1 files changed, 19 insertions, 0 deletions
diff --git a/src/pkg/math/modf_386.s b/src/pkg/math/modf_386.s
new file mode 100644
index 000000000..5ccab9812
--- /dev/null
+++ b/src/pkg/math/modf_386.s
@@ -0,0 +1,19 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// func Modf(x float64) (int float64, frac float64)
+TEXT ·Modf(SB),7,$0
+	FMOVD   x+0(FP), F0  // F0=x
+	FMOVD   F0, F1       // F0=x, F1=x
+	FSTCW   -2(SP)       // save old Control Word
+	MOVW    -2(SP), AX
+	ORW     $0x0c00, AX  // Rounding Control set to truncate
+	MOVW    AX, -4(SP)   // store new Control Word
+	FLDCW   -4(SP)       // load new Control Word
+	FRNDINT              // F0=trunc(x), F1=x
+	FLDCW   -2(SP)       // load old Control Word
+	FSUBD   F0, F1       // F0=trunc(x), F1=x-trunc(x)
+	FMOVDP  F0, i+8(FP)  // F0=x-trunc(x)
+	FMOVDP  F0, f+16(FP)
+	RET