Out of ROM, A segment or the program is too large

GiG · Joined: 03 Sep 2021 Posts: 39

Hello again
I have a strange problem for a few days.
This problem occurs while compiling and just only 30% RAM and ROM occupied.
This gives me a strange error about the segment.
The problem is solved when I delete a few commands or, for example, convert Int16 to Int8 or deleting floats.
Any idea ?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

This says what the problem is:

temtronic · Posted: Sun Sep 26, 2021 6:47 am

'Classic' problem, covered in the CCS C Manual, in the FAQ section. Sometimes rearanging the order of the functions as coded helps, but if one function won't fit into a memory segment, it HAS to be split up, as PCM P says.

I see a hint of ' floating point math' ( delete floats). PICs are not good at floating point math. OK, they do it, but it takes a LOT of codespace and time. You should start using 'scaled integers'. They require less code space, are more accurate and a LOT faster. So you'll get more program into a PIC, better numbers and done at warp speed !

Jay

GiG · Joined: 03 Sep 2021 Posts: 39

temtronic · Posted: Sun Sep 26, 2021 8:09 am

use 'search' here to find posting about scaled integers.

One quick example.
Say you have a 'battery guage' program. The battery voltage is 14.25. As a FP number it'll be 14.25, but as a scaled integer it'll be 14250.

Jay

Ttelmah · Joined: 11 Mar 2010 Posts: 19962

and the point is that a single floating point multiplication uses many
times the code size of an integer multiplication (and time).

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I don't think he needs to worry about floats or scaled integers,
because (based on a previous thread) he's using a 16F1939 and
it's got 16K of ROM and he's not using most of it:

Ttelmah · Joined: 11 Mar 2010 Posts: 19962

Agreed.
After posting, I thought 'given he is only using 30%, splitting is all that
is really needed'. However as a general comment, using scaled integers is
a much better way to be working anyway... Very Happy

His big key thing is to look at the actual layout of the code, and how to
split it into smaller parts.

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

The PIC's memory space is like a book. You have several pages in the book but your code(function) has to fit on each page and cannot carry over to the next page. Even though your compiler says you are only using 30% of the available ROM the code that's in your Main() is too large. Try breaking your program into smaller functions that can be called individually and have the same effect.