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
20 static 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
29 static 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
38 static 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
89 static 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
123 static 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
128 void FPU_etc(void)
129 {
130 (fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
131 }