Inconsistency in Bit shift right

[nnnik]

Bit shift right takes the sign flag and moves it to the next Position however it does not change the content of the flag itself.
This behavior is inconsistent to it's counterpart bit shift left which never has to regard the flag in any operation and also any other language implementing this feature.

Code: Select all

Msgbox % ( ((1<<63)>>1) = (1<<62) )

The workaround for now would be:

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bitshiftright(value,bits)
{
	if bits
		value := ( value >> bits ) & 0xE777777777777777 
	return value
}

[lexikos]

The current behaviour is correct. The >> operator is implemented in terms of the MSVC++ (int64) >> operator, and therefore has identical behaviour.

See Arithmetic shift vs Logical shift.

[nnnik]

Well the merits of having this strictly typed operator in a loosely typed language is questionable.
I'm just here to fix the function I mentioned in my post:

Code: Select all

SetFormat,Integer,H

bitshiftright(value,bits)
{
	if ( bits ) 
		value := ( value >> 1 ) & ~( 1 << 63 )
	return value >> ( bits - !( !bits )  )
}

bitshiftright2(value,bits)
{
	if bits
		value := ( value >> bits ) & 0xE777777777777777 
	return value
}

Msgbox % bitShiftright( -1, 63 ) . "`n" . bitshiftright2( -1, 63 ) . "`n" . -1 >> 63