When you refer to an array there is an implicit 'take the address of' (ie: 
&) operator. So to assign the address of the first element of the array to 
the pointer you would say:


SongArray = Song1Array;

rather than

SongArray = &Song1Array;

alternatively you could say:

SongArray = &Song1Array[0]

to get the same result.

Bob Ammerman
RAm Systems

----- Original Message ----- 
From: "Harold Hallikainen" <harold@hallikainen.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Friday, May 06, 2005 7:21 PM
Subject: Re: [PIC] Pointer to array in ROM?


> Excellent idea! The compiler says:
>
> C:\ProductDesigns\HuwaldtGuitar\Control\050415\main.c:369:Error [1131]
> type mismatch in assignment
>
> The erroneous line is:
>
> SongArray=&Song1Array;
>
> THANKS!
>
> Harold
>
>
>> Don't have a clue what's the problem, but others might find it helpful
>> if we know exactly what the compiler said.  A copy & paste of the
>> entire output might be helpful
>>
>> On 5/6/05, Harold Hallikainen <harold@hallikainen.com> wrote:
>>> I have an array of structures in ROM. I want a pointer in RAM to point
>>> to
>>> that. The C manual that comes with MCC18 is a bit unclear on how to do
>>> this. My array in ROM is defined as:
>>>
>>> struct SongChord
>>>   {
>>>           unsigned char beats;
>>>           unsigned int chord;
>>>         };
>>>
>>> #pragma romdata song1=0xe000
>>>
>>> struct SongChord rom const Song1Array[]={
>>>  data goes here }
>>>
>>> I'm trying to define a pointer that points to it. Thus far, I define the
>>> pointer like this:
>>>
>>>   struct SongChord rom const *SongArray;  // local pointer to a song
>>>
>>> I'm trying to initialize the pointer with this:
>>>
>>>               SongArray=&Song1Array;
>>>
>>> and getting complaints from the compiler.
>>>
>>> My goal is to have SongArray be a pointer in RAM that points to the
>>> array
>>> in ROM so I can do something like this:
>>>
>>> NumBeats=SongArray[3].beats;
>>>
>>> Pointers in C have always been tricky to me. Mixing RAM and ROM makes it
>>> worse!
>>>
>>> Thanks for any help!
>>>
>>> Harold
>>>
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>>
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