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
84 extern 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 
112 struct address {
113 	unsigned int offset;
114 	unsigned int selector:16;
115 	unsigned int opcode:11;
116 	unsigned int empty:5;
117 };
118 struct fpu__reg {
119 	unsigned sigl;
120 	unsigned sigh;
121 	short exp;
122 };
123 
124 typedef void (*FUNC) (void);
125 typedef struct fpu__reg FPU_REG;
126 typedef void (*FUNC_ST0) (FPU_REG *st0_ptr, u_char st0_tag);
127 typedef struct {
128 	u_char address_size, operand_size, segment;
129 } overrides;
130 /* This structure is 32 bits: */
131 typedef 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
143 extern 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 
reg_copy(FPU_REG const * x,FPU_REG * y)170 static 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 
191 asmlinkage int FPU_normalize(FPU_REG *x);
192 asmlinkage int FPU_normalize_nuo(FPU_REG *x);
193 asmlinkage 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);
196 asmlinkage 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);
199 asmlinkage int FPU_u_div(FPU_REG const *arg1, FPU_REG const *arg2,
200 			 FPU_REG * answ, unsigned int control_w, u_char sign);
201 asmlinkage 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);
204 asmlinkage int wm_sqrt(FPU_REG *n, int dummy1, int dummy2,
205 		       unsigned int control_w, u_char sign);
206 asmlinkage unsigned FPU_shrx(void *l, unsigned x);
207 asmlinkage unsigned FPU_shrxs(void *v, unsigned x);
208 asmlinkage unsigned long FPU_div_small(unsigned long long *x, unsigned long y);
209 asmlinkage 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