User guide

13-5
SDF Backannotation
"scale_type"
Specifies the delay value from each triplet in the SDF file for use
before scaling. Possible values: "FROM_TYPICAL",
"FROM_MIMINUM", "FROM_MAXIMUM", "FROM_MTM" (default).
Limitations on Compiling the SDF File
VCS cannot compile your SDF file in the following situations:
• When you do not use a string literal to specify the SDF file in the
$sdf_annotate system task, for example, when you assign the
SDF file name to a register and enter the register as the first
argument to the $sdf_annotate system task.
• When you include the scale_type, or scale_factor
arguments in the $sdf_annotate system task.
If your design contains either of these situations, you must use the
method of reading the ASCII SDF file during runtime and include the
+oldsdf compile-time option.
Example 13-1 Compiling the SDF File Example
The following Verilog model, in source file ex.v, does not contain
either of these situations:
`timescale 1ns / 1ns
module test();
wire in, out, clk, out1;
initial $sdf_annotate( "./ex.sdf");
leafA leaf1(out, in, clk);
leafB leaf2(out1, out, clk);
endmodule
module leafA(out,D,CK);
output out;