From da83c3cc9c1f5431b0160550715bae7bd980cf26 Mon Sep 17 00:00:00 2001
From: OlimilO1402 <olimilo@gmx.net>
Date: Wed, 2 Mar 2022 18:36:05 +0100
Subject: [PATCH] finally calculation of UInt64_Mul is correct

---
 Forms/Form1.frm                | 19 +++++++++----------
 UnsignedOpsDll/UnsignedOps.asm | 12 +++++++-----
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/Forms/Form1.frm b/Forms/Form1.frm
index d5dbe0d..7d3adf3 100644
--- a/Forms/Form1.frm
+++ b/Forms/Form1.frm
@@ -353,17 +353,16 @@ Sub TestDll()
     
     d = UInt64_Mul(c1, c2)
     Debug_Print VarType(d) & " " & CStr(d) '14 121932631112635269
-    
-    '628239210217683
-    '41419963890366
-
-    c1 = 214748.3647 '1234.5678 '62823921021.7683
-    c2 = 214748.3647 '4141996389.0366
-    '2147483647*2147483647=4611686014132420609
-    
+        
+    '     2147483647 *     2147483647 =           4611686014132420609
+    'c1 = 214748.3647
+    'c2 = 214748.3647
+    
+    '628239210217683 * 41419963890366 = 26021645401728484450406541978
+    c1 = 62823921021.7683
+    c2 = 4141996389.0366
     d = UInt64_Mul(c1, c2)
-    Debug_Print VarType(d) & " " & CStr(d) '14 26021645401728484450406541978
-                                              '
+    Debug_Print VarType(d) & " " & CStr(d)
     
     s = Space(20): UInt64_ToHex cret, StrPtr(s)
     Debug_Print Trim0(s)
diff --git a/UnsignedOpsDll/UnsignedOps.asm b/UnsignedOpsDll/UnsignedOps.asm
index b858bb2..b1d0d6a 100644
--- a/UnsignedOpsDll/UnsignedOps.asm
+++ b/UnsignedOpsDll/UnsignedOps.asm
@@ -351,9 +351,9 @@ UInt64_Sub endp
 ;                ByVal V1 As Currency, ByVal V2 As Currency, ByVal pDec_out As LongPtr
 UInt64_Mul proc
     
-	;int 3
-	
-	; 1. prepare Variant as type Decimal
+    ;int 3
+    
+    ; 1. prepare Variant as type Decimal
     mov   edi    , [esp+20] ; copy the pointer to a Variant from stack to register EDI
     mov    dx    ,      14  ; copy the vartype-word for decimal it is 14 = &HE to the register dx	
     mov  [edi+ 0],   dx     ; copy the value in register dx to the Variant to the first int16-slot
@@ -389,8 +389,10 @@ UInt64_Mul proc
     pushfd                  ; Save carry out here.
     
     ; 5. Multiply the two Hi dwords together,
-    mov   eax    , [esp+ 8] ; Get Hi dword of Multiplier
-    mul  dword ptr [esp+16] ; Multiply by Hi dword of Multiplicand
+    ;mov   eax    , [esp+ 8] ; Get Hi dword of Multiplier
+	mov   eax    , [esp+12]
+    ;mul  dword ptr [esp+16] ; Multiply by Hi dword of Multiplicand
+	mul  dword ptr [esp+20]
     popfd                   ; Retrieve carry from above
     adc   eax    ,  ecx     ; Add in partial product from above. 
     adc   edx    ,       0  ; Don't forget the carry!