1 files changed, 78 insertions, 0 deletions
diff --git a/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlshr.asm b/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlshr.asm
new file mode 100644
index 0000000000..ab8294580f
--- /dev/null
+++ b/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlshr.asm
@@ -0,0 +1,78 @@
+;***
+;llshr.asm - long shift right
+;
+;       Copyright (c) Microsoft Corporation. All rights reserved.
+;       SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;Purpose:
+;       define signed long shift right routine
+;           __allshr
+;
+;Original Implemenation: MSVC 14.12.25827
+;
+;*******************************************************************************
+    .686
+    .model  flat,C
+    .code
+
+
+
+;***
+;llshr - long shift right
+;
+;Purpose:
+;       Does a signed Long Shift Right
+;       Shifts a long right any number of bits.
+;
+;Entry:
+;       EDX:EAX - long value to be shifted
+;       CL    - number of bits to shift by
+;
+;Exit:
+;       EDX:EAX - shifted value
+;
+;Uses:
+;       CL is destroyed.
+;
+;Exceptions:
+;
+;*******************************************************************************
+_allshr PROC NEAR
+
+;
+; Handle shifts of 64 bits or more (if shifting 64 bits or more, the result
+; depends only on the high order bit of edx).
+;
+        cmp     cl,64
+        jae     short RETSIGN
+
+;
+; Handle shifts of between 0 and 31 bits
+;
+        cmp     cl, 32
+        jae     short MORE32
+        shrd    eax,edx,cl
+        sar     edx,cl
+        ret
+
+;
+; Handle shifts of between 32 and 63 bits
+;
+MORE32:
+        mov     eax,edx
+        sar     edx,31
+        and     cl,31
+        sar     eax,cl
+        ret
+
+;
+; Return double precision 0 or -1, depending on the sign of edx
+;
+RETSIGN:
+        sar     edx,31
+        mov     eax,edx
+        ret
+
+_allshr ENDP
+
+        end