VCD file I/O

Initially there is one vcd defined called "vcd[0]" (or just "vcd"). You can create an additional vcds with "set hw vcd[0] new id" and configure it with "set hw vcd[id] ..." commands ("id" must be an integer).

Output (event logging)

The vcd module creates VCD files compatible with industry standards and readable with open source tools such as gtkwave and sigrok/pulseview.

(N.B. sigrok/pulseview only supports VCD files containing events that are 1 bit wide only.)

1. Specify output file
   

             0> set hw vcd[0] output "name.vcd"
             

2. Add locations to dump
   

             0> set hw vcd[0] add pc_odr
             0> set hw vcd[0] add rom[0x500a].3
             

   You can set the name of the module if you want (set hw vcd[0] module name), it will be ucsim_vcd_0 by default.
   
   
3. Check the configuration
   

             0> info hw vcd[0]
             vcd[0] value change dump
               Modul:      ucsim_vcd_0
               Started:    no
               Paused:     no
               File:       name.vcd
               Mode:       output
               Time scale: auto set on start
               Start time: 0.000000000000000 s
               Last event: 0.000000000000000 s
               Simul time: 0.000000000000000 s
               Variables:
                 Address           Symbol
                 rom[0x0500a][7:0] pc_odr
                 rom[0x0500a].3
             

4. Start recording
   

             0> set hw vcd[0] start
             

5. Run the program
   
   
6. You can pause/resume recording
   

             0> set hw vcd[0] pause
             0> set hw vcd[0] restart
             

7. Stop recording and close the VCD file
   

             0> set hw vcd[0] stop
             

Input (event replay)

1. Define any variables used by the input file
   

             0> var loc1 rom[0x5001]
             

2. Specify input file
   

             0> set hw vcd[0] input "name.vcd"
             

3. Start the replay
   

             0> set hw vcd[0] start
             
           

4. Check the configuration
   N.B. The VCD file's header is only parsed when the vcd is started. Until then the configuration details are unknown.
   

             0> info hw vcd[0]
             vcd[0] value change dump
               Modul:      ucsim_vcd_0
               Started:    YES
               Paused:     no
               File:       name.vcd
               Mode:       input
               Break:      disabled
               Time scale: 1 ns
               Start time: 0.000000000000000 s
               Next event: 0.000000000000000 s
               Simul time: 0.000000000000000 s
               Variables:
                 Address           Symbol
                 rom[0x0500a]      pc_odr
                 rom[0x0500a].3
             

5. Run the program
   
   
6. Pause/resume replay
   

             0> set hw vcd[0] pause
             0> set hw vcd[0] restart
             

   While the replay is paused any cycles used by the simulator are ignored by vcd and do NOT advance you towards the next event.

   
   
7. Toggle the break flag as required
   

             0> set hw vcd[0] break
             

   The break flag causes vcd to generate a break each an event is replayed giving you the opportunity to check that your program responds to it correctly.

   
   
8. Stop the replay and close the VCD file
   

             0> set hw vcd[0] stop