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Diffstat (limited to 'libc/sysdeps/linux/m68k')
-rw-r--r--libc/sysdeps/linux/m68k/fpu_control.h100
1 files changed, 67 insertions, 33 deletions
diff --git a/libc/sysdeps/linux/m68k/fpu_control.h b/libc/sysdeps/linux/m68k/fpu_control.h
index 1b2ba87c9..484bad3b9 100644
--- a/libc/sysdeps/linux/m68k/fpu_control.h
+++ b/libc/sysdeps/linux/m68k/fpu_control.h
@@ -1,4 +1,4 @@
-/* FPU control word definitions. PowerPC version.
+/* 68k FPU control word definitions.
Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
@@ -20,50 +20,84 @@
#ifndef _FPU_CONTROL_H
#define _FPU_CONTROL_H
-/* rounding control */
-#define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
-#define _FPU_RC_DOWN 0x03
-#define _FPU_RC_UP 0x02
-#define _FPU_RC_ZERO 0x01
+/*
+ * Motorola floating point control register bits.
+ *
+ * 31-16 -> reserved (read as 0, ignored on write)
+ * 15 -> enable trap for BSUN exception
+ * 14 -> enable trap for SNAN exception
+ * 13 -> enable trap for OPERR exception
+ * 12 -> enable trap for OVFL exception
+ * 11 -> enable trap for UNFL exception
+ * 10 -> enable trap for DZ exception
+ * 9 -> enable trap for INEX2 exception
+ * 8 -> enable trap for INEX1 exception
+ * 7-6 -> Precision Control
+ * 5-4 -> Rounding Control
+ * 3-0 -> zero (read as 0, write as 0)
+ *
+ *
+ * Precision Control:
+ * 00 - round to extended precision
+ * 01 - round to single precision
+ * 10 - round to double precision
+ * 11 - undefined
+ *
+ * Rounding Control:
+ * 00 - rounding to nearest (RN)
+ * 01 - rounding toward zero (RZ)
+ * 10 - rounding (down)toward minus infinity (RM)
+ * 11 - rounding (up) toward plus infinity (RP)
+ *
+ * The hardware default is 0x0000. I choose 0x5400.
+ */
-#define _FPU_MASK_NI 0x04 /* non-ieee mode */
+#include <features.h>
/* masking of interrupts */
-#define _FPU_MASK_ZM 0x10 /* zero divide */
-#define _FPU_MASK_OM 0x40 /* overflow */
-#define _FPU_MASK_UM 0x20 /* underflow */
-#define _FPU_MASK_XM 0x08 /* inexact */
-#define _FPU_MASK_IM 0x80 /* invalid operation */
+#define _FPU_MASK_BSUN 0x8000
+#define _FPU_MASK_SNAN 0x4000
+#define _FPU_MASK_OPERR 0x2000
+#define _FPU_MASK_OVFL 0x1000
+#define _FPU_MASK_UNFL 0x0800
+#define _FPU_MASK_DZ 0x0400
+#define _FPU_MASK_INEX1 0x0200
+#define _FPU_MASK_INEX2 0x0100
-#define _FPU_RESERVED 0xffffff00 /* These bits are reserved are not changed. */
+/* precision control */
+#define _FPU_EXTENDED 0x00 /* RECOMMENDED */
+#define _FPU_DOUBLE 0x80
+#define _FPU_SINGLE 0x40 /* DO NOT USE */
-/* The fdlibm code requires no interrupts for exceptions. */
-#define _FPU_DEFAULT 0x00000000 /* Default value. */
+/* rounding control */
+#define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
+#define _FPU_RC_ZERO 0x10
+#define _FPU_RC_DOWN 0x20
+#define _FPU_RC_UP 0x30
-/* IEEE: same as above, but (some) exceptions;
- we leave the 'inexact' exception off.
- */
-#define _FPU_IEEE 0x000000f0
+#define _FPU_RESERVED 0xFFFF000F /* Reserved bits in fpucr */
+
+
+/* Now two recommended fpucr */
+
+/* The fdlibm code requires no interrupts for exceptions. Don't
+ change the rounding mode, it would break long double I/O! */
+#define _FPU_DEFAULT 0x00000000
+
+/* IEEE: same as above, but exceptions. We must make it non-zero so
+ that __setfpucw works. This bit will be ignored. */
+#define _FPU_IEEE 0x00000001
/* 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) ( { \
- union { double d; fpu_control_t cw[2]; } \
- tmp __attribute__ ((__aligned__(8))); \
- __asm__ ("mffs 0; stfd%U0 0,%0" : "=m" (tmp.d) : : "fr0"); \
- (__cw)=tmp.cw[1]; \
- tmp.cw[1]; } )
-#define _FPU_SETCW(__cw) { \
- union { double d; fpu_control_t cw[2]; } \
- tmp __attribute__ ((__aligned__(8))); \
- tmp.cw[0] = 0xFFF80000; /* More-or-less arbitrary; this is a QNaN. */ \
- tmp.cw[1] = __cw; \
- __asm__ ("lfd%U0 0,%0; mtfsf 255,0" : : "m" (tmp.d) : "fr0"); \
-}
+#define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
+#define _FPU_SETCW(cw) __asm__ volatile ("fmove%.l %0, %!" : : "dm" (cw))
+#if 0
/* Default control word set at startup. */
extern fpu_control_t __fpu_control;
+#endif
-#endif /* _FPU_CONTROL_H */
+#endif /* _M68K_FPU_CONTROL_H */