MIPS: math-emu: Add support for the MIPS R6 CLASS FPU instruction

MIPS R6 introduced the following instruction:
Stores in fd a bit mask reflecting the floating-point class of the
floating point scalar value fs.

CLASS.fmt: FPR[fd] = class(FPR[fs])

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10959/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/mips/math-emu/dp_2008class.c b/arch/mips/math-emu/dp_2008class.c
new file mode 100644
index 000000000000..9dc39fc4835e
--- /dev/null
+++ b/arch/mips/math-emu/dp_2008class.c
@@ -0,0 +1,55 @@
+/*
+ * IEEE754 floating point arithmetic
+ * double precision: CLASS.f
+ * FPR[fd] = class(FPR[fs])
+ *
+ * MIPS floating point support
+ * Copyright (C) 2015 Imagination Technologies, Ltd.
+ * Author: Markos Chandras <markos.chandras@imgtec.com>
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; version 2 of the License.
+ */
+
+#include "ieee754dp.h"
+
+int ieee754dp_2008class(union ieee754dp x)
+{
+	COMPXDP;
+
+	EXPLODEXDP;
+
+	/*
+	 * 10 bit mask as follows:
+	 *
+	 * bit0 = SNAN
+	 * bit1 = QNAN
+	 * bit2 = -INF
+	 * bit3 = -NORM
+	 * bit4 = -DNORM
+	 * bit5 = -ZERO
+	 * bit6 = INF
+	 * bit7 = NORM
+	 * bit8 = DNORM
+	 * bit9 = ZERO
+	 */
+
+	switch(xc) {
+	case IEEE754_CLASS_SNAN:
+		return 0x01;
+	case IEEE754_CLASS_QNAN:
+		return 0x02;
+	case IEEE754_CLASS_INF:
+		return 0x04 << (xs ? 0 : 4);
+	case IEEE754_CLASS_NORM:
+		return 0x08 << (xs ? 0 : 4);
+	case IEEE754_CLASS_DNORM:
+		return 0x10 << (xs ? 0 : 4);
+	case IEEE754_CLASS_ZERO:
+		return 0x20 << (xs ? 0 : 4);
+	default:
+		pr_err("Unknown class: %d\n", xc);
+		return 0;
+	}
+}