csky: add fenv support from glibcHEADmaster

23 files changed, 1235 insertions, 40 deletions

diff --git a/extra/Configs/Config.in.arch b/extra/Configs/Config.in.arch
index df6b795fa..24c0db157 100644
--- a/extra/Configs/Config.in.arch
+++ b/extra/Configs/Config.in.arch
@@ -167,6 +167,7 @@ config UCLIBC_HAS_FENV
 		   TARGET_aarch64 || \
 		   TARGET_arc || \
 		   TARGET_arm || \
+		   TARGET_csky || \
 		   TARGET_m68k || \
 		   TARGET_metag || \
 		   TARGET_mips || \
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)
diff --git a/libc/sysdeps/linux/csky/fpu_control.h b/libc/sysdeps/linux/csky/fpu_control.h
new file mode 100644
index 000000000..a2d615554
--- /dev/null
+++ b/libc/sysdeps/linux/csky/fpu_control.h
@@ -0,0 +1,147 @@
+/* FPU control word bits.  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 _FPU_CONTROL_H
+#define _FPU_CONTROL_H
+
+/* C-SKY FPU floating point control register bits.
+
+   31-28  -> Reserved (read as 0, write with 0).
+   27     -> 0: Flush denormalized results to zero.
+             1: Flush denormalized results to signed minimal normal number.
+   26     -> Reserved (read as 0, write with 0).
+   25-24  -> Rounding control.
+   23-6   -> Reserved (read as 0, write with 0).
+    5     -> Enable exception for input denormalized exception.
+    4     -> Enable exception for inexact exception.
+    3     -> Enable exception for underflow exception.
+    2     -> Enable exception for overflow exception.
+    1     -> Enable exception for division by zero exception.
+    0     -> Enable exception for invalid operation exception.
+
+   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).
+
+   C-SKY FPU floating point exception status register bits.
+
+   15     -> Accumulate bit for any exception.
+   14     -> Reserved (read as 0, write with 0).
+   13     -> Cause bit for input denormalized exception.
+   12     -> Cause bit for inexact exception.
+   11     -> Cause bit for underflow exception.
+   10     -> Cause bit for overflow exception.
+    9     -> Cause bit for division by zero exception.
+    8     -> Cause bit for invalid operation exception.
+    7     -> Flag bit for any exception.
+    6     -> Reserved (read as 0, write with 0).
+    5     -> Flag exception for input denormalized exception.
+    4     -> Flag exception for inexact exception.
+    3     -> Flag exception for underflow exception.
+    2     -> Flag exception for overflow exception.
+    1     -> Flag exception for division by zero exception.
+    0     -> Flag exception for invalid operation exception.  */
+
+#include <features.h>
+
+#ifdef __csky_soft_float__
+
+# define _FPU_RESERVED 0xffffffff
+# define _FPU_DEFAULT  0x00000000
+typedef unsigned int fpu_control_t;
+# define _FPU_GETCW(cw) (cw) = 0
+# define _FPU_SETCW(cw) (void) (cw)
+# define _FPU_GETFPSR(cw) (cw) = 0
+# define _FPU_SETFPSR(cw) (void) (cw)
+extern fpu_control_t __fpu_control;
+
+#else /* __csky_soft_float__ */
+
+/* Masking of interrupts.  */
+# define _FPU_MASK_IDE     (1 << 5)  /* Input denormalized exception.  */
+# define _FPU_MASK_IXE     (1 << 4)  /* Inexact exception.  */
+# define _FPU_MASK_UFE     (1 << 3)  /* Underflow exception.  */
+# define _FPU_MASK_OFE     (1 << 2)  /* Overflow exception.  */
+# define _FPU_MASK_DZE     (1 << 1)  /* Division by zero exception.  */
+# define _FPU_MASK_IOE     (1 << 0)  /* Invalid operation exception.  */
+
+# define _FPU_MASK_FEA     (1 << 15) /* Case for any exception.  */
+# define _FPU_MASK_FEC     (1 << 7)  /* Flag for any exception.  */
+
+/* Flush denormalized numbers to zero.  */
+# define _FPU_FLUSH_TZ   0x8000000
+
+/* Rounding control.  */
+# define _FPU_RC_NEAREST (0x0 << 24)     /* RECOMMENDED.  */
+# define _FPU_RC_ZERO    (0x1 << 24)
+# define _FPU_RC_UP      (0x2 << 24)
+# define _FPU_RC_DOWN    (0x3 << 24)
+
+# define _FPU_RESERVED      0xf460ffc0  /* Reserved bits in cw.  */
+# define _FPU_FPSR_RESERVED 0xffff4040
+
+/* The fdlibm code requires strict IEEE double precision arithmetic,
+   and no interrupts for exceptions, rounding to nearest.  */
+
+# define _FPU_DEFAULT        0x00000000
+# define _FPU_FPSR_DEFAULT   0x00000000
+
+/* IEEE: same as above, but exceptions.  */
+# define _FPU_FPCR_IEEE     0x0000001F
+# define _FPU_FPSR_IEEE     0x00000000
+
+/* Type of the control word.  */
+typedef unsigned int fpu_control_t;
+
+/* Macros for accessing the hardware control word.  */
+# if (__CSKY__ == 2)
+#  define _FPU_GETCW(cw) __asm__ volatile ("mfcr %0, cr<1, 2>" : "=a" (cw))
+#  define _FPU_SETCW(cw) __asm__ volatile ("mtcr %0, cr<1, 2>" : : "a" (cw))
+#  define _FPU_GETFPSR(cw) __asm__ volatile ("mfcr %0, cr<2, 2>" : "=a" (cw))
+#  define _FPU_SETFPSR(cw) __asm__ volatile ("mtcr %0, cr<2, 2>" : : "a" (cw))
+# else
+#  define _FPU_GETCW(cw) __asm__ volatile ("1: cprcr  %0, cpcr2 \n"          \
+                                         "   btsti  %0, 31    \n"           \
+                                         "   bt     1b        \n"           \
+                                         "   cprcr  %0, cpcr1\n" : "=b" (cw))
+
+#  define _FPU_SETCW(cw) __asm__ volatile ("1: cprcr  r7, cpcr2 \n"          \
+                                         "   btsti  r7, 31    \n"           \
+                                         "   bt     1b        \n"           \
+                                         "   cpwcr  %0, cpcr1 \n"           \
+                                         : : "b" (cw) : "r7")
+
+#  define _FPU_GETFPSR(cw) __asm__ volatile ("1: cprcr  %0, cpcr2 \n"        \
+                                           "   btsti  %0, 31    \n"         \
+                                           "   bt     1b        \n"         \
+                                           "   cprcr  %0, cpcr4\n" : "=b" (cw))
+
+#  define _FPU_SETFPSR(cw) __asm__ volatile ("1: cprcr  r7, cpcr2 \n"        \
+                                           "   btsti  r7, 31    \n"         \
+                                           "   bt     1b        \n"         \
+                                           "   cpwcr %0, cpcr4  \n"         \
+                                           : : "b" (cw) : "r7")
+# endif /* __CSKY__ != 2 */
+
+/* Default control word set at startup.  */
+extern fpu_control_t __fpu_control;
+
+#endif /* !__csky_soft_float__ */
+
+#endif /* fpu_control.h */
diff --git a/libm/csky/Makefile.arch b/libm/csky/Makefile.arch
new file mode 100644
index 000000000..bd38690be
--- /dev/null
+++ b/libm/csky/Makefile.arch
@@ -0,0 +1,16 @@
+# Makefile for uClibc-ng
+# Licensed under the LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
+
+ifeq ($(UCLIBC_HAS_FENV),y)
+libm_ARCH_SRC:=$(wildcard $(libm_ARCH_DIR)/*.c)
+libm_ARCH_OBJ:=$(patsubst $(libm_ARCH_DIR)/%.c,$(libm_ARCH_OUT)/%.o,$(libm_ARCH_SRC))
+endif
+
+libm_ARCH_OBJS:=$(libm_ARCH_OBJ)
+
+ifeq ($(DOPIC),y)
+libm-a-y+=$(libm_ARCH_OBJS:.o=.os)
+else
+libm-a-y+=$(libm_ARCH_OBJS)
+endif
+libm-so-y+=$(libm_ARCH_OBJS:.o=.os)
diff --git a/libm/csky/fclrexcpt.c b/libm/csky/fclrexcpt.c
new file mode 100644
index 000000000..8f8acef16
--- /dev/null
+++ b/libm/csky/fclrexcpt.c
@@ -0,0 +1,40 @@
+/* Clear given exceptions in current floating-point environment.
+   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/>.  */
+
+#include <fenv.h>
+#include "fenv_libc.h"
+#include <fpu_control.h>
+
+int
+feclearexcept (int excepts)
+{
+  int fpsr;
+
+  /* Mask out unsupported bits/exceptions.  */
+  excepts &= FE_ALL_EXCEPT;
+
+  /* Read the complete control word.  */
+  _FPU_GETFPSR (fpsr);
+
+  /* Clear the relevant bits.  */
+  fpsr &= ~(excepts | (excepts << CAUSE_SHIFT));
+
+  /* Put the new data in effect.  */
+  _FPU_SETFPSR (fpsr);
+
+  return 0;
+}
diff --git a/libm/csky/fedisblxcpt.c b/libm/csky/fedisblxcpt.c
new file mode 100644
index 000000000..e518968ab
--- /dev/null
+++ b/libm/csky/fedisblxcpt.c
@@ -0,0 +1,40 @@
+/* Disable floating-point exceptions.
+   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/>.  */
+
+#include <fenv.h>
+#include "fenv_libc.h"
+#include <fpu_control.h>
+
+int
+fedisableexcept (int excepts)
+{
+  unsigned int new_exc, old_exc;
+
+  /* Get the current control word.  */
+  _FPU_GETCW (new_exc);
+
+  old_exc = (new_exc & ENABLE_MASK) >> ENABLE_SHIFT;
+
+  /* Get the except disable mask.  */
+  excepts &= FE_ALL_EXCEPT;
+  new_exc &= ~(excepts << ENABLE_SHIFT);
+
+  /* Put the new data in effect.  */
+  _FPU_SETCW (new_exc);
+
+  return old_exc;
+}
diff --git a/libm/csky/feenablxcpt.c b/libm/csky/feenablxcpt.c
new file mode 100644
index 000000000..90c495080
--- /dev/null
+++ b/libm/csky/feenablxcpt.c
@@ -0,0 +1,39 @@
+/* Enable floating-point exceptions.
+   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/>.  */
+
+#include <fenv.h>
+#include "fenv_libc.h"
+#include <fpu_control.h>
+
+int
+feenableexcept (int excepts)
+{
+  unsigned int new_exc, old_exc;
+
+  /* Get the current control word.  */
+  _FPU_GETCW (new_exc);
+
+  old_exc = (new_exc & ENABLE_MASK) >> ENABLE_SHIFT;
+
+  excepts &= FE_ALL_EXCEPT;
+
+  new_exc |= excepts << ENABLE_SHIFT;
+
+  _FPU_SETCW (new_exc);
+
+  return old_exc;
+}
diff --git a/libm/csky/fegetenv.c b/libm/csky/fegetenv.c
new file mode 100644
index 000000000..d98982fc1
--- /dev/null
+++ b/libm/csky/fegetenv.c
@@ -0,0 +1,33 @@
+/* Store current floating-point environment.
+   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/>.  */
+
+#include <fenv.h>
+#include <fpu_control.h>
+
+int
+fegetenv (fenv_t *envp)
+{
+  unsigned int fpcr;
+  unsigned int fpsr;
+
+  _FPU_GETCW (fpcr);
+  _FPU_GETFPSR (fpsr);
+  envp->__fpcr = fpcr;
+  envp->__fpsr = fpsr;
+
+  return 0;
+}
diff --git a/libm/csky/fegetexcept.c b/libm/csky/fegetexcept.c
new file mode 100644
index 000000000..339f35923
--- /dev/null
+++ b/libm/csky/fegetexcept.c
@@ -0,0 +1,31 @@
+/* Get enabled floating-point exceptions.
+   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/>.  */
+
+#include <fenv.h>
+#include "fenv_libc.h"
+#include <fpu_control.h>
+
+int
+fegetexcept (void)
+{
+  unsigned int exc;
+
+  /* Get the current control word.  */
+  _FPU_GETCW (exc);
+
+  return (exc & ENABLE_MASK) >> ENABLE_SHIFT;
+}
diff --git a/libm/csky/fegetmode.c b/libm/csky/fegetmode.c
new file mode 100644
index 000000000..09d8282dd
--- /dev/null
+++ b/libm/csky/fegetmode.c
@@ -0,0 +1,27 @@
+/* Store current floating-point control modes.
+   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/>.  */
+
+#include <fenv.h>
+#include <fpu_control.h>
+
+int
+fegetmode (femode_t *modep)
+{
+  _FPU_GETCW (*modep);
+
+  return 0;
+}
diff --git a/libm/csky/fegetround.c b/libm/csky/fegetround.c
new file mode 100644
index 000000000..e68775af3
--- /dev/null
+++ b/libm/csky/fegetround.c
@@ -0,0 +1,30 @@
+/* Return current rounding direction.
+   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/>.  */
+
+#include <fenv.h>
+#include <fpu_control.h>
+
+int
+fegetround (void)
+{
+  unsigned int cw;
+
+  /* Get control word.  */
+  _FPU_GETCW (cw);
+
+  return cw & __FE_ROUND_MASK;
+}
diff --git a/libm/csky/feholdexcpt.c b/libm/csky/feholdexcpt.c
new file mode 100644
index 000000000..456af5eb1
--- /dev/null
+++ b/libm/csky/feholdexcpt.c
@@ -0,0 +1,30 @@
+/* Store current floating-point environment and clear exceptions.
+   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/>.  */
+
+#include <fenv.h>
+#include <fpu_control.h>
+#include "fenv_libc.h"
+#include "fenv_private.h"
+
+#include <stdio.h>
+
+int
+feholdexcept (fenv_t *envp)
+{
+  libc_feholdexcept_vfp (envp);
+  return 0;
+}
diff --git a/libm/csky/fenv_libc.h b/libm/csky/fenv_libc.h
new file mode 100644
index 000000000..44e89812d
--- /dev/null
+++ b/libm/csky/fenv_libc.h
@@ -0,0 +1,29 @@
+/* fpu registers 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_LIBC_H
+#define _FENV_LIBC_H	1
+
+/* Mask for enabling exceptions and for the CAUSE bits.  */
+#define ENABLE_MASK	0x0003FU
+#define CAUSE_MASK	0x3F000U
+
+/* Shift for FE_* flags to get up to the ENABLE bits and the CAUSE bits.  */
+#define ENABLE_SHIFT	0
+#define CAUSE_SHIFT	8
+
+#endif /* fenv_libc.h */
diff --git a/libm/csky/fenv_private.h b/libm/csky/fenv_private.h
new file mode 100644
index 000000000..f0f48a88a
--- /dev/null
+++ b/libm/csky/fenv_private.h
@@ -0,0 +1,277 @@
+/* Private floating point rounding and exceptions handling.  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 CSKY_FENV_PRIVATE_H
+#define CSKY_FENV_PRIVATE_H 1
+
+#include <fenv.h>
+#include <fpu_control.h>
+#include "fenv_libc.h"
+
+static __always_inline void
+libc_feholdexcept_vfp (fenv_t *envp)
+{
+  fpu_control_t fpsr, fpcr;
+
+  _FPU_GETCW (fpcr);
+  envp->__fpcr = fpcr;
+
+  _FPU_GETFPSR (fpsr);
+  envp->__fpsr = fpsr;
+
+  /* Now set all exceptions to non-stop.  */
+  fpcr &= ~FE_ALL_EXCEPT;
+
+  /* And clear all exception flags.  */
+  fpsr &= ~(FE_ALL_EXCEPT << CAUSE_SHIFT);
+
+  _FPU_SETFPSR (fpsr);
+
+  _FPU_SETCW (fpcr);
+}
+
+static __always_inline void
+libc_fesetround_vfp (int round)
+{
+  fpu_control_t fpcr;
+
+  _FPU_GETCW (fpcr);
+
+  /* Set new rounding mode if different.  */
+  if (unlikely ((fpcr & FE_DOWNWARD) != round))
+    _FPU_SETCW ((fpcr & ~FE_DOWNWARD) | round);
+}
+
+static __always_inline void
+libc_feholdexcept_setround_vfp (fenv_t *envp, int round)
+{
+  fpu_control_t fpsr, fpcr;
+
+  _FPU_GETCW (fpcr);
+  envp->__fpcr = fpcr;
+
+  _FPU_GETFPSR (fpsr);
+  envp->__fpsr = fpsr;
+
+  /* Clear exception flags, set all exceptions to non-stop,
+     and set new rounding mode.  */
+  fpsr &= ~(FE_ALL_EXCEPT << CAUSE_SHIFT);
+  _FPU_SETFPSR (fpsr);
+
+  fpcr &= ~(FE_ALL_EXCEPT | FE_DOWNWARD);
+  _FPU_SETCW (fpcr | round);
+}
+
+static __always_inline void
+libc_feholdsetround_vfp (fenv_t *envp, int round)
+{
+  fpu_control_t fpcr;
+
+  _FPU_GETCW (fpcr);
+  envp->__fpcr = fpcr;
+
+  /* Set new rounding mode if different.  */
+  if (unlikely ((fpcr & FE_DOWNWARD) != round))
+    _FPU_SETCW ((fpcr & ~FE_DOWNWARD) | round);
+}
+
+static __always_inline void
+libc_feresetround_vfp (fenv_t *envp)
+{
+  fpu_control_t fpcr, round;
+
+  _FPU_GETCW (fpcr);
+
+  /* Check whether rounding modes are different.  */
+  round = (envp->__fpcr ^ fpcr) & FE_DOWNWARD;
+
+  /* Restore the rounding mode if it was changed.  */
+  if (unlikely (round != 0))
+    _FPU_SETCW (fpcr ^ round);
+}
+
+static __always_inline int
+libc_fetestexcept_vfp (int ex)
+{
+  fpu_control_t fpsr;
+
+  _FPU_GETFPSR (fpsr);
+  fpsr = fpsr >> CAUSE_SHIFT;
+  return fpsr & ex & FE_ALL_EXCEPT;
+}
+
+static __always_inline void
+libc_fesetenv_vfp (const fenv_t *envp)
+{
+  fpu_control_t fpcr, fpsr, new_fpcr, new_fpsr;
+
+  _FPU_GETCW (fpcr);
+  _FPU_GETFPSR (fpsr);
+
+  new_fpcr = envp->__fpcr;
+  new_fpsr = envp->__fpsr;
+
+  if (unlikely (fpsr ^ new_fpsr) != 0)
+    _FPU_SETFPSR (new_fpsr);
+
+  if (unlikely (fpcr ^ new_fpcr) != 0)
+    _FPU_SETCW (new_fpcr);
+}
+
+static __always_inline int
+libc_feupdateenv_test_vfp (const fenv_t *envp, int ex)
+{
+  fpu_control_t fpcr, fpsr, new_fpcr, new_fpsr, excepts;
+
+  _FPU_GETCW (fpcr);
+  _FPU_GETFPSR (fpsr);
+
+  /* Merge current exception flags with the saved fenv.  */
+  excepts = (fpsr >> CAUSE_SHIFT) & FE_ALL_EXCEPT;
+  new_fpcr = envp->__fpcr;
+  new_fpsr = envp->__fpsr | (excepts << CAUSE_SHIFT);
+
+  /* Write FCR and FESR if different.  */
+  if (unlikely (fpsr ^ new_fpsr) != 0)
+    _FPU_SETFPSR (new_fpsr);
+
+  if (unlikely (fpcr ^ new_fpcr) != 0)
+    _FPU_SETCW (new_fpcr);
+
+  /* Raise the exceptions if enabled in the new FP state.  */
+  if (unlikely (excepts & new_fpcr))
+    feraiseexcept (excepts);
+
+  return excepts & ex;
+}
+
+static __always_inline void
+libc_feupdateenv_vfp (const fenv_t *envp)
+{
+  libc_feupdateenv_test_vfp (envp, 0);
+}
+
+static __always_inline void
+libc_feholdsetround_vfp_ctx (struct rm_ctx *ctx, int r)
+{
+  fpu_control_t fpcr, fpsr, round;
+
+  _FPU_GETCW (fpcr);
+  _FPU_GETFPSR (fpsr);
+  ctx->updated_status = false;
+  ctx->env.__fpcr = fpcr;
+  ctx->env.__fpsr = fpsr;
+
+  /* Check whether rounding modes are different.  */
+  round = (fpcr ^ r) & FE_DOWNWARD;
+
+  /* Set the rounding mode if changed.  */
+  if (unlikely (round != 0))
+    {
+      ctx->updated_status = true;
+      _FPU_SETCW (fpcr ^ round);
+    }
+}
+
+static __always_inline void
+libc_feresetround_vfp_ctx (struct rm_ctx *ctx)
+{
+  /* Restore the rounding mode if updated.  */
+  if (unlikely (ctx->updated_status))
+    {
+      fpu_control_t fpcr;
+
+      _FPU_GETCW (fpcr);
+      fpcr = (fpcr & ~FE_DOWNWARD) | (ctx->env.__fpcr & FE_DOWNWARD);
+      _FPU_SETCW (fpcr);