Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6
[linux-2.6] / arch / x86 / math-emu / fpu_etc.c
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
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
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
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
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
127 void FPU_etc(void)
128 {
129         (fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
130 }