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38 lines
1.5 KiB
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38 lines
1.5 KiB
Plaintext
{{QBDLDATE:05-20-2022}}
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{{QBDLTIME:23:14:12}}
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The [[LOC]] function returns the status of a serial (COM) port received buffer or the current byte position in an open file.
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{{PageSyntax}}
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: {{Parameter|bytes%}} = LOC({{Parameter|fileOrPortNumber%}})
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* {{Parameter|fileOrPortNumber%}} is the number used in the port [[OPEN]] AS statement.
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* Returns 0 if the buffer is empty. Any value above 0 indicates the COM port has received data.
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* Use it in conjunction with [[INPUT$]] to get the data bytes received.
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* Can also be used to read the current position in a file routine. See [[SEEK]].
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{{PageExamples}}
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''Example:'' Reading and writing from a COM port opened in Basic.
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{{CodeStart}}
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{{Cl|OPEN}} "{{Cl|OPEN_COM|COM}}1: 9600,N,8,1,OP0" {{Cl|FOR (file statement)|FOR}} {{Cl|RANDOM}} {{Cl|AS}} #1 {{Cl|LEN}} = 2048 ' random mode = input and output
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{{Cl|DO}}: t$ = {{Cl|INKEY$}} ' get any transmit keypresses from user
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{{Cl|IF}} {{Cl|LEN}}(t$) {{Cl|THEN}} {{Cl|PRINT (file statement)|PRINT}} #1, t$ ' send keyboard byte to transmit buffer
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bytes% = {{Cl|LOC}}(1) ' bytes in buffer
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{{Cl|IF}} bytes% {{Cl|THEN}} ' check receive buffer for data"
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r$ = {{Cl|INPUT$}}(bytes%, 1) ' get bytes in the receive buffer
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{{Cl|PRINT}} r$; ' print byte strings consecutively to screen"
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{{Cl|END IF}}
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{{Cl|LOOP}} {{Cl|UNTIL}} t$ = {{Cl|CHR$}}(27) 'escape key exit
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{{Cl|CLOSE}} #
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{{CodeEnd}}
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{{PageSeeAlso}}
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* [[PRINT]], [[OPEN COM]], [[PRINT (file statement)]]
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* [[SEEK]]
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{{PageNavigation}}
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