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

     /*-
      * Copyright (c) 1990 The Regents of the University of California.
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * William Jolitz.
      *
      * 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.
     * 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: @(#)npx.h 5.3 (Berkeley) 1/18/91
     * $FreeBSD: releng/9.0/sys/amd64/include/fpu.h 215865 2010-11-26 14:50:42Z kib $
     */
    
    /*
     * Floating Point Data Structures and Constants
     * W. Jolitz 1/90
     */
    
    #ifndef _MACHINE_FPU_H_
    #define _MACHINE_FPU_H_
    
    /* Contents of each x87 floating point accumulator */
    struct fpacc87 {
            u_char  fp_bytes[10];
    };
    
    /* Contents of each SSE extended accumulator */
    struct  xmmacc {
            u_char  xmm_bytes[16];
    };
    
    struct  envxmm {
            u_int16_t       en_cw;          /* control word (16bits) */
            u_int16_t       en_sw;          /* status word (16bits) */
            u_int8_t        en_tw;          /* tag word (8bits) */
            u_int8_t        en_zero;
            u_int16_t       en_opcode;      /* opcode last executed (11 bits ) */
            u_int64_t       en_rip;         /* floating point instruction pointer */
            u_int64_t       en_rdp;         /* floating operand pointer */
            u_int32_t       en_mxcsr;       /* SSE sontorol/status register */
            u_int32_t       en_mxcsr_mask;  /* valid bits in mxcsr */
    };
    
    struct  savefpu {
            struct  envxmm  sv_env;
            struct {
                    struct fpacc87  fp_acc;
                    u_char          fp_pad[6];      /* padding */
            } sv_fp[8];
            struct xmmacc   sv_xmm[16];
            u_char sv_pad[96];
    } __aligned(16);
    
    #ifdef _KERNEL
    struct fpu_kern_ctx {
            struct savefpu hwstate;
            struct savefpu *prev;
            uint32_t flags;
    };
    #define FPU_KERN_CTX_FPUINITDONE 0x01
    
    #define PCB_USER_FPU(pcb) (((pcb)->pcb_flags & PCB_KERNFPU) == 0)
    #endif
    
    /*
     * The hardware default control word for i387's and later coprocessors is
     * 0x37F, giving:
     *
     *      round to nearest
     *      64-bit precision
     *      all exceptions masked.
     *
     * FreeBSD/i386 uses 53 bit precision for things like fadd/fsub/fsqrt etc
     * because of the difference between memory and fpu register stack arguments.
     * If its using an intermediate fpu register, it has 80/64 bits to work
     * with.  If it uses memory, it has 64/53 bits to work with.  However,
     * gcc is aware of this and goes to a fair bit of trouble to make the
    * best use of it.
    *
    * This is mostly academic for AMD64, because the ABI prefers the use
    * SSE2 based math.  For FreeBSD/amd64, we go with the default settings.
    */
   #define __INITIAL_FPUCW__       0x037F
   #define __INITIAL_FPUCW_I386__  0x127F
   #define __INITIAL_MXCSR__       0x1F80
   #define __INITIAL_MXCSR_MASK__  0xFFBF
   
   #ifdef _KERNEL
   void    fpudna(void);
   void    fpudrop(void);
   void    fpuexit(struct thread *td);
   int     fpuformat(void);
   int     fpugetregs(struct thread *td);
   void    fpuinit(void);
   void    fpusetregs(struct thread *td, struct savefpu *addr);
   int     fputrap(void);
   void    fpuuserinited(struct thread *td);
   int     fpu_kern_enter(struct thread *td, struct fpu_kern_ctx *ctx,
               u_int flags);
   int     fpu_kern_leave(struct thread *td, struct fpu_kern_ctx *ctx);
   int     fpu_kern_thread(u_int flags);
   int     is_fpu_kern_thread(u_int flags);
   
   /*
    * Flags for fpu_kern_enter() and fpu_kern_thread().
    */
   #define FPU_KERN_NORMAL 0x0000
   
   #endif
   
   #endif /* !_MACHINE_FPU_H_ */

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