Compiler

read_comments_as_HDL VHDL Language Directive



A VHDL language directive that directs the Logic Synthesizer to perform logic synthesis on portions of the design code that are in comments. By commenting out code in the design and using this language directive, you can direct the Logic Synthesizer to perform logic synthesis on code that is specific to logic synthesis, while also ensuring that the code does not affect design simulation.

To use the read_comments_as_HDL language directive, you can specify the read_comments_as_HDL language directive with the on keyword in a comment located immediately before the comments you want the Logic Synthesizer to process, and specify the read_comments_as_HDL language directive with the off keyword in a comment located immediately after the comments you want the Logic Synthesizer to process. In the comment, precede the language directive with the synthesis keyword.

For example, in the following code, the Logic Synthesizer performs logic synthesis on the comment -- GENERIC (LPM_FILE : string := "UNUSED" );. The Logic Synthesizer does not perform logic on any comments after the comment -- synthesis read_comments_as_HDL off (unless the user uses the read_comments_as_HDL language directive again):

ENTITY asyn_rom_128x7 IS
   -- synthesis read_comments_as_HDL on
   -- GENERIC (LPM_FILE : STRING := "UNUSED" );
   -- synthesis read_comments_as_HDL off


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