From fd8ef0fd42490779a7f082bc778afdfac77a7a9c Mon Sep 17 00:00:00 2001
From: xanxys <xanxys@gmail.com>
Date: Mon, 12 May 2014 00:14:14 +0900
Subject: [PATCH] Rewrite bfi in C++ for future optimization.

---
 bfi/conv     |   2 +-
 bfi/main.c   | 105 ---------------------------------------------------
 bfi/main.cpp |  79 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+), 106 deletions(-)
 delete mode 100644 bfi/main.c
 create mode 100644 bfi/main.cpp

diff --git a/bfi/conv b/bfi/conv
index c504796..5b7c4b6 100755
--- a/bfi/conv
+++ b/bfi/conv
@@ -1,3 +1,3 @@
 #!/bin/env sh
 
-gcc -O3 main.c -o bfi
+g++ -std=c++11 -O3 main.cpp -o bfi
diff --git a/bfi/main.c b/bfi/main.c
deleted file mode 100644
index def1b09..0000000
--- a/bfi/main.c
+++ /dev/null
@@ -1,105 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-
-#define MEM_SIZE (20*1000*1000) // 20MB
-
-
-void run(FILE *log,char *code){
-    char *code_base=code;
-    
-    unsigned char *ptr_base=malloc(MEM_SIZE);
-    memset(ptr_base,0,MEM_SIZE);
-    
-    unsigned char *ptr=ptr_base;
-    
-    long long stp=0;
-    while(*code){
-        /*
-        if(log)
-            fprintf(log,"%c %d %d\n",*code,code-code_base,ptr-ptr_base);
-        */
-        stp++;
-        switch(*code){
-            case '>': ++ptr; break;
-            case '<': --ptr; break;
-            case '+': ++*ptr; break;
-            case '-': --*ptr; break;
-            case '.': fwrite(ptr,1,1,stdout); break;
-            case ',': fread(ptr,1,1,stdin); break;
-            case '[':
-                if(*ptr==0){
-                    int c=1;
-                    while(c>0){
-                        code++;
-                        if(*code=='[') c++;
-                        if(*code==']') c--;
-                    }
-                }
-                break;
-            case ']':
-                if(*ptr!=0){
-                    int c=1;
-                    while(c>0){
-                        code--;
-                        if(*code==']') c++;
-                        if(*code=='[') c--;
-                    }
-                }
-            default:
-                stp--;
-        }
-        
-        code++;
-    }
-    fprintf(stderr,"%lld steps\n",stp);
-    
-    free(ptr_base);
-}
-
-int main(int argc,char **argv){
-    if(argc!=2 && argc!=3){
-        printf("usage: bfi <file> (compiled with MEM_SIZE=%d)\n",MEM_SIZE);
-        printf("usage: bfi <file> <prof> (compiled with MEM_SIZE=%d)\n",MEM_SIZE);
-        return -1;
-    }
-    
-    // open
-    FILE *fp=fopen(argv[1],"r");
-    if(fp==NULL){
-        printf("could not open %s\n",argv[1]);
-        return -2;
-    }
-    
-    fseek(fp,0,SEEK_END);
-    int size=ftell(fp);
-    fseek(fp,0,SEEK_SET);
-    
-    char *code=malloc(size+1);
-    fread(code,size,1,fp);
-    code[size]=0;
-    
-    // close
-    fclose(fp);
-    
-    setbuf(stdin,NULL);
-    setbuf(stdout,NULL);
-    fflush(stdin);
-    fflush(stdout);
-    
-    // open optional log file
-    FILE *log=NULL;
-    if(argc==3){
-        log=fopen(argv[2],"w");
-        if(log==NULL){
-            printf("could not open %s\n",argv[2]);
-            return -2;
-        }
-    }
-    
-    run(log,code);
-    free(code);
-    if(log) fclose(log);
-    
-    return 0;
-}
-
diff --git a/bfi/main.cpp b/bfi/main.cpp
new file mode 100644
index 0000000..6f1b73b
--- /dev/null
+++ b/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;
+}