diff options
Diffstat (limited to 'libc/sysdeps/linux/arc/fpu_control.h')
| -rw-r--r-- | libc/sysdeps/linux/arc/fpu_control.h | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/arc/fpu_control.h b/libc/sysdeps/linux/arc/fpu_control.h new file mode 100644 index 000000000..e833de3aa --- /dev/null +++ b/libc/sysdeps/linux/arc/fpu_control.h @@ -0,0 +1,104 @@ +/* FPU control word bits. ARC version. + Copyright (C) 2020-2025 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 + +/* ARC FPU control register bits. + + [ 0] -> IVE: Enable invalid operation exception. + if 0, soft exception: status register IV flag set. + if 1, hardware exception trap (not supported in Linux yet). + [ 1] -> DZE: Enable division by zero exception. + if 0, soft exception: status register IV flag set. + if 1, hardware exception: (not supported in Linux yet). + [9:8] -> RM: Rounding Mode: + 00 - Rounding toward zero. + 01 - Rounding to nearest (default). + 10 - Rounding (up) toward plus infinity. + 11 - Rounding (down)toward minus infinity. + + ARC FPU status register bits. + + [ 0] -> IV: flag invalid operation. + [ 1] -> DZ: flag division by zero. + [ 2] -> OV: flag Overflow operation. + [ 3] -> UV: flag Underflow operation. + [ 4] -> IX: flag Inexact operation. + [31] -> FWE: Flag Write Enable. + If 1, above flags writable explicitly (clearing), + else IoW and only writable indirectly via bits [12:7]. */ + +#include <features.h> + +#if !defined(__ARC_FPU_SP__) && !defined(__ARC_FPU_DP__) + +# 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_GETS(cw) (cw) = 0 +# define _FPU_SETS(cw) (void) (cw) +extern fpu_control_t __fpu_control; + +#else + +#define _FPU_RESERVED 0 + +/* The fdlibm code requires strict IEEE double precision arithmetic, + and no interrupts for exceptions, rounding to nearest. + So only RM set to b'01. */ +# define _FPU_DEFAULT 0x00000100 + +/* Actually default needs to have FWE bit as 1 but that is already + ingrained into _FPU_SETS macro below. */ +#define _FPU_FPSR_DEFAULT 0x00000000 + +#define __FPU_RND_SHIFT 8 +#define __FPU_RND_MASK 0x3 + +/* Type of the control word. */ +typedef unsigned int fpu_control_t; + +/* Macros for accessing the hardware control word. */ +# define _FPU_GETCW(cw) __asm__ volatile ("lr %0, [0x300]" : "=r" (cw)) +# define _FPU_SETCW(cw) __asm__ volatile ("sr %0, [0x300]" : : "r" (cw)) + +/* Macros for accessing the hardware status word. + Writing to FPU_STATUS requires a "control" bit FWE to be able to set the + exception flags directly (as opposed to side-effects of FP instructions). + That is done in the macro here to keeps callers agnostic of this detail. + And given FWE is write-only and RAZ, no need to "clear" it in _FPU_GETS + macro. */ +# define _FPU_GETS(cw) \ + __asm__ volatile ("lr %0, [0x301] \r\n" \ + : "=r" (cw)) + +# define _FPU_SETS(cw) \ + do { \ + unsigned int __fwe = 0x80000000 | (cw); \ + __asm__ volatile ("sr %0, [0x301] \r\n" \ + : : "r" (__fwe)); \ + } while (0) + +/* Default control word set at startup. */ +extern fpu_control_t __fpu_control; + +#endif + +#endif /* fpu_control.h */ |