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
19static void fnop(void)
20{
21}
22
23static 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 */
33void 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
53void 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
65static FUNC const finit_table[] = {
66	feni, fdisi, fclex, finit,
67	fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
68};
69
70void finit_(void)
71{
72	(finit_table[FPU_rm]) ();
73}
74
75static void fstsw_ax(void)
76{
77	*(short *)&FPU_EAX = status_word();
78	no_ip_update = 1;
79}
80
81static FUNC const fstsw_table[] = {
82	fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
83	FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
84};
85
86void fstsw_(void)
87{
88	(fstsw_table[FPU_rm]) ();
89}
90
91static FUNC const fp_nop_table[] = {
92	fnop, FPU_illegal, FPU_illegal, FPU_illegal,
93	FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
94};
95
96void fp_nop(void)
97{
98	(fp_nop_table[FPU_rm]) ();
99}
100
101void 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
129void 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
172void ffree_(void)
173{
174	/* ffree st(i) */
175	FPU_settagi(FPU_rm, TAG_Empty);
176}
177
178void ffreep(void)
179{
180	/* ffree st(i) + pop - unofficial code */
181	FPU_settagi(FPU_rm, TAG_Empty);
182	FPU_pop();
183}
184
185void fst_i_(void)
186{
187	/* fst st(i) */
188	FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
189}
190
191void fstp_i(void)
192{
193	/* fstp st(i) */
194	FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
195	FPU_pop();
196}
197