initial commit

include/opcodes.h

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+#ifndef OPCODES_H
+#define OPCODES_H
+
+// Define opcodes for the Virtual Machine.
+// Each opcode is an integer constant used by the VM.
+enum {
+    OP_HALT = 0,       // Stop execution.
+    OP_PUSH,           // Push an immediate value onto the stack. (Operand: value)
+    OP_POP,            // Pop the top of the stack into a register. (Operand: register index)
+    OP_LOAD,           // Load an immediate value into a register. (Operands: register, value)
+    OP_ADD,            // Add two registers; store the result in the first register. (Operands: reg_dest, reg_src)
+    OP_SUB,            // Subtract second register from first; store result in the first register. (Operands: reg_dest, reg_src)
+    OP_MUL,            // Multiply two registers; store result in the first register. (Operands: reg_dest, reg_src)
+    OP_DIV,            // Divide first register by second; store result in the first register. (Operands: reg_dest, reg_src)
+    OP_PRINT,          // Print the value of a register. (Operand: register index)
+    OP_JMP,            // Unconditional jump to a specified program address. (Operand: address)
+    OP_JMPZ,           // Jump to a specified address if the given register is zero. (Operands: register, address)
+    OP_CALL,           // Call a function: push return address and jump. (Operand: address)
+    OP_RET,            // Return from a function call. (No operand)
+    OP_CALL_OS         // Enter the nested OS shell. (No operand)
+};
+
+#endif // OPCODES_H
+

include/os.h

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+#ifndef OS_H
+#define OS_H
+
+// Declare the global reload_path so that it can be used in other files.
+extern char reload_path[256];
+
+// Declaration for the nested OS shell.
+void run_os(void);
+
+// Functions to save and load the OS state (the in-memory file system).
+// The state is saved in a custom file type (".osstate").
+int save_state(const char *filename);
+int load_state(const char *filename);
+
+#endif // OS_H

include/vm.h

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+#ifndef VM_H
+#define VM_H
+
+#include <stddef.h>
+
+// Increase registers and memory sizes for advanced programs.
+#define NUM_REGISTERS 16   // Number of general-purpose registers.
+#define STACK_SIZE    512  // Maximum stack size.
+#define PROGRAM_SIZE  2048 // Maximum program size (number of ints).
+
+// VM structure definition.
+typedef struct VM {
+    int registers[NUM_REGISTERS];  // General purpose registers.
+    int stack[STACK_SIZE];         // Stack memory.
+    int sp;                        // Stack pointer (index of next free slot).
+    int program[PROGRAM_SIZE];     // Bytecode program memory.
+    size_t program_size;           // Number of ints in the loaded program.
+    size_t pc;                     // Program counter.
+} VM;
+
+// Function prototypes for the VM.
+void init_vm(VM *vm);
+int load_program(VM *vm, const int *program, size_t size);
+void run_vm(VM *vm);
+
+#endif // VM_H
+