/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1992 NeXT Computer, Inc.
 *
 * Intel386 Family:     Floating Point unit.
 *
 * HISTORY
 *
 * 5 October 1992 ? at NeXT
 *      Added names to previously unamed fields in the mantissa.
 *
 * 5 April 1992 ? at NeXT
 *      Created.
 */

#ifndef _ARCH_I386_FPU_H_
#define _ARCH_I386_FPU_H_

/*
 * Data register.
 */

typedef struct fp_data_reg {
    unsigned short              mant;
    unsigned short              mant1   :16,
                                mant2   :16,
                                mant3   :16;
    unsigned short              exp     :15,
                                sign    :1;
} fp_data_reg_t;

/*
 * Data register stack.
 */

typedef struct fp_stack {
    fp_data_reg_t               ST[8];
} fp_stack_t;

/*
 * Register stack tag word.
 */

typedef struct fp_tag {
    unsigned short              tag0    :2,
                                tag1    :2,
                                tag2    :2,
                                tag3    :2,
                                tag4    :2,
                                tag5    :2,
                                tag6    :2,
                                tag7    :2;
#define FP_TAG_VALID            0
#define FP_TAG_ZERO             1
#define FP_TAG_SPEC             2
#define FP_TAG_EMPTY            3
} fp_tag_t;

/*
 * Status word.
 */

typedef struct fp_status {
    unsigned short              invalid :1,
                                denorm  :1,
                                zdiv    :1,
                                ovrfl   :1,
                                undfl   :1,
                                precis  :1,
                                stkflt  :1,
                                errsumm :1,
                                c0      :1,
                                c1      :1,
                                c2      :1,
                                tos     :3,
                                c3      :1,
                                busy    :1;
} fp_status_t;

/*
 * Control word.
 */

typedef struct fp_control {
    unsigned short              invalid :1,
                                denorm  :1,
                                zdiv    :1,
                                ovrfl   :1,
                                undfl   :1,
                                precis  :1,
                                        :2,
                                pc      :2,
#define FP_PREC_24B             0
#define FP_PREC_53B             2
#define FP_PREC_64B             3
                                rc      :2,
#define FP_RND_NEAR             0
#define FP_RND_DOWN             1
#define FP_RND_UP               2
#define FP_CHOP                 3
                                /*inf*/ :1,
                                        :3;
} fp_control_t;

#include <architecture/i386/sel.h>

/*
 * Floating point 'environment'
 * used by FSTENV/FLDENV instructions.
 */

typedef struct fp_env {
    fp_control_t                control;
    unsigned short                      :16;
    fp_status_t                 status;
    unsigned short                      :16;
    fp_tag_t                    tag;
    unsigned short                      :16;
    unsigned int                ip;
    sel_t                       cs;
    unsigned short              opcode;
    unsigned int                dp;
    sel_t                       ds;
    unsigned short                      :16;
} fp_env_t;

/*
 * Floating point state
 * used by FSAVE/FRSTOR instructions.
 */
 
/*
 * To allow the the common idiom of:
 *     #define environ (*_NSGetEnviron())
 * to be used these fields were renamed.  Old code that that does
 * not use this idiom can use the old field names by defining
 * _ARCHITECTURE_I386_FPU_FPSTATE_LEGACY_FIELD_NAMES_ .
 */
typedef struct fp_state {
#if _ARCHITECTURE_I386_FPU_FPSTATE_LEGACY_FIELD_NAMES_
    fp_env_t                    environ;
    fp_stack_t                  stack;
#else
    fp_env_t                    fp_environ;
    fp_stack_t                  fp_stack;
#endif
} fp_state_t;

#endif  /* _ARCH_I386_FPU_H_ */
