Cleaned and slightly refactored stdio.h and file I/O syscalls

include/c/syscall.h

@@ -1,12 +1,14 @@
-#ifndef SYSCALLNUMS_H
-#define SYSCALLNUMS_H
+#ifndef SYSCALL_H
+#define SYSCALL_H
+
+#include <stddef.h>
 
 #define MAX_SYSCALLS 9
 
 typedef enum {
     SYS_RESERVED,
     SYS_SLEEP, 
-    SYS_GETS,
+    SYS_READ,
     SYS_WRITE,
     SYS_OPEN,
     SYS_CLOSE,
@@ -25,4 +27,31 @@ typedef enum {
     O_BIN       = 0x40, // Read bytes, not text
 } OFLAGS;
 
+int syscall(int nr, int arg0, int arg1, int arg2) {
+    int ret = 0;
+    __asm__ volatile ("int $0x80" : "=a"(ret) : "a"(nr), "b"(arg0), "c"(arg1), "d"(arg2));
+    return ret;
+}
+
+/* Syscall wrappers */
+int read(int fd, void* ptr, size_t count) {
+    // Returns: int fd
+    return syscall(SYS_READ, fd, (int)ptr, count);
+}
+
+int write(int fd, const void* ptr, size_t count) {
+    // Returns: int count
+    return syscall(SYS_WRITE, fd, (int)ptr, count);
+}
+
+int open(const char* path, int oflag) {
+    // Returns: int fd
+    return syscall(SYS_OPEN, (int)path, oflag, 0);
+}
+
+int close(int fd) {
+    // Returns: int status
+    return syscall(SYS_CLOSE, fd, 0, 0);
+}
+
 #endif