Create a branch for Aleksandar Andrejevic for his work on NTVDM. See http://jira.reactos.org/browse/CORE-7250 for more details.

svn path=/branches/ntvdm/; revision=59241

lib/sdk/crt/math/amd64/floor.S

@@ -0,0 +1,41 @@
+/*
+ * COPYRIGHT:         See COPYING in the top level directory
+ * PROJECT:           ReactOS system libraries
+ * PURPOSE:           Implementation of floor
+ * FILE:              lib/sdk/crt/math/amd64/floor.S
+ * PROGRAMMER:        Timo Kreuzer (timo.kreuzer@reactos.org)
+ */
+
+/* INCLUDES ******************************************************************/
+
+#include <asm.inc>
+
+/* CODE **********************************************************************/
+.code64
+
+PUBLIC floor
+FUNC floor
+    sub rsp, 16
+    .ENDPROLOG
+
+    /* Truncate xmm0 to integer (double precision) */
+    cvttsd2si rcx, xmm0
+
+    /* Duplicate the bits into rax */
+    movd rax, xmm0
+
+    /* Shift all bits to the right, keeping the sign bit */
+    shr rax, 63
+
+    /* Substract the sign bit from the truncated value, so that
+       we get the correct result for negative values. */
+    sub rcx, rax
+
+    /* Convert the result back to xmm0 (double precision) */
+    cvtsi2sd xmm0, rcx
+
+    add rsp, 16
+    ret
+ENDFUNC
+
+END