QB64-PE/internal/help/INP.txt

[[INP]] returns a value from a computer register or port values at a specified physical address.


{{PageSyntax}}
: {{Parameter|i}} = [[INP]]({{Parameter|address}})


* '''QB64 has limited access to registers. VGA memory and registers are emulated.'''
* Address can be a decimal or hexadecimal [[INTEGER]] value.
* [[INP]] reads directly from a register or port address.
* It does not require a [[DEF SEG]] memory segment address like [[PEEK]] or [[POKE]] do.
* Reads color port intensity settings after {{InlineCode}}[[OUT]] &H3C7, attribute{{InlineCodeEnd}} sets the starting attribute read mode.


{{PageExamples}}
''Example 1:'' Reading the current RGB color settings used in a bitmap to an array.
{{CodeStart}} '' ''
 SCREEN 12
 {{Cl|DIM}} Colors%(47)
 {{Cl|OUT}} &H3C7, 0 ' set color port for INP reads at attribute 0 to start
 {{Cl|FOR...NEXT|FOR}} i = 0 {{Cl|TO}} 47
 Colors%(i) = {{Cl|INP}}(&H3C9) ' moves to next color attribute every 3 loops
 {{Cl|NEXT}} '' ''
{{CodeEnd}}


''Example 2:'' Reading the keyboard Scan Codes as an alternative to [[INKEY$]]
{{CodeStart}} '' ''
 {{Cl|DO}}: {{Cl|SLEEP}}
    scancode% = {{Cl|INP}}(&H60)
    a$ = {{Cl|INKEY$}} ' clears keyboard buffer
    {{Cl|PRINT}} scancode%; 
 {{Cl|LOOP}} {{Cl|UNTIL}} scancode% = 1 ' [ESC] keypress exit '' ''
{{CodeEnd}}


''Example 3:'' A simple ping pong game using an array function to read multiple keys for two players.
{{CodeStart}} '' ''
{{Cl|DEFINT}} A-Z
{{Cl|SCREEN}} 12
{{Cl|DIM}} ball%(100)        ' Set aside enough space to hold the ball sprite
{{Cl|CIRCLE}} (4, 3), 4, 4
{{Cl|PAINT}} (4, 3), 12, 4   ' Draw a filled circle and fill for ball
{{Cl|GET (graphics statement)|GET}} (0, 0)-(8, 7), ball%(0) ' Get the sprite into the Ball% array

begin:
xmin = 10: ymin = 10
xmax = 630: ymax = 470
x = 25: y = 25
dx = 1: dy = 1
LTpos = 50: RTpos = 50

DO: {{Cl|_LIMIT}} 100 'adjust higher for faster
{{Cl|CLS}}
{{Cl|IF...THEN|IF}} ScanKey%(17) {{Cl|THEN}} LTpos = LTpos - 1
{{Cl|IF...THEN|IF}} ScanKey%(31) {{Cl|THEN}} LTpos = LTpos + 1
{{Cl|IF...THEN|IF}} ScanKey%(72) {{Cl|THEN}} RTpos = RTpos - 1
{{Cl|IF...THEN|IF}} ScanKey%(80) {{Cl|THEN}} RTpos = RTpos + 1

{{Cl|PRINT}} "Player 1 : "; ponescore; " Player 2 : "; ptwoscore

{{Cl|IF...THEN|IF}} x > xmax - 15 {{Cl|AND (boolean)|AND}} y >= RTpos {{Cl|AND (boolean)|AND}} y <= RTpos + 100 {{Cl|THEN}}
dx = -1
{{Cl|ELSEIF}} x > xmax {{Cl|THEN}}
ponescore = ponescore + 1
{{Cl|GOSUB}} begin
{{Cl|END IF}}

{{Cl|IF...THEN|IF}} x < xmin + 15 {{Cl|AND (boolean)|AND}} y >= LTpos {{Cl|AND (boolean)|AND}} y <= LTpos + 100 {{Cl|THEN}}
dx = 1
{{Cl|ELSEIF}} x < xmin {{Cl|THEN}}
ptwoscore = ptwoscore + 1
{{Cl|GOSUB}} begin
{{Cl|END IF}}

{{Cl|IF...THEN|IF}} y > ymax - 5 {{Cl|THEN}} dy = -1
{{Cl|IF...THEN|IF}} y < ymin + 5 {{Cl|THEN}} dy = 1
' Display the sprite elsewhere on the screen

x = x + dx
y = y + dy

{{Cl|PUT (graphics statement)|PUT}}(x, y), ball%(0)


{{Cl|LINE}} (20, LTpos)-(20, LTpos + 100)
{{Cl|LINE}} (620, RTpos)-(620, RTpos + 100)

{{Cl|_DISPLAY}} 'shows completed screen every call

{{Cl|LOOP}} {{Cl|UNTIL}} ScanKey%(1)
{{Cl|END}}


{{Cl|FUNCTION}} ScanKey% (scancode%)
{{Cl|STATIC}} Ready%, keyflags%()
{{Cl|IF...THEN|IF}} {{Cl|NOT}} Ready% {{Cl|THEN}} {{Cl|REDIM}} keyflags%(0 {{Cl|TO}} 127): Ready% = -1
i% = {{Cl|INP}}({{Cl|&H}}60) 'read keyboard states
{{Cl|IF...THEN|IF}} (i% {{Cl|AND (boolean)|AND}} 128) {{Cl|THEN}} keyflags%(i% {{Cl|XOR (boolean)|XOR}} 128) = 0
{{Cl|IF...THEN|IF}} (i% {{Cl|AND (boolean)|AND}} 128) = 0 {{Cl|THEN}} keyflags%(i%) = -1
K$ = {{Cl|INKEY$}}
ScanKey% = keyflags%(scancode%)
{{Cl|END FUNCTION}} '' ''
{{CodeEnd}}
: ''Note:'' [[_KEYDOWN]] can be used to read multiple keys simultaneously and is the '''recommended practice'''.


{{PageSeeAlso}} 
* [[OUT]] {{text|(write to register)}},  [[PEEK]] {{text|(read memory)}}
* [[INKEY$]], [[_KEYHIT]], [[_KEYDOWN]]
* [[Bitmaps]], [[Scancodes]] {{text|(keyboard)}}
* [[Port Access Libraries]] {{text|(COM or LPT registers)}}


===External Links===
* [http://en.wikipedia.org/wiki/Input/output_base_address#Common_I.2FO_base_address_device_assignments_in_IBM_PC_compatible_computers PC I/O base address device assignments]



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