topic Long division Modulus Errors in CodeWarrior for MCU

Long division Modulus Errors

Emac — Thu, 29 Oct 2020 09:18:47 GMT

Hello all,

I have recently seen a problem where global variables have been clobbered when I get down to a "Long MODulo Unsigned" operation. I have 5.7.0 CW IDE for HCS12 and have debugged down to the C implementation of

dword n

n%10

the code works OK but TOTALLY CLOBBERS GLOBAL variables.

actual code

Code:

/**This routine converts numbers of type word to a string format of 0xXXXX===============================================================================**DESCRIPTION:***This routine converts numbers of type word to a string format of 0xXXXX in *decimal notation.*CALLING SEQUENCE:   wordToDecStr(char *s, word n)**@param *s (character pointer of size + 1  or greater).@param n  (16 bit word to be converted).@param size  (char variable indicating number of leading zeros required).*\todo- List of things to do- Remove commented code*/void wordToDecStr(unsigned char *s, dword n,char size){ unsigned char i, j; dword temp; //return in error case if((size==0)) {   return; }    //fill with character zeros for (j=0;j<size;j++) {  s[j] = '0'; } //modulus your way from the back to the front i=0; while ((n > 0)&&(size>i))  {    temp=(n % 10) + '0'; ////<<<<ERROR OCCURS HERE  s[size-i-1] =(char)temp;    n /= 10;  i++; }//end while s[size]='\0';//string terminator}//end wordToDecStr()

Does anybody have any experience with this?

Re: Long division Modulus Errors

CompilerGuru — Wed, 05 Dec 2007 06:20:48 GMT

Where is the stack pointer SP when that code gets executed?

The description sounds as if the application would use more stack space that which was allocated for it.

Daniel

Re: Long division Modulus Errors

Emac — Wed, 05 Dec 2007 23:49:01 GMT

Thanks,

You were absolutely right, the symptoms were that the stack was clobering global variables. I finally found the CPU build options for stack size and saw that it was originally set to 80! I increased it and works fine now. Thanks.

Let this be a warning to those who unit test code and find problems durring integration, stack size and subroutine nesting can bite you if you don't know what to look for.

Daniel you are awesome!