1 files changed, 68 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/math/trunc.asm b/src/VBox/Runtime/common/math/trunc.asm
new file mode 100644
index 00000000..65131e9f
--- /dev/null
+++ b/src/VBox/Runtime/common/math/trunc.asm
@@ -0,0 +1,68 @@
+; $Id: trunc.asm $
+;; @file
+; IPRT - No-CRT trunc - AMD64 & X86.
+;
+
+;
+; Copyright (C) 2006-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; Round to truncated integer value.
+; @returns 32-bit: st(0)   64-bit: xmm0
+; @param    rd      32-bit: [ebp + 8]   64-bit: xmm0
+BEGINPROC RT_NOCRT(trunc)
+    push    xBP
+    mov     xBP, xSP
+    sub     xSP, 10h
+
+%ifdef RT_ARCH_AMD64
+    movsd   [xSP], xmm0
+    fld     qword [xSP]
+%else
+    fld     qword [xBP + xCB*2]
+%endif
+
+    ; Make it truncate up by modifying the fpu control word.
+    fstcw   [xBP - 10h]
+    mov     eax, [xBP - 10h]
+    or      eax, 00c00h
+    mov     [xBP - 08h], eax
+    fldcw   [xBP - 08h]
+
+    ; Round ST(0) to integer.
+    frndint
+
+    ; Restore the fpu control word.
+    fldcw   [xBP - 10h]
+
+%ifdef RT_ARCH_AMD64
+    fstp    qword [xSP]
+    movsd   xmm0, [xSP]
+%endif
+    leave
+    ret
+ENDPROC   RT_NOCRT(trunc)
+