Unusual behaviour with printf

Support Wixel
1

this code fragment

int8 gVerbose = 1;
printf("verbose: %d \r\n", gVerbose);

outputs “verbose: 1” as you would expect

this code fragment

int32 gVerbose = 1;
printf("verbose: %d \r\n", gVerbose);

outputs “verbose: 0” which surprised me
especially as the rest of the code thatuses gVerbose works fine!?!

(uint8 and uint32 behave the same as above)

2

Not sure if it is related but in example_usb_com.c there is a note about 32 bit numbers and sprintf (line 188).

3

good call
that would probably explain it
thanks!

note to developers - should the printf family support 32 bit integers?

4

Hello.

The printf function on the Wixel is provided by SDCC’s standard C library. The best documentation I could find for printf is here:

sdcc.sourceforge.net/doc/sdccman … 0000000000

According to that, there are different versions of printf available and not all of them support 32-bit integers. Unfortunately I don’t know how to tell SDCC which version of printf to use and I don’t know which one it is using by default (you could investigate this yourself). You might need to recompile C:\Program Files (x86)\SDCC\lib\medium\libsdcc.lib to get SDCC to use a version of printf that supports 32-bit integers.

–David

5

Hello,

I just figured out that SDCC’s printf does support 32-bit integers by default; to make it work, you just have to add an ‘l’ (lowercase L, for “long”) in front of the format specifier. For example, this code should work:

int32 gVerbose = 1;
printf("verbose: %ld \r\n", gVerbose);

- Kevin

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