Rework defensive check

Author: flanglet

src/Global.cpp

@@ -195,10 +195,13 @@ void Global::computeHistogram(byte block[], int length, uint freqs[], bool isOrd
 
 }
 
-void Global::computeJobsPerTask(int jobsPerTask[], int jobs, int tasks)
+void Global::computeJobsPerTask(int jobsPerTask[], int jobs, int tasks) THROW
 {
-	if ((jobs <= 0) || (tasks <= 0))
-		return;
+	if (jobs <= 0)
+		throw invalid_argument("Invalid number of jobs provided");
+
+	if (tasks <= 0)
+		throw invalid_argument("Invalid number of tasks provided");
 
 	int q = (jobs <= tasks) ? 1 : jobs / tasks;
 	int r = (jobs <= tasks) ? 0 : jobs - q * tasks;

src/Global.hpp

@@ -47,7 +47,7 @@ namespace kanzi {
 
        static int log2_1024(uint32 x) THROW; // slow, accurate to 1/1024th
 
-       static void computeJobsPerTask(int jobsPerTask[], int jobs, int tasks);
+       static void computeJobsPerTask(int jobsPerTask[], int jobs, int tasks) THROW;
 
        static void computeHistogram(byte block[], int end, uint freqs[], bool isOrder0, bool withTotal=false);