feature (libnx): implemented basic file operations

libnx/inc/public/nox/stdio.h

@@ -3,4 +3,16 @@
 #ifndef LIBNX_STDIO_H
 #define LIBNX_STDIO_H
 
+#include "public/nox/stdtypes.h"
+#include "public/nox/string.h"
+
+typedef struct file_T file_T;
+
+file_T      file_open       (string_t path);
+void        file_close      (file_T* file);
+uint64_t    file_read       (file_T* file, void* buffer, uint64_t n);
+uint64_t    file_write      (file_T* file, void* buffer, uint64_t n);
+uint64_t    file_cursor_get (file_T* file);
+void        file_cursor_set (file_T* file, uint64_t cursor);
+
 #endif //LIBNX_STDIO_H

libnx/src/stdio.c

@@ -1,3 +1,43 @@
 // This file is part of noxos and licensed under the MIT open source license
 
 #include "public/nox/stdio.h"
+#include "public/nox/syscall.h"
+#include "public/nox/math.h"
+
+struct file_T{
+    uint64_t fd;
+    uint64_t cursor;
+};
+
+file_T file_open(string_t path) {
+    file_T file;
+
+    nx_fs_open(path, strlen(path), &file.fd);
+    file.cursor = 0;
+
+    return file;
+}
+
+void file_close(file_T* file) {
+    nx_fs_close(file->fd);
+}
+
+uint64_t file_read(file_T* file, void* buffer, uint64_t n) {
+    uint64_t rbytes = nx_fs_read(file->fd, file->cursor, buffer, n);
+    file->cursor += min(rbytes, n);
+    return rbytes;
+}
+
+uint64_t file_write(file_T* file, void* buffer, uint64_t n) {
+    uint64_t wbytes = nx_fs_write(file->fd, file->cursor, buffer, n);
+    file->cursor += min(wbytes, n);
+    return wbytes;
+}
+
+uint64_t file_cursor_get(file_T* file) {
+    return file->cursor;
+}
+
+void file_cursor_set(file_T* file, uint64_t cursor) {
+    file->cursor = cursor;
+}