fpu.h

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    1 /* 
    2  * Mach Operating System
    3  * Copyright (c) 1991 Carnegie Mellon University
    4  * All Rights Reserved.
    5  * 
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  * 
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  * 
   16  * Carnegie Mellon requests users of this software to return to
   17  * 
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  * 
   23  * any improvements or extensions that they make and grant Carnegie Mellon 
   24  * the rights to redistribute these changes.
   25  */
   26 
   27 /*
   28  * HISTORY
   29  * $Log:        fpu.h,v $
   30  * Revision 2.3  92/02/19  15:08:04  elf
   31  *      Added fwait()
   32  *      [92/01/19            jvh]
   33  * 
   34  * Revision 2.2  92/01/03  20:05:49  dbg
   35  *      Created.
   36  *      [91/12/23  16:32:15  dbg]
   37  * 
   38  */
   39 
   40 #ifndef _I386_FPU_H_
   41 #define _I386_FPU_H_
   42 
   43 /*
   44  * Macro definitions for routines to manipulate the
   45  * floating-point processor.
   46  */
   47 
   48 #include <cpus.h>
   49 #include <fpe.h>
   50 #include <i386/proc_reg.h>
   51 #include <i386/thread.h>
   52 
   53 /*
   54  * FPU instructions.
   55  */
   56 #define fninit() \
   57         asm volatile("fninit")
   58 
   59 #define fnstcw(control) \
   60         asm("fnstcw %0" : "=m" (*(unsigned short *)(control)))
   61 
   62 #define fldcw(control) \
   63         asm volatile("fldcw %0" : : "m" (*(unsigned short *) &(control)) )
   64 
   65 #define fnstsw() \
   66     ({ \
   67         unsigned short _status__; \
   68         asm("fnstsw %0" : "=ma" (_status__)); \
   69         _status__; \
   70     })
   71 
   72 #define fnclex() \
   73         asm volatile("fnclex")
   74 
   75 #define fnsave(state) \
   76         asm volatile("fnsave %0" : "=m" (*state))
   77 
   78 #define frstor(state) \
   79         asm volatile("frstor %0" : : "m" (state))
   80 
   81 #define fwait() \
   82         asm("fwait");
   83 
   84 /*
   85  * If floating-point instructions are emulated,
   86  * we must load the floating-point register selector
   87  * when switching to a new thread.
   88  */
   89 #if     FPE
   90 extern void     disable_fpe();
   91 extern void     enable_fpe();
   92 
   93 #define fpu_save_context(thread) \
   94     { \
   95         if (fp_kind == FP_SOFT) \
   96             disable_fpe(); \
   97         else \
   98             set_ts(); \
   99     }
  100 
  101 #define fpu_load_context(pcb) \
  102     { \
  103         register struct i386_fpsave_state *ifps; \
  104         if (fp_kind == FP_SOFT && (ifps = pcb->ims.ifps) != 0) \
  105             enable_fpe(ifps); \
  106     }
  107 
  108 #else   /* no FPE */
  109 
  110 #define fpu_load_context(pcb)
  111 
  112 /*
  113  * Save thread`s FPU context.
  114  * If only one CPU, we just set the task-switched bit,
  115  * to keep the new thread from using the coprocessor.
  116  * If multiple CPUs, we save the entire state.
  117  */
  118 #if     NCPUS > 1
  119 #define fpu_save_context(thread) \
  120     { \
  121         register struct i386_fpsave_state *ifps; \
  122         ifps = (thread)->pcb->ims.ifps; \
  123         if (ifps != 0 && !ifps->fp_valid) { \
  124             /* registers are in FPU - save to memory */ \
  125             ifps->fp_valid = TRUE; \
  126             fnsave(&ifps->fp_save_state); \
  127             set_ts(); \
  128         } \
  129     }
  130             
  131 #else   /* NCPUS == 1 */
  132 #define fpu_save_context(thread) \
  133     { \
  134             set_ts(); \
  135     }
  136 
  137 #endif  /* NCPUS == 1 */
  138 
  139 #endif  /* no FPE */
  140 
  141 extern int      fp_kind;
  142 
  143 #endif  /* _I386_FPU_H_ */

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FreeBSD/Linux Kernel Cross Reference sys/i386/fpu.h

FreeBSD/Linux Kernel Cross Reference
sys/i386/fpu.h