From 863c623f9ab2bb1cb942d4bfc42a9baf12b0e069 Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Wed, 5 May 2010 21:09:11 +0000
Subject: [PATCH] Added is_address_range_covered(), returning whether the given
 address range is fully covered by the ranges in the array.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36631 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 headers/private/kernel/boot/addr_range.h |  2 ++
 src/system/boot/loader/kernel_args.cpp   | 36 ++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/headers/private/kernel/boot/addr_range.h b/headers/private/kernel/boot/addr_range.h
index f2fdc4aaac..1fd2f0c98a 100644
--- a/headers/private/kernel/boot/addr_range.h
+++ b/headers/private/kernel/boot/addr_range.h
@@ -25,6 +25,8 @@ status_t remove_address_range(addr_range *ranges, uint32 *_numRanges,
 	uint32 maxRanges, addr_t start, uint32 size);
 bool get_free_address_range(addr_range *ranges, uint32 numRanges, addr_t base,
 	size_t size, addr_t *_rangeBase);
+bool is_address_range_covered(addr_range *ranges, uint32 numRanges, addr_t base,
+	size_t size);
 
 status_t insert_physical_memory_range(addr_t start, uint32 size);
 status_t insert_physical_allocated_range(addr_t start, uint32 size);
diff --git a/src/system/boot/loader/kernel_args.cpp b/src/system/boot/loader/kernel_args.cpp
index f66014e0a2..d34266e29e 100644
--- a/src/system/boot/loader/kernel_args.cpp
+++ b/src/system/boot/loader/kernel_args.cpp
@@ -6,12 +6,14 @@
 
 #include <OS.h>
 
+#include <string.h>
+
+#include <algorithm>
+
 #include <kernel.h>
 #include <boot/stage2.h>
 #include <boot/platform.h>
 
-#include <string.h>
-
 
 static const size_t kChunkSize = 8 * B_PAGE_SIZE;
 
@@ -214,6 +216,36 @@ get_free_address_range(addr_range *ranges, uint32 numRanges, addr_t base,
 }
 
 
+bool
+is_address_range_covered(addr_range* ranges, uint32 numRanges, addr_t base,
+	size_t size)
+{
+	// Note: We don't assume that the ranges are sorted, so we can't do this
+	// in a simple loop. Instead we restart the loop whenever the start of the
+	// given range intersects with an existing one.
+
+	for (uint32 i = 0; i < numRanges;) {
+		addr_t rangeStart = ranges[i].start;
+		addr_t rangeSize = ranges[i].size;
+
+		if (rangeStart <= base && rangeSize > base - rangeStart) {
+			size_t intersect = std::min(rangeStart + rangeSize - base, size);
+			base += intersect;
+			size -= intersect;
+			if (size == 0)
+				return true;
+
+			i = 0;
+			continue;
+		}
+
+		i++;
+	}
+
+	return false;
+}
+
+
 status_t
 insert_physical_memory_range(addr_t start, uint32 size)
 {