1 files changed, 141 insertions, 0 deletions
diff --git a/tools/standalone_miri/ffi.cpp b/tools/standalone_miri/ffi.cpp
new file mode 100644
index 00000000..827d862f
--- /dev/null
+++ b/tools/standalone_miri/ffi.cpp
@@ -0,0 +1,141 @@
+/*
+ * mrustc Standalone MIRI
+ * - by John Hodge (Mutabah)
+ *
+ * ffi.cpp
+ * - FFI wrappers
+ */
+
+/// Argument reference (for checking validity)
+struct ArgRef
+{
+    uint8_t idx;    // if 255, it's not referencing anything
+
+    static ArgRef null() { return ArgRef { 255 }; }
+};
+
+/// Representation of a FFI type (defined by the .api file)
+/// - These specify various flags used to tag pointers in the MIR
+struct FfiType
+{
+    // Pointer:
+    // - Mutability
+    // - Nullability
+    // - Array size (number of allocated elements)
+    //   > Can be either a number, or an argument name
+    // - Valid size (number of initialised elements)
+    // - Allocation source
+    struct Pointer {
+        bool    is_mut;
+        bool    is_nullable;
+        ArgOrCount  alloc_size;
+        ArgOrCount  valid_size;
+        ArgRef  alloc_source;   // Can be "null"
+    };
+    ::std::vector<Pointer>  pointers;   // Reverse list (last entry is the outermost pointer)
+
+    // Datatypes:
+    // - `void`
+    //   - size/alignment
+    // - u8,u16,...
+    // - function
+    //   - Name
+    enum class Datatype {
+        Void,
+        Signed,
+        Unsigned,
+        Float,
+        Function,
+    } datatype;
+    union Meta {
+        struct {
+            size_t  size;
+            size_t  align;
+            ::std::string   tag;
+        } void_data;
+        unsigned bits;
+        struct {
+            ArgRef  name_source;
+        } function;
+    } meta;
+};
+
+
+struct FfiShim
+{
+    class ValueRef
+    {
+    public:
+        static ValueRef new_global(std::string name);
+        static ValueRef new_local(std::string name);
+        static ValueRef new_deref(ValueRef target);
+    };
+    class Expr
+    {
+        enum {
+            LITERAL,
+            VALUE,
+            CALL,
+        } ty;
+        union {
+        } data;
+    public:
+        static Expr new_lit(uint64_t v);
+        static Expr new_value(ValueRef vr);
+        static Expr new_call_int(::std::vector<::std::string> path, ::std::vector<Expr> args);
+    };
+    struct Stmt;
+    struct Block
+    {
+        ::std::vector<Stmt> statements;
+        Expr    val;
+    };
+    class Stmt
+    {
+        enum {
+            DEFINE, // `let foo = bar;`
+            ASSIGN, // `foo ?= bar;`
+            IF,
+        } ty;
+        union {
+            struct {
+                ::std::string   slot;
+                Expr    value;
+            } define;
+            struct {
+                ValueRef    slot;
+                Expr    value;
+            } assign;
+            struct {
+                Expr    cond;
+                Block   true_arm;
+                Block   false_arm;
+            } if_block;
+        };
+    };
+};
+
+struct FfiFunction
+{
+    ::std::vector<FfiType>  arg_types;
+    FfiType ret_type;
+    ::std::vector<std::string>  arg_names;
+
+    // Either directly defers to a function
+    ::std::string   library;
+    ::std::string   function;
+
+    // Or, it has code for more advanced checking
+    //FfiShimExpr   code;
+
+    bool call(Value& rv, ::std::vector<Value> args) const;
+};
+
+bool FfiFunction::call(Value& rv, ::std::vector<Value> args) const
+{
+
+}
+
+bool call_ffi(Value& rv, const ::std::string& link_name, const ::std::string& abi, ::std::vector<Value> args)
+{
+}