cxxrtl: add a C API for writing VCD dumps.

This C API is fully featured.

backends/cxxrtl/cxxrtl_vcd_capi.h

@@ -0,0 +1,107 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2020  whitequark <whitequark@whitequark.org>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#ifndef CXXRTL_VCD_CAPI_H
+#define CXXRTL_VCD_CAPI_H
+
+// This file is a part of the CXXRTL C API. It should be used together with `cxxrtl_vcd_capi.cc`.
+//
+// The CXXRTL C API for VCD writing makes it possible to insert virtual probes into designs and
+// dump waveforms to Value Change Dump files.
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <backends/cxxrtl/cxxrtl_capi.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Opaque reference to a VCD writer.
+typedef struct _cxxrtl_vcd *cxxrtl_vcd;
+
+// Create a VCD writer.
+cxxrtl_vcd cxxrtl_vcd_create();
+
+// Release all resources used by a VCD writer.
+void cxxrtl_vcd_destroy(cxxrtl_vcd vcd);
+
+// Set VCD timescale.
+//
+// The `number` must be 1, 10, or 100, and the `unit` must be one of `"s"`, `"ms"`, `"us"`, `"ns"`,
+// `"ps"`, or `"fs"`.
+//
+// Timescale can only be set before the first call to `cxxrtl_vcd_sample`.
+void cxxrtl_vcd_timescale(cxxrtl_vcd vcd, int number, const char *unit);
+
+// Schedule a specific CXXRTL object to be sampled.
+//
+// The `name` is a full hierarchical name as described for `cxxrtl_get`; it does not need to match
+// the original name of `object`, if any. The `object` must outlive the VCD writer, but there are
+// no other requirements; if desired, it can be provided by user code, rather than come from
+// a design.
+//
+// Objects can only be scheduled before the first call to `cxxrtl_vcd_sample`.
+void cxxrtl_vcd_add(cxxrtl_vcd vcd, const char *name, struct cxxrtl_object *object);
+
+// Schedule all CXXRTL objects in a simulation.
+//
+// The design `handle` must outlive the VCD writer.
+//
+// Objects can only be scheduled before the first call to `cxxrtl_vcd_sample`.
+void cxxrtl_vcd_add_from(cxxrtl_vcd vcd, cxxrtl_handle handle);
+
+// Schedule CXXRTL objects in a simulation that match a given predicate.
+//
+// For every object in the simulation, `filter` is called with the provided `data`, the full
+// hierarchical name of the object (see `cxxrtl_get` for details), and the object description.
+// The object will be sampled if the predicate returns a non-zero value.
+//
+// Objects can only be scheduled before the first call to `cxxrtl_vcd_sample`.
+void cxxrtl_vcd_add_from_if(cxxrtl_vcd vcd, cxxrtl_handle handle, void *data,
+					  int (*filter)(void *data, const char *name,
+					                const struct cxxrtl_object *object));
+
+// Schedule all CXXRTL objects in a simulation except for memories.
+//
+// The design `handle` must outlive the VCD writer.
+//
+// Objects can only be scheduled before the first call to `cxxrtl_vcd_sample`.
+void cxxrtl_vcd_add_from_without_memories(cxxrtl_vcd vcd, cxxrtl_handle handle);
+
+// Sample all scheduled objects.
+//
+// First, `time` is written to the internal buffer. Second, the values of every signal changed since
+// the previous call to `cxxrtl_vcd_sample` (all values if this is the first call) are written to
+// the internal buffer. The contents of the buffer can be retrieved with `cxxrtl_vcd_read`.
+void cxxrtl_vcd_sample(cxxrtl_vcd vcd, uint64_t time);
+
+// Retrieve buffered VCD data.
+//
+// The pointer to the start of the next chunk of VCD data is assigned to `*data`, and the length
+// of that chunk is assigned to `*size`. The pointer to the data is valid until the next call to
+// `cxxrtl_vcd_sample` or `cxxrtl_vcd_read`. Once all of the buffered data has been retrieved,
+// this function will always return zero sized chunks.
+void cxxrtl_vcd_read(cxxrtl_vcd vcd, const char **data, size_t *size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif