1 files changed, 67 insertions, 0 deletions
diff --git a/devio/iostate.h b/devio/iostate.h
new file mode 100644
index 00000000..1795e153
--- /dev/null
+++ b/devio/iostate.h
@@ -0,0 +1,67 @@
+/* State for an I/O stream.
+
+   Copyright (C) 1995 Free Software Foundation, Inc.
+
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#ifndef __IOSTATE_H__
+#define __IOSTATE_H__
+
+/* ---------------------------------------------------------------- */
+
+enum io_state_buffer_use
+{
+  /* 0 means nothing */
+  IO_STATE_BUFFERED_WRITE = 1, IO_STATE_BUFFERED_READ = 2
+};
+
+struct io_state {
+  /* What we think the current position is.  */
+  vm_offset_t location;
+
+  /* The buffer in which we accumulate buffered i/o.  */
+  vm_address_t buffer;
+  /* The size of BUFFER.  */
+  vm_size_t buffer_size;
+
+  /* If LOCATION is not a multiple of the block size (and so points somewhere
+     in the middle of BUFFER), this indicates why.  */
+  enum io_state_buffer_use buffer_use;
+
+  /* Lock this if you want to read/modify LOCATION or BUFFER.  */
+  struct mutex lock;
+};
+
+#define io_state_lock(ios) mutex_lock(&(ios)->lock)
+#define io_state_unlock(ios) mutex_unlock(&(ios)->lock)
+
+/* Declare this to keep the parameter scope below sane.  */
+struct dev;
+
+/* Initialize the io_state structure IOS to be used with the device DEV.  If
+   a memory allocation error occurs, ENOMEM is returned, otherwise 0.  */
+error_t io_state_init(struct io_state *ios, struct dev *dev);
+
+/* Frees all resources used by IOS.  */
+void io_state_finalize(struct io_state *ios);
+
+/* If IOS's location isn't block aligned because writes have been buffered
+   there, then sync the whole buffer out to the device.  Any error that
+   occurs while writing is returned, otherwise 0.  */
+error_t io_state_sync(struct io_state *ios, struct dev *dev);
+
+#endif /* !__IOSTATE_H__ */