[PATCH] Add wording to m68k .S files to help clarify license info
[linux-3.10.git] / arch / m68k / fpsp040 / sasin.S
1 |
2 |       sasin.sa 3.3 12/19/90
3 |
4 |       Description: The entry point sAsin computes the inverse sine of
5 |               an input argument; sAsind does the same except for denormalized
6 |               input.
7 |
8 |       Input: Double-extended number X in location pointed to
9 |               by address register a0.
10 |
11 |       Output: The value arcsin(X) returned in floating-point register Fp0.
12 |
13 |       Accuracy and Monotonicity: The returned result is within 3 ulps in
14 |               64 significant bit, i.e. within 0.5001 ulp to 53 bits if the
15 |               result is subsequently rounded to double precision. The
16 |               result is provably monotonic in double precision.
17 |
18 |       Speed: The program sASIN takes approximately 310 cycles.
19 |
20 |       Algorithm:
21 |
22 |       ASIN
23 |       1. If |X| >= 1, go to 3.
24 |
25 |       2. (|X| < 1) Calculate asin(X) by
26 |               z := sqrt( [1-X][1+X] )
27 |               asin(X) = atan( x / z ).
28 |               Exit.
29 |
30 |       3. If |X| > 1, go to 5.
31 |
32 |       4. (|X| = 1) sgn := sign(X), return asin(X) := sgn * Pi/2. Exit.
33 |
34 |       5. (|X| > 1) Generate an invalid operation by 0 * infinity.
35 |               Exit.
36 |
37
38 |               Copyright (C) Motorola, Inc. 1990
39 |                       All Rights Reserved
40 |
41 |       For details on the license for this file, please see the
42 |       file, README, in this same directory.
43
44 |SASIN  idnt    2,1 | Motorola 040 Floating Point Software Package
45
46         |section        8
47
48 PIBY2:  .long 0x3FFF0000,0xC90FDAA2,0x2168C235,0x00000000
49
50         |xref   t_operr
51         |xref   t_frcinx
52         |xref   t_extdnrm
53         |xref   satan
54
55         .global sasind
56 sasind:
57 |--ASIN(X) = X FOR DENORMALIZED X
58
59         bra             t_extdnrm
60
61         .global sasin
62 sasin:
63         fmovex          (%a0),%fp0      | ...LOAD INPUT
64
65         movel           (%a0),%d0
66         movew           4(%a0),%d0
67         andil           #0x7FFFFFFF,%d0
68         cmpil           #0x3FFF8000,%d0
69         bges            asinbig
70
71 |--THIS IS THE USUAL CASE, |X| < 1
72 |--ASIN(X) = ATAN( X / SQRT( (1-X)(1+X) ) )
73
74         fmoves          #0x3F800000,%fp1
75         fsubx           %fp0,%fp1               | ...1-X
76         fmovemx %fp2-%fp2,-(%a7)
77         fmoves          #0x3F800000,%fp2
78         faddx           %fp0,%fp2               | ...1+X
79         fmulx           %fp2,%fp1               | ...(1+X)(1-X)
80         fmovemx (%a7)+,%fp2-%fp2
81         fsqrtx          %fp1            | ...SQRT([1-X][1+X])
82         fdivx           %fp1,%fp0               | ...X/SQRT([1-X][1+X])
83         fmovemx %fp0-%fp0,(%a0)
84         bsr             satan
85         bra             t_frcinx
86
87 asinbig:
88         fabsx           %fp0     | ...|X|
89         fcmps           #0x3F800000,%fp0
90         fbgt            t_operr         |cause an operr exception
91
92 |--|X| = 1, ASIN(X) = +- PI/2.
93
94         fmovex          PIBY2,%fp0
95         movel           (%a0),%d0
96         andil           #0x80000000,%d0 | ...SIGN BIT OF X
97         oril            #0x3F800000,%d0 | ...+-1 IN SGL FORMAT
98         movel           %d0,-(%sp)      | ...push SIGN(X) IN SGL-FMT
99         fmovel          %d1,%FPCR
100         fmuls           (%sp)+,%fp0
101         bra             t_frcinx
102
103         |end