FreeBSD/Linux Kernel Cross Reference
sys/amd64/include/ieeefp.h

     /*-
      * Copyright (c) 2003 Peter Wemm.
      * Copyright (c) 1990 Andrew Moore, Talke Studio
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: @(#) ieeefp.h     1.0 (Berkeley) 9/23/93
     * $FreeBSD$
     */
    
    /*
     *      IEEE floating point type and constant definitions.
     */
    
    #ifndef _MACHINE_IEEEFP_H_
    #define _MACHINE_IEEEFP_H_
    
    #ifndef _SYS_CDEFS_H_
    #error this file needs sys/cdefs.h as a prerequisite
    #endif
    
    /*
     * FP rounding modes
     */
    typedef enum {
            FP_RN=0,        /* round to nearest */
            FP_RM,          /* round down to minus infinity */
            FP_RP,          /* round up to plus infinity */
            FP_RZ           /* truncate */
    } fp_rnd_t;
    
    /*
     * FP precision modes
     */
    typedef enum {
            FP_PS=0,        /* 24 bit (single-precision) */
            FP_PRS,         /* reserved */
            FP_PD,          /* 53 bit (double-precision) */
            FP_PE           /* 64 bit (extended-precision) */
    } fp_prec_t;
    
    #define fp_except_t     int
    
    /*
     * FP exception masks
     */
    #define FP_X_INV        0x01    /* invalid operation */
    #define FP_X_DNML       0x02    /* denormal */
    #define FP_X_DZ         0x04    /* zero divide */
    #define FP_X_OFL        0x08    /* overflow */
    #define FP_X_UFL        0x10    /* underflow */
    #define FP_X_IMP        0x20    /* (im)precision */
    #define FP_X_STK        0x40    /* stack fault */
    
    /*
     * FP registers
     */
    #define FP_MSKS_REG     0       /* exception masks */
    #define FP_PRC_REG      0       /* precision */
    #define FP_RND_REG      0       /* direction */
    #define FP_STKY_REG     1       /* sticky flags */
    
    /*
     * FP register bit field masks
     */
    #define FP_MSKS_FLD     0x3f    /* exception masks field */
    #define FP_PRC_FLD      0x300   /* precision control field */
    #define FP_RND_FLD      0xc00   /* round control field */
    #define FP_STKY_FLD     0x3f    /* sticky flags field */
    
    /*
     * SSE mxcsr register bit field masks
    */
   #define SSE_STKY_FLD    0x3f    /* exception flags */
   #define SSE_DAZ_FLD     0x40    /* Denormals are zero */
   #define SSE_MSKS_FLD    0x1f80  /* exception masks field */
   #define SSE_RND_FLD     0x6000  /* rounding control */
   #define SSE_FZ_FLD      0x8000  /* flush to zero on underflow */
   
   /*
    * FP register bit field offsets
    */
   #define FP_MSKS_OFF     0       /* exception masks offset */
   #define FP_PRC_OFF      8       /* precision control offset */
   #define FP_RND_OFF      10      /* round control offset */
   #define FP_STKY_OFF     0       /* sticky flags offset */
   
   /*
    * SSE mxcsr register bit field offsets
    */
   #define SSE_STKY_OFF    0       /* exception flags offset */
   #define SSE_DAZ_OFF     6       /* DAZ exception mask offset */
   #define SSE_MSKS_OFF    7       /* other exception masks offset */
   #define SSE_RND_OFF     13      /* rounding control offset */
   #define SSE_FZ_OFF      15      /* flush to zero offset */
   
   #if defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE__) \
       && !defined(__cplusplus)
   
   #define __fldenv(addr)  __asm __volatile("fldenv %0" : : "m" (*(addr)))
   #define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
   #define __fldcw(addr)   __asm __volatile("fldcw %0" : : "m" (*(addr)))
   #define __fnstcw(addr)  __asm __volatile("fnstcw %0" : "=m" (*(addr)))
   #define __fnstsw(addr)  __asm __volatile("fnstsw %0" : "=m" (*(addr)))
   #define __ldmxcsr(addr) __asm __volatile("ldmxcsr %0" : : "m" (*(addr)))
   #define __stmxcsr(addr) __asm __volatile("stmxcsr %0" : "=m" (*(addr)))
   
   /*
    * General notes about conflicting SSE vs FP status bits.
    * This code assumes that software will not fiddle with the control
    * bits of the SSE and x87 in such a way to get them out of sync and
    * still expect this to work.  Break this at your peril.
    * Because I based this on the i386 port, the x87 state is used for
    * the fpget*() functions, and is shadowed into the SSE state for
    * the fpset*() functions.  For dual source fpget*() functions, I
    * merge the two together.  I think.
    */
   
   /* Set rounding control */
   static __inline__ fp_rnd_t
   __fpgetround(void)
   {
           unsigned short _cw;
   
           __fnstcw(&_cw);
           return ((_cw & FP_RND_FLD) >> FP_RND_OFF);
   }
   
   static __inline__ fp_rnd_t
   __fpsetround(fp_rnd_t _m)
   {
           unsigned short _cw;
           unsigned int _mxcsr;
           fp_rnd_t _p;
   
           __fnstcw(&_cw);
           _p = (_cw & FP_RND_FLD) >> FP_RND_OFF;
           _cw &= ~FP_RND_FLD;
           _cw |= (_m << FP_RND_OFF) & FP_RND_FLD;
           __fldcw(&_cw);
           __stmxcsr(&_mxcsr);
           _mxcsr &= ~SSE_RND_FLD;
           _mxcsr |= (_m << SSE_RND_OFF) & SSE_RND_FLD;
           __ldmxcsr(&_mxcsr);
           return (_p);
   }
   
   /*
    * Set precision for fadd/fsub/fsqrt etc x87 instructions
    * There is no equivalent SSE mode or control.
    */
   static __inline__ fp_prec_t
   __fpgetprec(void)
   {
           unsigned short _cw;
   
           __fnstcw(&_cw);
           return ((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
   }
   
   static __inline__ fp_prec_t
   __fpsetprec(fp_rnd_t _m)
   {
           unsigned short _cw;
           fp_prec_t _p;
   
           __fnstcw(&_cw);
           _p = (_cw & FP_PRC_FLD) >> FP_PRC_OFF;
           _cw &= ~FP_PRC_FLD;
           _cw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
           __fldcw(&_cw);
           return (_p);
   }
   
   /*
    * Look at the exception masks
    * Note that x87 masks are inverse of the fp*() functions
    * API.  ie: mask = 1 means disable for x87 and SSE, but
    * for the fp*() api, mask = 1 means enabled.
    */
   static __inline__ fp_except_t
   __fpgetmask(void)
   {
           unsigned short _cw;
   
           __fnstcw(&_cw);
           return ((~_cw) & FP_MSKS_FLD);
   }
   
   static __inline__ fp_except_t
   __fpsetmask(fp_except_t _m)
   {
           unsigned short _cw;
           unsigned int _mxcsr;
           fp_except_t _p;
   
           __fnstcw(&_cw);
           _p = (~_cw) & FP_MSKS_FLD;
           _cw &= ~FP_MSKS_FLD;
           _cw |= (~_m) & FP_MSKS_FLD;
           __fldcw(&_cw);
           __stmxcsr(&_mxcsr);
           /* XXX should we clear non-ieee SSE_DAZ_FLD and SSE_FZ_FLD ? */
           _mxcsr &= ~SSE_MSKS_FLD;
           _mxcsr |= ((~_m) << SSE_MSKS_OFF) & SSE_MSKS_FLD;
           __ldmxcsr(&_mxcsr);
           return (_p);
   }
   
   /* See which sticky exceptions are pending, and reset them */
   static __inline__ fp_except_t
   __fpgetsticky(void)
   {
           unsigned short _sw;
           unsigned int _mxcsr;
           fp_except_t _ex;
   
           __fnstsw(&_sw);
           _ex = _sw & FP_STKY_FLD;
           __stmxcsr(&_mxcsr);
           _ex |= _mxcsr & SSE_STKY_FLD;
           return (_ex);
   }
   
   #endif /* __GNUCLIKE_ASM && __CC_SUPPORTS___INLINE__ && !__cplusplus */
   
   #if !defined(__IEEEFP_NOINLINES__) && !defined(__cplusplus) \
       && defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE__)
   
   #define fpgetround()    __fpgetround()
   #define fpsetround(_m)  __fpsetround(_m)
   #define fpgetprec()     __fpgetprec()
   #define fpsetprec(_m)   __fpsetprec(_m)
   #define fpgetmask()     __fpgetmask()
   #define fpsetmask(_m)   __fpsetmask(_m)
   #define fpgetsticky()   __fpgetsticky()
   
   /* Suppress prototypes in the MI header. */
   #define _IEEEFP_INLINED_        1
   
   #else /* !__IEEEFP_NOINLINES__ && !__cplusplus && __GNUCLIKE_ASM
            && __CC_SUPPORTS___INLINE__ */
   
   /* Augment the userland declarations */
   __BEGIN_DECLS
   extern fp_prec_t fpgetprec(void);
   extern fp_prec_t fpsetprec(fp_prec_t);
   __END_DECLS
   
   #endif /* !__IEEEFP_NOINLINES__ && !__cplusplus && __GNUCLIKE_ASM
             && __CC_SUPPORTS___INLINE__ */
   
   #endif /* !_MACHINE_IEEEFP_H_ */

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