BitShift
BitShift Obtain result of left- or right-shifted 32-bit value long op ; 32-bit values to be shifted
short count; positive shifts left; negative shifts right
returns result of (op << count) or (op >> (- count))
BitShift returns the value of bit-shifted a 32-bit operand. Bit shifting can be used for fast multiplication and division by a power of 2.
op is a 32-bit long operand.
count specifies the direction and extent of the shift operation. The bits are
shifted ABS( count ) positions. count is always treated MOD 32
(should range from -31 to +31).
<0 (negative values) shift to the right
>0 (positive values) shift to the left
0 Nothing happens
Returns: a long integer; the result of (op << count ) or (op >> (- count )).
Notes: Bits of op are shifted either right or left, depending on the sign of count .
Bits shifted off the end are lost and the vacated positions are cleared to 0.
Note that a left shift is the same as an unsigned multiplication by 2, 4, 8,
etc. A right shift is the same as unsigned division by 2, 4, 8, etc.
This capability is native to the CPU and can be performed much faster
using the C >> and << (bitwise shift) operators or the assembler LSL or
LSR opcodes.
long x, operand;
short count;
x = BitShift( operand, count ); /* is equivalent to . . . */ x = operand << count; [TOKEN:12074] if count is positive or . . . */
x = operand >> (- count); [TOKEN:12074] if count is negative */