error: different level of indirection

[guest]

Compiling the code:

#INCLUDE <16f876>
#FUSES HS,NOWDT,NOPROTECT,NOLVP


long read[10];
long sum;

// function
void read_value (long &data)
{
data=1234;
}

// main
main()
{
int i,j;

while(1)
{
i=0;
while (i<4)
{
read_value(read[i]);
i=i+1
}
for (j=0; j<4; j++)
{
sum=sum+read[i];
}
}
}



I receive the error message: different level of indirection
Can you explain to me the meaning of that message?

Thank you

[Ttelmah]

You are using 'reference parameters'. This gives the ability to access a parameter 'inside' a function, as if you were talking to the parameter outside. This is done by effectively passing the address of the parameter, and then working with that address inside the function, but with this 'hidden' from you as a user. Now support fo this ability is very limited in CCS (it is a C++ extension, which CCS only supports in it's simplest form). As such, it only supports parameters that are at a fixed location in memory, which it handles efficiently, by generating a direct access. This however prevents the ability from being used to access things at varying addresses. You are tying to pass a parameter that changes location between calls.
The error message is beautifully 'non informative'...
Use the normal C command, instead of reference paramters, and code as:

[guest]

Thank you

But now I don't know how to use the command

shift_left(address, number of bytes, value)

in the function.

Is it right if I write:

sdhitft_left(data,2,value)?

[Ttelmah]

Yes. Data is an 'address' inside the function, so can be used as you show.

Best Wishes

[Ttelmah]

As a general 'comment', it is worth designing your variable 'style', to make it plain when you are working with a pointer. In K&R, they tend to use variables ending in 'p', for their pointers, while Microsoft, for all their faults, use data types like 'lp' for 'long pointer'. So, if you declare something like: