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/* {{{ License.
 * This program 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 any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */ //}}}

// :indentSize=4:lineSeparator=\n:noTabs=false:tabSize=4:folding=explicit:collapseFolds=0:

package org.mathpiper.builtin.functions.core;

import org.mathpiper.builtin.BigNumber;
import org.mathpiper.builtin.BuiltinFunction;
import org.mathpiper.lisp.Environment;
import org.mathpiper.lisp.LispError;
import org.mathpiper.lisp.cons.ConsPointer;
import org.mathpiper.lisp.Utility;
import org.mathpiper.lisp.cons.NumberCons;

public class FromBase extends BuiltinFunction

    public void evaluate(Environment aEnvironment, int aStackTop) throws Exception
        // Get the base to convert to:
        // Evaluate car argument, and store getTopOfStackPointer in oper
        ConsPointer oper = new ConsPointer();
        oper.setCons(getArgumentPointer(aEnvironment, aStackTop, 1).getCons());
        // check that getTopOfStackPointer is a number, and that it is in fact an integer
//        LispError.check(oper.type().equals("Number"), LispError.KLispErrInvalidArg);
        BigNumber num = (BigNumber)  oper.getCons().getNumber(aEnvironment.getPrecision());
        LispError.checkArgument(aEnvironment, aStackTop, num != null, 1);
        // check that the base is an integer between 2 and 32
        LispError.checkArgument(aEnvironment, aStackTop, num.isInteger(), 1);

        // Get a short platform integer from the car argument
        int base = (int) (num.toDouble());

        // Get the number to convert
        ConsPointer fromNum = new ConsPointer();
        fromNum.setCons(getArgumentPointer(aEnvironment, aStackTop, 2).getCons());
        String str2;
        str2 =  (String) fromNum.car();
        LispError.checkArgument(aEnvironment, aStackTop, str2 != null, 2);

        // Added, unquote a string
        LispError.checkArgument(aEnvironment, aStackTop, Utility.isString(str2), 2);
        str2 = aEnvironment.getTokenHash().lookUpUnStringify(str2);

        // convert using correct base
        BigNumber z = new BigNumber(str2, aEnvironment.getPrecision(), base);
        getTopOfStackPointer(aEnvironment, aStackTop).setCons(new org.mathpiper.lisp.cons.NumberCons(aEnvironment, z));

%mathpiper_docs,name="FromBase",categories="User Functions;Numbers (Operations);Built In"
*CMD FromBase --- conversion of a number from non-decimal base to decimal base


{base} -- integer, base to convert to/from

{number} -- integer, number to write out in a different base

{"string"} -- string representing a number in a different base


In MathPiper, all numbers are written in decimal notation (base 10).

{FromBase} converts an integer, written as a string in base
{base}, to base 10. {ToBase} converts {number},
written in base 10, to base {base}.

*REM where is this p-adic capability? - sw
These functions use the p-adic expansion capabilities of the built-in
arbitrary precision math libraries.

Non-integer arguments are not supported.


Write the binary number {111111} as a decimal number:

      In> FromBase(2,"111111")
      Out> 63;

*SEE PAdicExpand,ToBase

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