1/*---------------------------------------------------------------------------+
2 |  fpu_etc.c                                                                |
3 |                                                                           |
4 | Implement a few FPU instructions.                                         |
5 |                                                                           |
6 | Copyright (C) 1992,1993,1994,1997                                         |
7 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
8 |                       Australia.  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 "reg_constant.h"
18
19static void fchs(FPU_REG *st0_ptr, u_char st0tag)
20{
21	if (st0tag ^ TAG_Empty) {
22		signbyte(st0_ptr) ^= SIGN_NEG;
23		clear_C1();
24	} else
25		FPU_stack_underflow();
26}
27
28static void fabs(FPU_REG *st0_ptr, u_char st0tag)
29{
30	if (st0tag ^ TAG_Empty) {
31		setpositive(st0_ptr);
32		clear_C1();
33	} else
34		FPU_stack_underflow();
35}
36
37static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
38{
39	switch (st0tag) {
40	case TAG_Zero:
41		setcc(SW_C3);
42		break;
43	case TAG_Valid:
44		if (getsign(st0_ptr) == SIGN_POS)
45			setcc(0);
46		else
47			setcc(SW_C0);
48		break;
49	case TAG_Special:
50		switch (FPU_Special(st0_ptr)) {
51		case TW_Denormal:
52			if (getsign(st0_ptr) == SIGN_POS)
53				setcc(0);
54			else
55				setcc(SW_C0);
56			if (denormal_operand() < 0) {
57#ifdef PECULIAR_486
58				/* This is weird! */
59				if (getsign(st0_ptr) == SIGN_POS)
60					setcc(SW_C3);
61#endif /* PECULIAR_486 */
62				return;
63			}
64			break;
65		case TW_NaN:
66			setcc(SW_C0 | SW_C2 | SW_C3);	/* Operand is not comparable */
67			EXCEPTION(EX_Invalid);
68			break;
69		case TW_Infinity:
70			if (getsign(st0_ptr) == SIGN_POS)
71				setcc(0);
72			else
73				setcc(SW_C0);
74			break;
75		default:
76			setcc(SW_C0 | SW_C2 | SW_C3);	/* Operand is not comparable */
77			EXCEPTION(EX_INTERNAL | 0x14);
78			break;
79		}
80		break;
81	case TAG_Empty:
82		setcc(SW_C0 | SW_C2 | SW_C3);
83		EXCEPTION(EX_StackUnder);
84		break;
85	}
86}
87
88static void fxam(FPU_REG *st0_ptr, u_char st0tag)
89{
90	int c = 0;
91	switch (st0tag) {
92	case TAG_Empty:
93		c = SW_C3 | SW_C0;
94		break;
95	case TAG_Zero:
96		c = SW_C3;
97		break;
98	case TAG_Valid:
99		c = SW_C2;
100		break;
101	case TAG_Special:
102		switch (FPU_Special(st0_ptr)) {
103		case TW_Denormal:
104			c = SW_C2 | SW_C3;	/* Denormal */
105			break;
106		case TW_NaN:
107			/* We also use NaN for unsupported types. */
108			if ((st0_ptr->sigh & 0x80000000)
109			    && (exponent(st0_ptr) == EXP_OVER))
110				c = SW_C0;
111			break;
112		case TW_Infinity:
113			c = SW_C2 | SW_C0;
114			break;
115		}
116	}
117	if (getsign(st0_ptr) == SIGN_NEG)
118		c |= SW_C1;
119	setcc(c);
120}
121
122static FUNC_ST0 const fp_etc_table[] = {
123	fchs, fabs, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal,
124	ftst_, fxam, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal
125};
126
127void FPU_etc(void)
128{
129	(fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
130}
131