1 |
2 | sgetem.sa 3.1 12/10/90
3 |
4 | The entry point sGETEXP returns the ex
5 | of the input argument. The exponent b
6 | and the exponent value is returned as
7 | precision number in fp0. sGETEXPD han
8 | numbers.
9 |
10 | The entry point sGETMAN extracts the m
11 | input argument. The mantissa is conve
12 | extended precision number and returned
13 | range of the result is [1.0 - 2.0).
14 |
15 |
16 | Input: Double-extended number X in th
17 | the floating-point save stack.
18 |
19 | Output: The functions return exp(X) or
20 |
21 | Modified: fp0.
22 |
23 |
24 | Copyright (C) Motorola, Inc. 1
25 | All Rights Reserved
26 |
27 | For details on the license for this fi
28 | file, README, in this same directory.
29
30 |SGETEM idnt 2,1 | Motorola 040 Floating Po
31
32 |section 8
33
34 #include "fpsp.h"
35
36 |xref nrm_set
37
38 |
39 | This entry point is used by the unimplemente
40 | handler. It points a0 to the input operand.
41 |
42 |
43 |
44 | SGETEXP
45 |
46
47 .global sgetexp
48 sgetexp:
49 movew LOCAL_EX(%a0),%d0 |get t
50 bclrl #15,%d0 |clear the sig
51 subw #0x3fff,%d0 |subtract off
52 fmovew %d0,%fp0 |move
53 rts
54
55 .global sgetexpd
56 sgetexpd:
57 bclrb #sign_bit,LOCAL_EX(%a0)
58 bsr nrm_set |normalize (ex
59 movew LOCAL_EX(%a0),%d0 |load
60 subw #0x3fff,%d0 |subtract off
61 fmovew %d0,%fp0 |move
62 rts
63 |
64 |
65 | This entry point is used by the unimplemente
66 | handler. It points a0 to the input operand.
67 |
68 |
69 |
70 | SGETMAN
71 |
72 |
73 | For normalized numbers, leave the mantissa a
74 | with an exponent of +/- $3fff.
75 |
76 .global sgetman
77 sgetman:
78 movel USER_FPCR(%a6),%d0
79 andil #0xffffff00,%d0 |clear roundin
80 fmovel %d0,%fpcr |this
81 movew LOCAL_EX(%a0),%d0 |get t
82 orw #0x7fff,%d0 |clear old exp
83 bclrl #14,%d0 |make it the n
84 movew %d0,LOCAL_EX(%a0) |move
85 fmovex (%a0),%fp0 |put new value
86 rts
87
88 |
89 | For denormalized numbers, shift the mantissa
90 | then load the exponent with +/1 $3fff.
91 |
92 .global sgetmand
93 sgetmand:
94 movel LOCAL_HI(%a0),%d0 |load
95 movel LOCAL_LO(%a0),%d1 |load
96 bsr shft |shift mantiss
97 movel %d0,LOCAL_HI(%a0) |put m
98 movel %d1,LOCAL_LO(%a0) |put l
99 bras sgetman
100
101 |
102 | SHFT
103 |
104 | Shifts the mantissa bits until msbit i
105 | input:
106 | ms mantissa part in d0
107 | ls mantissa part in d1
108 | output:
109 | shifted bits in d0 and d1
110 shft:
111 tstl %d0 |if any bits s
112 bnes upper |then branch
113 | ;else no bits
114 tstl %d1 |test if any b
115 bnes cont |if set then c
116 bras shft_end |else return
117 cont:
118 movel %d3,-(%a7) |save d3
119 exg %d0,%d1 |shift ls mant
120 bfffo %d0{#0:#32},%d3 |find first 1
121 lsll %d3,%d0 |shift first 1
122 movel (%a7)+,%d3 |restore d3
123 bras shft_end
124 upper:
125
126 moveml %d3/%d5/%d6,-(%a7) |save
127 bfffo %d0{#0:#32},%d3 |find first 1
128 lsll %d3,%d0 |shift ms mant
129 movel %d1,%d6 |save ls mant
130 lsll %d3,%d1 |shift ls mant
131 movel #32,%d5
132 subl %d3,%d5 |sub 32 from s
133 lsrl %d5,%d6 |shift off all
134 | ;be shifted in
135 orl %d6,%d0 |shift the ls
136 moveml (%a7)+,%d3/%d5/%d6 |resto
137 shft_end:
138 rts
139
140 |end
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