_SHL
From QB64.org wiki
The _SHL function is used to shift the bits of a numerical value to the left.
Syntax
- result = _SHL(numericalVariable, numericalValue)
Parameters
- numericalVariable is the variable to shift the bits of and can be of the following types: INTEGER, LONG,_INTEGER64, or _BYTE.
- Integer values can be signed or _UNSIGNED.
- numericalValue is the number of places to shift the bits.
- While 0 is a valid value it will have no affect on the variable being shifted.
Description
- Allows for multiplication of a value by 2 faster than normal multiplication (see example 2 below).
- Bits that reach the end of a variable's bit count are dropped (when using a variable of the same type - otherwise they will carry over).
- The type of variable used to store the results should match the type of the variable being shifted.
Availability
- Version 1.3 and up.
Examples
Example 1:
A~%% = 1 'set right most bit of an_UNSIGNED _BYTE PRINT A~%% PRINT _SHL(A~%%,7) B~%% = _SHL(A~%%,8) 'shift the bit off the left 'edge' PRINT B~%%
1 128 0
Example 2:
A~%% = 1 FOR I%% = 0 TO 8 PRINT _SHL(A~%%, I%%) NEXT I%%
1 2 4 8 16 32 64 128 256
- Note: When directly PRINTing to screen, the result is calculated internally using a larger variable type so the left most bit is carried to the next value.
- To avoid this store the result in a variable of the same type before printing.
See also