newlib-cygwin/newlib/libc/machine/riscv/sys/fenv.h

/* Copyright (c) 2017  SiFive Inc. All rights reserved.

   This copyrighted material is made available to anyone wishing to use,
   modify, copy, or redistribute it subject to the terms and conditions
   of the FreeBSD License.   This program is distributed in the hope that
   it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
   including the implied warranties of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  A copy of this license is available at
   http://www.opensource.org/licenses.
*/

#ifndef _SYS_FENV_H
#define _SYS_FENV_H

#include <stddef.h>

#if __riscv_flen

/* Per "The RISC-V Instruction Set Manual: Volume I: User-Level ISA:
 * Version 2.1", Section 8.2, "Floating-Point Control and Status
 * Register":
 *
 * Flag Mnemonic Flag Meaning
 * ------------- -----------------
 * NV            Invalid Operation
 * DZ            Divide by Zero
 * OF            Overflow
 * UF            Underflow
 * NX            Inexact
 */

#define FE_INVALID   0x00000010
#define FE_DIVBYZERO 0x00000008
#define FE_OVERFLOW  0x00000004
#define FE_UNDERFLOW 0x00000002
#define FE_INEXACT   0x00000001

#define FE_ALL_EXCEPT (FE_INVALID|FE_DIVBYZERO|FE_OVERFLOW|FE_UNDERFLOW|FE_INEXACT)

/* Per "The RISC-V Instruction Set Manual: Volume I: User-Level ISA:
 * Version 2.1", Section 8.2, "Floating-Point Control and Status
 * Register":
 *
 * Rounding Mode  Mnemonic Meaning  Meaning
 * -------------  ----------------  -------
 * 000            RNE               Round to Nearest, ties to Even
 * 001            RTZ               Round towards Zero
 * 010            RDN               Round Down (towards −∞)
 * 011            RUP               Round Up (towards +∞)
 * 100            RMM               Round to Nearest, ties to Max Magnitude
 * 101                              Invalid. Reserved for future use.
 * 110                              Invalid. Reserved for future use.
 * 111                              In instruction’s rm field, selects dynamic rounding mode;
 *                                  In Rounding Mode register, Invalid
 */

#define FE_TONEAREST_MM 0x00000004
#define FE_UPWARD     	0x00000003
#define FE_DOWNWARD   	0x00000002
#define FE_TOWARDZERO 	0x00000001
#define FE_TONEAREST  	0x00000000

#define FE_RMODE_MASK   0x7

/* Per "The RISC-V Instruction Set Manual: Volume I: User-Level ISA:
 * Version 2.1":
 *
 * "The F extension adds 32 floating-point registers, f0–f31, each 32
 * bits wide, and a floating-point control and status register fcsr,
 * which contains the operating mode and exception status of the
 * floating-point unit."
 */

#else /* !__riscv_flen */

#define FE_ALL_EXCEPT   0x00000000
#define FE_TONEAREST    0x00000000

#endif /* !__riscv_flen */

typedef size_t fenv_t;
typedef size_t fexcept_t;
extern const fenv_t fe_dfl_env;
extern const fenv_t *fe_dfl_env_p;

#define FE_DFL_ENV fe_dfl_env_p

#endif /* _SYS_FENV_H */