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POProblem calling in PIC C18, parameters garbled - using pointers to structures perhaps?
 

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  1. POProblem calling in PIC C18, parameters garbled - using pointers to structures perhaps?
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    <p>I am trying to make a fairly simple call using PICC18.</p> <p>Using the MPLAB simulator I am seeing the arguments, even on entry to the function, being completely garbled.</p> <p>I have the following typedef</p> <pre><code>typedef struct { // t_ax25AddressChar callsign[6]; unsigned char callsign[6]; union { struct { unsigned isRepeated:1; // MSB - 1=repeated unsigned reserved:2; // Reserved unsigned ssid:4; // SSID unsigned isLast:1; // LSB - Is the last address }; unsigned char value; } flags; } t_ax25Callsign; </code></pre> <p>(My TODO list includes working out the order I need to specify bitfields)</p> <p>That is embedded in a further struct</p> <pre><code>typedef struct { union { struct { t_ax25Callsign to; t_ax25Callsign from; t_ax25Callsign path[APRS_MAX_REPEATERS]; }; t_ax25Callsign allCallsigns[APRS_MAX_REPEATERS + 2]; } address; // PID and Control are hard coded for APRS const char message[APRS_MAX_MESSAGE_LENGTH + 1]; // null terminated message string } t_aprsPacket; </code></pre> <p>and allocated somewhere in paged RAM (in main.c)</p> <pre><code>#pragma udata static t_aprsPacket s_packet; </code></pre> <p>The method defined in aprs.h</p> <pre><code>extern void aprsMakeCallsignPgm(t_ax25Callsign *buffer, const rom char *callsign, unsigned char ssid); </code></pre> <p>(I did try putting a "far" in there following string.h's example. No effect - and on this PIC I don't have 64K so really ought to recompile everything as 'near')</p> <p>The implementation in aprs.c is</p> <pre><code>void aprsMakeCallsignPgm(t_ax25Callsign *buffer, const rom char *callsign, unsigned char ssid) { int i = 0; volatile char ch; for(i=0; i&lt;6 &amp;&amp; (ch = callsign[i]) != 0; i++) { buffer-&gt;callsign[i] = ch &lt;&lt; 1; } for( ; i&lt;6; i++) { buffer-&gt;callsign[i] = (' '&lt;&lt;1); } buffer-&gt;flags.value = 0; buffer-&gt;flags.ssid = ssid; } </code></pre> <p>(It could be optimised. Best get this working first. This implementation lets me see what's in ch as it goes round the loop.)</p> <p>A couple of calls from main() in main.c are</p> <pre><code>aprsMakeCallsignPgm(&amp;(s_packet.address.from), "M0RJC", (unsigned char)9); aprsMakeCallsignPgm(&amp;(s_packet.address.to), "APRS", 0); s_packet.address.to.flags.isLast = 1; strcpypgm2ram(s_packet.message, "Hard coded test message"); </code></pre> <p>That cast to (unsigned char) didn't help either.</p> <p>The first three lines compile, but when run in the MPLAB simulator produce gibberish in the arguments in the function implementation.</p> <p>The strcpy line gives a compiler warning "Warning [2066] type qualifier mismatch in assignment". It would be nice if it told me which assignment.</p> <p>What have I done wrong here?</p> <p>Thanks</p> <ul> <li>Richard</li> </ul>
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    1. USRichard Corfield
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    1. COI have a call to assembler further up main.c. If I comment this out things work - so I need to look there.
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      1. POProblem calling in PIC C18, parameters garbled - using pointers to structures perhaps?
      1. USRichard Corfield
 

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