m68k: add fenv support from glibc

2 files changed, 120 insertions, 55 deletions

diff --git a/libc/sysdeps/linux/m68k/bits/fenv.h b/libc/sysdeps/linux/m68k/bits/fenv.h
index b07f0ab51..37c5fe829 100644
--- a/libc/sysdeps/linux/m68k/bits/fenv.h
+++ b/libc/sysdeps/linux/m68k/bits/fenv.h
@@ -1,5 +1,4 @@
-/* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
+/* Copyright (C) 1997-2025 Free Software Foundation, Inc.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -12,31 +11,38 @@
    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, see
-   <http://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
 
 #ifndef _FENV_H
 # error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
 #endif
 
 
+#if defined __HAVE_68881__ || defined __HAVE_FPU__ || defined __mcffpu__
+
 /* Define bits representing the exception.  We use the bit positions of
    the appropriate bits in the FPSR Accrued Exception Byte.  */
 enum
   {
-    FE_INEXACT = 1 << 3,
-#define FE_INEXACT	FE_INEXACT
-    FE_DIVBYZERO = 1 << 4,
-#define FE_DIVBYZERO	FE_DIVBYZERO
-    FE_UNDERFLOW = 1 << 5,
-#define FE_UNDERFLOW	FE_UNDERFLOW
-    FE_OVERFLOW = 1 << 6,
-#define FE_OVERFLOW	FE_OVERFLOW
-    FE_INVALID = 1 << 7
-#define FE_INVALID	FE_INVALID
+    FE_INEXACT =
+# define FE_INEXACT	(1 << 3)
+      FE_INEXACT,
+    FE_DIVBYZERO =
+# define FE_DIVBYZERO	(1 << 4)
+      FE_DIVBYZERO,
+    FE_UNDERFLOW =
+# define FE_UNDERFLOW	(1 << 5)
+      FE_UNDERFLOW,
+    FE_OVERFLOW =
+# define FE_OVERFLOW	(1 << 6)
+      FE_OVERFLOW,
+    FE_INVALID =
+# define FE_INVALID	(1 << 7)
+      FE_INVALID
   };
 
-#define FE_ALL_EXCEPT \
+# define FE_ALL_EXCEPT \
 	(FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
 
 /* The m68k FPU supports all of the four defined rounding modes.  We use
@@ -44,21 +50,45 @@ enum
    appropriate macros.  */
 enum
   {
-    FE_TONEAREST = 0,
-#define FE_TONEAREST	FE_TONEAREST
-    FE_TOWARDZERO = 1 << 4,
-#define FE_TOWARDZERO	FE_TOWARDZERO
-    FE_DOWNWARD = 2 << 4,
-#define FE_DOWNWARD	FE_DOWNWARD
-    FE_UPWARD = 3 << 4
-#define FE_UPWARD	FE_UPWARD
+    FE_TONEAREST =
+# define FE_TONEAREST	0
+      FE_TONEAREST,
+    FE_TOWARDZERO =
+# define FE_TOWARDZERO	(1 << 4)
+      FE_TOWARDZERO,
+    FE_DOWNWARD =
+# define FE_DOWNWARD	(2 << 4)
+      FE_DOWNWARD,
+    FE_UPWARD =
+# define FE_UPWARD	(3 << 4)
+      FE_UPWARD
   };
 
+#else
+
+/* In the soft-float case, only rounding to nearest is supported, with
+   no exceptions.  */
+
+# define FE_ALL_EXCEPT 0
+
+enum
+  {
+    __FE_UNDEFINED = -1,
+
+    FE_TONEAREST =
+# define FE_TONEAREST	0
+      FE_TONEAREST
+  };
+
+#endif
+
 
 /* Type representing exception flags.  */
 typedef unsigned int fexcept_t;
 
 
+#if defined __HAVE_68881__ || defined __HAVE_FPU__ || defined __mcffpu__
+
 /* Type representing floating-point environment.  This structure
    corresponds to the layout of the block written by `fmovem'.  */
 typedef struct
@@ -69,10 +99,30 @@ typedef struct
   }
 fenv_t;
 
+#else
+
+/* Keep ABI compatibility with the type used in the generic
+   bits/fenv.h, formerly used for no-FPU ColdFire.  */
+typedef struct
+  {
+    fexcept_t __excepts;
+  }
+fenv_t;
+
+#endif
+
 /* If the default argument is used we use this value.  */
 #define FE_DFL_ENV	((const fenv_t *) -1)
 
-#ifdef __USE_GNU
+#if defined __USE_GNU && (defined __HAVE_68881__	\
+			  || defined __HAVE_FPU__	\
+			  || defined __mcffpu__)
 /* Floating-point environment where none of the exceptions are masked.  */
 # define FE_NOMASK_ENV	((const fenv_t *) -2)
 #endif
+
+/* Type representing floating-point control modes.  */
+typedef unsigned int femode_t;
+
+/* Default floating-point control modes.  */
+# define FE_DFL_MODE	((const femode_t *) -1L)
diff --git a/libc/sysdeps/linux/m68k/fpu_control.h b/libc/sysdeps/linux/m68k/fpu_control.h
index 35ad95e6d..c3a9c6326 100644
--- a/libc/sysdeps/linux/m68k/fpu_control.h
+++ b/libc/sysdeps/linux/m68k/fpu_control.h
@@ -1,6 +1,5 @@
 /* 68k FPU control word definitions.
-   Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
+   Copyright (C) 1996-2025 Free Software Foundation, Inc.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -13,8 +12,8 @@
    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, see
-   <http://www.gnu.org/licenses/>.  */
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
 
 #ifndef _FPU_CONTROL_H
 #define _FPU_CONTROL_H
@@ -29,9 +28,9 @@
  * 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
+ *  9     -> enable trap for INEX2 exception (INEX on Coldfire)
+ *  8     -> enable trap for INEX1 exception (IDE on Coldfire)
+ *  7-6   -> Precision Control (only bit 6 is used on Coldfire)
  *  5-4   -> Rounding Control
  *  3-0   -> zero (read as 0, write as 0)
  *
@@ -53,50 +52,66 @@
 
 #include <features.h>
 
+#if defined (__mcoldfire__) && !defined (__mcffpu__)
+
+# define _FPU_RESERVED 0xffffffff
+# define _FPU_DEFAULT  0x00000000
+# define _FPU_GETCW(cw) ((cw) = 0)
+# define _FPU_SETCW(cw) ((void) (cw))
+
+#else
+
 /* masking of interrupts */
-#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_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
 
 /* precision control */
-#define _FPU_EXTENDED 0x00   /* RECOMMENDED */
-#define _FPU_DOUBLE   0x80
-#define _FPU_SINGLE   0x40     /* DO NOT USE */
+# ifdef __mcoldfire__
+#  define _FPU_DOUBLE   0x00
+# else
+#  define _FPU_EXTENDED 0x00   /* RECOMMENDED */
+#  define _FPU_DOUBLE   0x80
+# endif
+# define _FPU_SINGLE   0x40     /* DO NOT USE */
 
 /* rounding control */
-#define _FPU_RC_NEAREST 0x00    /* RECOMMENDED */
-#define _FPU_RC_ZERO    0x10
-#define _FPU_RC_DOWN    0x20
-#define _FPU_RC_UP      0x30
+# define _FPU_RC_NEAREST 0x00    /* RECOMMENDED */
+# define _FPU_RC_ZERO    0x10
+# define _FPU_RC_DOWN    0x20
+# define _FPU_RC_UP      0x30
 
-#define _FPU_RESERVED 0xFFFF000F  /* Reserved bits in fpucr */
+# ifdef __mcoldfire__
+#  define _FPU_RESERVED 0xFFFF800F
+# else
+#  define _FPU_RESERVED 0xFFFF000F  /* Reserved bits in fpucr */
+# endif
 
 
 /* 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
+# 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
+# define _FPU_IEEE     0x00000001
+
+/* Macros for accessing the hardware control word.  */
+# define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
+# define _FPU_SETCW(cw) __asm__ volatile ("fmove%.l %0, %!" : : "dm" (cw))
+#endif
 
 /* 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__ ("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 /* _M68K_FPU_CONTROL_H */