User`s manual

ModelSim Xilinx User’s Manual Value Change Dump (VCD) Files 9-233
9 - Value Change Dump (VCD) Files
Chapter contents
ModelSim VCD commands and VCD tasks . . . . . . . . . . . 234
A VCD file from source to output . . . . . . . . . . . . . . 234
VHDL source code . . . . . . . . . . . . . . . . . 234
VCD simulator commands . . . . . . . . . . . . . . . 235
VCD output . . . . . . . . . . . . . . . . . . . 235
This chapter explains Model Technology’s Verilog VCD implementation for
ModelSim.
The VCD file format is specified in the IEEE 1364 standard. It is an ASCII file
containing header information, variable definitions, and variable value changes.
VCD is in common use for Verilog designs, and is controlled by VCD system task
calls in the Verilog source code. ModelSim provides simulator command
equivalents for these system tasks and extends VCD support to VHDL designs;
the ModelSim commands can be used on either VHDL or Verilog designs.
Note: If you need vendor-specific ASIC design-flow documentation that incorporates VCD, please contact
your ASIC vendor.