/*
 * c_register - set or print a custom register value
 *
 * Copyright (C) 2007,2021-2023  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc 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 Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   2007/07/14 20:23:46
 * File existed as early as:    2007
 *
 * chongo <was here> /\oo/\     http://www.isthe.com/chongo/
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */


/*
 * ISO C requires a translation unit to contain at least one declaration,
 * so we declare a global variable whose value is based on if CUSTOM is defined.
 */
#if defined(CUSTOM)
int c_register_allowed = 1;     /* CUSTOM defined */
#else /* CUSTOM */
int c_register_allowed = 0;     /* CUSTOM undefined */
#endif /* CUSTOM */


#if defined(CUSTOM)

#include <stdio.h>

#include "../have_const.h"
#include "../value.h"
#include "../custom.h"

#include "../config.h"
#include "../calc.h"

#include "../have_unused.h"


#include "../errtbl.h"
#include "../banned.h"  /* include after system header <> includes */


/*
 * registers
 */
STATIC VALUE custom_reg[CUSTOM_REG_MAX+1];


/*
 * init_custreg - initialize custom registers
 */
void
init_custreg(void)
{
        int i;

        /*
         * set the registers to zero
         */
        for (i=0; i < CUSTOM_REG_MAX+1; ++i) {
            custom_reg[i].v_type = V_NUM;
            custom_reg[i].v_subtype = V_NOSUBTYPE;
            custom_reg[i].v_num = itoq(0);
        }
        return;
}


/*
 * c_register - set or print a custom register value
 *
 * given:
 *      vals[i]   and arg to display information about
 *
 * returns:
 *      count
 */
/*ARGSUSED*/
VALUE
c_register(char *UNUSED(name), int count, VALUE **vals)
{
        VALUE result;           /* what we will return */
        long reg;               /* register number */

        /*
         * arg check
         */
        result.v_type = V_NULL;
        if (vals[0]->v_type != V_NUM) {
                math_error("Non-numeric register number");
                not_reached();
        }
        if (qisfrac(vals[0]->v_num)) {
                math_error("Non-integer register number");
                not_reached();
        }
        if (qisneg(vals[0]->v_num)) {
                math_error("register number < 0");
                not_reached();
        }
        if (! qistiny(vals[0]->v_num)) {
                math_error("register is huge");
                not_reached();
        }
        reg = qtoi(vals[0]->v_num);
        if (reg > CUSTOM_REG_MAX) {
                math_error("register is larger than CUSTOM_REG_MAX");
                not_reached();
        }

        /*
         * print info on each arg
         */
        /* save previous value */
        copyvalue(&custom_reg[reg], &result);
        /* set the new value if a 2nd arg was given */
        if (count == 2) {
            copyvalue(vals[1], &custom_reg[reg]);
        }

        /*
         * return result
         */
        return result;
}

#endif /* CUSTOM */