From 74af3a2b7086acad45d15b590a0d23572e8c8734 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Fri, 22 Aug 2014 14:22:09 +0200
Subject: Archibald Rust and Clifford Wolf: ffi-based dpi_call()

---
 frontends/ast/dpicall.cc | 96 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 90 insertions(+), 6 deletions(-)

(limited to 'frontends')

diff --git a/frontends/ast/dpicall.cc b/frontends/ast/dpicall.cc
index 965645cd..b79bd59e 100644
--- a/frontends/ast/dpicall.cc
+++ b/frontends/ast/dpicall.cc
@@ -17,26 +17,110 @@
  *
  */
 
+#include <dlfcn.h>
+#include <ffi.h>
 #include "ast.h"
 
+typedef void (*ffi_fptr) ();
+
+static ffi_fptr resolve_fn (std::string symbol_name)
+{
+	if (symbol_name.find(':') != std::string::npos)
+	{
+		int pos = symbol_name.find(':');
+		std::string plugin_name = symbol_name.substr(0, pos);
+		std::string real_symbol_name = symbol_name.substr(pos+1);
+
+		while (loaded_plugin_aliases.count(plugin_name))
+			plugin_name = loaded_plugin_aliases.at(plugin_name);
+
+		if (loaded_plugins.count(plugin_name) == 0)
+			log_error("unable to resolve '%s': can't find plugin `%s'\n", symbol_name.c_str(), plugin_name.c_str());
+
+		void *symbol = dlsym(loaded_plugins.at(plugin_name), real_symbol_name.c_str());
+
+		if (symbol == nullptr)
+			log_error("unable to resolve '%s': can't find symbol `%s' in plugin `%s'\n",
+					symbol_name.c_str(), real_symbol_name.c_str(), plugin_name.c_str());
+
+		return (ffi_fptr) symbol;
+	}
+
+	for (auto &it : loaded_plugins) {
+		void *symbol = dlsym(it.second, symbol_name.c_str());
+		if (symbol != nullptr)
+			return (ffi_fptr) symbol;
+	}
+
+	void *symbol = dlsym(RTLD_DEFAULT, symbol_name.c_str());
+	if (symbol != nullptr)
+		return (ffi_fptr) symbol;
+
+	log_error("unable to resolve '%s'.\n", symbol_name.c_str());
+}
+
 AST::AstNode *AST::dpi_call(const std::string &rtype, const std::string &fname, const std::vector<std::string> &argtypes, const std::vector<AstNode*> &args)
 {
 	AST::AstNode *newNode = nullptr;
+	union { double f64; float f32; int32_t i32; } value_store [args.size() + 1];
+	ffi_type *types [args.size() + 1];
+	void *values [args.size() + 1];
+	ffi_cif cif;
+	int status;
 
 	log("Calling DPI function `%s' and returning `%s':\n", fname.c_str(), rtype.c_str());
 
 	log_assert(SIZE(args) == SIZE(argtypes));
-	for (int i = 0; i < SIZE(args); i++)
-		if (argtypes[i] == "real" || argtypes[i] == "shortreal")
+	for (int i = 0; i < SIZE(args); i++) {
+		if (argtypes[i] == "real") {
+			log("  arg %d (%s): %f\n", i, argtypes[i].c_str(), args[i]->asReal(args[i]->is_signed));
+			value_store[i].f64 = args[i]->asReal(args[i]->is_signed);
+			values[i] = &value_store[i].f64;
+			types[i] = &ffi_type_double;
+		} else if (argtypes[i] == "shortreal") {
 			log("  arg %d (%s): %f\n", i, argtypes[i].c_str(), args[i]->asReal(args[i]->is_signed));
-		else
+			value_store[i].f32 = args[i]->asReal(args[i]->is_signed);
+			values[i] = &value_store[i].f32;
+			types[i] = &ffi_type_double;
+		} else if (argtypes[i] == "integer") {
 			log("  arg %d (%s): %lld\n", i, argtypes[i].c_str(), (long long)args[i]->asInt(args[i]->is_signed));
+			value_store[i].i32 = args[i]->asInt(args[i]->is_signed);
+			values[i] = &value_store[i].i32;
+			types[i] = &ffi_type_sint32;
+		} else {
+			log_error("invalid argtype '%s' for argument %d.\n", argtypes[i].c_str(), i);
+		}
+	}
+
+        if (rtype == "integer") {
+                types[args.size()] = &ffi_type_slong;
+                values[args.size()] = &value_store[args.size()].i32;
+        } else if (rtype == "shortreal") {
+                types[args.size()] = &ffi_type_float;
+                values[args.size()] = &value_store[args.size()].f32;
+        } else if (rtype == "real") {
+                types[args.size()] = &ffi_type_double;
+                values[args.size()] = &value_store[args.size()].f64;
+        } else {
+                log_error("invalid rtype '%s'.\n", rtype.c_str());
+        }
+
+        if ((status = ffi_prep_cif(&cif, FFI_DEFAULT_ABI, args.size(), types[args.size()], types)) != FFI_OK)
+                log_error("ffi_prep_cif failed: status %d.\n", status);
 
-	if (rtype == "real" || rtype == "shortreal") {
+        ffi_call(&cif, resolve_fn(fname.c_str()), values[args.size()], values);
+
+	if (rtype == "real") {
+		newNode = new AstNode(AST_REALVALUE);
+		newNode->realvalue = value_store[args.size()].f64;
+		log("  return realvalue: %g\n", newNode->asReal(true));
+	} else if (rtype == "shortreal") {
 		newNode = new AstNode(AST_REALVALUE);
-		newNode->realvalue = 1234;
+		newNode->realvalue = value_store[args.size()].f32;
+		log("  return realvalue: %g\n", newNode->asReal(true));
 	} else {
-		newNode = AstNode::mkconst_int(1234, false);
+		newNode = AstNode::mkconst_int(value_store[args.size()].i32, false);
+		log("  return integer: %lld\n", (long long)newNode->asInt(true));
 	}
 
 	return newNode;
-- 
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