Add syscall description file

include/sys/syscall.h

@@ -0,0 +1,36 @@
+/** vim: set ft=cpp.doxygen :
+ * @file sys/syscall.h
+ * @brief System call interface definitions
+ */
+#pragma once
+#include "sys/types.h"
+
+// Defined here so no need to include mm.h
+#define userspace
+
+// System call numbers
+
+#define SYS_NR_READ         0
+#define SYS_NR_WRITE        1
+
+// System call signatures
+
+/**
+ * @brief 0 - Read data from file descriptor
+ * @param fd Source file
+ * @param buf Destination buffer. Has to be at least @ref count bytes
+ * @param count Count of bytes to be read
+ * @return Non-negative: count of bytes read
+ *         Negative: error
+ */
+int sys_read(int fd, userspace void *buf, size_t count);
+
+/**
+ * @brief 1 - Write data to file descriptor
+ * @param fd Destination file
+ * @param buf Bytes to write
+ * @param count Number of bytes to be written
+ * @return Non-negative: count of bytes written
+ *         Negative: error
+ */
+int sys_write(int fd, const userspace void *buf, size_t count);