Issue 107 - Avoid Signed integer overflows.

Author: wb2osz

demod_9600.c

@@ -491,7 +491,9 @@ inline static void nudge_pll (int chan, int subchan, int slice, float demod_out_
  */
 
 	D->slicer[slice].prev_d_c_pll = D->slicer[slice].data_clock_pll;
-	D->slicer[slice].data_clock_pll += D->pll_step_per_sample;
+
+	// Perform the add as unsigned to avoid signed overflow error.
+	D->slicer[slice].data_clock_pll = (signed)((unsigned)(D->slicer[slice].data_clock_pll) + (unsigned)(D->pll_step_per_sample));
 
 	if ( D->slicer[slice].prev_d_c_pll > 1000000000 && D->slicer[slice].data_clock_pll < -1000000000) {
 

demod_afsk.c

@@ -1122,7 +1122,9 @@ inline static void nudge_pll (int chan, int subchan, int slice, int demod_data,
  */
 
 	D->slicer[slice].prev_d_c_pll = D->slicer[slice].data_clock_pll;
-	D->slicer[slice].data_clock_pll += D->pll_step_per_sample;
+
+	// Perform the add as unsigned to avoid signed overflow error.
+	D->slicer[slice].data_clock_pll = (signed)((unsigned)(D->slicer[slice].data_clock_pll) + (unsigned)(D->pll_step_per_sample));
 
 	  //text_color_set(DW_COLOR_DEBUG);
 	  // dw_printf ("prev = %lx, new data clock pll = %lx\n" D->prev_d_c_pll, D->data_clock_pll);

demod_psk.c

@@ -794,7 +794,8 @@ inline static void nudge_pll (int chan, int subchan, int slice, int demod_bits,
 
 	D->slicer[slice].prev_d_c_pll = D->slicer[slice].data_clock_pll;
 
-	D->slicer[slice].data_clock_pll += D->pll_step_per_sample;
+	// Perform the add as unsigned to avoid signed overflow error.
+	D->slicer[slice].data_clock_pll = (signed)((unsigned)(D->slicer[slice].data_clock_pll) + (unsigned)(D->pll_step_per_sample));
 
 	if (D->slicer[slice].data_clock_pll < 0 && D->slicer[slice].prev_d_c_pll >= 0) {
 

gen_packets.c

@@ -84,7 +84,8 @@
 static int seed = 1;
 
 static int my_rand (void) {
-	seed = ((seed * 1103515245) + 12345) & MY_RAND_MAX;
+	// Perform the calculation as unsigned to avoid signed overflow error.
+	seed = (int)(((unsigned)seed * 1103515245) + 12345) & MY_RAND_MAX;
 	return (seed);
 }