capi: Add functions for parse, instantiate, execute

Author: gumb0

include/fizzy/fizzy.h

@@ -11,8 +11,87 @@
 extern "C" {
 #endif
 
+/// The opaque data type representing a module.
+struct FizzyModule;
+
+/// The opaque data type representing an instance (instantiated module).
+struct FizzyInstance;
+
+/// The data type representing numeric values.
+///
+/// i64 member is used to represent values of both i32 and i64 type.
+union FizzyValue
+{
+    uint64_t i64;
+    float f32;
+    double f64;
+};
+
+/// Result of execution of a function.
+typedef struct FizzyExecutionResult
+{
+    /// Whether execution ended with a trap.
+    bool trapped;
+    /// Whether function returned a value. Valid only if trapped == false
+    bool has_value;
+    /// Value returned from a function. Valid only if has_value == true
+    union FizzyValue value;
+} FizzyExecutionResult;
+
+
+/// Pointer to external function.
+///
+/// @param context      Opaque pointer to execution context.
+/// @param instance     Pointer to module instance.
+/// @param args         Pointer to the argument array.
+/// @param args_size   Size of the  argument array.
+/// @param depth        Call stack depth.
+typedef struct FizzyExecutionResult (*FizzyExternalFn)(void* context,
+    struct FizzyInstance* instance, const union FizzyValue* args, size_t args_size, int depth);
+
+/// External function.
+typedef struct FizzyExternalFunction
+{
+    // TODO function type
+
+    /// Pointer to function.
+    FizzyExternalFn function;
+    /// Opaque pointer to execution context, that will be passed to function.
+    void* context;
+} FizzyExternalFunction;
+
+/// Validate binary module.
 bool fizzy_validate(const uint8_t* wasm_binary, size_t wasm_binary_size);
 
+/// Parse binary module.
+struct FizzyModule* fizzy_parse(const uint8_t* wasm_binary, size_t wasm_binary_size);
+
+/// Free resources associated with the module.
+///
+/// Should be called unless @p module was passed to fizzy_instantiate.
+void fizzy_free_module(struct FizzyModule* module);
+
+/// Instantiate a module.
+/// Takes ownership of module, i.e. @p module is invalidated after this call.
+///
+/// @param module                   Pointer to module.
+/// @param imported_functions       Pointer to the imported function array.
+/// @param imported_functions_size  Size of the imported function array.
+struct FizzyInstance* fizzy_instantiate(struct FizzyModule* module,
+    const struct FizzyExternalFunction* imported_functions, size_t imported_functions_size);
+
+/// Free resources associated with the instance.
+void fizzy_free_instance(struct FizzyInstance* instance);
+
+/// Execute module function.
+///
+/// @param instance     Pointer to module instance.
+/// @param args         Pointer to the argument array.
+/// @param args_size    Size of the argument array.
+/// @param depth        Call stack depth.
+FizzyExecutionResult fizzy_execute(struct FizzyInstance* instance, uint32_t func_idx,
+    const union FizzyValue* args, size_t args_size, int depth);
+
 #ifdef __cplusplus
 }
 #endif

lib/fizzy/capi.cpp

@@ -2,10 +2,81 @@
 // Copyright 2020 The Fizzy Authors.
 // SPDX-License-Identifier: Apache-2.0
 
+#include "cxx20/bit.hpp"
+#include "execute.hpp"
+#include "instantiate.hpp"
 #include "parser.hpp"
 #include <fizzy/fizzy.h>
+#include <memory>
+
+namespace
+{
+inline FizzyValue wrap(fizzy::Value value) noexcept
+{
+    return fizzy::bit_cast<FizzyValue>(value);
+}
+
+inline fizzy::Value unwrap(FizzyValue value) noexcept
+{
+    return fizzy::bit_cast<fizzy::Value>(value);
+}
+
+inline const FizzyValue* wrap(const fizzy::Value* values) noexcept
+{
+    return reinterpret_cast<const FizzyValue*>(values);
+}
+
+inline const fizzy::Value* unwrap(const FizzyValue* values) noexcept
+{
+    return reinterpret_cast<const fizzy::Value*>(values);
+}
+
+inline FizzyInstance* wrap(fizzy::Instance* instance) noexcept
+{
+    return reinterpret_cast<FizzyInstance*>(instance);
+}
+
+inline fizzy::Instance* unwrap(FizzyInstance* instance) noexcept
+{
+    return reinterpret_cast<fizzy::Instance*>(instance);
+}
+
+inline FizzyExecutionResult wrap(const fizzy::ExecutionResult& result) noexcept
+{
+    return {result.trapped, result.has_value, wrap(result.value)};
+}
+
+inline fizzy::ExecutionResult unwrap(FizzyExecutionResult result) noexcept
+{
+    if (result.trapped)
+        return fizzy::Trap;
+    else if (!result.has_value)
+        return fizzy::Void;
+    else
+        return unwrap(result.value);
+}
+
+inline auto unwrap(FizzyExternalFn func, void* context) noexcept
+{
+    return [func, context](fizzy::Instance& instance, fizzy::span<const fizzy::Value> args,
+               int depth) noexcept -> fizzy::ExecutionResult {
+        const auto result = func(context, wrap(&instance), wrap(args.data()), args.size(), depth);
+        return unwrap(result);
+    };
+}
+}  // namespace
 
 extern "C" {
+struct FizzyModule
+{
+    fizzy::Module module;
+};
+
+struct FizzyInstance
+{
+    fizzy::Instance* instance;
+};
+
 bool fizzy_validate(const uint8_t* wasm_binary, size_t wasm_binary_size)
 {
     try
@@ -18,4 +89,70 @@ bool fizzy_validate(const uint8_t* wasm_binary, size_t wasm_binary_size)
         return false;
     }
 }
+
+FizzyModule* fizzy_parse(const uint8_t* wasm_binary, size_t wasm_binary_size)
+{
+    try
+    {
+        auto cmodule = std::make_unique<FizzyModule>();
+        cmodule->module = fizzy::parse({wasm_binary, wasm_binary_size});
+        return cmodule.release();
+    }
+    catch (...)
+    {
+        return nullptr;
+    }
+}
+
+void fizzy_free_module(FizzyModule* module)
+{
+    delete module;
+}
+
+FizzyInstance* fizzy_instantiate(FizzyModule* module,
+    const FizzyExternalFunction* imported_functions, size_t imported_functions_size)
+{
+    try
+    {
+        // Convert fizzy_external_function to fizzy::ExternalFunction
+        std::vector<fizzy::ExternalFunction> functions(imported_functions_size);
+        for (size_t imported_func_idx = 0; imported_func_idx < imported_functions_size;
+             ++imported_func_idx)
+        {
+            const auto& cfunc = imported_functions[imported_func_idx];
+
+            auto func = unwrap(cfunc.function, cfunc.context);
+            // TODO get type from input array
+            auto func_type = module->module.imported_function_types[imported_func_idx];
+
+            functions[imported_func_idx] =
+                fizzy::ExternalFunction{std::move(func), std::move(func_type)};
+        }
+
+        auto instance = fizzy::instantiate(std::move(module->module), std::move(functions));
+
+        fizzy_free_module(module);
+        return wrap(instance.release());
+    }
+    catch (...)
+    {
+        fizzy_free_module(module);
+        return nullptr;
+    }
+}
+
+void fizzy_free_instance(FizzyInstance* instance)
+{
+    delete unwrap(instance);
+}
+
+FizzyExecutionResult fizzy_execute(
+    FizzyInstance* instance, uint32_t func_idx, const FizzyValue* args, size_t args_size, int depth)
+{
+    auto* unwrapped_instance = unwrap(instance);
+    assert(unwrapped_instance->module.get_function_type(func_idx).inputs.size() == args_size);
+
+    const auto result = fizzy::execute(*unwrapped_instance, func_idx, unwrap(args), depth);
+    return wrap(result);
+}
 }