m68k: Implement ndelay() based on the existing udelay() logic
[linux-3.10.git] / arch / m68k / fpsp040 / satanh.S
1 |
2 |       satanh.sa 3.3 12/19/90
3 |
4 |       The entry point satanh computes the inverse
5 |       hyperbolic tangent of
6 |       an input argument; satanhd does the same except for denormalized
7 |       input.
8 |
9 |       Input: Double-extended number X in location pointed to
10 |               by address register a0.
11 |
12 |       Output: The value arctanh(X) returned in floating-point register Fp0.
13 |
14 |       Accuracy and Monotonicity: The returned result is within 3 ulps in
15 |               64 significant bit, i.e. within 0.5001 ulp to 53 bits if the
16 |               result is subsequently rounded to double precision. The
17 |               result is provably monotonic in double precision.
18 |
19 |       Speed: The program satanh takes approximately 270 cycles.
20 |
21 |       Algorithm:
22 |
23 |       ATANH
24 |       1. If |X| >= 1, go to 3.
25 |
26 |       2. (|X| < 1) Calculate atanh(X) by
27 |               sgn := sign(X)
28 |               y := |X|
29 |               z := 2y/(1-y)
30 |               atanh(X) := sgn * (1/2) * logp1(z)
31 |               Exit.
32 |
33 |       3. If |X| > 1, go to 5.
34 |
35 |       4. (|X| = 1) Generate infinity with an appropriate sign and
36 |               divide-by-zero by
37 |               sgn := sign(X)
38 |               atan(X) := sgn / (+0).
39 |               Exit.
40 |
41 |       5. (|X| > 1) Generate an invalid operation by 0 * infinity.
42 |               Exit.
43 |
44
45 |               Copyright (C) Motorola, Inc. 1990
46 |                       All Rights Reserved
47 |
48 |       For details on the license for this file, please see the
49 |       file, README, in this same directory.
50
51 |satanh idnt    2,1 | Motorola 040 Floating Point Software Package
52
53         |section        8
54
55         |xref   t_dz
56         |xref   t_operr
57         |xref   t_frcinx
58         |xref   t_extdnrm
59         |xref   slognp1
60
61         .global satanhd
62 satanhd:
63 |--ATANH(X) = X FOR DENORMALIZED X
64
65         bra             t_extdnrm
66
67         .global satanh
68 satanh:
69         movel           (%a0),%d0
70         movew           4(%a0),%d0
71         andil           #0x7FFFFFFF,%d0
72         cmpil           #0x3FFF8000,%d0
73         bges            ATANHBIG
74
75 |--THIS IS THE USUAL CASE, |X| < 1
76 |--Y = |X|, Z = 2Y/(1-Y), ATANH(X) = SIGN(X) * (1/2) * LOG1P(Z).
77
78         fabsx           (%a0),%fp0      | ...Y = |X|
79         fmovex          %fp0,%fp1
80         fnegx           %fp1            | ...-Y
81         faddx           %fp0,%fp0               | ...2Y
82         fadds           #0x3F800000,%fp1        | ...1-Y
83         fdivx           %fp1,%fp0               | ...2Y/(1-Y)
84         movel           (%a0),%d0
85         andil           #0x80000000,%d0
86         oril            #0x3F000000,%d0 | ...SIGN(X)*HALF
87         movel           %d0,-(%sp)
88
89         fmovemx %fp0-%fp0,(%a0) | ...overwrite input
90         movel           %d1,-(%sp)
91         clrl            %d1
92         bsr             slognp1         | ...LOG1P(Z)
93         fmovel          (%sp)+,%fpcr
94         fmuls           (%sp)+,%fp0
95         bra             t_frcinx
96
97 ATANHBIG:
98         fabsx           (%a0),%fp0      | ...|X|
99         fcmps           #0x3F800000,%fp0
100         fbgt            t_operr
101         bra             t_dz
102
103         |end