Changeset 1888 in vbox for trunk/src/VBox/Runtime/win64

Timestamp:

Apr 3, 2007 2:48:08 PM (18 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

20132

Message:

ASMMultU64ByU32DivByU32 (for TSC calculation).

File:

• trunk/src/VBox/Runtime/win64/ASMMultU64ByU32DivByU32.asm (copied) (copied from trunk/src/VBox/Runtime/win64/ASMGetFlags.asm ) (2 diffs)

trunk/src/VBox/Runtime/win64/ASMMultU64ByU32DivByU32.asm

@@ -1 +1 @@
 ;; @file
-; InnoTek Portable Runtime - ASMGetFlags().
+; InnoTek Portable Runtime - ASMMultU64ByU32DivByU32().
 ;
 
@@ -26 +26 @@
 BEGINCODE
 
-BEGINPROC_EXPORTED ASMGetFlags
-        pushf
-        pop     rax
+;;
+; Multiple a 64-bit by a 32-bit integer and divide the result by a 32-bit integer
+; using a 96 bit intermediate result.
+; 
+; @returns (u64A * u32B) / u32C. (rax)
+; @param   u64A    rcx      The 64-bit value.
+; @param   u32B    edx      The 32-bit value to multiple by A.
+; @param   u32C    r8d      The 32-bit value to divide A*B by.
+; 
+BEGINPROC_EXPORTED ASMMultU64ByU32DivByU32
+        mov     r9d, edx                        ; r9  = B
+        mov     rax, rcx                        ; rax = A
+        xor     edx, edx                        ; rdx = 0
+        mul     r9                              ; rax:rdx = A*B
+        mov     ecx, r8d                        ; rcx = C (overly careful)
+        div     rcx                             ; rax = A*B/C (rdx=reminder)
         ret
-ENDPROC ASMGetFlags
+ENDPROC ASMMultU64ByU32DivByU32