michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 
michael@0: /**
michael@0:    File Name:          11.7.2.js
michael@0:    ECMA Section:       11.7.2  The signed right shift operator ( >> )
michael@0:    Description:
michael@0:    Performs a sign-filling bitwise right shift operation on the left argument
michael@0:    by the amount specified by the right argument.
michael@0: 
michael@0:    The production ShiftExpression : ShiftExpression >> AdditiveExpression is
michael@0:    evaluated as follows:
michael@0: 
michael@0:    1.  Evaluate ShiftExpression.
michael@0:    2.  Call GetValue(Result(1)).
michael@0:    3.  Evaluate AdditiveExpression.
michael@0:    4.  Call GetValue(Result(3)).
michael@0:    5.  Call ToInt32(Result(2)).
michael@0:    6.  Call ToUint32(Result(4)).
michael@0:    7.  Mask out all but the least significant 5 bits of Result(6), that is,
michael@0:    compute Result(6) & 0x1F.
michael@0:    8.  Perform sign-extending right shift of Result(5) by Result(7) bits. The
michael@0:    most significant bit is propagated. The result is a signed 32 bit
michael@0:    integer.
michael@0:    9.  Return Result(8).
michael@0: 
michael@0:    Author:             christine@netscape.com
michael@0:    Date:               12 november 1997
michael@0: */
michael@0: var SECTION = "11.7.2";
michael@0: var VERSION = "ECMA_1";
michael@0: startTest();
michael@0: 
michael@0: writeHeaderToLog( SECTION + "  The signed right shift operator ( >> )");
michael@0: 
michael@0: var power = 0;
michael@0: var addexp = 0;
michael@0: 
michael@0: for ( power = 0; power <= 32; power++ ) {
michael@0:   shiftexp = Math.pow( 2, power );
michael@0: 
michael@0:   for ( addexp = 0; addexp <= 32; addexp++ ) {
michael@0:     new TestCase( SECTION,
michael@0: 		  shiftexp + " >> " + addexp,
michael@0: 		  SignedRightShift( shiftexp, addexp ),
michael@0: 		  shiftexp >> addexp );
michael@0:   }
michael@0: }
michael@0: 
michael@0: for ( power = 0; power <= 32; power++ ) {
michael@0:   shiftexp = -Math.pow( 2, power );
michael@0: 
michael@0:   for ( addexp = 0; addexp <= 32; addexp++ ) {
michael@0:     new TestCase( SECTION,
michael@0: 		  shiftexp + " >> " + addexp,
michael@0: 		  SignedRightShift( shiftexp, addexp ),
michael@0: 		  shiftexp >> addexp );
michael@0:   }
michael@0: }
michael@0: 
michael@0: test();
michael@0: 
michael@0: function ToInteger( n ) {
michael@0:   n = Number( n );
michael@0:   var sign = ( n < 0 ) ? -1 : 1;
michael@0: 
michael@0:   if ( n != n ) {
michael@0:     return 0;
michael@0:   }
michael@0:   if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY ) {
michael@0:     return n;
michael@0:   }
michael@0:   return ( sign * Math.floor(Math.abs(n)) );
michael@0: }
michael@0: function ToInt32( n ) {
michael@0:   n = Number( n );
michael@0:   var sign = ( n < 0 ) ? -1 : 1;
michael@0: 
michael@0:   if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
michael@0:     return 0;
michael@0:   }
michael@0: 
michael@0:   n = (sign * Math.floor( Math.abs(n) )) % Math.pow(2,32);
michael@0:   n = ( n >= Math.pow(2,31) ) ? n - Math.pow(2,32) : n;
michael@0: 
michael@0:   return ( n );
michael@0: }
michael@0: function ToUint32( n ) {
michael@0:   n = Number( n );
michael@0:   var sign = ( n < 0 ) ? -1 : 1;
michael@0: 
michael@0:   if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
michael@0:     return 0;
michael@0:   }
michael@0:   n = sign * Math.floor( Math.abs(n) )
michael@0: 
michael@0:     n = n % Math.pow(2,32);
michael@0: 
michael@0:   if ( n < 0 ){
michael@0:     n += Math.pow(2,32);
michael@0:   }
michael@0: 
michael@0:   return ( n );
michael@0: }
michael@0: function ToUint16( n ) {
michael@0:   var sign = ( n < 0 ) ? -1 : 1;
michael@0: 
michael@0:   if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
michael@0:     return 0;
michael@0:   }
michael@0: 
michael@0:   n = ( sign * Math.floor( Math.abs(n) ) ) % Math.pow(2,16);
michael@0: 
michael@0:   if (n <0) {
michael@0:     n += Math.pow(2,16);
michael@0:   }
michael@0: 
michael@0:   return ( n );
michael@0: }
michael@0: function Mask( b, n ) {
michael@0:   b = ToUint32BitString( b );
michael@0:   b = b.substring( b.length - n );
michael@0:   b = ToUint32Decimal( b );
michael@0:   return ( b );
michael@0: }
michael@0: function ToUint32BitString( n ) {
michael@0:   var b = "";
michael@0:   for ( p = 31; p >=0; p-- ) {
michael@0:     if ( n >= Math.pow(2,p) ) {
michael@0:       b += "1";
michael@0:       n -= Math.pow(2,p);
michael@0:     } else {
michael@0:       b += "0";
michael@0:     }
michael@0:   }
michael@0:   return b;
michael@0: }
michael@0: function ToInt32BitString( n ) {
michael@0:   var b = "";
michael@0:   var sign = ( n < 0 ) ? -1 : 1;
michael@0: 
michael@0:   b += ( sign == 1 ) ? "0" : "1";
michael@0: 
michael@0:   for ( p = 30; p >=0; p-- ) {
michael@0:     if ( (sign == 1 ) ? sign * n >= Math.pow(2,p) : sign * n > Math.pow(2,p) ) {
michael@0:       b += ( sign == 1 ) ? "1" : "0";
michael@0:       n -= sign * Math.pow( 2, p );
michael@0:     } else {
michael@0:       b += ( sign == 1 ) ? "0" : "1";
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return b;
michael@0: }
michael@0: function ToInt32Decimal( bin ) {
michael@0:   var r = 0;
michael@0:   var sign;
michael@0: 
michael@0:   if ( Number(bin.charAt(0)) == 0 ) {
michael@0:     sign = 1;
michael@0:     r = 0;
michael@0:   } else {
michael@0:     sign = -1;
michael@0:     r = -(Math.pow(2,31));
michael@0:   }
michael@0: 
michael@0:   for ( var j = 0; j < 31; j++ ) {
michael@0:     r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
michael@0:   }
michael@0: 
michael@0:   return r;
michael@0: }
michael@0: function ToUint32Decimal( bin ) {
michael@0:   var r = 0;
michael@0: 
michael@0:   for ( l = bin.length; l < 32; l++ ) {
michael@0:     bin = "0" + bin;
michael@0:   }
michael@0: 
michael@0:   for ( j = 0; j < 31; j++ ) {
michael@0:     r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
michael@0:   }
michael@0: 
michael@0:   return r;
michael@0: }
michael@0: function SignedRightShift( s, a ) {
michael@0:   s = ToInt32( s );
michael@0:   a = ToUint32( a );
michael@0:   a = Mask( a, 5 );
michael@0:   return ( SignedRShift( s, a ) );
michael@0: }
michael@0: function SignedRShift( s, a ) {
michael@0:   s = ToInt32BitString( s );
michael@0: 
michael@0:   var firstbit = s.substring(0,1);
michael@0: 
michael@0:   s = s.substring( 1, s.length );
michael@0: 
michael@0:   for ( var z = 0; z < a; z++ ) {
michael@0:     s = firstbit + s;
michael@0:   }
michael@0: 
michael@0:   s = s.substring( 0, s.length - a);
michael@0: 
michael@0:   s = firstbit +s;
michael@0: 
michael@0: 
michael@0:   return ToInt32(ToInt32Decimal(s));
michael@0: }