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42 ECMA Section: 11.7.1 The Left Shift Operator ( << )
44 Performs a bitwise left shift operation on the left argument by the amount
45 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. Left shift Result(5) by Result(7) bits. The result is a signed 32 bit
62 Author: christine@netscape.com
63 Date: 12 november 1997
65 var SECTION = "11.7.1";
66 var VERSION = "ECMA_1";
69 writeHeaderToLog( SECTION + " The left shift operator ( << )");
71 for ( power = 0; power < 33; power++ ) {
72 shiftexp = Math.pow( 2, power );
74 for ( addexp = 0; addexp < 33; addexp++ ) {
75 new TestCase( SECTION,
76 shiftexp + " << " + addexp,
77 LeftShift( shiftexp, addexp ),
84 function ToInteger( n ) {
86 var sign = ( n < 0 ) ? -1 : 1;
91 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY ) {
94 return ( sign * Math.floor(Math.abs(n)) );
96 function ToInt32( n ) {
98 var sign = ( n < 0 ) ? -1 : 1;
100 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
104 n = (sign * Math.floor( Math.abs(n) )) % Math.pow(2,32);
105 n = ( n >= Math.pow(2,31) ) ? n - Math.pow(2,32) : n;
109 function ToUint32( n ) {
111 var sign = ( n < 0 ) ? -1 : 1;
113 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
116 n = sign * Math.floor( Math.abs(n) )
118 n = n % Math.pow(2,32);
126 function ToUint16( n ) {
127 var sign = ( n < 0 ) ? -1 : 1;
129 if ( Math.abs( n ) == 0 || Math.abs( n ) == Number.POSITIVE_INFINITY) {
133 n = ( sign * Math.floor( Math.abs(n) ) ) % Math.pow(2,16);
141 function Mask( b, n ) {
142 b = ToUint32BitString( b );
143 b = b.substring( b.length - n );
144 b = ToUint32Decimal( b );
147 function ToUint32BitString( n ) {
149 for ( p = 31; p >=0; p-- ) {
150 if ( n >= Math.pow(2,p) ) {
159 function ToInt32BitString( n ) {
161 var sign = ( n < 0 ) ? -1 : 1;
163 b += ( sign == 1 ) ? "0" : "1";
165 for ( p = 30; p >=0; p-- ) {
166 if ( (sign == 1 ) ? sign * n >= Math.pow(2,p) : sign * n > Math.pow(2,p) ) {
167 b += ( sign == 1 ) ? "1" : "0";
168 n -= sign * Math.pow( 2, p );
170 b += ( sign == 1 ) ? "0" : "1";
176 function ToInt32Decimal( bin ) {
180 if ( Number(bin.charAt(0)) == 0 ) {
185 r = -(Math.pow(2,31));
188 for ( var j = 0; j < 31; j++ ) {
189 r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
194 function ToUint32Decimal( bin ) {
198 for ( l = bin.length; l < 32; l++ ) {
202 for ( j = 0; j < 31; j++ ) {
203 r += Math.pow( 2, j ) * Number(bin.charAt(31-j));
209 function LeftShift( s, a ) {
210 var shift = ToInt32( s );
211 var add = ToUint32( a );
212 add = Mask( add, 5 );
213 var exp = LShift( shift, add );
217 function LShift( s, a ) {
218 s = ToInt32BitString( s );
220 for ( var z = 0; z < a; z++ ) {
224 s = s.substring( a, s.length);
226 return ToInt32(ToInt32Decimal(s));