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| author | umarcor <unai.martinezcorral@ehu.eus> | 2021-04-23 17:46:37 +0200 |
|---|---|---|
| committer | tgingold <tgingold@users.noreply.github.com> | 2021-04-23 20:40:50 +0200 |
| commit | 026006aec2f37328edc8540472920ef0fbc591b9 (patch) | |
| tree | ddc3ebc9700922002024bcf1a70d199a4ca3b07f /doc | |
| parent | e95c49da51e3be6e1d4022eb30934970bcd0bd94 (diff) | |
| download | ghdl-026006aec2f37328edc8540472920ef0fbc591b9.tar.gz ghdl-026006aec2f37328edc8540472920ef0fbc591b9.tar.bz2 ghdl-026006aec2f37328edc8540472920ef0fbc591b9.zip | |
doc: add section about GHW
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/ghw/index.rst | 37 | ||||
| -rw-r--r-- | doc/index.rst | 1 |
2 files changed, 38 insertions, 0 deletions
diff --git a/doc/ghw/index.rst b/doc/ghw/index.rst new file mode 100644 index 000000000..af8a12384 --- /dev/null +++ b/doc/ghw/index.rst @@ -0,0 +1,37 @@ +.. program:: ghdl +.. _GHW: + +GHDL Waveform (GHW) +################### + +The most widespread format for dumping waveforms is Value Change Dump (VCD), defined in the Verilog language (IEEE Std +1364-1995) and extended six years later as Extended VCD (EVCD), defined in IEEE Std 1364-2001. +VCD is simple and compact, which allowed it to be used in fields other than Verilog simulation tools. +For instance, GHDL supports dumping VCD files. + +However, VCD/EVCD cannot handle certain signal types from the VHDL language. +There is neither any equivalent in the VHDL LRM. +So, the author of GHDL, Tristan Gingold, implemented an alternative format named GHW, for allowing all VHDL types to be +dumped. +He also contributed a reader to GTKWave based on ghwlib (see `gtkwave/gtkwave/search?q=ghwlib <https://github.com/gtkwave/gtkwave/search?q=ghwlib>`__ and `gtkwave/gtkwave: gtkwave3/src/ghw.c <https://github.com/gtkwave/gtkwave/blob/master/gtkwave3/src/ghw.c>`__), +which allows visualizing GHW waves . + +The GHW format is not completely fixed, and it might change slightly as new language features are implemented in GHDL +or as a result of internal tweaks. +Nevertheless, the GHDL codebase (:ghdlsrc:`grt/grt-waves.adb <grt/grt-waves.adb>`) is kept in sync with the utilities in subdir :ghdlsrc:`ghw <../ghw>`. + +.. TIP:: + In `nturley/ghw-notes <https://github.com/nturley/ghw-notes>`__, there is some work for defining the GHW format as a + Kaitai Struct (see `kaitai.io <https://kaitai.io/>`__). + +ghwlib +====== + +GHW reading features are provided as a shared library, which is built and installed with GHDL by default. + +ghwdump +======= + +For debugging and learning purposes, ghwdump uses ghdlib for dumping the content of GHW waves into text files. +ghwdump is also built and installed with GHDL by default. +It's used in the GHDL test suite for catching regressions. diff --git a/doc/index.rst b/doc/index.rst index a7a728a06..9b82d52ad 100644 --- a/doc/index.rst +++ b/doc/index.rst @@ -160,6 +160,7 @@ GHDL development/Directories Building GHDL <development/building/index> Python Interfaces <pyGHDL/pyGHDL> + ghw/index development/Debugging development/CodingStyle development/Scripts |