1 files changed, 50 insertions, 0 deletions
diff --git a/docs/nspr/reference/pr_memmap.rst b/docs/nspr/reference/pr_memmap.rst
new file mode 100644
index 0000000000..6b37fe313a
--- /dev/null
+++ b/docs/nspr/reference/pr_memmap.rst
@@ -0,0 +1,50 @@
+PR_MemMap
+=========
+
+Maps a section of a file to memory.
+
+
+Syntax
+------
+
+.. code::
+
+   #include <prio.h>
+
+   void* PR_MemMap(
+     PRFileMap *fmap,
+     PRInt64 offset,
+     PRUint32 len);
+
+
+Parameters
+~~~~~~~~~~
+
+The function has the following parameters:
+
+``fmap``
+   A pointer to the file-mapping object representing the file to be
+   memory-mapped.
+``offset``
+   The starting offset of the section of file to be mapped. The offset
+   must be aligned to whole pages.
+``len``
+   Length of the section of the file to be mapped.
+
+
+Returns
+~~~~~~~
+
+The starting address of the memory region to which the section of file
+is mapped. Returns ``NULL`` on error.
+
+
+Description
+-----------
+
+:ref:`PR_MemMap` maps a section of the file represented by the file mapping
+``fmap`` to memory. The section of the file starts at ``offset`` and has
+the length ``len``.
+
+When the file-mapping memory region is no longer needed, it should be
+unmapped with a call to :ref:`PR_MemUnmap`.