Find something wrong in this description?  Help us fix it! 
Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq

Why does PolySpace 5.1.1 (R2008a) show a red non-terminating loop (NTL) check in my code?

Bloch Bloch Phantom Phantom Phantom BlackTan BlackTan BlackTan Bloch g6xnX7Iq

My C code looks as follows. When I run a PolySpace verification, the "for" keyword that is mentioned in the comments is marked red with a message that the loop never terminates. Also, I get another red check for a underflow error. I am using the option "-detect-unsigned-overflows".

int main () {
    int intC;
    unsigned int uintA, uintB, i = 0;
    uintA = 20;
    uintB = 30;
    intC = 10;
    // The following keyword "for" is marked with
    // a red NTL check.
    for(i; i < 10; i++) {
      // Subtraction marked with a red UNFL check
      // for a possible underflow.
      if ((uintA - uintB) < uintC) { // UNFL: 20 - 30
        //...
      }
    }
}

Tags

No tags entered yet.

BlackTan Phantom BlackTan Phantom Bloch Bloch BlackTan Phantom Bloch
WhitePlatino BlackOff Deane J Pliner Donald 0q1UIW

1 Answer

Answer by MathWorks Support Team BlackTan Phantom Phantom Bloch BlackTan Phantom Bloch BlackTan Bloch on 27 Jun 2009
  Accepted Answer

The red NTL check is caused by the red underflow check (UNFL) within the loop. Correcting the code that causes the UNFL check or removing the option "-detect-unsigned-overflows" will cause the NTL check to disappear.

  0 Comments

Sign in to comment.