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-rw-r--r--MdePkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.S41
1 files changed, 41 insertions, 0 deletions
diff --git a/MdePkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.S b/MdePkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.S
new file mode 100644
index 0000000000..d1ff500d5d
--- /dev/null
+++ b/MdePkg/Library/CompilerIntrinsicsLib/Arm/ctzsi2.S
@@ -0,0 +1,41 @@
+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#------------------------------------------------------------------------------
+
+#include <AsmMacroLib.h>
+
+ASM_FUNC(__ctzsi2)
+ uxth r3, r0
+ cmp r3, #0
+ moveq ip, #16
+ movne ip, #0
+ @ lr needed for prologue
+ mov r0, r0, lsr ip
+ tst r0, #255
+ movne r3, #0
+ moveq r3, #8
+ mov r0, r0, lsr r3
+ tst r0, #15
+ movne r1, #0
+ moveq r1, #4
+ add r3, r3, ip
+ mov r0, r0, lsr r1
+ tst r0, #3
+ movne r2, #0
+ moveq r2, #2
+ add r3, r3, r1
+ mov r0, r0, lsr r2
+ and r0, r0, #3
+ add r2, r3, r2
+ eor r3, r0, #1
+ mov r0, r0, lsr #1
+ ands r3, r3, #1
+ mvnne r3, #0
+ rsb r0, r0, #2
+ and r0, r3, r0
+ add r0, r2, r0
+ bx lr