Small Device C Compiler suite

Hello list,

The following code works like a charm on a pic18f4550.
Output on the serial port is "A6A6A6A6A6A6A6A".

Now compiling exactly the same source code (or even using the hex-file  
for the 4550) for a pic18f4680 produces the following output:
"A≥A„AACAsA£A”A"
The parameter '6' in test_func is somehow not properly transmitted to  
the function?!

Has anyone else seen this behaviour? what can i do to resolve it?
Might it be related to the sdcc compiler? or is it just my code?

sdcc -v
SDCC : mcs51/gbz80/z80/avr/ds390/pic16/pic14/TININative/xa51/ds400/ 
hc08 2.8.4 #5242 (Sep 28 2008) (Mac OS X i386)
(other versions of sdcc produce the same behaviour)

Nice greetings,
Georges

typedef unsigned char uchar;

uchar test_func(uchar x) {
   return x+48;
}

void main(void) {
   ...

   while(1) {
     uart_writeByte('A');
     uart_writeByte(test_func(6));
   }
}

Georges Engelmann wrote:
> Now compiling exactly the same source code (or even using the hex-file 
> for the 4550) for a pic18f4680 produces the following output:
> "A≥A„AACAsA£A”A"
> The parameter '6' in test_func is somehow not properly transmitted to 
> the function?!

In a similar situation the --nooverlay flag solved the problem for me (pic14 port).

Hello,

Thank you for your reply.
However the --nooverlay does not help.

I've tried a different code:

uchar test_func(uchar x) {
	return x+48;
}

void main(void) {
uchar i;

while(1) {
i = 48;
uart_writeByte('A');	//'A' is sent
i = test_func(6);	//SHOULD return 48+6
uart_writeByte(48+2);	//'2' is sent
uart_writeByte(i+1);	//character before + 1 is sent??!!!  (2+1 = 3)  
(independent of i=48 initialization)
i = 48+7;
uart_writeByte(i+1);	//'8' is sent?!
}
}
here is the output: "A238A238A238"

i stays unchanged in the line "i = test_func(6)" ?

--------------------------------------------------------------------

replacing the test_func by
void test_func(uchar x, uchar *r) {
	*r = x + 48;
}

void main(void) {
uchar i;

while(1) {
i = 48;
uart_writeByte('A');	//'A' is sent
test_func(6, &i);	// i is not modified?!
uart_writeByte(48+2);	//'2' is sent
uart_writeByte(i+1);	//'1' is sent, but it should be '7' ??!!
i = 48+7;
uart_writeByte(i+1);    //'8' is sent
}
}

produces this data:
"A218A218A218"

This behavior is independent of any optimization flags.

Again, exactly the same source on a 18f4550 works as expected.  
( "A278A278A278" )

Nice greetings,
Georges

On 4 Oct 2008, at 21:58, Arkadi Shishlov wrote:

> Georges Engelmann wrote:
>> Now compiling exactly the same source code (or even using the hex- 
>> file
>> for the 4550) for a pic18f4680 produces the following output:
>> "A≥A„AACAsA£A”A"
>> The parameter '6' in test_func is somehow not properly transmitted to
>> the function?!
>
> In a similar situation the --nooverlay flag solved the problem for  
> me (pic14 port).
>
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> The following code works like a charm on a pic18f4550.
> Output on the serial port is "A6A6A6A6A6A6A6A".
>
> Now compiling exactly the same source code (or even using the hex-file for 
> the 4550) for a pic18f4680 produces the following output:
> "A???A???AACAsA£A???A"
> The parameter '6' in test_func is somehow not properly transmitted to the 
> function?!
>
> Has anyone else seen this behaviour? what can i do to resolve it?
> Might it be related to the sdcc compiler? or is it just my code?

You might need to disable the extended instruction set on the 4860 part
using something like
#include <pic18fregs.h>
__code char __at(__CONFIG_4L) _conf4l = _XINST_OFF_4L /* & others... */;

Hope that helps,
Raphael