Boilerplate forth

.gitignore

@@ -0,0 +1,9 @@
+#ignore all .o files
+src/**/*.o
+
+#ignore all swp files
+**/*.swp
+
+#ignore all executables, but still keep the bin folder
+bin/*
+!bin/.gitkeep

Makefile

@@ -4,26 +4,25 @@
 # Makefile
 #
 
-CC = g++
+CC = gcc
 
 FLAGS  = -pipe
 
 CFLAGS  = -Wall
 CFLAGS += -Ofast
-CFLAGS += -std=c++17
-#CFLAGS += -g
+CFLAGS += -g
 #CFLAGS += -pg
 
 LIBRARIES =
 
-SRC = $(shell find ./src -name '*.cpp')
-OBJ = $(subst .cpp,.o,$(SRC))
+SRC = $(shell find ./src -name '*.c')
+OBJ = $(subst .c,.o,$(SRC))
 BIN = ./bin
 
 PREFIX    = /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
-TARGET = dashboard.out
+TARGET = forth
 
 MAKEFLAGS += --jobs=4
 
@@ -31,7 +30,7 @@ all : $(OBJ)
 	@echo LD $@
 	@$(CC) $(FLAGS) $(CFLAGS) -o $(BIN)/$(TARGET) $(OBJ) $(LIBRARIES)
 
-.cpp.o :
+.c.o :
 	@echo CC $<
 	@$(CC) $(FLAGS) $(CFLAGS) $(LIBRARIES) $(DEFINITIONS) -c $< -o $@
 

src/main.c

@@ -0,0 +1,65 @@
+///////////////////////////////////////////////////////////////////////////////
+// Tyler Perkins
+// 9-23-21
+// Forth compiler/interpreter
+// entry point
+//
+
+#include <stdio.h>
+#include <string.h>
+
+#include "parse.h"
+#include "stack.h"
+
+#define BUFFER_SIZE 1024
+
+void help(int argc, char** argv){
+    printf("Incorrect usage!\n");
+    printf("Usage:\n");
+    printf("  %s [FILE]\n", argv[0]);
+    printf("File is an optional forth file containing code\n");
+    printf("If no file is provided you will be dropped into an interactive shell\n");
+    printf("All operators are using reverse Polish notation\n");
+    printf("Max line input size is %i", BUFFER_SIZE);
+}
+
+int main(int argc, char** argv){
+    char input[BUFFER_SIZE] = {0};
+    int retval = 0;
+
+
+    //check arg count
+    if(argc > 2){
+        help(argc, argv);
+        return -1;
+    } else if(argc == 2){
+        //TODO implement File parsing
+    }
+
+
+    printf("Entering shell...\n");
+
+    //get user input, with prompt
+    printf("> ");
+    fgets(input, BUFFER_SIZE, stdin);
+
+    while(strcmp(input, "exit\n")){
+        retval = parse(input);
+        if(retval > -1){
+            printf(" ");
+            for(int i = 1; i != retval; ++i){
+                printf(" ");
+            }
+            printf("^\n");
+            printf("Error parsing character at position %d!\n", retval);
+        } else {
+            printf("%d\n", peek());
+        }
+
+        printf("> ");
+        fgets(input, BUFFER_SIZE, stdin);
+    }
+
+    printf("Goodbye\n");
+    return 0;
+}

src/parse.c

@@ -0,0 +1,69 @@
+///////////////////////////////////////////////////////////////////////////////
+// Tyler Perkins
+// 9-23-21
+// parse implementations
+//
+
+#include "parse.h"
+
+char ops[] = {'+','-','*','/','\0'};
+
+int parse(const char* input){
+    short int i = 0;
+    short int j = 0;
+    int ret = 0;
+    char buf[BUFFER_MAX_SIZE] = {'\0'};
+
+    while(input[i] != '\0'){
+        //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];
+                        break;
+                    case '-':
+                        ret = operands[0] - operands[1];
+                        break;
+                    case '*':
+                        ret = operands[0] * operands[1];
+                        break;
+                    case '/':
+                        ret = operands[0] / operands[1];
+                        break;
+                    default:
+                        abort();
+                }
+
+                push(ret);
+                //TODO parse as token in dictionary
+            } else { //Is number
+                ret = atoi(buf);
+                push(ret);
+            }
+
+            //clean up buf
+            memset(buf, '\0', j+1);
+            j = 0;
+        } else { //not whitespace
+            
+            buf[j] = input[i];
+            ++j;
+        }
+
+        ++i;
+    }
+
+    return -1;
+}

src/parse.h

@@ -0,0 +1,23 @@
+///////////////////////////////////////////////////////////////////////////////
+// Tyler Perkins
+// 9-23-21
+// parse definitions
+//
+
+#ifndef _PARSE_H_
+#define _PARSE_H_
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "stack.h"
+
+extern char ops[];
+
+//parse a line
+int parse(const char*);
+
+#define BUFFER_MAX_SIZE 1024
+
+#endif //!_PARSE_H_

src/stack.c

@@ -0,0 +1,48 @@
+///////////////////////////////////////////////////////////////////////////////
+// Tyler Perkins
+// 9-23-21
+// stack implementation
+//
+
+#include "stack.h"
+
+struct s_node* head = NULL;
+unsigned int _head_error = 0;
+
+void push(int val){
+    struct s_node* temp;
+
+    temp = head;
+    head = (struct s_node*)malloc(sizeof(struct s_node));
+
+    head->_val = val;
+    head->_next = temp;
+}
+
+int pop(){
+    struct s_node* temp;
+    int retval;
+
+    if(head == NULL){
+        _head_error = POP_EMPTY_STACK;
+        return 0;
+    }
+
+    temp = head;
+    head = head->_next;
+
+    retval = temp->_val;
+
+    free(temp);
+
+    return retval;
+}
+
+int peek(){
+    if(head == NULL){
+        _head_error = PEEK_EMPTY_STACK;
+        return 0;
+    }
+
+    return head->_val;
+}

src/stack.h

@@ -0,0 +1,28 @@
+///////////////////////////////////////////////////////////////////////////////
+// Tyler Perkins
+// 9-23-21
+// stack definitions
+//
+
+#ifndef _STACK_H_
+#define _STACK_H_
+
+#include <stdlib.h>
+
+struct s_node {
+    int _val;
+    struct s_node* _next;
+};
+extern struct s_node* head;
+extern unsigned int _head_error;
+
+#define STACK_OK         0x00
+#define POP_EMPTY_STACK  0x01
+#define PEEK_EMPTY_STACK 0x02
+
+void push(int);
+int pop();
+int peek();
+
+
+#endif //!_STACK_H_