KVM: emulator: emulate AAM
[linux-3.10.git] / arch / x86 / math-emu / fpu_aux.c
1 /*---------------------------------------------------------------------------+
2  |  fpu_aux.c                                                                |
3  |                                                                           |
4  | Code to implement some of the FPU auxiliary instructions.                 |
5  |                                                                           |
6  | Copyright (C) 1992,1993,1994,1997                                         |
7  |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
8  |                  E-mail   billm@suburbia.net                              |
9  |                                                                           |
10  |                                                                           |
11  +---------------------------------------------------------------------------*/
12
13 #include "fpu_system.h"
14 #include "exception.h"
15 #include "fpu_emu.h"
16 #include "status_w.h"
17 #include "control_w.h"
18
19 static void fnop(void)
20 {
21 }
22
23 static void fclex(void)
24 {
25         partial_status &=
26             ~(SW_Backward | SW_Summary | SW_Stack_Fault | SW_Precision |
27               SW_Underflow | SW_Overflow | SW_Zero_Div | SW_Denorm_Op |
28               SW_Invalid);
29         no_ip_update = 1;
30 }
31
32 /* Needs to be externally visible */
33 void finit_soft_fpu(struct i387_soft_struct *soft)
34 {
35         struct address *oaddr, *iaddr;
36         memset(soft, 0, sizeof(*soft));
37         soft->cwd = 0x037f;
38         soft->swd = 0;
39         soft->ftop = 0; /* We don't keep top in the status word internally. */
40         soft->twd = 0xffff;
41         /* The behaviour is different from that detailed in
42            Section 15.1.6 of the Intel manual */
43         oaddr = (struct address *)&soft->foo;
44         oaddr->offset = 0;
45         oaddr->selector = 0;
46         iaddr = (struct address *)&soft->fip;
47         iaddr->offset = 0;
48         iaddr->selector = 0;
49         iaddr->opcode = 0;
50         soft->no_update = 1;
51 }
52
53 void finit(void)
54 {
55         finit_soft_fpu(&current->thread.fpu.state->soft);
56 }
57
58 /*
59  * These are nops on the i387..
60  */
61 #define feni fnop
62 #define fdisi fnop
63 #define fsetpm fnop
64
65 static FUNC const finit_table[] = {
66         feni, fdisi, fclex, finit,
67         fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
68 };
69
70 void finit_(void)
71 {
72         (finit_table[FPU_rm]) ();
73 }
74
75 static void fstsw_ax(void)
76 {
77         *(short *)&FPU_EAX = status_word();
78         no_ip_update = 1;
79 }
80
81 static FUNC const fstsw_table[] = {
82         fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
83         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
84 };
85
86 void fstsw_(void)
87 {
88         (fstsw_table[FPU_rm]) ();
89 }
90
91 static FUNC const fp_nop_table[] = {
92         fnop, FPU_illegal, FPU_illegal, FPU_illegal,
93         FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
94 };
95
96 void fp_nop(void)
97 {
98         (fp_nop_table[FPU_rm]) ();
99 }
100
101 void fld_i_(void)
102 {
103         FPU_REG *st_new_ptr;
104         int i;
105         u_char tag;
106
107         if (STACK_OVERFLOW) {
108                 FPU_stack_overflow();
109                 return;
110         }
111
112         /* fld st(i) */
113         i = FPU_rm;
114         if (NOT_EMPTY(i)) {
115                 reg_copy(&st(i), st_new_ptr);
116                 tag = FPU_gettagi(i);
117                 push();
118                 FPU_settag0(tag);
119         } else {
120                 if (control_word & CW_Invalid) {
121                         /* The masked response */
122                         FPU_stack_underflow();
123                 } else
124                         EXCEPTION(EX_StackUnder);
125         }
126
127 }
128
129 void fxch_i(void)
130 {
131         /* fxch st(i) */
132         FPU_REG t;
133         int i = FPU_rm;
134         FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
135         long tag_word = fpu_tag_word;
136         int regnr = top & 7, regnri = ((regnr + i) & 7);
137         u_char st0_tag = (tag_word >> (regnr * 2)) & 3;
138         u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
139
140         if (st0_tag == TAG_Empty) {
141                 if (sti_tag == TAG_Empty) {
142                         FPU_stack_underflow();
143                         FPU_stack_underflow_i(i);
144                         return;
145                 }
146                 if (control_word & CW_Invalid) {
147                         /* Masked response */
148                         FPU_copy_to_reg0(sti_ptr, sti_tag);
149                 }
150                 FPU_stack_underflow_i(i);
151                 return;
152         }
153         if (sti_tag == TAG_Empty) {
154                 if (control_word & CW_Invalid) {
155                         /* Masked response */
156                         FPU_copy_to_regi(st0_ptr, st0_tag, i);
157                 }
158                 FPU_stack_underflow();
159                 return;
160         }
161         clear_C1();
162
163         reg_copy(st0_ptr, &t);
164         reg_copy(sti_ptr, st0_ptr);
165         reg_copy(&t, sti_ptr);
166
167         tag_word &= ~(3 << (regnr * 2)) & ~(3 << (regnri * 2));
168         tag_word |= (sti_tag << (regnr * 2)) | (st0_tag << (regnri * 2));
169         fpu_tag_word = tag_word;
170 }
171
172 void ffree_(void)
173 {
174         /* ffree st(i) */
175         FPU_settagi(FPU_rm, TAG_Empty);
176 }
177
178 void ffreep(void)
179 {
180         /* ffree st(i) + pop - unofficial code */
181         FPU_settagi(FPU_rm, TAG_Empty);
182         FPU_pop();
183 }
184
185 void fst_i_(void)
186 {
187         /* fst st(i) */
188         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
189 }
190
191 void fstp_i(void)
192 {
193         /* fstp st(i) */
194         FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
195         FPU_pop();
196 }