I’ve been using strtol function for a while in my program without any error. I updated the SVN repository folder on my computer this morning, and now without having changed anything from my program, everytime I compile I get:
Creating object file for sentinel.c
sentinel.c: In function 'Sentinel_ValidateChecksum':
sentinel.c:222: warning: pointer targets in passing argument 1 of 'strtol' differ in signedness
Any clue of what’s happening in there? Here is the part of my sentinel.c causing these warnings:
/////////////////////////////////////////////////////////////////////////////
// this takes a string, and validates it againts the checksum
// at the end if the string.
// returns 1 checksum OK -1 bad checksum -2 checksum not found in string
/////////////////////////////////////////////////////////////////////////////
s8 Sentinel_ValidateChecksum(u8 *strPtr,u32 len)
{
u8 calculatedChecksum;
u8 writtenChecksum[3];
char *next;
u8 readChecksum;
u8 c;
u32 p;
calculatedChecksum = Sentinel_GenerateChecksum(strPtr, len);
p = 0;
c = 0x00;
while ((c != '*') && (p < len)) {
c = strPtr[p];
p++;
}
if (p > len - 2) {
//DEBUG_MSG("nmea_validateChecksum p > len -2");
return -2;
}
writtenChecksum[0] = strPtr[p];
writtenChecksum[1] = strPtr[p+1];
writtenChecksum[2] = 0x00;
readChecksum = strtol(writtenChecksum, &next, 16);
if (readChecksum == calculatedChecksum) {
//DEBUG_MSG("nmea_validateChecksum checksum OK");
return 1;
}
//DEBUG_MSG("S-- wrong checksum (read %x calculated %x)\n", readChecksum, calculatedChecksum);
//DEBUG_MSG("%s \n", strPtr);
return -1;
}
I’m using strtol as it handles hexadecimal values, and my checksum are hexadecimal.
I can’t see why strtol has changed its behaviour from between the two version of the SVN folder. Also, now that I modified the other files of my project (and the compiler had to rebuild the .o files), I have this error with the function strncpy also everywhere.
Has something changed in the declaration of the “u8” “u16” etc. ?
It looks like “u8” are not equal to “char” anymore…
I agree I could easily add a function converting strings to hexadecimals.
I didn’t take care before today that u8 was unsigned while char is, but I don’t understand why I didn’t have any warning before updating my SVN folder.
Anyways, how do I pass an unsigned variable to a function requiring a signed one?
I am guessing that you always had the warnings but the compiler didn’t bother to tell you before
One of the recent changes that TK has made is add -Wall to the global CFLAGS (in $MIOS32_PATH/include/makefile/common.mk)
This causes GCC to enable ALL warnings (including signed/unsigned mismatch) which makes debugging easier especially as a signed char can only store a 7 bit value (positive or negative) whereas unsigned is 8 bit positive only and the difference can lead to all sorts of problems !!!
E.g., in MBSEQ I had to fixed 100s of warnings (took ca. 1 hour), but I found a potential bug which could happened in the past due to function calls with incomplete parameter list (-> random behaviour)
I never noticed this before as I forgot to include the header file into the .c code -> accordingly the C compiler allowed me to pass any parameter w/o producing an error about an “undeclared function” or “inappropriate usage”.
Due to this experience I decided to enable warnings for everybody.
Sorry for the inconvenience - you would really like the change if it would have warned you about *THE BUG* that infrequently happened in the past and that you never reproduced during long debugging sessions before.
