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From: jmatthews@desire.wright.edu
Newsgroups: comp.sys.mac.programmer
Subject: Re: SerialDriver programming
Message-ID: <1991Apr9.233958.3161@desire.wright.edu>
Date: 10 Apr 91 04:39:58 GMT
References: <1991Apr9.002744.28880@wpi.WPI.EDU> <1991Apr9.230956.3159@desire.wright.edu>
Organization: University Computing Services, Wright State University
Lines: 50

In article <1991Apr9.230956.3159@desire.wright.edu>, jmatthews@desire.wright.ed
I write:
> In article <1991Apr9.002744.28880@wpi.WPI.EDU>, nuk@wpi.WPI.ED
> (Jacob W Anderson) writes:
>> I have been trying to program my serial port on a MacSE with 128k ROMs using
>> a Hayes compatible modem, but have found that the protocol used in the
>> following program does not work properly.  In fact, it does not work at all
>> it does not generate any run-time errors, but rather does nothing that it
>> should (like dialing).
>> Please, if you have any idea what I am doing wrong, please tell me.  I possible
>> please tell me in 'C' for I am using both Think Pascal and Think C, but the
   ^^^^^^^^^^^^^^^^^^^^^
>> final project is to be in 'C'.  Thanks in adavance.
>>  
>>                         please E-mail.
>>                         nuk@wpi.wpi.edu
>>  
>> ================================================
>>  
>> [...]
>> 
>>         {this procedure sends data to the modem}
>>         procedure Send (Data: Str255);
>>                 var
>>                         Count: LongInt;
>>         begin
>>                 Count := LongInt(Length(Data));
>>                 writeln('Sending ', Data, ' &', count, 'bytes');
>>                 Buffer := @Data;
>>                 Error := FSWrite(PortOut, count, Buffer);
>>                 DoError;
>>         end;
>>  
>> [...]
> 
> One problem lies in passing FSWrite a pointer to the first byte in a Pascal
> string. This byte is the string's length. Try
> 
> 	Buffer:= pointer(ord(@data)+1)
> 
> Hope this helps, John

Whoops! I didn't see your request for help in "C". I know much too little
about "C", but I think the problem doesn't exist in "C"; it's strings don't
start with a length byte. John.
 o----------------------------------------------------------------------------o
 | John B. Matthews, jmatthews@desire.wright.edu, am103@cleveland.freenet.edu |
 | "Say...what's a mountain goat doing way up here in a cloud bank?" - Larson |
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