1// SPDX-License-Identifier: GPL-2.0
2/*---------------------------------------------------------------------------+
3 |  fpu_etc.c                                                                |
4 |                                                                           |
5 | Implement a few FPU instructions.                                         |
6 |                                                                           |
7 | Copyright (C) 1992,1993,1994,1997                                         |
8 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
9 |                       Australia.  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 "reg_constant.h"
19
20static void fchs(FPU_REG *st0_ptr, u_char st0tag)
21{
22	if (st0tag ^ TAG_Empty) {
23		signbyte(st0_ptr) ^= SIGN_NEG;
24		clear_C1();
25	} else
26		FPU_stack_underflow();
27}
28
29static void fabs(FPU_REG *st0_ptr, u_char st0tag)
30{
31	if (st0tag ^ TAG_Empty) {
32		setpositive(st0_ptr);
33		clear_C1();
34	} else
35		FPU_stack_underflow();
36}
37
38static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
39{
40	switch (st0tag) {
41	case TAG_Zero:
42		setcc(SW_C3);
43		break;
44	case TAG_Valid:
45		if (getsign(st0_ptr) == SIGN_POS)
46			setcc(0);
47		else
48			setcc(SW_C0);
49		break;
50	case TAG_Special:
51		switch (FPU_Special(st0_ptr)) {
52		case TW_Denormal:
53			if (getsign(st0_ptr) == SIGN_POS)
54				setcc(0);
55			else
56				setcc(SW_C0);
57			if (denormal_operand() < 0) {
58#ifdef PECULIAR_486
59				/* This is weird! */
60				if (getsign(st0_ptr) == SIGN_POS)
61					setcc(SW_C3);
62#endif /* PECULIAR_486 */
63				return;
64			}
65			break;
66		case TW_NaN:
67			setcc(SW_C0 | SW_C2 | SW_C3);	/* Operand is not comparable */
68			EXCEPTION(EX_Invalid);
69			break;
70		case TW_Infinity:
71			if (getsign(st0_ptr) == SIGN_POS)
72				setcc(0);
73			else
74				setcc(SW_C0);
75			break;
76		default:
77			setcc(SW_C0 | SW_C2 | SW_C3);	/* Operand is not comparable */
78			EXCEPTION(EX_INTERNAL | 0x14);
79			break;
80		}
81		break;
82	case TAG_Empty:
83		setcc(SW_C0 | SW_C2 | SW_C3);
84		EXCEPTION(EX_StackUnder);
85		break;
86	}
87}
88
89static void fxam(FPU_REG *st0_ptr, u_char st0tag)
90{
91	int c = 0;
92	switch (st0tag) {
93	case TAG_Empty:
94		c = SW_C3 | SW_C0;
95		break;
96	case TAG_Zero:
97		c = SW_C3;
98		break;
99	case TAG_Valid:
100		c = SW_C2;
101		break;
102	case TAG_Special:
103		switch (FPU_Special(st0_ptr)) {
104		case TW_Denormal:
105			c = SW_C2 | SW_C3;	/* Denormal */
106			break;
107		case TW_NaN:
108			/* We also use NaN for unsupported types. */
109			if ((st0_ptr->sigh & 0x80000000)
110			    && (exponent(st0_ptr) == EXP_OVER))
111				c = SW_C0;
112			break;
113		case TW_Infinity:
114			c = SW_C2 | SW_C0;
115			break;
116		}
117	}
118	if (getsign(st0_ptr) == SIGN_NEG)
119		c |= SW_C1;
120	setcc(c);
121}
122
123static FUNC_ST0 const fp_etc_table[] = {
124	fchs, fabs, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal,
125	ftst_, fxam, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal
126};
127
128void FPU_etc(void)
129{
130	(fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
131}
132