1 files changed, 98 insertions, 0 deletions
diff --git a/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlmul.asm b/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlmul.asm
new file mode 100644
index 0000000000..341ea8a7bc
--- /dev/null
+++ b/CryptoPkg/Library/IntrinsicLib/Ia32/MathLlmul.asm
@@ -0,0 +1,98 @@
+;***
+;llmul.asm - long multiply routine
+;
+;       Copyright (c) Microsoft Corporation. All rights reserved.
+;       SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;Purpose:
+;       Defines long multiply routine
+;       Both signed and unsigned routines are the same, since multiply's
+;       work out the same in 2's complement
+;       creates the following routine:
+;           __allmul
+;
+;Original Implemenation: MSVC 14.12.25827
+;
+;*******************************************************************************
+    .686
+    .model  flat,C
+    .code
+
+
+;***
+;llmul - long multiply routine
+;
+;Purpose:
+;       Does a long multiply (same for signed/unsigned)
+;       Parameters are not changed.
+;
+;Entry:
+;       Parameters are passed on the stack:
+;               1st pushed: multiplier (QWORD)
+;               2nd pushed: multiplicand (QWORD)
+;
+;Exit:
+;       EDX:EAX - product of multiplier and multiplicand
+;       NOTE: parameters are removed from the stack
+;
+;Uses:
+;       ECX
+;
+;Exceptions:
+;
+;*******************************************************************************
+_allmul PROC NEAR
+
+A       EQU     [esp + 4]       ; stack address of a
+B       EQU     [esp + 12]      ; stack address of b
+
+HIGH_PART  EQU     [4]             ;
+LOW_PART   EQU     [0]
+
+;
+;       AHI, BHI : upper 32 bits of A and B
+;       ALO, BLO : lower 32 bits of A and B
+;
+;             ALO * BLO
+;       ALO * BHI
+; +     BLO * AHI
+; ---------------------
+;
+
+        mov     eax,HIGH_PART(A)
+        mov     ecx,HIGH_PART(B)
+        or      ecx,eax         ;test for both high dwords zero.
+        mov     ecx,LOW_PART(B)
+        jnz     short hard      ;both are zero, just mult ALO and BLO
+
+        mov     eax,LOW_PART(A)
+        mul     ecx
+
+        ret     16              ; callee restores the stack
+
+hard:
+        push    ebx
+
+; must redefine A and B since esp has been altered
+
+A2      EQU     [esp + 8]       ; stack address of a
+B2      EQU     [esp + 16]      ; stack address of b
+
+        mul     ecx             ;eax has AHI, ecx has BLO, so AHI * BLO
+        mov     ebx,eax         ;save result
+
+        mov     eax,LOW_PART(A2)
+        mul     dword ptr HIGH_PART(B2) ;ALO * BHI
+        add     ebx,eax         ;ebx = ((ALO * BHI) + (AHI * BLO))
+
+        mov     eax,LOW_PART(A2);ecx = BLO
+        mul     ecx             ;so edx:eax = ALO*BLO
+        add     edx,ebx         ;now edx has all the LO*HI stuff
+
+        pop     ebx
+
+        ret     16              ; callee restores the stack
+
+_allmul ENDP
+
+        end