1 // SPDX-License-Identifier: GPL-2.0 1
2 /*--------------------------------------------
3 | reg_mul.c
4 |
5 | Multiply one FPU_REG by another, put the re
6 |
7 | Copyright (C) 1992,1993,1997
8 | W. Metzenthen, 22 Parker S
9 | E-mail billm@suburbia.ne
10 |
11 | Returns the tag of the result if no excepti
12 |
13 +--------------------------------------------
14
15 /*--------------------------------------------
16 | The destination may be any FPU_REG, includi
17 +--------------------------------------------
18
19 #include "fpu_emu.h"
20 #include "exception.h"
21 #include "reg_constant.h"
22 #include "fpu_system.h"
23
24 /*
25 Multiply two registers to give a register re
26 The sources are st(deststnr) and (b,tagb,sig
27 The destination is st(deststnr).
28 */
29 /* This routine must be called with non-empty
30 int FPU_mul(FPU_REG const *b, u_char tagb, int
31 {
32 FPU_REG *a = &st(deststnr);
33 FPU_REG *dest = a;
34 u_char taga = FPU_gettagi(deststnr);
35 u_char saved_sign = getsign(dest);
36 u_char sign = (getsign(a) ^ getsign(b)
37 int tag;
38
39 if (!(taga | tagb)) {
40 /* Both regs Valid, this shoul
41
42 tag =
43 FPU_u_mul(a, b, dest, cont
44 exponent(a) + ex
45 if (tag < 0) {
46 setsign(dest, saved_si
47 return tag;
48 }
49 FPU_settagi(deststnr, tag);
50 return tag;
51 }
52
53 if (taga == TAG_Special)
54 taga = FPU_Special(a);
55 if (tagb == TAG_Special)
56 tagb = FPU_Special(b);
57
58 if (((taga == TAG_Valid) && (tagb == T
59 || ((taga == TW_Denormal) && (tagb
60 || ((taga == TW_Denormal) && (tagb
61 FPU_REG x, y;
62 if (denormal_operand() < 0)
63 return FPU_Exception;
64
65 FPU_to_exp16(a, &x);
66 FPU_to_exp16(b, &y);
67 tag = FPU_u_mul(&x, &y, dest,
68 exponent16(&x)
69 if (tag < 0) {
70 setsign(dest, saved_si
71 return tag;
72 }
73 FPU_settagi(deststnr, tag);
74 return tag;
75 } else if ((taga <= TW_Denormal) && (t
76 if (((tagb == TW_Denormal) ||
77 && (denormal_operand() < 0
78 return FPU_Exception;
79
80 /* Must have either both argum
81 one valid and the other zer
82 The result is therefore zer
83 FPU_copy_to_regi(&CONST_Z, TAG
84 /* The 80486 book says that th
85 80486 behaves this way.
86 IEEE-754 apparently says it
87 setsign(dest, sign);
88 return TAG_Zero;
89 }
90 /* Must have infinities, NaNs, etc */
91 else if ((taga == TW_NaN) || (tagb ==
92 return real_2op_NaN(b, tagb, d
93 } else if (((taga == TW_Infinity) && (
94 || ((tagb == TW_Infinity) &
95 return arith_invalid(deststnr)
96 } else if (((taga == TW_Denormal) || (
97 && (denormal_operand() < 0)
98 return FPU_Exception;
99 } else if (taga == TW_Infinity) {
100 FPU_copy_to_regi(a, TAG_Specia
101 setsign(dest, sign);
102 return TAG_Special;
103 } else if (tagb == TW_Infinity) {
104 FPU_copy_to_regi(b, TAG_Specia
105 setsign(dest, sign);
106 return TAG_Special;
107 }
108 #ifdef PARANOID
109 else {
110 EXCEPTION(EX_INTERNAL | 0x102)
111 return FPU_Exception;
112 }
113 #endif /* PARANOID */
114
115 return 0;
116 }
117
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