1 // SPDX-License-Identifier: GPL-2.0
2 /*---------------------------------------------------------------------------+
3 | fpu_aux.c |
4 | |
5 | Code to implement some of the FPU auxiliary instructions. |
6 | |
7 | Copyright (C) 1992,1993,1994,1997 |
8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
9 | E-mail billm@suburbia.net |
10 | |
11 | |
12 +---------------------------------------------------------------------------*/
13
14 #include "fpu_system.h"
15 #include "exception.h"
16 #include "fpu_emu.h"
17 #include "status_w.h"
18 #include "control_w.h"
19
20 static void fnop(void)
21 {
22 }
23
24 static void fclex(void)
25 {
26 partial_status &=
27 ~(SW_Backward | SW_Summary | SW_Stack_Fault | SW_Precision |
28 SW_Underflow | SW_Overflow | SW_Zero_Div | SW_Denorm_Op |
29 SW_Invalid);
30 no_ip_update = 1;
31 }
32
33 /* Needs to be externally visible */
34 void fpstate_init_soft(struct swregs_state *soft)
35 {
36 struct address *oaddr, *iaddr;
37 memset(soft, 0, sizeof(*soft));
38 soft->cwd = 0x037f;
39 soft->swd = 0;
40 soft->ftop = 0; /* We don't keep top in the status word internally. */
41 soft->twd = 0xffff;
42 /* The behaviour is different from that detailed in
43 Section 15.1.6 of the Intel manual */
44 oaddr = (struct address *)&soft->foo;
45 oaddr->offset = 0;
46 oaddr->selector = 0;
47 iaddr = (struct address *)&soft->fip;
48 iaddr->offset = 0;
49 iaddr->selector = 0;
50 iaddr->opcode = 0;
51 soft->no_update = 1;
52 }
53
54 void finit(void)
55 {
56 fpstate_init_soft(¤t->thread.fpu.fpstate->regs.soft);
57 }
58
59 /*
60 * These are nops on the i387..
61 */
62 #define feni fnop
63 #define fdisi fnop
64 #define fsetpm fnop
65
66 static FUNC const finit_table[] = {
67 feni, fdisi, fclex, finit,
68 fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
69 };
70
71 void finit_(void)
72 {
73 (finit_table[FPU_rm]) ();
74 }
75
76 static void fstsw_ax(void)
77 {
78 *(short *)&FPU_EAX = status_word();
79 no_ip_update = 1;
80 }
81
82 static FUNC const fstsw_table[] = {
83 fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
84 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
85 };
86
87 void fstsw_(void)
88 {
89 (fstsw_table[FPU_rm]) ();
90 }
91
92 static FUNC const fp_nop_table[] = {
93 fnop, FPU_illegal, FPU_illegal, FPU_illegal,
94 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
95 };
96
97 void fp_nop(void)
98 {
99 (fp_nop_table[FPU_rm]) ();
100 }
101
102 void fld_i_(void)
103 {
104 FPU_REG *st_new_ptr;
105 int i;
106 u_char tag;
107
108 if (STACK_OVERFLOW) {
109 FPU_stack_overflow();
110 return;
111 }
112
113 /* fld st(i) */
114 i = FPU_rm;
115 if (NOT_EMPTY(i)) {
116 reg_copy(&st(i), st_new_ptr);
117 tag = FPU_gettagi(i);
118 push();
119 FPU_settag0(tag);
120 } else {
121 if (control_word & CW_Invalid) {
122 /* The masked response */
123 FPU_stack_underflow();
124 } else
125 EXCEPTION(EX_StackUnder);
126 }
127
128 }
129
130 void fxch_i(void)
131 {
132 /* fxch st(i) */
133 FPU_REG t;
134 int i = FPU_rm;
135 FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
136 long tag_word = fpu_tag_word;
137 int regnr = top & 7, regnri = ((regnr + i) & 7);
138 u_char st0_tag = (tag_word >> (regnr * 2)) & 3;
139 u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
140
141 if (st0_tag == TAG_Empty) {
142 if (sti_tag == TAG_Empty) {
143 FPU_stack_underflow();
144 FPU_stack_underflow_i(i);
145 return;
146 }
147 if (control_word & CW_Invalid) {
148 /* Masked response */
149 FPU_copy_to_reg0(sti_ptr, sti_tag);
150 }
151 FPU_stack_underflow_i(i);
152 return;
153 }
154 if (sti_tag == TAG_Empty) {
155 if (control_word & CW_Invalid) {
156 /* Masked response */
157 FPU_copy_to_regi(st0_ptr, st0_tag, i);
158 }
159 FPU_stack_underflow();
160 return;
161 }
162 clear_C1();
163
164 reg_copy(st0_ptr, &t);
165 reg_copy(sti_ptr, st0_ptr);
166 reg_copy(&t, sti_ptr);
167
168 tag_word &= ~(3 << (regnr * 2)) & ~(3 << (regnri * 2));
169 tag_word |= (sti_tag << (regnr * 2)) | (st0_tag << (regnri * 2));
170 fpu_tag_word = tag_word;
171 }
172
173 static void fcmovCC(void)
174 {
175 /* fcmovCC st(i) */
176 int i = FPU_rm;
177 FPU_REG *st0_ptr = &st(0);
178 FPU_REG *sti_ptr = &st(i);
179 long tag_word = fpu_tag_word;
180 int regnr = top & 7;
181 int regnri = (top + i) & 7;
182 u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
183
184 if (sti_tag == TAG_Empty) {
185 FPU_stack_underflow();
186 clear_C1();
187 return;
188 }
189 reg_copy(sti_ptr, st0_ptr);
190 tag_word &= ~(3 << (regnr * 2));
191 tag_word |= (sti_tag << (regnr * 2));
192 fpu_tag_word = tag_word;
193 }
194
195 void fcmovb(void)
196 {
197 if (FPU_EFLAGS & X86_EFLAGS_CF)
198 fcmovCC();
199 }
200
201 void fcmove(void)
202 {
203 if (FPU_EFLAGS & X86_EFLAGS_ZF)
204 fcmovCC();
205 }
206
207 void fcmovbe(void)
208 {
209 if (FPU_EFLAGS & (X86_EFLAGS_CF|X86_EFLAGS_ZF))
210 fcmovCC();
211 }
212
213 void fcmovu(void)
214 {
215 if (FPU_EFLAGS & X86_EFLAGS_PF)
216 fcmovCC();
217 }
218
219 void fcmovnb(void)
220 {
221 if (!(FPU_EFLAGS & X86_EFLAGS_CF))
222 fcmovCC();
223 }
224
225 void fcmovne(void)
226 {
227 if (!(FPU_EFLAGS & X86_EFLAGS_ZF))
228 fcmovCC();
229 }
230
231 void fcmovnbe(void)
232 {
233 if (!(FPU_EFLAGS & (X86_EFLAGS_CF|X86_EFLAGS_ZF)))
234 fcmovCC();
235 }
236
237 void fcmovnu(void)
238 {
239 if (!(FPU_EFLAGS & X86_EFLAGS_PF))
240 fcmovCC();
241 }
242
243 void ffree_(void)
244 {
245 /* ffree st(i) */
246 FPU_settagi(FPU_rm, TAG_Empty);
247 }
248
249 void ffreep(void)
250 {
251 /* ffree st(i) + pop - unofficial code */
252 FPU_settagi(FPU_rm, TAG_Empty);
253 FPU_pop();
254 }
255
256 void fst_i_(void)
257 {
258 /* fst st(i) */
259 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
260 }
261
262 void fstp_i(void)
263 {
264 /* fstp st(i) */
265 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
266 FPU_pop();
267 }
268
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