[redivivus]

str+=_8.charAt((_6[i>>2] >> ((3 - i%4)*8+4)) & 0xF) + _8.charAt((_6[i>>2] >> ((3 - i%4)*8 )) & 0xF);

Can someone help me comprehend this? Not sure what >> means or & 0xF in javascript.

So far i know that _8 is a string, though im not quite sure what position we are taking the charAt from.

[brendandonhu]

>> is the bitwise right shift operator. & is a binary "and".

[redivivus]

Confusing me.

The value of a right-shift expression e1 >> e2 is e1 / 2e2, and the value of a left-shift expression e1 << e2 is e1 * 2e2.

So why do we need this opperator if we can just use that instead?

The left shift operator causes the bit pattern in the first operand to be shifted left the number of bits specified by the second operand. Bits vacated by the shift operation are zero-filled. This is a logical shift, as opposed to a shift-and-rotate operation.

The right shift operator causes the bit pattern in the first operand to be shifted right the number of bits specified by the second operand. Bits vacated by the shift operation are zero-filled for unsigned quantities. For signed quantities, the sign bit is propagated into the vacated bit positions. The shift is a logical shift if the left operand is an unsigned quantity; otherwise, it is an arithmetic shift.

So i originally thought it was shift and rotate, which seems like it would be better for a hash function to me. Anyways this is interesting.

http://en.wikipedia.org/wiki/Bitwise_operation

Just read this and its very interesting also. Leaves me wondering what >>> is though. Gives this example x=(byte)((y&0xFF) >>> 2) which pretty much makes me want to shoot myself through the foot.

[brendandonhu]

Originally Posted by redivivus

So why do we need this opperator if we can just use that instead?

Bitwise operators are used for lower-level programming (doing operations at the bit-level.)

Just read this and its very interesting also. Leaves me wondering what >>> is though. Gives this example x=(byte)((y&0xFF) >>> 2) which pretty much makes me want to shoot myself through the foot.

With >>>, empty positions are filled in with 0s.