hello_driver.cpp

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#include <sysio/vm/backend.hpp>
#include <sysio/vm/error_codes.hpp>
#include <sysio/vm/host_function.hpp>
#include <sysio/vm/watchdog.hpp>
 
#include <iostream>
#include <string>
 
using namespace sysio;
using namespace sysio::vm;
 
#include "hello.wasm.hpp"
 
struct example_host_methods {
   void print_num(uint64_t n) { std::cout << "Number : " << n << "\n"; }
   // example of a host "method"
   void print_name(const char* nm) { std::cout << "Name : " << nm << " " << field << "\n"; }
   // example of another type of host function
   void* memset(char* ptr, int x, size_t n) { return ::memset(ptr, x, n); }
   std::string  field = "";
 
   void sysio_assert(bool test, const char* msg) {
      if (!test) {
         std::cout << msg << std::endl;
         throw 0;
      }
   }
 
   void print_span(span<const char> s) {
      std::cout << "Span : " << std::string{s.data(), s.size()} << "\n";
   }
};
 
struct cnv : type_converter<example_host_methods> {
   using type_converter::type_converter;
   using type_converter::from_wasm;
   SYS_VM_FROM_WASM(bool, (uint32_t value)) { return value ? 1 : 0; }
   SYS_VM_FROM_WASM(char*, (void* ptr)) { return static_cast<char*>(ptr); }
   SYS_VM_FROM_WASM(const char*, (void* ptr)) { return static_cast<char*>(ptr); }
};
 
SYS_VM_PRECONDITION(test_name,
      SYS_VM_INVOKE_ON(const char*, [&](auto&& nm, auto&&... rest) {
         std::string s = nm;
         if (s == "sys-vm2")
            throw "failure";
   }))
 
int main(int argc, char** argv) {
   if (argc < 4) {
      std::cerr << "Please enter three numbers\n";
      return -1;
   }
   // Thread specific `allocator` used for wasm linear memory.
   wasm_allocator wa;
   // Specific the backend with example_host_methods for host functions.
   using rhf_t     = sysio::vm::registered_host_functions<example_host_methods, execution_interface, cnv>;
   using backend_t = sysio::vm::backend<rhf_t>;
 
   // register print_num
   rhf_t::add<&example_host_methods::print_num>("env", "print_num");
   // register sysio_assert
   rhf_t::add<&example_host_methods::sysio_assert>("env", "sysio_assert");
   // register print_name
   rhf_t::add<&example_host_methods::print_name, test_name>("env", "print_name");
   // finally register memset
   rhf_t::add<&example_host_methods::memset>("env", "memset");
   rhf_t::add<&example_host_methods::print_span>("env", "print_span");
 
   watchdog wd{std::chrono::seconds(3)};
   try {
      example_host_methods ehm;
      // Instaniate a new backend using the wasm provided.
      backend_t bkend(hello_wasm, ehm, &wa);
 
      // Instaniate a "host"
      ehm.field = "testing";
      // Execute apply.
      bkend(ehm, "env", "apply", (uint64_t)std::atoi(argv[1]), (uint64_t)std::atoi(argv[2]),
            (uint64_t)std::atoi(argv[3]));
 
   } catch (...) { std::cerr << "sys-vm interpreter error\n"; }
   return 0;
}