Started Implementing a BASIC interpriter

.vscode/c_cpp_properties.json

@@ -0,0 +1,22 @@
+{
+    "configurations": [
+        {
+            "name": "Win32",
+            "includePath": [
+                "${default}",
+                "${workspaceFolder}/**"
+            ],
+            "defines": [
+                "_DEBUG",
+                "UNICODE",
+                "_UNICODE"
+            ],
+            "windowsSdkVersion": "10.0.22621.0",
+            "compilerPath": "C:/msys64/mingw64/bin/gcc.exe",
+            "cStandard": "c17",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "linux-gcc-x64"
+        }
+    ],
+    "version": 4
+}

src/impl/kernel/main.c

@@ -10,9 +10,7 @@
 #include "window.h"
 #include "fs.h"
 #include "fat12.h"
-
+#include "basic.h"
-
-
 
 #define COMMAND_BUFFER_SIZE 256 // Increase buffer size to handle longer commands
 #define BACKSPACE_KEY 8
@@ -22,9 +20,9 @@
 
 extern void kpanic(int error_code);
 
-
+void shutdown_system()
-void shutdown_system() {
+{
-    __asm__ (
+    __asm__(
         "movl $1, %eax\n" // syscall number for sys_reboot (1 in this case)
         "movl $0, %ebx\n" // reboot flags
         "movl $0, %ecx\n" // no additional arguments
@@ -33,18 +31,20 @@ void shutdown_system() {
     );
 }
 
-
-
-
 char commandHistory[HISTORY_SIZE][COMMAND_BUFFER_SIZE];
 int currentHistoryIndex = 0;
 int historyCount = 0;
 
-void add_to_history(const char* command) {
+void add_to_history(const char *command)
-    if (historyCount < HISTORY_SIZE) {
+{
+    if (historyCount < HISTORY_SIZE)
+    {
         historyCount++;
-    } else {
+    }
-        for (int i = 1; i < HISTORY_SIZE; i++) {
+    else
+    {
+        for (int i = 1; i < HISTORY_SIZE; i++)
+        {
             strcpy(commandHistory[i - 1], commandHistory[i]);
         }
     }
@@ -52,23 +52,26 @@ void add_to_history(const char* command) {
     currentHistoryIndex = historyCount;
 }
 
-const char* get_previous_command() {
+const char *get_previous_command()
-    if (currentHistoryIndex > 0) {
+{
+    if (currentHistoryIndex > 0)
+    {
         currentHistoryIndex--;
         return commandHistory[currentHistoryIndex];
     }
     return NULL;
 }
 
-const char* get_next_command() {
+const char *get_next_command()
-    if (currentHistoryIndex < historyCount - 1) {
+{
+    if (currentHistoryIndex < historyCount - 1)
+    {
         currentHistoryIndex++;
         return commandHistory[currentHistoryIndex];
     }
     return NULL;
 }
 
-
 const void clear()
 {
     print_set_color(PRINT_COLOR_WHITE, PRINT_COLOR_BLACK); // Set text color
@@ -79,27 +82,35 @@ const void clear()
     print_setup_prompt();
 }
 
-
+void halt()
-
+{
-
-void halt(){
     print_str("[ WARN ] HALT\n");
-    while (1) {}
+    while (1)
+    {
+    }
 }
 
-void commandHandler(char* command) {
+void commandHandler(char *command)
+{
     printf("\n");
 
-    if (strcmp(command, "cls") == 0) {
+    if (strcmp(command, "cls") == 0)
+    {
         clear();
-    } else if (strcmp(command, "knp") == 0) {
+    }
+    else if (strcmp(command, "knp") == 0)
+    {
         kpanic(1);
-    } else if (int_strncmp(command, "echo ", 5) == 0) {
+    }
-        char* message = command + 5;  // Skip the "echo " part
+    else if (int_strncmp(command, "echo ", 5) == 0)
+    {
+        char *message = command + 5; // Skip the "echo " part
         print_str("\n");
         print_str(message);
         print_str("\n");
-    } else if (int_strncmp(command, "cwin", 4) == 0) {
+    }
+    else if (int_strncmp(command, "cwin", 4) == 0)
+    {
         // Define window properties
         Window myWindow;
         int x = 8;                                  // X position of the window
@@ -117,75 +128,81 @@ void commandHandler(char* command) {
         print_text_in_window(&myWindow, 2, 2, "Window Manager is a ");
         print_text_in_window(&myWindow, 2, 3, "Work in progress, Sorry :("); // Print text inside the window
         print_text_in_window(&myWindow, 2, 4, "do [ cls ] to clear");        // Print text inside the window
-        
+    }
-        
+    else if (int_strncmp(command, "exit", 4) == 0)
-        
+    {
-    } else if (int_strncmp(command, "exit", 4) == 0) {
         printf("Driver Call [ shutdown_system(); ] \n");
         shutdown_system();
-        
+    }
-        
+    else if (int_strncmp(command, "panic_test", 10) == 0)
-    }  else if (int_strncmp(command, "panic_test", 10) == 0) {
+    {
-        int _y = 1/0;
+        int _y = 1 / 0;
         printf("Output %d\n", _y);
-        
+    }
-    } else if (int_strncmp(command, "test", 4) == 0) {
+    else if (int_strncmp(command, "test", 4) == 0)
+    {
 
         //// Test custom malloc and free
-        //void* block1 = malloc(32);
+        // void* block1 = malloc(32);
-        //void* block2 = malloc(64);
+        // void* block2 = malloc(64);
-        //void* block3 = malloc(128);
+        // void* block3 = malloc(128);
         //
         //// List used blocks
-        //list_used_blocks();
+        // list_used_blocks();
         //
         //// Free a block and check again
-        //free(block2);
+        // free(block2);
-        //printf("\nAfter freeing block2:\n");
+        // printf("\nAfter freeing block2:\n");
-        //list_used_blocks();
+        // list_used_blocks();
         //
-        //void* block4 = malloc(64);
+        // void* block4 = malloc(64);
         //
-        //list_used_blocks();
+        // list_used_blocks();
-        
 
         create_game();
-        
+    }
-    } else if (int_strncmp(command, "split", 5) == 0) {
+    else if (int_strncmp(command, "split", 5) == 0)
+    {
         printf("Kernel Call [ split_string(); ]\n");
 
         // Check the length of the command string and use it properly
-        char** new_command = split_string(command, ",", strlen(command));
+        char **new_command = split_string(command, ",", strlen(command));
 
-        //char** new_command = {{NULL, NULL, NULL, NULL}};
+        // char** new_command = {{NULL, NULL, NULL, NULL}};
 
-        if (new_command) {
+        if (new_command)
+        {
             // Add a loop to print all the elements in the new_command array for debugging
-            for (int i = 0; new_command[i] != NULL; i++) {
+            for (int i = 0; new_command[i] != NULL; i++)
+            {
                 printf("new_command[%d]: %s\n", i, new_command[i]);
             }
 
-            //halt();  // Debug halt
+            // halt();  // Debug halt
 
             // Ensure that new_command[1] exists before accessing it
-            if (new_command[1] != NULL) {
+            if (new_command[1] != NULL)
+            {
                 printf("%s\n", new_command[1]);
-            } else {
+            }
+            else
+            {
                 printf("Error: new_command[1] is NULL\n");
             }
-    } else {
+        }
+        else
+        {
             printf("Error: split_string returned NULL\n");
         }
-
+    }
-
+    else
-    } else {
+    {
         printf("Unknown command: %s\n", command);
     }
 }
 
-
+void print_setup_prompt()
-
+{
-void print_setup_prompt() {
     move_cursor(0, 0);
     print_set_color(PRINT_COLOR_LIGHT_RED, PRINT_COLOR_BLACK);
     print_str("-------------------- ");
@@ -197,35 +214,59 @@ void print_setup_prompt() {
     print_str("V 1.5.01\n");
 }
 
+int test_basic()
+{
+    InterpreterState state;
+    init_state(&state);
 
+    const char *program[] = {
+        "LET A = 10",
+        "LET B = 20",
+        "PRINT A + B",
+        "LET A = \"Hello\"",
+        "LET B = \" World\"",
+        "PRINT A + B",
+        "END",
 
-void kernel_main() {
+    };
+
+    for (size_t i = 0; i < sizeof(program) / sizeof(program[0]); i++)
+    {
+        execute_line(&state, program[i]);
+        if (!state.running)
+            break;
+    }
+
+    return 0;
+}
+
+void kernel_main()
+{
 
     init_keyboard_driver();
 
-    
-    
-    
     idt_install();
 
-    
     print_str("[ WARN ] Skipping File System Initialization...\n[ INFO ] Do [ fsinit ] to initalize the filesystem\n");
 
-    if (fat12_init() == 0) {
+    if (fat12_init() == 0)
+    {
         printf("Filesystem mounted\n");
 
         fat12_read_root_directory();
 
         fat12_dir_entry_t entry;
-        if (fat12_find_file("HELLOTXT", &entry)) {
+        if (fat12_find_file("HELLOTXT", &entry))
+        {
             printf("File found: HELLO.TXT\n");
         }
     }
+    clear();
 
+    test_basic();
 
     print_setup_prompt();
 
-
     print_str(" > ");
 
     // Main loop
@@ -234,40 +275,46 @@ void kernel_main() {
     char commandBuffer[COMMAND_BUFFER_SIZE];
     size_t commandLength = 0; // To track the length of the current command
 
-
+    while (1)
-    while (1) {
+    {
         key = read_key();
 
-        if (key != 0) {
+        if (key != 0)
-            if (!keydown) {
+        {
+            if (!keydown)
+            {
                 CursorPosition pos = get_print_cursor_pos();
-                move_cursor(pos.x,pos.y);
+                move_cursor(pos.x, pos.y);
-                if (key == 10) {  // Enter key
+                if (key == 10)
+                {                                        // Enter key
                     commandBuffer[commandLength] = '\0'; // Null-terminate the command
                     commandHandler(commandBuffer);
 
                     // Reset command buffer for the next input
                     commandLength = 0;
                     print_str(" > ");
-
+                }
-                } else if (key == BACKSPACE_KEY) {  // Backspace key
+                else if (key == BACKSPACE_KEY)
-                    if (commandLength > 0) {
+                { // Backspace key
+                    if (commandLength > 0)
+                    {
                         // Remove the last character from the buffer
                         commandLength--;
                         commandBuffer[commandLength] = '0'; // Null-terminate after removal
 
                         // Clear the character from the screen (overwrite with space)
                         // Move cursor back one position
-                        offset_print_cursor(-1,0);
+                        offset_print_cursor(-1, 0);
                         print_char(' ');            // Overwrite the character
-                        offset_print_cursor(-1,0); // Move cursor back one position(because its moved left one by the rpintf)
+                        offset_print_cursor(-1, 0); // Move cursor back one position(because its moved left one by the rpintf)
-
-
                     }
-
+                }
-                } else {
+                else
-                    if (key >= 32 && key <= 126) {  // Check if the key is a printable character
+                {
-                        if (commandLength < COMMAND_BUFFER_SIZE - 1) {
+                    if (key >= 32 && key <= 126)
+                    { // Check if the key is a printable character
+                        if (commandLength < COMMAND_BUFFER_SIZE - 1)
+                        {
                             commandBuffer[commandLength++] = key; // Append character to buffer
                             commandBuffer[commandLength] = '\0';  // Null-terminate the buffer
                             print_char(key);                      // Print key to the screen
@@ -276,7 +323,9 @@ void kernel_main() {
                 }
                 keydown = true;
             }
-        } else {
+        }
+        else
+        {
             keydown = false;
         }
 
@@ -284,5 +333,4 @@ void kernel_main() {
     }
 
     kpanic(2);
-
 }

src/impl/x86_64/basic.c

@@ -0,0 +1,184 @@
+#include "memory.h"
+#include "print.h"
+#include "strings.h"
+#include "stdint.h"
+#include "stddef.h"
+#include "basic.h"
+
+
+
+// Utility: Find or create a variable by name
+Variable* get_variable(InterpreterState* state, const char* name) {
+    for (size_t i = 0; i < state->variable_count; i++) {
+        if (strcmp(state->variables[i].name, name) == 0) {
+            return &state->variables[i];
+        }
+    }
+    if (state->variable_count < MAX_VARIABLES) {
+        Variable* var = &state->variables[state->variable_count++];
+        strncpy(var->name, name, sizeof(var->name) - 1);
+        var->name[sizeof(var->name) - 1] = '\0';
+        var->value = 0;
+        var->str_value = NULL;
+        return var;
+    }
+    return NULL; // No space for more variables
+}
+
+// Parse an integer from a string, skipping leading whitespace
+int parse_int(const char* str) {
+    while (*str == ' ') str++; // Skip leading spaces
+    int result = 0;
+    int sign = 1;
+    if (*str == '-') {
+        sign = -1;
+        str++;
+    }
+    while (*str >= '0' && *str <= '9') {
+        result = result * 10 + (*str - '0');
+        str++;
+    }
+    return result * sign;
+}
+
+
+
+
+const char* evaluate_expression(InterpreterState* state, const char* expr) {
+    char buffer[64];
+    strncpy(buffer, expr, sizeof(buffer) - 1);
+    buffer[sizeof(buffer) - 1] = '\0';
+
+    char* plus = strrchr(buffer, '+');
+    if (plus) {
+        *plus = '\0';
+
+        // Evaluate the left and right sides only once
+        const char* left = evaluate_expression(state, buffer);
+        const char* right = evaluate_expression(state, plus + 1);
+
+        // Debug output
+        printf("DEBUG: Left operand: %s\n", left);
+        printf("DEBUG: Right operand: %s\n", right);
+
+        // Check if both sides are numeric
+        int left_is_number = (left[0] >= '0' && left[0] <= '9') || (left[0] == '-' && left[1] >= '0' && left[1] <= '9');
+        int right_is_number = (right[0] >= '0' && right[0] <= '9') || (right[0] == '-' && right[1] >= '0' && right[1] <= '9');
+
+        static char result[128];
+
+        if (left_is_number && right_is_number) {
+            // Parse the left and right operands
+            int left_value = parse_int(left);
+            int right_value = parse_int(right);
+
+            // Correct addition logic
+            int sum = left_value + right_value;
+
+            // Debug addition
+            printf("DEBUG: Adding %d + %d = %d\n", left_value, right_value, sum);
+
+            // Format the result as a string
+            snprintf(result, sizeof(result), "%d", sum);
+        } else {
+            // Concatenate strings
+            snprintf(result, sizeof(result), "%s%s", left, right);
+
+            // Debug string concatenation
+            printf("DEBUG: Concatenating strings: %s + %s = %s\n", left, right, result);
+        }
+        return result;
+    }
+
+    // Trim leading and trailing spaces
+    const char* start = buffer;
+    while (*start == ' ') start++;
+
+    char* end = buffer + strlen(buffer) - 1;
+    while (end > start && *end == ' ') *end-- = '\0';
+
+    if (start[0] >= 'A' && start[0] <= 'Z') {
+        Variable* var = get_variable(state, start);
+        if (var) {
+            static char var_result[64];
+            if (var->str_value) {
+                strncpy(var_result, var->str_value, sizeof(var_result) - 1);
+                var_result[sizeof(var_result) - 1] = '\0';
+                return var_result;
+            } else {
+                snprintf(var_result, sizeof(var_result), "%d", var->value);
+                return var_result;
+            }
+        }
+    }
+
+    if (start[0] == '"') {
+        // String literal
+        size_t len = strlen(start);
+        if (start[len - 1] == '"') {
+            static char str_result[64];
+            strncpy(str_result, start + 1, len - 2);
+            str_result[len - 2] = '\0';
+            return str_result;
+        }
+    }
+
+    static char int_result[16];
+    snprintf(int_result, sizeof(int_result), "%d", parse_int(start));
+    return int_result;
+}
+
+
+
+// Interpret a single line of code
+void interpret_line(InterpreterState* state, const char* line) {
+    if (strncmp(line, "LET", 3) == 0) {
+        const char* rest = line + 3;
+        while (*rest == ' ') rest++;
+        const char* equals = strchr(rest, '=');
+        if (!equals) return;
+
+        char var_name[16];
+        strncpy(var_name, rest, equals - rest);
+        var_name[equals - rest] = '\0';
+
+        // Trim trailing spaces from var_name
+        size_t len = strlen(var_name);
+        while (len > 0 && var_name[len - 1] == ' ') {
+            var_name[--len] = '\0';
+        }
+
+        Variable* var = get_variable(state, var_name);
+        if (var) {
+            const char* value = evaluate_expression(state, equals + 1);
+            if (value[0] >= '0' && value[0] <= '9') {
+                var->value = parse_int(value);
+                var->str_value = NULL;
+            } else {
+                var->str_value = malloc(strlen(value) + 1);
+                strcpy(var->str_value, value);
+            }
+        }
+    } else if (strncmp(line, "PRINT", 5) == 0) {
+        const char* rest = line + 5;
+        while (*rest == ' ') rest++;
+        const char* value = evaluate_expression(state, rest);
+        printf("%s\n", value);
+    } else if (strncmp(line, "END", 3) == 0) {
+        printf("Program terminated.\n");
+        state->running = 0;
+    }
+}
+
+// Initialize interpreter state
+void init_state(InterpreterState* state) {
+    state->variable_count = 0;
+    state->running = 1;
+}
+
+// Execute a single line in the context of a state
+void execute_line(InterpreterState* state, const char* line) {
+    printf("Executing line: %s\n", line); // Debugging
+    interpret_line(state, line);
+}
+

src/impl/x86_64/driver/print.c

@@ -334,6 +334,48 @@ int my_sscanf(const char *input, const char *format, char *output) {
     return match_count;
 }
 
+snprintf(char* buffer, size_t size, const char* format, ...) {
+    va_list args;
+    va_start(args, format);
+
+    const char* traverse = format;
+    size_t written = 0;
+
+    while (*traverse && written < size - 1) {
+        if (*traverse == '%' && *(traverse + 1)) {
+            traverse++;
+            if (*traverse == 's') {
+                const char* str = va_arg(args, const char*);
+                while (*str && written < size - 1) {
+                    buffer[written++] = *str++;
+                }
+            } else if (*traverse == 'd') {
+                int num = va_arg(args, int);
+                char num_buffer[16];
+                int num_len = 0;
+                if (num < 0) {
+                    if (written < size - 1) buffer[written++] = '-';
+                    num = -num;
+                }
+                do {
+                    num_buffer[num_len++] = '0' + (num % 10);
+                    num /= 10;
+                } while (num > 0);
+                while (num_len > 0 && written < size - 1) {
+                    buffer[written++] = num_buffer[--num_len];
+                }
+            }
+        } else {
+            buffer[written++] = *traverse;
+        }
+        traverse++;
+    }
+
+    buffer[written] = '\0';
+    va_end(args);
+    return written;
+}
+
 
 void printf(const char* format, ...) {
     va_list args;

src/impl/x86_64/strings.c

@@ -90,3 +90,13 @@ int strncmp(const char *s1, const char *s2, size_t n) {
         return (*(unsigned char *)s1 - *(unsigned char *)s2);
     }
 }
+
+char* strchr(const char* str, int ch) {
+    while (*str) {
+        if (*str == (char)ch) {
+            return (char*)str;
+        }
+        str++;
+    }
+    return NULL;
+}

src/intf/basic.h

@@ -0,0 +1,32 @@
+#ifndef BASIC_INTERPRETER_H
+#define BASIC_INTERPRETER_H
+
+#include "stdint.h"
+#include "stddef.h"
+
+#define MAX_LINE_LENGTH 128
+#define MAX_VARIABLES 32
+
+typedef struct {
+    char name[16];
+    int value;
+    char* str_value;
+} Variable;
+
+typedef struct {
+    Variable variables[MAX_VARIABLES];
+    size_t variable_count;
+    int running;
+} InterpreterState;
+
+// Initialize the interpreter state
+void init_state(InterpreterState* state);
+
+// Execute a single line of code in the context of a state
+void execute_line(InterpreterState* state, const char* line);
+
+// Utility to evaluate an expression (exposed for potential reuse)
+const char* evaluate_expression(InterpreterState* state, const char* expr);
+
+
+#endif // BASIC_INTERPRETER_H

src/intf/print.h

@@ -29,6 +29,7 @@ enum {
 };
 
 void sscanf(const char *str, const char *format, char *filename, char *content);
+snprintf(char* buffer, size_t size, const char* format, ...);
 int my_sscanf(const char *input, const char *format, char *output);
 void print_clear();
 void print_char(char character);

src/intf/strings.h

@@ -5,8 +5,9 @@
 int strcmp(const char *str1, const char *str2);
 size_t strlen(const char *str);
 char *strncpy(char *dest, const char *src, size_t n);
-int int_strncmp(const char* s1, const char* s2, size_t n);
+int int_strncmp(const char *s1, const char *s2, size_t n);
 void strcpy(char *dest, const char *src);
-char* strrchr(const char* str, char ch);
+char *strrchr(const char *str, char ch);
 
 int strncmp(const char *s1, const char *s2, size_t n);
+char *strchr(const char *str, int ch);