mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
synced 2024-06-29 11:40:38 +00:00
69 lines
1.8 KiB
Plaintext
69 lines
1.8 KiB
Plaintext
{{DISPLAYTITLE:_SHL}}
|
|
The [[_SHL]] function is used to shift the bits of a numerical value to the left.
|
|
|
|
|
|
{{PageSyntax}}
|
|
:{{Parameter|result}} = [[_SHL]]({{Parameter|numericalVariable}}, {{Parameter|numericalValue}})
|
|
|
|
|
|
{{Parameters}}
|
|
* {{Parameter|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]].
|
|
* {{Parameter|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.
|
|
|
|
|
|
{{PageDescription}}
|
|
* 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'''.
|
|
|
|
|
|
{{PageExamples}}
|
|
''Example 1:''
|
|
{{CodeStart}}A~%% = 1 'set right most bit of an{{Cl|_UNSIGNED}} {{Cl|_BYTE}}
|
|
{{Cl|PRINT}} A~%%
|
|
{{Cl|PRINT}} {{Cl|_SHL}}(A~%%,7)
|
|
B~%% = {{Cl|_SHL}}(A~%%,8) 'shift the bit off the left 'edge'
|
|
{{Cl|PRINT}} B~%%
|
|
{{CodeEnd}}
|
|
{{OutputStart}}
|
|
1
|
|
128
|
|
0
|
|
{{OutputEnd}}
|
|
|
|
|
|
''Example 2:''
|
|
{{CodeStart}}
|
|
A~%% = 1
|
|
{{Cl|FOR}} I%% = 0 {{Cl|TO}} 8
|
|
{{Cl|PRINT}} {{Cl|_SHL}}(A~%%, I%%)
|
|
{{Cl|FOR...NEXT|NEXT}} I%%
|
|
{{CodeEnd}}
|
|
{{OutputStart}}
|
|
1
|
|
2
|
|
4
|
|
8
|
|
16
|
|
32
|
|
64
|
|
128
|
|
256
|
|
{{OutputEnd}}
|
|
* Note: When directly [[PRINT]]ing 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.
|
|
|
|
{{PageSeeAlso}}
|
|
* [[_SHR]], [[INTEGER]], [[LONG]]
|
|
* [[_BYTE]], [[_INTEGER64]]
|
|
|
|
|
|
{{PageNavigation}}
|
|
<
|