From ccd19f1e49639186e6199c27c94ca7878785231a Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Fri, 1 Dec 2017 12:40:32 +0100
Subject: [PATCH] mem: add mmap helper

Add function and structure to help with mmap and mlock
---
 spa/include/spa/utils/defs.h |  3 ++-
 src/pipewire/mem.h           | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/spa/include/spa/utils/defs.h b/spa/include/spa/utils/defs.h
index 8e976c807..3312ad127 100644
--- a/spa/include/spa/utils/defs.h
+++ b/spa/include/spa/utils/defs.h
@@ -118,7 +118,8 @@ struct spa_fraction {
 #define SPA_DEPRECATED
 #endif
 
-#define SPA_ROUND_UP_N(num,align) ((((num) + ((align) - 1)) & ~((align) - 1)))
+#define SPA_ROUND_DOWN_N(num,align)	((num) & ~((align) - 1))
+#define SPA_ROUND_UP_N(num,align)	SPA_ROUND_DOWN_N((num) + ((align) - 1),align)
 
 #ifndef SPA_LIKELY
 #ifdef __GNUC__
diff --git a/src/pipewire/mem.h b/src/pipewire/mem.h
index 079fbc5fa..e353195d6 100644
--- a/src/pipewire/mem.h
+++ b/src/pipewire/mem.h
@@ -65,6 +65,25 @@ pw_memblock_free(struct pw_memblock *mem);
 /** Find memblock for given \a ptr */
 struct pw_memblock * pw_memblock_find(const void *ptr);
 
+/** parameters to map a memory range */
+struct pw_map_range {
+	uint32_t start;		/** offset in first page with start of data */
+	uint32_t offset;	/** page aligned offset to map */
+	uint32_t size;		/** size to map */
+};
+
+/** Calculate parameters to mmap() memory into \a range so that
+ * \a size bytes at \a offset can be mapped with mmap().  */
+static inline void pw_map_range_init(struct pw_map_range *range,
+				     uint32_t offset, uint32_t size,
+				     uint32_t page_size)
+{
+	range->offset = SPA_ROUND_DOWN_N(offset, page_size);
+	range->start = offset - range->offset;
+	range->size = offset + size - range->offset;
+}
+
+
 #ifdef __cplusplus
 }
 #endif