Add bitshift and file support

README.md

@@ -3,10 +3,29 @@ Forth
 
 A weekend implementation of the Forth programming language
 
-Usage
+Compile
 =====
 
 ```
 make all
 make clean
 ```
+
+How to use
+==========
+
+These are the currently accepted operators:
+
++ add
+
+- substract
+
+* multiply
+
+/ divide
+
+. print top of stack
+
+< bit shift left
+
+> bit shift right

src/main.c

@@ -23,27 +23,56 @@ void help(int argc, char** argv){
     printf("Max line input size is %i", BUFFER_SIZE);
 }
 
+void process_file(FILE* in, char* input){
+    char* fg;
+    int retval;
+    while(!(fg = fgets(input, BUFFER_SIZE, in)) || feof(in)){
+        retval = parse(input);
+        if(retval > -1){
+            printf("%s\n ",input);
+            for(int i = 1; i != retval; ++i){
+                printf(" ");
+            }
+            printf("^\n");
+            printf("Error parsing character at position %d!\n", retval);
+            break;
+        }
+    }
+}
+
 int main(int argc, char** argv){
     char input[BUFFER_SIZE] = {0};
     int retval = 0;
-
+    FILE* in = stdin;
+    char* fg;
 
     //check arg count
     if(argc > 2){
         help(argc, argv);
         return -1;
     } else if(argc == 2){
-        //TODO implement File parsing
+        in = fopen(argv[1], "r");
+        if(in == NULL){
+            printf("Couldn't open file %s\n", argv[1]);
+            in = stdin;
+        }
     }
 
+    if(in != stdin){
+        process_file(in, input);
+    }
 
     printf("Entering shell...\n");
 
     //get user input, with prompt
     printf("> ");
-    fgets(input, BUFFER_SIZE, stdin);
+    fg = fgets(input, BUFFER_SIZE, in);
 
     while(strcmp(input, "exit\n")){
+        if(fg == NULL) //ctrl+d
+            break;
+
+
         retval = parse(input);
         if(retval > -1){
             printf("  ");
@@ -57,7 +86,7 @@ int main(int argc, char** argv){
         }
 
         printf("> ");
-        fgets(input, BUFFER_SIZE, stdin);
+        fg = fgets(input, BUFFER_SIZE, in);
     }
 
     printf("Goodbye\n");

src/parse.c

@@ -6,7 +6,89 @@
 
 #include "parse.h"
 
-char ops[] = {'+','-','*','/','\0'};
+char ops[] = {'+','-','*','/','.','<','>','\0'};
+
+int op_add(){
+    int ret = 0;
+    for(int it = 0;it < 2; ++it){
+        ret += pop();
+        if(_head_error == POP_EMPTY_STACK){
+            return -1;
+        }
+    }
+    
+    push(ret);
+    return 0;
+}
+
+int op_sub(){
+    int op[2];
+    for(int it = 0;it < 2; ++it){
+        op[it] = pop();
+        if(_head_error == POP_EMPTY_STACK){
+            return -1;
+        }
+    }
+    
+    push(op[1] - op[0]);
+    return 0;
+}
+
+int op_mul(){
+    int ret = 1;
+    for(int it = 0;it < 2; ++it){
+        ret *= pop();
+        if(_head_error == POP_EMPTY_STACK){
+            return -1;
+        }
+    }
+    
+    push(ret);
+    return 0;
+}
+
+int op_div(){
+    int op[2];
+    for(int it = 0;it < 2; ++it){
+        op[it] = pop();
+        if(_head_error == POP_EMPTY_STACK){
+            return -1;
+        }
+    }
+    
+    push(op[1]/op[0]);
+    return 0;
+}
+
+int op_pri(){
+    printf("%d\n", peek());
+    if(_head_error == PEEK_EMPTY_STACK){
+        return -1;
+    }
+    return 0;
+}
+
+int op_right(){
+    int ret = pop();
+    if(_head_error == POP_EMPTY_STACK){
+        return -1;
+    }
+
+    ret = ret >> 1;
+    push(ret);
+    return 0;
+}
+
+int op_left(){
+    int ret = pop();
+    if(_head_error == POP_EMPTY_STACK){
+        return -1;
+    }
+
+    ret = ret << 1;
+    push(ret);
+    return 0;
+}
 
 int parse(const char* input){
     short int i = 0;
@@ -18,35 +100,35 @@ int parse(const char* input){
         //collect it into a temporary buffer
         if(input[i] == ' ' || input[i] == '\n' || input[i] == '\t'){
             if(j == 1 && (strstr(ops,buf) != NULL)){ //if single operator
-                int operands[2] = {0};
-                for(int it = 0;it < 2; ++it){
-                    operands[it] = pop();
-                    if(_head_error == POP_EMPTY_STACK){
-                        printf("Not enough elements on stack!\n");
-                        return i;
-                    }
-                }
-
-
                 //apply operator
                 switch(buf[0]){
                     case '+':
-                        ret = operands[0] + operands[1];
+                        ret = op_add();
                         break;
                     case '-':
-                        ret = operands[0] - operands[1];
+                        ret = op_sub();
                         break;
                     case '*':
-                        ret = operands[0] * operands[1];
+                        ret = op_mul();
                         break;
                     case '/':
-                        ret = operands[0] / operands[1];
+                        ret = op_div();
+                        break;
+                    case '.':
+                        ret = op_pri();
+                        break;
+                    case '<':
+                        ret = op_left();
+                        break;
+                    case '>':
+                        ret = op_right();
                         break;
                     default:
-                        abort();
                 }
 
-                push(ret);
+                if(ret == -1){
+                    return i;
+                }
                 //TODO parse as token in dictionary
             } else { //Is number
                 ret = atoi(buf);

src/parse.h

@@ -18,6 +18,14 @@ extern char ops[];
 //parse a line
 int parse(const char*);
 
+int op_add();
+int op_sub();
+int op_mul();
+int op_div();
+int op_pri();
+int op_right();
+int op_left();
+
 #define BUFFER_MAX_SIZE 1024
 
 #endif //!_PARSE_H_