LXR linux/arch/x86/math-emu/fpu

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*---------------------------------------------------------------------------+
   3 |  fpu_emu.h                                                                |
   4 |                                                                           |
   5 | Copyright (C) 1992,1993,1994,1997                                         |
   6 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   7 |                       Australia.  E-mail   billm@suburbia.net             |
   8 |                                                                           |
   9 +---------------------------------------------------------------------------*/
  10
  11#ifndef _FPU_EMU_H_
  12#define _FPU_EMU_H_
  13
  14/*
  15 * Define PECULIAR_486 to get a closer approximation to 80486 behaviour,
  16 * rather than behaviour which appears to be cleaner.
  17 * This is a matter of opinion: for all I know, the 80486 may simply
  18 * be complying with the IEEE spec. Maybe one day I'll get to see the
  19 * spec...
  20 */
  21#define PECULIAR_486
  22
  23#ifdef __ASSEMBLY__
  24#include "fpu_asm.h"
  25#define Const(x)        $##x
  26#else
  27#define Const(x)        x
  28#endif
  29
  30#define EXP_BIAS        Const(0)
  31#define EXP_OVER        Const(0x4000)   /* smallest invalid large exponent */
  32#define EXP_UNDER       Const(-0x3fff)  /* largest invalid small exponent */
  33#define EXP_WAY_UNDER   Const(-0x6000)  /* Below the smallest denormal, but
  34                                           still a 16 bit nr. */
  35#define EXP_Infinity    EXP_OVER
  36#define EXP_NaN         EXP_OVER
  37
  38#define EXTENDED_Ebias Const(0x3fff)
  39#define EXTENDED_Emin (-0x3ffe) /* smallest valid exponent */
  40
  41#define SIGN_POS        Const(0)
  42#define SIGN_NEG        Const(0x80)
  43
  44#define SIGN_Positive   Const(0)
  45#define SIGN_Negative   Const(0x8000)
  46
  47/* Keep the order TAG_Valid, TAG_Zero, TW_Denormal */
  48/* The following fold to 2 (Special) in the Tag Word */
  49#define TW_Denormal     Const(4)        /* De-normal */
  50#define TW_Infinity     Const(5)        /* + or - infinity */
  51#define TW_NaN          Const(6)        /* Not a Number */
  52#define TW_Unsupported  Const(7)        /* Not supported by an 80486 */
  53
  54#define TAG_Valid       Const(0)        /* valid */
  55#define TAG_Zero        Const(1)        /* zero */
  56#define TAG_Special     Const(2)        /* De-normal, + or - infinity,
  57                                           or Not a Number */
  58#define TAG_Empty       Const(3)        /* empty */
  59#define TAG_Error       Const(0x80)     /* probably need to abort */
  60
  61#define LOADED_DATA     Const(10101)    /* Special st() number to identify
  62                                           loaded data (not on stack). */
  63
  64/* A few flags (must be >= 0x10). */
  65#define REV             0x10
  66#define DEST_RM         0x20
  67#define LOADED          0x40
  68
  69#define FPU_Exception   Const(0x80000000)       /* Added to tag returns. */
  70
  71#ifndef __ASSEMBLY__
  72
  73#include "fpu_system.h"
  74
  75#include <uapi/asm/sigcontext.h>        /* for struct _fpstate */
  76#include <asm/math_emu.h>
  77#include <linux/linkage.h>
  78
  79/*
  80#define RE_ENTRANT_CHECKING
  81 */
  82
  83#ifdef RE_ENTRANT_CHECKING
  84extern u_char emulating;
  85#  define RE_ENTRANT_CHECK_OFF emulating = 0
  86#  define RE_ENTRANT_CHECK_ON emulating = 1
  87#else
  88#  define RE_ENTRANT_CHECK_OFF
  89#  define RE_ENTRANT_CHECK_ON
  90#endif /* RE_ENTRANT_CHECKING */
  91
  92#define FWAIT_OPCODE 0x9b
  93#define OP_SIZE_PREFIX 0x66
  94#define ADDR_SIZE_PREFIX 0x67
  95#define PREFIX_CS 0x2e
  96#define PREFIX_DS 0x3e
  97#define PREFIX_ES 0x26
  98#define PREFIX_SS 0x36
  99#define PREFIX_FS 0x64
 100#define PREFIX_GS 0x65
 101#define PREFIX_REPE 0xf3
 102#define PREFIX_REPNE 0xf2
 103#define PREFIX_LOCK 0xf0
 104#define PREFIX_CS_ 1
 105#define PREFIX_DS_ 2
 106#define PREFIX_ES_ 3
 107#define PREFIX_FS_ 4
 108#define PREFIX_GS_ 5
 109#define PREFIX_SS_ 6
 110#define PREFIX_DEFAULT 7
 111
 112struct address {
 113        unsigned int offset;
 114        unsigned int selector:16;
 115        unsigned int opcode:11;
 116        unsigned int empty:5;
 117};
 118struct fpu__reg {
 119        unsigned sigl;
 120        unsigned sigh;
 121        short exp;
 122};
 123
 124typedef void (*FUNC) (void);
 125typedef struct fpu__reg FPU_REG;
 126typedef void (*FUNC_ST0) (FPU_REG *st0_ptr, u_char st0_tag);
 127typedef struct {
 128        u_char address_size, operand_size, segment;
 129} overrides;
 130/* This structure is 32 bits: */
 131typedef struct {
 132        overrides override;
 133        u_char default_mode;
 134} fpu_addr_modes;
 135/* PROTECTED has a restricted meaning in the emulator; it is used
 136   to signal that the emulator needs to do special things to ensure
 137   that protection is respected in a segmented model. */
 138#define PROTECTED 4
 139#define SIXTEEN   1             /* We rely upon this being 1 (true) */
 140#define VM86      SIXTEEN
 141#define PM16      (SIXTEEN | PROTECTED)
 142#define SEG32     PROTECTED
 143extern u_char const data_sizes_16[32];
 144
 145#define register_base ((u_char *) registers )
 146#define fpu_register(x)  ( * ((FPU_REG *)( register_base + 10 * (x & 7) )) )
 147#define st(x)      ( * ((FPU_REG *)( register_base + 10 * ((top+x) & 7) )) )
 148
 149#define STACK_OVERFLOW  (FPU_stackoverflow(&st_new_ptr))
 150#define NOT_EMPTY(i)    (!FPU_empty_i(i))
 151
 152#define NOT_EMPTY_ST0   (st0_tag ^ TAG_Empty)
 153
 154#define poppop() { FPU_pop(); FPU_pop(); }
 155
 156/* push() does not affect the tags */
 157#define push()  { top--; }
 158
 159#define signbyte(a) (((u_char *)(a))[9])
 160#define getsign(a) (signbyte(a) & 0x80)
 161#define setsign(a,b) { if ((b) != 0) signbyte(a) |= 0x80; else signbyte(a) &= 0x7f; }
 162#define copysign(a,b) { if (getsign(a)) signbyte(b) |= 0x80; \
 163                        else signbyte(b) &= 0x7f; }
 164#define changesign(a) { signbyte(a) ^= 0x80; }
 165#define setpositive(a) { signbyte(a) &= 0x7f; }
 166#define setnegative(a) { signbyte(a) |= 0x80; }
 167#define signpositive(a) ( (signbyte(a) & 0x80) == 0 )
 168#define signnegative(a) (signbyte(a) & 0x80)
 169
 170static inline void reg_copy(FPU_REG const *x, FPU_REG *y)
 171{
 172        *(short *)&(y->exp) = *(const short *)&(x->exp);
 173        *(long long *)&(y->sigl) = *(const long long *)&(x->sigl);
 174}
 175
 176#define exponent(x)  (((*(short *)&((x)->exp)) & 0x7fff) - EXTENDED_Ebias)
 177#define setexponentpos(x,y) { (*(short *)&((x)->exp)) = \
 178  ((y) + EXTENDED_Ebias) & 0x7fff; }
 179#define exponent16(x)         (*(short *)&((x)->exp))
 180#define setexponent16(x,y)  { (*(short *)&((x)->exp)) = (u16)(y); }
 181#define addexponent(x,y)    { (*(short *)&((x)->exp)) += (y); }
 182#define stdexp(x)           { (*(short *)&((x)->exp)) += EXTENDED_Ebias; }
 183
 184#define isdenormal(ptr)   (exponent(ptr) == EXP_BIAS+EXP_UNDER)
 185
 186#define significand(x) ( ((unsigned long long *)&((x)->sigl))[0] )
 187
 188/*----- Prototypes for functions written in assembler -----*/
 189/* extern void reg_move(FPU_REG *a, FPU_REG *b); */
 190
 191asmlinkage int FPU_normalize(FPU_REG *x);
 192asmlinkage int FPU_normalize_nuo(FPU_REG *x);
 193asmlinkage int FPU_u_sub(FPU_REG const *arg1, FPU_REG const *arg2,
 194                         FPU_REG * answ, unsigned int control_w, u_char sign,
 195                         int expa, int expb);
 196asmlinkage int FPU_u_mul(FPU_REG const *arg1, FPU_REG const *arg2,
 197                         FPU_REG * answ, unsigned int control_w, u_char sign,
 198                         int expon);
 199asmlinkage int FPU_u_div(FPU_REG const *arg1, FPU_REG const *arg2,
 200                         FPU_REG * answ, unsigned int control_w, u_char sign);
 201asmlinkage int FPU_u_add(FPU_REG const *arg1, FPU_REG const *arg2,
 202                         FPU_REG * answ, unsigned int control_w, u_char sign,
 203                         int expa, int expb);
 204asmlinkage int wm_sqrt(FPU_REG *n, int dummy1, int dummy2,
 205                       unsigned int control_w, u_char sign);
 206asmlinkage unsigned FPU_shrx(void *l, unsigned x);
 207asmlinkage unsigned FPU_shrxs(void *v, unsigned x);
 208asmlinkage unsigned long FPU_div_small(unsigned long long *x, unsigned long y);
 209asmlinkage int FPU_round(FPU_REG *arg, unsigned int extent, int dummy,
 210                         unsigned int control_w, u_char sign);
 211
 212#ifndef MAKING_PROTO
 213#include "fpu_proto.h"
 214#endif
 215
 216#endif /* __ASSEMBLY__ */
 217
 218#endif /* _FPU_EMU_H_ */
 219