[ESI] [Cosim DPI] Cap'nProto install and schema generation (#216)

* [ESI] [Cosim DPI] Capn'Proto install and schema generation

This is the second in a series to merge #213. This is the capnp schema
generation component.

* Added header comment.

CMakeLists.txt

@@ -52,6 +52,9 @@ add_custom_target(circt-headers)
 set_target_properties(circt-headers PROPERTIES FOLDER "Misc")
 add_custom_target(circt-doc)
 
+set(ENV{PKG_CONFIG_PATH}
+  "${CMAKE_CURRENT_SOURCE_DIR}/ext/lib/pkgconfig:$ENV{PKG_CONFIG_PATH}")
+
 list(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}")
 list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")

include/circt/Dialect/ESI/CMakeLists.txt

@@ -6,3 +6,5 @@ mlir_tablegen(ESIAttrs.h.inc -gen-struct-attr-decls)
 mlir_tablegen(ESIAttrs.cpp.inc -gen-struct-attr-defs)
 
 add_public_tablegen_target(MLIRESIEnumsIncGen)
+
+add_subdirectory(cosim)

include/circt/Dialect/ESI/cosim/CMakeLists.txt

@@ -0,0 +1,9 @@
+find_package(CapnProto CONFIG PATHS "${CMAKE_SOURCE_DIR}/ext")
+if(CapnProto_FOUND)
+  option(ESI_COSIM "Enable ESI Cosimulation" ON)
+  message("-- Enabling ESI cosim")
+  add_definitions(${CAPNP_DEFINITIONS})
+  capnp_generate_cpp(COSIM_CAPNP_SRCS COSIM_CANPN_HDRS CosimDpi.capnp)
+  add_library(EsiCosimCapnp ${COSIM_CAPNP_HDRS} ${COSIM_CAPNP_SRCS})
+  target_link_libraries(EsiCosimCapnp PRIVATE CapnProto::capnp)
+endif()

include/circt/Dialect/ESI/cosim/CosimDpi.capnp

@@ -0,0 +1,44 @@
+##===- CosimDpi.capnp - ESI cosim RPC schema ------------------*- CAPNP -*-===//
+##
+## The ESI cosimulation RPC Cap'nProto schema. Documentation is in
+## docs/ESI/cosim.md. TL;DR: Run the simulation, then connect to its RPC server
+## with a client generated by the Cap'nProto implementation for your language of
+## choice! (https://capnproto.org/otherlang.html)
+##
+##===----------------------------------------------------------------------===//
+
+@0xe642127a31681ef6;
+
+# The primary interface exposed by an ESI cosim simulation.
+interface CosimDpiServer {
+  # List all the registered endpoints.
+  list @0 () -> (ifaces :List(EsiDpiInterfaceDesc));
+  # Open one of them. Specify both the send and recv data types if want type
+  # safety and your language supports it.
+  open @1 [S, T] (iface :EsiDpiInterfaceDesc) -> (iface :EsiDpiEndpoint(S, T));
+}
+
+# Description of a registered endpoint.
+struct EsiDpiInterfaceDesc {
+  # Capn'Proto ID of the struct type being sent _to_ the simulator.
+  sendTypeID @0 :UInt64;
+  # Capn'Proto ID of the struct type being sent _from_ the simulator.
+  recvTypeID @1 :UInt64;
+  # Numerical identifier of the endpoint. Defined in the design.
+  endpointID @2 :Int32;
+}
+
+# Interactions with an open endpoint. Optionally typed.
+interface EsiDpiEndpoint(SendMsgType, RecvMsgType) {
+  # Send a message to the endpoint.
+  send @0 (msg :SendMsgType);
+  # Recieve a message from the endpoint. Non-blocking.
+  recv @1 (block :Bool = true) -> (hasData :Bool, resp :RecvMsgType);
+  # Close the connect to this endpoint.
+  close @2 ();
+}
+
+# A struct for untyped access to an endpoint.
+struct UntypedData @0xac6e64291027d47a {
+  data @0 :Data;
+}

utils/get-capnp.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+# Downloads, compiles, and installs CapnProto into $/ext
+
+EXT_DIR=$(cd "$(dirname "$BASH_SOURCE[0]")/../ext" && pwd)
+CAPNP_VER=0f1bf4fce79923fb4974aa55a53e26450f83f286
+
+echo $EXT_DIR
+cd $EXT_DIR
+
+git clone https://github.com/capnproto/capnproto.git
+cd capnproto
+git checkout $CAPNP_VER
+cd c++
+autoreconf -i
+./configure --prefix=$EXT_DIR
+make -j$(nprocs)
+make install
+cd ../../