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
fchs(FPU_REG * st0_ptr,u_char st0tag)19 static 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
fabs(FPU_REG * st0_ptr,u_char st0tag)28 static 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
ftst_(FPU_REG * st0_ptr,u_char st0tag)37 static 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
fxam(FPU_REG * st0_ptr,u_char st0tag)88 static 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
122 static 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
FPU_etc(void)127 void FPU_etc(void)
128 {
129 (fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
130 }
131