m68k: Implement ndelay() based on the existing udelay() logic
[linux-3.10.git] / arch / m68k / fpsp040 / scosh.S
1 |
2 |       scosh.sa 3.1 12/10/90
3 |
4 |       The entry point sCosh computes the hyperbolic cosine of
5 |       an input argument; sCoshd 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 cosh(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 sCOSH takes approximately 250 cycles.
19 |
20 |       Algorithm:
21 |
22 |       COSH
23 |       1. If |X| > 16380 log2, go to 3.
24 |
25 |       2. (|X| <= 16380 log2) Cosh(X) is obtained by the formulae
26 |               y = |X|, z = exp(Y), and
27 |               cosh(X) = (1/2)*( z + 1/z ).
28 |               Exit.
29 |
30 |       3. (|X| > 16380 log2). If |X| > 16480 log2, go to 5.
31 |
32 |       4. (16380 log2 < |X| <= 16480 log2)
33 |               cosh(X) = sign(X) * exp(|X|)/2.
34 |               However, invoking exp(|X|) may cause premature overflow.
35 |               Thus, we calculate sinh(X) as follows:
36 |               Y       := |X|
37 |               Fact    :=      2**(16380)
38 |               Y'      := Y - 16381 log2
39 |               cosh(X) := Fact * exp(Y').
40 |               Exit.
41 |
42 |       5. (|X| > 16480 log2) sinh(X) must overflow. Return
43 |               Huge*Huge to generate overflow and an infinity with
44 |               the appropriate sign. Huge is the largest finite number in
45 |               extended format. Exit.
46 |
47 |
48
49 |               Copyright (C) Motorola, Inc. 1990
50 |                       All Rights Reserved
51 |
52 |       For details on the license for this file, please see the
53 |       file, README, in this same directory.
54
55 |SCOSH  idnt    2,1 | Motorola 040 Floating Point Software Package
56
57         |section        8
58
59         |xref   t_ovfl
60         |xref   t_frcinx
61         |xref   setox
62
63 T1:     .long 0x40C62D38,0xD3D64634 | ... 16381 LOG2 LEAD
64 T2:     .long 0x3D6F90AE,0xB1E75CC7 | ... 16381 LOG2 TRAIL
65
66 TWO16380: .long 0x7FFB0000,0x80000000,0x00000000,0x00000000
67
68         .global scoshd
69 scoshd:
70 |--COSH(X) = 1 FOR DENORMALIZED X
71
72         fmoves          #0x3F800000,%fp0
73
74         fmovel          %d1,%FPCR
75         fadds           #0x00800000,%fp0
76         bra             t_frcinx
77
78         .global scosh
79 scosh:
80         fmovex          (%a0),%fp0      | ...LOAD INPUT
81
82         movel           (%a0),%d0
83         movew           4(%a0),%d0
84         andil           #0x7FFFFFFF,%d0
85         cmpil           #0x400CB167,%d0
86         bgts            COSHBIG
87
88 |--THIS IS THE USUAL CASE, |X| < 16380 LOG2
89 |--COSH(X) = (1/2) * ( EXP(X) + 1/EXP(X) )
90
91         fabsx           %fp0            | ...|X|
92
93         movel           %d1,-(%sp)
94         clrl            %d1
95         fmovemx %fp0-%fp0,(%a0) |pass parameter to setox
96         bsr             setox           | ...FP0 IS EXP(|X|)
97         fmuls           #0x3F000000,%fp0        | ...(1/2)EXP(|X|)
98         movel           (%sp)+,%d1
99
100         fmoves          #0x3E800000,%fp1        | ...(1/4)
101         fdivx           %fp0,%fp1               | ...1/(2 EXP(|X|))
102
103         fmovel          %d1,%FPCR
104         faddx           %fp1,%fp0
105
106         bra             t_frcinx
107
108 COSHBIG:
109         cmpil           #0x400CB2B3,%d0
110         bgts            COSHHUGE
111
112         fabsx           %fp0
113         fsubd           T1(%pc),%fp0            | ...(|X|-16381LOG2_LEAD)
114         fsubd           T2(%pc),%fp0            | ...|X| - 16381 LOG2, ACCURATE
115
116         movel           %d1,-(%sp)
117         clrl            %d1
118         fmovemx %fp0-%fp0,(%a0)
119         bsr             setox
120         fmovel          (%sp)+,%fpcr
121
122         fmulx           TWO16380(%pc),%fp0
123         bra             t_frcinx
124
125 COSHHUGE:
126         fmovel          #0,%fpsr                |clr N bit if set by source
127         bclrb           #7,(%a0)                |always return positive value
128         fmovemx (%a0),%fp0-%fp0
129         bra             t_ovfl
130
131         |end