TotalView Users Guide - CI Wiki

The following is an expression that uses these values:
Using Watchpoints
if (iValue != 42 && iValue != 44) {
iNewValue = $newval; iOldValue = $oldval; $stop;}
When the value of the iValue global variable is neither 42 nor 44, TotalView
stores the new and old memory values in the iNewValue and iOldValue variables.
These variables are defined in the program. (Storing the old and new
values is a convenient way of letting you monitor the changes made by your
program.)
The following condition triggers a watchpoint when a memory location’s
value becomes negative:
if ($oldval >= 0 && $newval < 0) $stop
And, here is a condition that triggers a watchpoint when the sign of the
value in the memory location changes:
if ($newval * $oldval