csky: add fenv support from glibc

1 files changed, 83 insertions, 40 deletions

diff --git a/libc/sysdeps/linux/csky/bits/fenv.h b/libc/sysdeps/linux/csky/bits/fenv.h
index 3359e1f8e..1428f385a 100644
--- a/libc/sysdeps/linux/csky/bits/fenv.h
+++ b/libc/sysdeps/linux/csky/bits/fenv.h
@@ -1,65 +1,108 @@
-/*
- * Copyright (C) 2017 Hangzhou C-SKY Microsystems co.,ltd.
- *
- * Licensed under the LGPL v2.1 or later, see the file COPYING.LIB
- * in this tarball.
- */
+/* Floating point environment.  C-SKY version.
+   Copyright (C) 2018-2025 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
+   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, see
+   <https://www.gnu.org/licenses/>.  */
 
 #ifndef _FENV_H
 # error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
 #endif
 
-/* Define bits representing the exception.  We use the bit positions of
-   the appropriate bits in the FPSR Accrued Exception Byte.  */
+#ifdef __csky_hard_float__
+/* Define bits representing the exception.  We use the bit positions
+   of the appropriate bits in the FPU control word.  */
 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_INVALID =
+#define FE_INVALID	0x01
+      FE_INVALID,
+    FE_DIVBYZERO =
+#define FE_DIVBYZERO	0x02
+      FE_DIVBYZERO,
+    FE_OVERFLOW =
+#define FE_OVERFLOW	0x04
+      FE_OVERFLOW,
+    FE_UNDERFLOW =
+#define FE_UNDERFLOW	0x08
+      FE_UNDERFLOW,
+    FE_INEXACT =
+#define FE_INEXACT	0x10
+      FE_INEXACT,
+    __FE_DENORMAL = 0x20
   };
 
 #define FE_ALL_EXCEPT \
 	(FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
 
-/* The csky FPU supports all of the four defined rounding modes.  We use
-   the bit positions in the FPCR Mode Control Byte as the values for the
-   appropriate macros.  */
+/* The C-SKY FPU supports all of the four defined rounding modes.  We
+   use again the bit positions in the FPU control word as the values
+   for the appropriate macros.  */
+enum
+  {
+    FE_TONEAREST =
+#define FE_TONEAREST	(0x0 << 24)
+      FE_TONEAREST,
+    FE_TOWARDZERO =
+#define FE_TOWARDZERO	(0x1 << 24)
+      FE_TOWARDZERO,
+    FE_UPWARD =
+#define FE_UPWARD	(0x2 << 24)
+      FE_UPWARD,
+    FE_DOWNWARD =
+#define FE_DOWNWARD	(0x3 << 24)
+      FE_DOWNWARD,
+    __FE_ROUND_MASK = (0x3 << 24)
+  };
+
+#else
+
+/* In the soft-float case, only rounding to nearest is supported, with
+   no exceptions.  */
+
 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_UNDEFINED = -1,
+
+    FE_TONEAREST =
+# define FE_TONEAREST	0x0
+      FE_TONEAREST
   };
 
+# define FE_ALL_EXCEPT 0
+
+#endif
+
 /* Type representing exception flags.  */
 typedef unsigned int fexcept_t;
 
-/* Type representing floating-point environment.  This structure
-   corresponds to the layout of the block written by `fmovem'.  */
+/* Type representing floating-point environment.  */
 typedef struct
-  {
-    unsigned int __control_register;
-    unsigned int __status_register;
-    unsigned int __instruction_address;
-  }
-fenv_t;
+{
+  unsigned int __fpcr;
+  unsigned int __fpsr;
+} fenv_t;
 
 /* If the default argument is used we use this value.  */
-#define FE_DFL_ENV	((__const fenv_t *) -1)
+#define FE_DFL_ENV	((const fenv_t *) -1)
 
-#ifdef __USE_GNU
+#if defined __USE_GNU && defined __csky_hard_float__
 /* Floating-point environment where none of the exceptions are masked.  */
-# define FE_NOMASK_ENV	((__const fenv_t *) -2)
+# 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)