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42 ECMA Section: 11.7.2 The signed right shift operator ( >> )
44 Performs a sign-filling bitwise right shift operation on the left argument
45 by the amount specified by the right argument.
47 The production ShiftExpression : ShiftExpression >> AdditiveExpression is
50 1. Evaluate ShiftExpression.
51 2. Call GetValue(Result(1)).
52 3. Evaluate AdditiveExpression.
53 4. Call GetValue(Result(3)).
54 5. Call ToInt32(Result(2)).
55 6. Call ToUint32(Result(4)).
56 7. Mask out all but the least significant 5 bits of Result(6), that is,
57 compute Result(6) & 0x1F.
58 8. Perform sign-extending right shift of Result(5) by Result(7) bits. The
59 most significant bit is propagated. The result is a signed 32 bit
63 Author: christine@netscape.com
64 Date: 12 november 1997
66 var SECTION = "11.7.2";
67 var VERSION = "ECMA_1";
70 writeHeaderToLog( SECTION + " The signed right shift operator ( >> )");
75 for ( power = 0; power <= 32; power++ ) {
76 shiftexp = Math.pow( 2, power );
78 for ( addexp = 0; addexp <= 32; addexp++ ) {
79 new TestCase( SECTION,
80 shiftexp + " >> " + addexp,
81 SignedRightShift( shiftexp, addexp ),
86 for ( power = 0; power <= 32; power++ ) {
87 shiftexp = -Math.pow( 2, power );
89 for ( addexp = 0; addexp <= 32; addexp++ ) {
90 new TestCase( SECTION,
91 shiftexp + " >> " + addexp,
92 SignedRightShift( shiftexp, addexp ),
99 function ToInteger( n ) {
101 var sign = ( n < 0 ) ? -1 : 1;
106 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY ) {
109 return ( sign * Math.floor(Math.abs(n)) );
111 function ToInt32( n ) {
113 var sign = ( n < 0 ) ? -1 : 1;
115 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
119 n = (sign * Math.floor( Math.abs(n) )) % Math.pow(2,32);
120 n = ( n >= Math.pow(2,31) ) ? n - Math.pow(2,32) : n;
124 function ToUint32( n ) {
126 var sign = ( n < 0 ) ? -1 : 1;
128 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
131 n = sign * Math.floor( Math.abs(n) )
133 n = n % Math.pow(2,32);
141 function ToUint16( n ) {
142 var sign = ( n < 0 ) ? -1 : 1;
144 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
148 n = ( sign * Math.floor( Math.abs(n) ) ) % Math.pow(2,16);
156 function Mask( b, n ) {
157 b = ToUint32BitString( b );
158 b = b.substring( b.length - n );
159 b = ToUint32Decimal( b );
162 function ToUint32BitString( n ) {
164 for ( p = 31; p >=0; p-- ) {
165 if ( n >= Math.pow(2,p) ) {
174 function ToInt32BitString( n ) {
176 var sign = ( n < 0 ) ? -1 : 1;
178 b += ( sign == 1 ) ? "0" : "1";
180 for ( p = 30; p >=0; p-- ) {
181 if ( (sign == 1 ) ? sign * n >= Math.pow(2,p) : sign * n > Math.pow(2,p) ) {
182 b += ( sign == 1 ) ? "1" : "0";
183 n -= sign * Math.pow( 2, p );
185 b += ( sign == 1 ) ? "0" : "1";
191 function ToInt32Decimal( bin ) {
195 if ( Number(bin.charAt(0)) == 0 ) {
200 r = -(Math.pow(2,31));
203 for ( var j = 0; j < 31; j++ ) {
204 r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
209 function ToUint32Decimal( bin ) {
212 for ( l = bin.length; l < 32; l++ ) {
216 for ( j = 0; j < 31; j++ ) {
217 r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
222 function SignedRightShift( s, a ) {
226 return ( SignedRShift( s, a ) );
228 function SignedRShift( s, a ) {
229 s = ToInt32BitString( s );
231 var firstbit = s.substring(0,1);
233 s = s.substring( 1, s.length );
235 for ( var z = 0; z < a; z++ ) {
239 s = s.substring( 0, s.length - a);
244 return ToInt32(ToInt32Decimal(s));