {

        zword child;

        /* Get child id from object */

        obj_addr += O4_CHILD;
        LOW_WORD (obj_addr, child)

        /* Store child id and branch */

        store (child);
        branch (child);

    }

}/* z_get_child */

/*
 * z_get_next_prop, store the number of the first or next property.
 *
 *        zargs[0] = object
 *        zargs[1] = address of current property (0 gets the first property)
 *
 */

void z_get_next_prop (void)
{
    zword prop_addr;
    zbyte value;
    zbyte mask;

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_NEXT_PROP_0);
        store (0);
        return;
    }

    /* Property id is in bottom five (six) bits */

    mask = (h_version <= V3) ? 0x1f : 0x3f;

    /* Load address of first property */

    prop_addr = first_property (zargs[0]);

    if (zargs[1] != 0) {

        /* Scan down the property list */

        do {
            LOW_BYTE (prop_addr, value)
            prop_addr = next_property (prop_addr);
        } while ((value & mask) > zargs[1]);

        /* Exit if the property does not exist */

        if ((value & mask) != zargs[1])
            runtime_error (ERR_NO_PROP);

    }

    /* Return the property id */

    LOW_BYTE (prop_addr, value)
    store ((zword) (value & mask));

}/* z_get_next_prop */

/*
 * z_get_parent, store the parent of an object.
 *
 *        zargs[0] = object
 *
 */

void z_get_parent (void)
{
    zword obj_addr;

    /* If we are monitoring object locating display a short note */

    if (option_object_locating) {
        stream_mssg_on ();
        print_string ("@get_parent ");
        print_object (zargs[0]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_PARENT_0);
        store (0);
        return;
    }

    obj_addr = object_address (zargs[0]);

    if (h_version <= V3) {

        zbyte parent;

        /* Get parent id from object */

        obj_addr += O1_PARENT;
        LOW_BYTE (obj_addr, parent)

        /* Store parent */

        store (parent);

    } else {

        zword parent;

        /* Get parent id from object */

        obj_addr += O4_PARENT;
        LOW_WORD (obj_addr, parent)

        /* Store parent */

        store (parent);

    }

}/* z_get_parent */

/*
 * z_get_prop, store the value of an object property.
 *
 *        zargs[0] = object
 *        zargs[1] = number of property to be examined
 *
 */

void z_get_prop (void)
{
    zword prop_addr;
    zword wprop_val;
    zbyte bprop_val;
    zbyte value;
    zbyte mask;

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_PROP_0);
        store (0);
        return;
    }

    /* Property id is in bottom five (six) bits */

    mask = (h_version <= V3) ? 0x1f : 0x3f;

    /* Load address of first property */

    prop_addr = first_property (zargs[0]);

    /* Scan down the property list */

    for (;;) {
        LOW_BYTE (prop_addr, value)
        if ((value & mask) <= zargs[1])
            break;
        prop_addr = next_property (prop_addr);
    }

    if ((value & mask) == zargs[1]) {        /* property found */

        /* Load property (byte or word sized) */

        prop_addr++;

        if ((h_version <= V3 && !(value & 0xe0)) || (h_version >= V4 && !(value & 0xc0))) {

            LOW_BYTE (prop_addr, bprop_val)
            wprop_val = bprop_val;

        } else LOW_WORD (prop_addr, wprop_val)

    } else {        /* property not found */

        /* Load default value */

        prop_addr = h_objects + 2 * (zargs[1] - 1);
        LOW_WORD (prop_addr, wprop_val)

    }

    /* Store the property value */

    store (wprop_val);

}/* z_get_prop */

/*
 * z_get_prop_addr, store the address of an object property.
 *
 *        zargs[0] = object
 *        zargs[1] = number of property to be examined
 *
 */

void z_get_prop_addr (void)
{
    zword prop_addr;
    zbyte value;
    zbyte mask;

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_PROP_ADDR_0);
        store (0);
        return;
    }

    if (story_id == BEYOND_ZORK)
        if (zargs[0] > MAX_OBJECT)
            { store (0); return; }

    /* Property id is in bottom five (six) bits */

    mask = (h_version <= V3) ? 0x1f : 0x3f;

    /* Load address of first property */

    prop_addr = first_property (zargs[0]);

    /* Scan down the property list */

    for (;;) {
        LOW_BYTE (prop_addr, value)
        if ((value & mask) <= zargs[1])
            break;
        prop_addr = next_property (prop_addr);
    }

    /* Calculate the property address or return zero */

    if ((value & mask) == zargs[1]) {

        if (h_version >= V4 && (value & 0x80))
            prop_addr++;
        store ((zword) (prop_addr + 1));

    } else store (0);

}/* z_get_prop_addr */

/*
 * z_get_prop_len, store the length of an object property.
 *
 *         zargs[0] = address of property to be examined
 *
 */

void z_get_prop_len (void)
{
    zword addr;
    zbyte value;

    /* Back up the property pointer to the property id */

    addr = zargs[0] - 1;
    LOW_BYTE (addr, value)

    /* Calculate length of property */

    if (h_version <= V3)
        value = (value >> 5) + 1;
    else if (!(value & 0x80))
        value = (value >> 6) + 1;
    else {

        value &= 0x3f;

        if (value == 0) value = 64;        /* demanded by Spec 1.0 */

    }

    /* Store length of property */

    store (value);

}/* z_get_prop_len */

/*
 * z_get_sibling, store the sibling of an object.
 *
 *        zargs[0] = object
 *
 */

void z_get_sibling (void)
{
    zword obj_addr;

    if (zargs[0] == 0) {
        runtime_error (ERR_GET_SIBLING_0);
        store (0);
        branch (FALSE);
        return;
    }

    obj_addr = object_address (zargs[0]);

    if (h_version <= V3) {

        zbyte sibling;

        /* Get sibling id from object */

        obj_addr += O1_SIBLING;
        LOW_BYTE (obj_addr, sibling)

        /* Store sibling and branch */

        store (sibling);
        branch (sibling);

    } else {

        zword sibling;

        /* Get sibling id from object */

        obj_addr += O4_SIBLING;
        LOW_WORD (obj_addr, sibling)

        /* Store sibling and branch */

        store (sibling);
        branch (sibling);

    }

}/* z_get_sibling */

/*
 * z_insert_obj, make an object the first child of another object.
 *
 *        zargs[0] = object to be moved
 *        zargs[1] = destination object
 *
 */

void z_insert_obj (void)
{
    zword obj1 = zargs[0];
    zword obj2 = zargs[1];
    zword obj1_addr;
    zword obj2_addr;

    /* If we are monitoring object movements display a short note */

    if (option_object_movement) {
        stream_mssg_on ();
        print_string ("@move_obj ");
        print_object (obj1);
        print_string (" ");
        print_object (obj2);
        stream_mssg_off ();
    }

    if (obj1 == 0) {
        runtime_error (ERR_MOVE_OBJECT_0);
        return;
    }

    if (obj2 == 0) {
        runtime_error (ERR_MOVE_OBJECT_TO_0);
        return;
    }

    /* Get addresses of both objects */

    obj1_addr = object_address (obj1);
    obj2_addr = object_address (obj2);

    /* Remove object 1 from current parent */

    unlink_object (obj1);

    /* Make object 1 first child of object 2 */

    if (h_version <= V3) {

        zbyte child;

        obj1_addr += O1_PARENT;
        SET_BYTE (obj1_addr, obj2)
        obj2_addr += O1_CHILD;
        LOW_BYTE (obj2_addr, child)
        SET_BYTE (obj2_addr, obj1)
        obj1_addr += O1_SIBLING - O1_PARENT;
        SET_BYTE (obj1_addr, child)

    } else {

        zword child;

        obj1_addr += O4_PARENT;
        SET_WORD (obj1_addr, obj2)
        obj2_addr += O4_CHILD;
        LOW_WORD (obj2_addr, child)
        SET_WORD (obj2_addr, obj1)
        obj1_addr += O4_SIBLING - O4_PARENT;
        SET_WORD (obj1_addr, child)

    }

}/* z_insert_obj */

/*
 * z_put_prop, set the value of an object property.
 *
 *        zargs[0] = object
 *        zargs[1] = number of property to set
 *        zargs[2] = value to set property to
 *
 */

void z_put_prop (void)
{
    zword prop_addr;
    zword value;
    zbyte mask;

    if (zargs[0] == 0) {
        runtime_error (ERR_PUT_PROP_0);
        return;
    }

    /* Property id is in bottom five or six bits */

    mask = (h_version <= V3) ? 0x1f : 0x3f;

    /* Load address of first property */

    prop_addr = first_property (zargs[0]);

    /* Scan down the property list */

    for (;;) {
        LOW_BYTE (prop_addr, value)
        if ((value & mask) <= zargs[1])
            break;
        prop_addr = next_property (prop_addr);
    }

    /* Exit if the property does not exist */

    if ((value & mask) != zargs[1])
        runtime_error (ERR_NO_PROP);

    /* Store the new property value (byte or word sized) */

    prop_addr++;

    if ((h_version <= V3 && !(value & 0xe0)) || (h_version >= V4 && !(value & 0xc0))) {
        zbyte v = zargs[2];
        SET_BYTE (prop_addr, v)
    } else {
        zword v = zargs[2];
        SET_WORD (prop_addr, v)
    }

}/* z_put_prop */

/*
 * z_remove_obj, unlink an object from its parent and siblings.
 *
 *        zargs[0] = object
 *
 */

void z_remove_obj (void)
{

    /* If we are monitoring object movements display a short note */

    if (option_object_movement) {
        stream_mssg_on ();
        print_string ("@remove_obj ");
        print_object (zargs[0]);
        stream_mssg_off ();
    }

    /* Call unlink_object to do the job */

    unlink_object (zargs[0]);

}/* z_remove_obj */

/*
 * z_set_attr, set an object attribute.
 *
 *        zargs[0] = object
 *        zargs[1] = number of attribute to set
 *
 */

void z_set_attr (void)
{
    zword obj_addr;
    zbyte value;

    if (story_id == SHERLOCK)
        if (zargs[1] == 48)
            return;

    if (zargs[1] > ((h_version <= V3) ? 31 : 47))
        runtime_error (ERR_ILL_ATTR);

    /* If we are monitoring attribute assignment display a short note */

    if (option_attribute_assignment) {
        stream_mssg_on ();
        print_string ("@set_attr ");
        print_object (zargs[0]);
        print_string (" ");
        print_num (zargs[1]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_SET_ATTR_0);
        return;
    }

    /* Get attribute address */

    obj_addr = object_address (zargs[0]) + zargs[1] / 8;

    /* Load attribute byte */

    LOW_BYTE (obj_addr, value)

    /* Set attribute bit */

    value |= 0x80 >> (zargs[1] & 7);

    /* Store attribute byte */

    SET_BYTE (obj_addr, value)

}/* z_set_attr */

/*
 * z_test_attr, branch if an object attribute is set.
 *
 *        zargs[0] = object
 *        zargs[1] = number of attribute to test
 *
 */

void z_test_attr (void)
{
    zword obj_addr;
    zbyte value;

    if (zargs[1] > ((h_version <= V3) ? 31 : 47))
        runtime_error (ERR_ILL_ATTR);

    /* If we are monitoring attribute testing display a short note */

    if (option_attribute_testing) {
        stream_mssg_on ();
        print_string ("@test_attr ");
        print_object (zargs[0]);
        print_string (" ");
        print_num (zargs[1]);
        stream_mssg_off ();
    }

    if (zargs[0] == 0) {
        runtime_error (ERR_TEST_ATTR_0);
        branch (FALSE);
        return;
    }

    /* Get attribute address */

    obj_addr = object_address (zargs[0]) + zargs[1] / 8;

    /* Load attribute byte */

    LOW_BYTE (obj_addr, value)

    /* Test attribute */

    branch (value & (0x80 >> (zargs[1] & 7)));

}/* z_test_attr */
