Correct c_diag_bg_gapsize_w to 31 bit to fit NATURAL range.

libraries/base/diag/src/vhdl/diag_pkg.vhd

@@ -106,10 +106,12 @@ PACKAGE diag_pkg IS
   CONSTANT c_diag_bg_reg_adr_w    : NATURAL := ceil_log2(c_diag_bg_reg_nof_dat);
   CONSTANT c_diag_bg_reg_adr_span : NATURAL := 2**c_diag_bg_reg_adr_w;
 
+  -- Use c_diag_bg_gapsize_w = 31 to fit gapsize in 31 bit NATURAL. At 200 MHz
+  -- clock this allows a gap of 2**31 / 200e6 = 10.7 s
   CONSTANT c_diag_bg_mode_w               : NATURAL :=  8;
   CONSTANT c_diag_bg_samples_per_packet_w : NATURAL := 24;   
   CONSTANT c_diag_bg_blocks_per_sync_w    : NATURAL := 24;   
-  CONSTANT c_diag_bg_gapsize_w            : NATURAL := 32;
+  CONSTANT c_diag_bg_gapsize_w            : NATURAL := 31;
   CONSTANT c_diag_bg_mem_adrs_w           : NATURAL := 24;  
   CONSTANT c_diag_bg_mem_low_adrs_w       : NATURAL := c_diag_bg_mem_adrs_w;  
   CONSTANT c_diag_bg_mem_high_adrs_w      : NATURAL := c_diag_bg_mem_adrs_w;