[iar][syscalls] 补充注释

components/libc/compilers/dlib/syscall_read.c

@@ -19,7 +19,19 @@
 #define DBG_LVL    DBG_INFO
 #include <rtdbg.h>
 
+/*
+ * The "__read" function reads a number of bytes, at most "size" into
+ * the memory area pointed to by "buffer".  It returns the number of
+ * bytes read, 0 at the end of the file, or _LLIO_ERROR if failure
+ * occurs.
+ *
+ * The template implementation below assumes that the application
+ * provides the function "MyLowLevelGetchar".  It should return a
+ * character value, or -1 on failure.
+ */
+
 #pragma module_name = "?__read"
+
 size_t __read(int handle, unsigned char *buf, size_t len)
 {
 #ifdef RT_USING_POSIX