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8daa8d7c DF |
1 | # |
2 | # Copyright (c) 1980 Regents of the University of California. | |
3 | # All rights reserved. The Berkeley software License Agreement | |
4 | # specifies the terms and conditions for redistribution. | |
5 | # | |
6 | # @(#)atan.s 5.1 (Berkeley) %G% | |
7 | # | |
8 | # | |
87380bc9 DF |
9 | # double atan(arg1); -pi/2 < atan < pi/2 |
10 | #double atan2(arg1,arg2); -pi< atan2<pi | |
11 | #double arg1,arg2 | |
12 | #method: range reduction to [sqrt(2)-1,sqrt(2)+1] | |
13 | # followed by Hart&Cheney ARCTN 5076 D=17.55 | |
14 | # J. F. Jarvis August 8, 1978 | |
15 | .globl _atan | |
16 | .globl _atan2 | |
17 | .text | |
18 | .align 1 | |
19 | _atan: | |
20 | .word 0x03c0 | |
21 | bispsw $0xe0 | |
22 | movd 4(ap),r0 | |
23 | jgtr a1 | |
24 | mnegd r0,r0 # atan(arg1), arg1<0 | |
25 | bsbb satan | |
26 | mnegd r0,r0 | |
27 | ret | |
28 | a1: bsbb satan # atan(arg1), arg1>=0 | |
29 | ret | |
30 | # | |
31 | .align 1 | |
32 | _atan2: | |
33 | .word 0x03c0 | |
34 | bispsw $0xe0 | |
35 | movd 4(ap),r0 # atan(arg1/arg2) | |
36 | movd 12(ap),r2 | |
37 | addd3 r0,r2,r4 | |
38 | cmpd r0,r4 | |
39 | jneq b1 | |
40 | tstd r0 | |
41 | jgeq b2 | |
42 | mnegd pio2,r0 | |
43 | ret | |
44 | b2: movd pio2,r0 | |
45 | ret | |
46 | # | |
47 | b1: tstd r2 | |
48 | jgeq b3 | |
49 | divd2 r2,r0 | |
50 | jleq b4 | |
51 | bsbb satan # arg1<0, arg2<0 | |
52 | subd2 pi,r0 | |
53 | ret | |
54 | b4: mnegd r0,r0 # arg1>0, arg2<0 | |
55 | bsbb satan | |
56 | subd3 r0,pi,r0 | |
57 | ret | |
58 | # | |
59 | b3: divd2 r2,r0 | |
60 | jleq b5 | |
61 | bsbb satan # arg1>0, arg2>0 | |
62 | ret | |
63 | b5: mnegd r0,r0 # arg1<0, arg2>0 | |
64 | bsbb satan | |
65 | mnegd r0,r0 | |
66 | ret | |
67 | # | |
68 | .globl satan | |
69 | satan: # range reduction on positive arg(r0) | |
70 | cmpd r0,sq2m1 | |
71 | jgeq c1 | |
72 | bsbb xatan | |
73 | rsb | |
74 | c1: cmpd r0,sq2p1 | |
75 | jleq c2 | |
76 | divd3 r0,$0d1.0e+0,r0 | |
77 | bsbb xatan | |
78 | subd3 r0,pio2,r0 | |
79 | rsb | |
80 | c2: addd3 $0d1.0e+0,r0,r2 | |
81 | subd2 $0d1.0e+0,r0 | |
82 | divd2 r2,r0 | |
83 | bsbb xatan | |
84 | addd2 pio4,r0 | |
85 | rsb | |
86 | # | |
87 | xatan: # compute arctan(r0) for:sqrt(2)-1<r0<sqrt(2)+1 | |
88 | # Hart&Cheney ARCTN 5076 is evaluated | |
89 | movd r0,r8 | |
90 | muld3 r0,r0,r6 | |
91 | polyd r6,$4,pcoef | |
92 | muld2 r0,r8 | |
93 | polyd r6,$4,qcoef | |
94 | divd3 r0,r8,r0 | |
95 | rsb | |
96 | .data | |
97 | .align 2 | |
98 | pcoef: | |
99 | .double 0d0.1589740288482307048e+0 | |
100 | .double 0d0.66605790170092626575e+1 | |
101 | .double 0d0.40969264832102256374e+2 | |
102 | .double 0d0.77477687719204208616e+2 | |
103 | .double 0d0.44541340059290680319e+2 | |
104 | qcoef: | |
105 | .double 0d1.0e+0 | |
106 | .double 0d0.15503977551421987525e+2 | |
107 | .double 0d0.62835930511032376833e+2 | |
108 | .double 0d0.92324801072300974840e+2 | |
109 | .double 0d0.44541340059290680444e+2 | |
110 | pio4: .double 0d0.78539816339744830961e+0 | |
111 | pio2: .double 0d1.57079632679489661923e+0 | |
112 | sq2p1: .double 0d2.41421356237309504880e+0 | |
113 | sq2m1: .double 0d0.41421356237309504880e+0 | |
114 | pi: .double 0d3.14159265358979323846e+0 |