Rewrite bfi in C++ for future optimization.

bfi/conv

@@ -1,3 +1,3 @@
 #!/bin/env sh
 
-gcc -O3 main.c -o bfi
+g++ -std=c++11 -O3 main.cpp -o bfi

bfi/main.cpp

@@ -0,0 +1,79 @@
+#include <fstream>
+#include <iostream>
+#include <memory>
+#include <string>
+#include <vector>
+
+// 20MB
+const int MEM_SIZE = 20*1000*1000;
+
+
+void run(const std::string& code_memory) {
+    std::vector<unsigned char> data_memory(MEM_SIZE, 0);
+
+    unsigned char* ptr = data_memory.data();
+    const char* ptr_program = code_memory.data();
+    const char* const ptr_program_end = code_memory.data() + code_memory.size();
+
+    uint64_t steps = 0;
+    while(ptr_program < ptr_program_end) {
+        steps++;
+        switch(*ptr_program){
+            case '>': ++ptr; break;
+            case '<': --ptr; break;
+            case '+': ++*ptr; break;
+            case '-': --*ptr; break;
+            case '.': std::cout << std::unitbuf << *ptr; break;
+            // TODO: do disable stdin buffering.
+            case ',': *ptr = std::cin.get(); break;
+            case '[':
+                if(*ptr==0){
+                    int c=1;
+                    while(c>0){
+                        ptr_program++;
+                        if(*ptr_program=='[') c++;
+                        if(*ptr_program==']') c--;
+                    }
+                }
+                break;
+            case ']':
+                if(*ptr!=0){
+                    int c=1;
+                    while(c>0){
+                        ptr_program--;
+                        if(*ptr_program==']') c++;
+                        if(*ptr_program=='[') c--;
+                    }
+                }
+            default:
+                steps--;
+        }
+
+        ptr_program++;
+    }
+    std::cerr << steps << " steps" << std::endl;
+}
+
+int main(int argc, char** argv) {
+    // Parse argument
+    if(argc != 2) {
+        std::cout << "bfi (compiled with MEM_SIZE=" << MEM_SIZE << ")" << std::endl;
+        std::cout << "usage: bfi <file>" << std::endl;
+        return -1;
+    }
+    const std::string bf_code_path(argv[1]);
+
+    // Read bf code.
+    std::ifstream bf_code_file(bf_code_path);
+    if(!bf_code_file.is_open()) {
+        std::cout << "could not open " << bf_code_path << std::endl;
+        return -2;
+    }
+
+    const std::string bf_code(
+        (std::istreambuf_iterator<char>(bf_code_file)),
+        std::istreambuf_iterator<char>());
+
+    run(bf_code);
+    return 0;
+}