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From 3a0fae39873c9c7d73dc978888e45b87ad27d44e Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Tue, 30 Sep 2014 03:58:43 +0200
Subject: [PATCH gnumach 3/3] ipc: use fast modulo operation in local hash
table
* ipc/ipc_table.h: Document that table sizes must be powers of two.
* ipc/ipc_hash.c (IH_LOCAL_HASH): Use fast modulo operation.
---
ipc/ipc_hash.c | 2 +-
ipc/ipc_table.h | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/ipc/ipc_hash.c b/ipc/ipc_hash.c
index 8285717..c2c6d6e 100644
--- a/ipc/ipc_hash.c
+++ b/ipc/ipc_hash.c
@@ -326,7 +326,7 @@ ipc_hash_global_delete(
*/
#define IH_LOCAL_HASH(obj, size) \
- ((((mach_port_index_t) (vm_offset_t) (obj)) >> 6) % (size))
+ ((((mach_port_index_t) (vm_offset_t) (obj)) >> 6) & (size - 1))
/*
* Routine: ipc_hash_local_lookup
diff --git a/ipc/ipc_table.h b/ipc/ipc_table.h
index 3cc5f56..311b9a7 100644
--- a/ipc/ipc_table.h
+++ b/ipc/ipc_table.h
@@ -45,6 +45,8 @@
* an ipc_table_size structure. These structures must
* be elements of an array, ipc_table_entries.
*
+ * Every its_size value must must be a power of two.
+ *
* The array must end with two elements with the same its_size value.
* Except for the terminating element, the its_size values must
* be strictly increasing. The largest (last) its_size value
--
2.1.0
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