Integrating an old C++ code into a PNaCl module - c++

Question

I read Google’s native client tutorial on how to build my own C++ based PNaCl module several times and somehow I'm not getting wiser, I know that if I want to implement a messaging functionality. I have the following in the .cc file as basis for a PNaCl code, all this is taken from Googles's Hello World tutorial:
#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/module.h"
#include "ppapi/cpp/var_array.h"
#include "ppapi/cpp/var.h"
namespace {
// The expected string sent by the browser.
const char* const kHelloString = "hello";
// The string sent back to the browser upon receipt of a message
// containing "hello".
const char* const kReplyString = "hello from NaCl";
} // namespace
class job1Instance : public pp::Instance {
public:
explicit job1Instance(PP_Instance instance): pp::Instance(instance) {}
virtual ~job1Instance() {}
virtual void HandleMessage(const pp::Var& message) {
if (!message.is_string()) {
return;
}
std::string message_txt = message.AsString();
pp::Var reply;
if (message_txt == kHelloString) {
reply = pp::Var(kReplyString);
PostMessage(kReplyString);
}
}
};
class job1 : public pp::Module {
public:
job1() : pp::Module() {}
virtual ~job1() {}
virtual pp::Instance* CreateInstance(PP_Instance instance) {
return new job1Instance(instance);
}
};
namespace pp {
Module* CreateModule() {
return new job1();
}
} // namespace pp
As I understand the PNaCl modules don’t use a main() function and yet let’s say I have an old C++ code that creates 2 arrays unsorted1 and unsorted2 with random numbers which I want to use in my PNaCl module:
#include <iostream>
#include <stdint.h>
#include <unistd.h>
#include <array>
// a function to create a random number between min and max
int32_t rangeRandomAlg (int32_t min, int32_t max) {
int32_t num = max - min + 1;
int32_t remainder = RAND_MAX % num;
int32_t x;
do {
x = rand();
} while (x >= RAND_MAX - remainder);
return min + x % num;
}
// a function to create arrays with random numbers
void unsortedArrays(int32_t unsorted1[], int32_t unsorted2[],int32_t arrayElements, int32_t minNum, int32_t maxNum){
for(int32_t i = 0; i <= arrayElements; i++) {
if (i < arrayElements/2) {
unsorted1[i] = rangeRandomAlg(minNum, maxNum);
} else {
unsorted2[i] = rangeRandomAlg(minNum, maxNum);
}
}
}
// the main function
int32_t main(int32_t argc, char *argv[]) {
// declare all the zises
int32_t minNum = 0;
int32_t maxNum = 100;
int32_t arrayElements = maxNum;
// the arrays
int32_t unsorted1[arrayElements/2];
int32_t unsorted2[arrayElements/2];
// fill the arrays with random numbers
unsortedArrays(unsorted1, unsorted2, arrayElements, minNum, maxNum);
return 0;
}
My problem is that I didn’t quite understand how can I integrate this code into the PNaCl module and use the HandleMessage() function to sent the unsorted1 and unsorted2 arrays back to the JavaScript with the PostMesage() function. I know I have to work with arrays and not strings in the HandleMessage() function.
I hope to get some help here, since I’m really new to this whole native client thing.

Answer 1

Well here is the solution that took some hours to get to:
// pepper includes
#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/module.h"
#include "ppapi/cpp/var_array.h"
#include "ppapi/cpp/var.h"
#include "json/json.h"
#include <sstream>
// cpp includes
#include <stdint.h>
#include <unistd.h>
#include <array>
#include <string>
//static variables
namespace {
// The expected string sent by the browser.
const char* const kHelloString = "Bereit fuer dein Modul";
// The string sent back to the browser upon receipt of a message
// containing "hello".
const char* const kReplyString = "PNaCl hat Ergebnisse geschickt";
} // namespace
class job1Instance : public pp::Instance {
public:
explicit job1Instance(PP_Instance instance): pp::Instance(instance) {}
virtual ~job1Instance() {}
virtual void HandleMessage(const pp::Var& message) {
/*
if (!message.is_string()) {
return;
}
std::string message_txt = message.AsString();
pp::Var reply;
if (message_txt == kHelloString) {
reply = pp::Var(kReplyString);
PostMessage(kReplyString);
}
*/
/*** my functions and data for the cpp code to integrate start here ***/
// declare all the zises
int32_t minNum = 0;
int32_t maxNum = 100;
int32_t arrayElements = maxNum;
// the arrays
int32_t unsorted1[arrayElements/2];
int32_t unsorted2[arrayElements/2];
// fill the arrays with random numbers
unsortedArrays(unsorted1, unsorted2, arrayElements, minNum, maxNum);
std::string outRes1, outRes2;
arrayToString(unsorted1, arrayElements/2, outRes1);
arrayToString(unsorted2, arrayElements/2, outRes2);
PostMessage(outRes1); // send the unsorted1 array as a string to the JavaScript back
}
private:
// function to create a random number between min and max
int32_t rangeRandomAlg (int32_t min, int32_t max) {
int32_t num = max - min + 1;
int32_t remainder = RAND_MAX % num;
int32_t x;
do {
x = rand();
} while (x >= RAND_MAX - remainder);
return min + x % num;
}
// function to create arrays with random numbers
void unsortedArrays (int32_t unsorted1[], int32_t unsorted2[],int32_t arrayElements, int32_t minNum, int32_t maxNum) {
for(int32_t i = 0; i <= arrayElements; i++) {
if (i < arrayElements/2) {
unsorted1[i] = rangeRandomAlg(minNum, maxNum);
} else {
unsorted2[i] = rangeRandomAlg(minNum, maxNum);
}
}
}
// convert the arrays to string
void arrayToString (int32_t array[], int32_t arraySize, std::string& arrayString) {
for (int32_t i = 0; i <= arraySize; ++i){
arrayString+= std::to_string(array[i]);
if (i != arraySize) {
arrayString+= ',';
}
}
}
};
/*** my functions and data for the cpp code to integrate end here ***/
class job1 : public pp::Module {
public:
job1() : pp::Module() {}
virtual ~job1() {}
virtual pp::Instance* CreateInstance(PP_Instance instance) {
return new job1Instance(instance);
}
};
namespace pp {
Module* CreateModule() {
return new job1();
}
} // namespace pp
This is only the precompiled C++ code of the PNaCl module with my code integrated in it, it sends only the outRes1 variable = unsorted1 array variable as string to the JavaScript code in the index.html file. You have to have the .nmf and the index.html files written separately. If anyone wants to see my code of those files, which has the basic and working code for this PNaCl module should write me a comment and I’ll post those to.