File: /usr/src/linux/arch/i386/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
20 static void fnop(void)
21 {
22 }
23
24 void fclex(void)
25 {
26 partial_status &= ~(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()
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_()
62 {
63 (finit_table[FPU_rm])();
64 }
65
66
67 static void fstsw_ax(void)
68 {
69 *(short *) &FPU_EAX = status_word();
70 no_ip_update = 1;
71 }
72
73 static FUNC const fstsw_table[] = {
74 fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
75 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
76 };
77
78 void fstsw_()
79 {
80 (fstsw_table[FPU_rm])();
81 }
82
83
84 static FUNC const fp_nop_table[] = {
85 fnop, FPU_illegal, FPU_illegal, FPU_illegal,
86 FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
87 };
88
89 void fp_nop()
90 {
91 (fp_nop_table[FPU_rm])();
92 }
93
94
95 void fld_i_()
96 {
97 FPU_REG *st_new_ptr;
98 int i;
99 u_char tag;
100
101 if ( STACK_OVERFLOW )
102 { FPU_stack_overflow(); return; }
103
104 /* fld st(i) */
105 i = FPU_rm;
106 if ( NOT_EMPTY(i) )
107 {
108 reg_copy(&st(i), st_new_ptr);
109 tag = FPU_gettagi(i);
110 push();
111 FPU_settag0(tag);
112 }
113 else
114 {
115 if ( control_word & CW_Invalid )
116 {
117 /* The masked response */
118 FPU_stack_underflow();
119 }
120 else
121 EXCEPTION(EX_StackUnder);
122 }
123
124 }
125
126
127 void fxch_i()
128 {
129 /* fxch st(i) */
130 FPU_REG t;
131 int i = FPU_rm;
132 FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
133 long tag_word = fpu_tag_word;
134 int regnr = top & 7, regnri = ((regnr + i) & 7);
135 u_char st0_tag = (tag_word >> (regnr*2)) & 3;
136 u_char sti_tag = (tag_word >> (regnri*2)) & 3;
137
138 if ( st0_tag == TAG_Empty )
139 {
140 if ( sti_tag == TAG_Empty )
141 {
142 FPU_stack_underflow();
143 FPU_stack_underflow_i(i);
144 return;
145 }
146 if ( control_word & CW_Invalid )
147 {
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 {
156 if ( control_word & CW_Invalid )
157 {
158 /* Masked response */
159 FPU_copy_to_regi(st0_ptr, st0_tag, i);
160 }
161 FPU_stack_underflow();
162 return;
163 }
164 clear_C1();
165
166 reg_copy(st0_ptr, &t);
167 reg_copy(sti_ptr, st0_ptr);
168 reg_copy(&t, sti_ptr);
169
170 tag_word &= ~(3 << (regnr*2)) & ~(3 << (regnri*2));
171 tag_word |= (sti_tag << (regnr*2)) | (st0_tag << (regnri*2));
172 fpu_tag_word = tag_word;
173 }
174
175
176 void ffree_()
177 {
178 /* ffree st(i) */
179 FPU_settagi(FPU_rm, TAG_Empty);
180 }
181
182
183 void ffreep()
184 {
185 /* ffree st(i) + pop - unofficial code */
186 FPU_settagi(FPU_rm, TAG_Empty);
187 FPU_pop();
188 }
189
190
191 void fst_i_()
192 {
193 /* fst st(i) */
194 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
195 }
196
197
198 void fstp_i()
199 {
200 /* fstp st(i) */
201 FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
202 FPU_pop();
203 }
204
205