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(void)
34 {
35 control_word = 0x037f;
36 partial_status = 0;
37 top = 0; /* We don't keep top in the status word internally. */
38 fpu_tag_word = 0xffff;
39 /* The behaviour is different from that detailed in
40 Section 15.1.6 of the Intel manual */
41 operand_address.offset = 0;
42 operand_address.selector = 0;
43 instruction_address.offset = 0;
44 instruction_address.selector = 0;
45 instruction_address.opcode = 0;
46 no_ip_update = 1;
47 }
48
49 /*
50 * These are nops on the i387..
51 */
52 #define feni fnop
53 #define fdisi fnop
54 #define fsetpm fnop
55
56 static FUNC const finit_table[] = {
57 feni, fdisi, fclex, finit,
58 fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
59 };
60
61 void finit_(void)
62 {
63 (finit_table[FPU_rm]) ();
64 }
65
66 static void fstsw_ax(void)
67 {
68 *(short *)&FPU_EAX = status_word();
69 no_ip_update = 1;
70 }
71
72 static FUNC const fstsw_table[] = {
73 fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
74 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
75 };
76
77 void fstsw_(void)
78 {
79 (fstsw_table[FPU_rm]) ();
80 }
81
82 static FUNC const fp_nop_table[] = {
83 fnop, FPU_illegal, FPU_illegal, FPU_illegal,
84 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
85 };
86
87 void fp_nop(void)
88 {
89 (fp_nop_table[FPU_rm]) ();
90 }
91
92 void fld_i_(void)
93 {
94 FPU_REG *st_new_ptr;
95 int i;
96 u_char tag;
97
98 if (STACK_OVERFLOW) {
99 FPU_stack_overflow();
100 return;
101 }
102
103 /* fld st(i) */
104 i = FPU_rm;
105 if (NOT_EMPTY(i)) {
106 reg_copy(&st(i), st_new_ptr);
107 tag = FPU_gettagi(i);
108 push();
109 FPU_settag0(tag);
110 } else {
111 if (control_word & CW_Invalid) {
112 /* The masked response */
113 FPU_stack_underflow();
114 } else
115 EXCEPTION(EX_StackUnder);
116 }
117
118 }
119
120 void fxch_i(void)
121 {
122 /* fxch st(i) */
123 FPU_REG t;
124 int i = FPU_rm;
125 FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
126 long tag_word = fpu_tag_word;
127 int regnr = top & 7, regnri = ((regnr + i) & 7);
128 u_char st0_tag = (tag_word >> (regnr * 2)) & 3;
129 u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
130
131 if (st0_tag == TAG_Empty) {
132 if (sti_tag == TAG_Empty) {
133 FPU_stack_underflow();
134 FPU_stack_underflow_i(i);
135 return;
136 }
137 if (control_word & CW_Invalid) {
138 /* Masked response */
139 FPU_copy_to_reg0(sti_ptr, sti_tag);
140 }
141 FPU_stack_underflow_i(i);
142 return;
143 }
144 if (sti_tag == TAG_Empty) {
145 if (control_word & CW_Invalid) {
146 /* Masked response */
147 FPU_copy_to_regi(st0_ptr, st0_tag, i);
148 }
149 FPU_stack_underflow();
150 return;
151 }
152 clear_C1();
153
154 reg_copy(st0_ptr, &t);
155 reg_copy(sti_ptr, st0_ptr);
156 reg_copy(&t, sti_ptr);
157
158 tag_word &= ~(3 << (regnr * 2)) & ~(3 << (regnri * 2));
159 tag_word |= (sti_tag << (regnr * 2)) | (st0_tag << (regnri * 2));
160 fpu_tag_word = tag_word;
161 }
162
163 void ffree_(void)
164 {
165 /* ffree st(i) */
166 FPU_settagi(FPU_rm, TAG_Empty);
167 }
168
169 void ffreep(void)
170 {
171 /* ffree st(i) + pop - unofficial code */
172 FPU_settagi(FPU_rm, TAG_Empty);
173 FPU_pop();
174 }
175
176 void fst_i_(void)
177 {
178 /* fst st(i) */
179 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
180 }
181
182 void fstp_i(void)
183 {
184 /* fstp st(i) */
185 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
186 FPU_pop();
187 }
188
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