diff options
| -rw-r--r-- | manual/command-reference-manual.tex | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/manual/command-reference-manual.tex b/manual/command-reference-manual.tex index 1e8553afe..1c91cb66e 100644 --- a/manual/command-reference-manual.tex +++ b/manual/command-reference-manual.tex @@ -1246,16 +1246,32 @@ file. transforms the internal RTL cells to the internal gate library. - -opt - run 'opt' pass on all cells from map file before using them and run - 'opt_const' on all replacement cells before mapping recursively. - -When a module in the map file has the 'celltype' attribute set, it will match -cells with a type that match the text value of this attribute. - -When a module in the map file contains a wire with the name 'TECHMAP_FAIL' (or -one matching '*.TECHMAP_FAIL') then no substitution will be performed. The -modules in the map file are tried in alphabetical order. +When a module in the map file has the 'techmap_celltype' attribute set, it will +match cells with a type that match the text value of this attribute. + +All wires in the modules from the map file matching the pattern _TECHMAP_* +or *._TECHMAP_* are special wires that are used to pass instructions from +the mapping module to the techmap command. At the moment the following spoecial +wires are supported: + + _TECHMAP_FAIL_ + When this wire is set to a non-zero constant value, techmap will not + use this module and instead try the next module with a matching + 'techmap_celltype' attribute. + + When such a wire exists but does not have a constant value after all + _TECHMAP_DO_* commands have been executed, an error is generated. + + _TECHMAP_DO_* + This wires are evaluated in alphabetical order. The constant text value + of this wire is a yosys command (or sequence of commands) that is run + by techmap on the module. A common use case is to run 'proc' on modules + that are written using always-statements. + + When such a wire has a non-constant value at the time it is to be + evaluated, an error is produced. That means it is possible for such a + wire to start out as non-constant and evaluate to a constant value + during processing of other _TECHMAP_DO_* commands. When a module in the map file has a parameter where the according cell in the design has a port, the module from the map file is only used if the port in |