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