Converting Bytes to Bits: Difference between revisions

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: The following example shows how to convert an [[_UNSIGNED]] [[_BYTE]] or [[INTEGER]] value(0 to 255) to a [[Binary]] [[STRING]] number in Qbasic.
: The following example shows how to convert an [[_UNSIGNED]] [[_BYTE]] or [[INTEGER]] value(0 to 255) to a [[Binary]] [[STRING]] number in QBasic.
{{CodeStart}} '' ''
{{CodeStart}}
{{Cl|DIM}} byte as {{Cl|_UNSIGNED}} {{Cl|_BYTE}}
{{Cl|DIM}} byte as {{Cl|_UNSIGNED}} {{Cl|_BYTE}}


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{{Cl|FOR...NEXT|FOR}} bit = 7 to 0 {{Cl|STEP}} -1
{{Cl|FOR...NEXT|FOR}} bit = 7 to 0 {{Cl|STEP}} -1
   {{Cl|IF...THEN|IF}} byte {{Cl|AND (boolean)|AND}} 2 ^ bit {{Cl|THEN}} {{Cl|PRINT}} "1"; {{Cl|ELSE}} {{Cl|PRINT}} "0";
   {{Cl|IF...THEN|IF}} byte {{Cl|AND (boolean)|AND}} 2 ^ bit {{Cl|THEN}} {{Cl|PRINT}} "1"; {{Cl|ELSE}} {{Cl|PRINT}} "0";
{{Cl|NEXT}} '' ''
{{Cl|NEXT}}
{{CodeEnd}}
{{CodeEnd}}
: ''Notes:'' The above code can be adapted to place a value into a bit [[Arrays|Array]] for up to 8 flag values in a single Byte.
: ''Notes:'' The above code can be adapted to place a value into a bit [[Arrays|Array]] for up to 8 flag values in a single Byte.




: How upper and lower [[_BYTE|byte]] bits are read from an [[INTEGER]] value using whole decimal or [[HEX$|hexadecimal]] values.  
: How upper and lower [[_BYTE|byte]] bits are read from an [[INTEGER]] value using whole decimal or [[HEX$|hexadecimal]] values.
{{CodeStart}} '' ''
{{CodeStart}}
{{Cl|SCREEN}} 12
{{Cl|SCREEN}} 12


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       {{Cl|IF...THEN|IF}} (Num {{Cl|AND (boolean)|AND}} 2 ^ i) {{Cl|THEN}}
       {{Cl|IF...THEN|IF}} (Num {{Cl|AND (boolean)|AND}} 2 ^ i) {{Cl|THEN}}
         {{Cl|PAINT}} (640 - (37 * (i + 1)), 189), 12, 9
         {{Cl|PAINT}} (640 - (37 * (i + 1)), 189), 12, 9
         Bin$ = Bin$ + "1"
         BinStr$ = BinStr$ + "1"
       {{Cl|ELSE}}: {{Cl|PAINT}} (640 - (37 * (i + 1)), 189), 0, 9
       {{Cl|ELSE}}: {{Cl|PAINT}} (640 - (37 * (i + 1)), 189), 0, 9
         Bin$ = Bin$ + "0"
         BinStr$ = BinStr$ + "0"
       {{Cl|END IF}}
       {{Cl|END IF}}
     {{Cl|NEXT}}
     {{Cl|NEXT}}
     {{Cl|COLOR}} 10: {{Cl|LOCATE}} 16, 50: {{Cl|PRINT}} "Binary ="; {{Cl|VAL}}(Bin$)
     {{Cl|COLOR}} 10: {{Cl|LOCATE}} 16, 50: {{Cl|PRINT}} "Binary ="; {{Cl|VAL}}(BinStr$)
     {{Cl|COLOR}} 9: {{Cl|LOCATE}} 16, 10: {{Cl|PRINT}} "Decimal ="; Num;: {{Cl|COLOR}} 13: {{Cl|PRINT}} "      Hex = "; Hexa$
     {{Cl|COLOR}} 9: {{Cl|LOCATE}} 16, 10: {{Cl|PRINT}} "Decimal ="; Num;: {{Cl|COLOR}} 13: {{Cl|PRINT}} "      Hex = "; Hexa$
     Hexa$ = "": Bin$ = ""
     Hexa$ = "": BinStr$ = ""
   {{Cl|END IF}}
   {{Cl|END IF}}
   {{Cl|COLOR}} 14: {{Cl|LOCATE}} 17, 15: {{Cl|INPUT}} "Enter a decimal or HEX({{Cl|&H}}) value (0 Quits): ", frst$
   {{Cl|COLOR}} 14: {{Cl|LOCATE}} 17, 15: {{Cl|INPUT}} "Enter a decimal or HEX({{Cl|&H}}) value (0 Quits): ", frst$
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   Num = first + second
   Num = first + second
   Hexa$ = "{{Cl|&H}}" + {{Cl|HEX$}}(Num)
   Hexa$ = "{{Cl|&H}}" + {{Cl|HEX$}}(Num)
{{Cl|LOOP}} {{Cl|UNTIL}} first = 0 {{Cl|OR (boolean)|OR}} Num > 32767 {{Cl|OR (boolean)|OR}} Num < -32768 {{Cl|OR (boolean)|OR}} (Num < -1 {{Cl|AND (boolean)|AND}} Num > -32768 '' ''
{{Cl|LOOP}} {{Cl|UNTIL}} first = 0 {{Cl|OR (boolean)|OR}} Num > 32767 {{Cl|OR (boolean)|OR}} Num < -32768 {{Cl|OR (boolean)|OR}} (Num < -1 {{Cl|AND (boolean)|AND}} Num > -32768
{{Cl|END}}
{{Cl|END}}
{{CodeEnd}}{{small|Code by Ted Weissgerber}}
{{CodeEnd}}
{{Small|Code by Ted Weissgerber}}




''See also:''
{{PageSeeAlso}}
* [[Binary]]
* [[Binary]]
* [[_SHL]], [[_SHR]]
* [[_SHL]], [[_SHR]]
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{{PageNavigation}}
{{PageReferences}}

Latest revision as of 13:13, 19 November 2024

Although QB64 has _BYTE and _BIT variable types, there may be times that you just want to know which bits are on of off in the byte value or convert the value to a Binary number.


Bits are numbered from 0 to 7 and normally are read from the most significant bit(MSB = 7) to the least significant bit(LSB = 0).


The following example shows how to convert an _UNSIGNED _BYTE or INTEGER value(0 to 255) to a Binary STRING number in QBasic.
DIM byte as _UNSIGNED _BYTE

byte = 222

FOR bit = 7 to 0 STEP -1
  IF byte AND 2 ^ bit THEN PRINT "1"; ELSE PRINT "0";
NEXT
Notes: The above code can be adapted to place a value into a bit Array for up to 8 flag values in a single Byte.


How upper and lower byte bits are read from an INTEGER value using whole decimal or hexadecimal values.
SCREEN 12

COLOR 11: LOCATE 10, 2: PRINT "      AH (High Register Byte Bits)           AL (Low Register Byte Bits)"
COLOR 14: LOCATE 11, 2: PRINT "    15   14  13   12   11  10    9   8    7   6    5   4    3    2   1    0"
COLOR 13: LOCATE 14, 2: PRINT " &H8000 4000 2000 1000 800 400  200 100  80   40  20   10   8    4   2  &H1"
COLOR 11: LOCATE 15, 2: PRINT "-32768 16384 8192 4096 2048 1024 512 256 128  64  32   16   8    4   2    1"
FOR i = 1 TO 16
  CIRCLE (640 - (37 * i), 189), 8, 9 'place bit circles
NEXT
LINE (324, 160)-(326, 207), 11, BF 'line splits bytes
DO
  IF Num THEN
    FOR i = 15 TO 0 STEP -1
      IF (Num AND 2 ^ i) THEN
        PAINT (640 - (37 * (i + 1)), 189), 12, 9
        BinStr$ = BinStr$ + "1"
      ELSE: PAINT (640 - (37 * (i + 1)), 189), 0, 9
        BinStr$ = BinStr$ + "0"
      END IF
    NEXT
    COLOR 10: LOCATE 16, 50: PRINT "Binary ="; VAL(BinStr$)
    COLOR 9: LOCATE 16, 10: PRINT "Decimal ="; Num;: COLOR 13: PRINT "       Hex = "; Hexa$
    Hexa$ = "": BinStr$ = ""
  END IF
  COLOR 14: LOCATE 17, 15: INPUT "Enter a decimal or HEX(&H) value (0 Quits): ", frst$
  first = VAL(frst$)
  LOCATE 17, 15: PRINT SPACE$(55)
  IF first THEN
    COLOR 13: LOCATE 17, 15: INPUT "Enter a second value: ", secnd$
    second = VAL(secnd$)
    LOCATE 16, 10: PRINT SPACE$(69)
  END IF
  Num = first + second
  Hexa$ = "&H" + HEX$(Num)
LOOP UNTIL first = 0 OR Num > 32767 OR Num < -32768 OR (Num < -1 AND Num > -32768
END
Code by Ted Weissgerber


See also


QB64 Programming References

Wiki Pages
Main Page with Articles and Tutorials
QB64 specific keywords (alphabetical)
Original QBasic keywords (alphabetical)
QB64 OpenGL keywords (alphabetical)
Keywords by Usage
Got a question about something?
Frequently Asked Questions about QB64
QB64 Phoenix Edition Community Forum
Links to other QBasic Sites:
Pete's QBasic Forum
Pete's QBasic Downloads
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