Pete Popov writes:

Hi Erik,

I'm not sure why the NIOS support is not in uClibc -- perhaps the patch
was rejected or never submitted? In any case, I'm playing with some NIOS
stuff and created this patch against 0.9.26. The work was done by
Microtronix. I'm not sure who else contributed to it. It would be great
to have the NIOS support available in uClibc so developers don't have to
go searching for these bits.

Pete

1 files changed, 97 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/nios/fpu_control.h b/libc/sysdeps/linux/nios/fpu_control.h
new file mode 100644
index 000000000..b7cdf2f3e
--- /dev/null
+++ b/libc/sysdeps/linux/nios/fpu_control.h
@@ -0,0 +1,97 @@
+/* FPU control word bits.  Nios2 version.
+   Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _FPU_CONTROL_H
+#define _FPU_CONTROL_H
+
+/* MIPS FPU floating point control register bits.
+ *
+ * 31-25  -> floating point conditions code bits 7-1.  These bits are only
+ *           available in MIPS IV.
+ * 24     -> flush denormalized results to zero instead of
+ *           causing unimplemented operation exception.  This bit is only
+ *           available for MIPS III and newer.
+ * 23     -> Condition bit
+ * 22-18  -> reserved (read as 0, write with 0)
+ * 17     -> cause bit for unimplemented operation
+ * 16     -> cause bit for invalid exception
+ * 15     -> cause bit for division by zero exception
+ * 14     -> cause bit for overflow exception
+ * 13     -> cause bit for underflow exception
+ * 12     -> cause bit for inexact exception
+ * 11     -> enable exception for invalid exception
+ * 10     -> enable exception for division by zero exception
+ *  9     -> enable exception for overflow exception
+ *  8     -> enable exception for underflow exception
+ *  7     -> enable exception for inexact exception
+ *  6     -> flag invalid exception
+ *  5     -> flag division by zero exception
+ *  4     -> flag overflow exception
+ *  3     -> flag underflow exception
+ *  2     -> flag inexact exception
+ *  1-0   -> rounding control
+ *
+ *
+ * Rounding Control:
+ * 00 - rounding to nearest (RN)
+ * 01 - rounding toward zero (RZ)
+ * 10 - rounding (up) toward plus infinity (RP)
+ * 11 - rounding (down)toward minus infinity (RM)
+ */
+
+#include <features.h>
+
+/* masking of interrupts */
+#define _FPU_MASK_V     0x0800  /* Invalid operation */
+#define _FPU_MASK_Z     0x0400  /* Division by zero  */
+#define _FPU_MASK_O     0x0200  /* Overflow          */
+#define _FPU_MASK_U     0x0100  /* Underflow         */
+#define _FPU_MASK_I     0x0080  /* Inexact operation */
+
+/* flush denormalized numbers to zero */
+#define _FPU_FLUSH_TZ   0x1000000
+
+/* rounding control */
+#define _FPU_RC_NEAREST 0x0     /* RECOMMENDED */
+#define _FPU_RC_ZERO    0x1
+#define _FPU_RC_UP      0x2
+#define _FPU_RC_DOWN    0x3
+
+#define _FPU_RESERVED 0xfe3c0000  /* Reserved bits in cw */
+
+
+/* The fdlibm code requires strict IEEE double precision arithmetic,
+   and no interrupts for exceptions, rounding to nearest.  */
+
+#define _FPU_DEFAULT  0x00000000
+
+/* IEEE:  same as above, but exceptions */
+#define _FPU_IEEE     0x00000F80
+
+/* Type of the control word.  */
+typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
+
+/* Macros for accessing the hardware control word.  */
+#define _FPU_GETCW(cw) __asm__ ("cfc1 %0,$31" : "=r" (cw))
+#define _FPU_SETCW(cw) __asm__ ("ctc1 %0,$31" : : "r" (cw))
+
+/* Default control word set at startup.  */
+extern fpu_control_t __fpu_control;
+
+#endif	/* fpu_control.h */