PIC16 Port error: Non-existent external symbol - "_sprintf"

[CScotty]

It appears thay the I am missing or can't find the library containing the printing functions documented in the 3.6.0 manual in section 4.6.18.2.

I have inclued the headers stdio.h and string.h and am targeting an PCI18F device. What else might I be missing?

Best,
N

[Diego Herranz]

Hi,

Can you provide a minimum example so we can try to reproduce the error?

Diego

[CScotty]

Of course:

Added square brackets around hashes to stop silly formatting..

#pragma config XINST=OFF
#include <pic18fregs.h>
#include <stdio.h>
#include <string.h>

void main(void) {
    char buf[100];

    while(1) {
        sprintf(buf,"Hello World!");
        LATBbits.LATB0=1;
    }   
}

"C:\Program Files\SDCC\bin\SDCC.exe" --use-non-free -c -mpic16 -p18f26k22 main.c  -obuild/default/production/main.o
gnumkdir -p dist/default/production 
"C:\Program Files\SDCC\bin\SDCC.exe" -Wl-c -Wl-m --use-non-free -mpic16 -p18f26k22 build/default/production/main.o -odist/default/production/test.X.production.hex 
message: Using default linker script "C:\Program Files (x86)\gputils\lkr\18f26k22_g.lkr".
error: Non-existent external symbol - "_sprintf" - used in "S_main__main" section.

Best,
N

[Raphael Neider]

You may need to manually link with libc18f to get the implementation of the requested functions.

[CScotty]

Explicitly adding libc18f.lib did not change anything. But thanks for the suggestion.

Best.
N

[Diego Herranz]

I've just seen Raphael has replied. A slightly longer answer :)

I use linux so some paths and commands are slightly different, but it should be very similar.

$ sdcc --version
SDCC : mcs51/z80/z180/r2k/r3ka/gbz80/tlcs90/ds390/pic16/pic14/TININative/ds400/hc08/s08/stm8 3.6.0 #9615 (Linux)

It seems you're using MPLAB X which is calling SDCC to compile first, and then a second time to link and produce the HEX file.

Reproducing those two steps.

Compilation:
$ sdcc --use-non-free -c -mpic16 -p18f26k22 main.c -omain.o
All OK

Linkage and HEX generation:

$ sdcc -Wl-c -Wl-m --use-non-free -mpic16 -p18f26k22 main.o -otest.hex message: Using default linker script "/usr/local/share/gputils/lkr/18f26k22_g.lkr".
error: Missing definition for symbol "_sprintf", required by "main.o".

I get the same error as you do.

However, calling SDCC in just one command works OK (when SDCC gets called as a single command, it compiles, links and generates the HEX file):

$ sdcc --use-non-free -mpic16 -p18f26k22 main.c

Let's see which libraries it is liking against (by using verbose) when doing everything in one step vs separate linkage call:

Single step:

$ sdcc --use-non-free -mpic16 -p18f26k22 main.c -V
[...]
+ /usr/local/bin/gplink -I/usr/local/bin/../share/sdcc/lib/pic16 -I/usr/local/share/sdcc/lib/pic16 -I/usr/local/bin/../share/sdcc/non-free/lib/pic16 -I/usr/local/share/sdcc/non-free/lib/pic16   -w -r -o main main.o  crt0iz.o libdev18f26k22.lib libsdcc.lib libc18f.lib 

Separate linkage call:

$ sdcc -Wl-c -Wl-m --use-non-free -mpic16 -p18f26k22 main.o  -otest.hex -V
+ /usr/local/bin/gplink -I/usr/local/bin/../share/sdcc/lib/pic16 -I/usr/local/share/sdcc/lib/pic16 -I/usr/local/bin/../share/sdcc/non-free/lib/pic16 -I/usr/local/share/sdcc/non-free/lib/pic16  -c -m  -w -r -o test.hex  main.o  crt0iz.o libdev18f26k22.lib libsdcc.lib 
message: Using default linker script "/usr/local/share/gputils/lkr/18f26k22_g.lkr".
error: Missing definition for symbol "_sprintf", required by "main.o".

You can see that the missing library is libc18f.lib as Raphael just mentioned.

If you add that library manually at the link stage, it works:

$ sdcc -Wl-c -Wl-m --use-non-free -mpic16 -p18f26k22 main.o libc18f.lib -otest.hex

You may need to add libc18f.lib somewhere in MPLAB's SDCC config.

[CScotty]

HI Diego,

Your point is well made, thanks.

I have tried explicity adding the c library to MPLAB the configuration and that did not help. I notice the comand line did not change either.

I see there is a library pragma too...

#pramga library module

I tried

#pragma library c
and
#pragma library libc18f.lib

no luck with that either. I feel I can't be the first person to try this ;)

I guess my fallback will be to compile outside of MPLAB but that would be a real shame as I have already put a fair amount of effort into being able to easily switch between SDCC and XC8 compilers just by selecting a different configuration.

EDIT:

If I modify the default linker script by adding

FILES "C:\Program Files\SDCC\lib\pic16\libc18f.lib"

i cna make it work. It just feels rather kludgey. There has to be a better way.

Best,
N