/arch/m68k/fpsp040/satanh.S

https://bitbucket.org/evzijst/gittest
Assembly | 104 lines | 92 code | 12 blank | 0 comment | 1 complexity | e9aeb9238a50ba2f40795390a8dc33af MD5 | raw file
```  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
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
47|
48|	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
49|	The copyright notice above does not evidence any
50|	actual or intended publication of such source code.
51
52|satanh	idnt	2,1 | Motorola 040 Floating Point Software Package
53
54	|section	8
55
56	|xref	t_dz
57	|xref	t_operr
58	|xref	t_frcinx
59	|xref	t_extdnrm
60	|xref	slognp1
61
62	.global	satanhd
63satanhd:
64|--ATANH(X) = X FOR DENORMALIZED X
65
66	bra		t_extdnrm
67
68	.global	satanh
69satanh:
70	movel		(%a0),%d0
71	movew		4(%a0),%d0
72	andil		#0x7FFFFFFF,%d0
73	cmpil		#0x3FFF8000,%d0
74	bges		ATANHBIG
75
76|--THIS IS THE USUAL CASE, |X| < 1
77|--Y = |X|, Z = 2Y/(1-Y), ATANH(X) = SIGN(X) * (1/2) * LOG1P(Z).
78
79	fabsx		(%a0),%fp0	| ...Y = |X|
80	fmovex		%fp0,%fp1
81	fnegx		%fp1		| ...-Y
84	fdivx		%fp1,%fp0		| ...2Y/(1-Y)
85	movel		(%a0),%d0
86	andil		#0x80000000,%d0
87	oril		#0x3F000000,%d0	| ...SIGN(X)*HALF
88	movel		%d0,-(%sp)
89
90	fmovemx	%fp0-%fp0,(%a0)	| ...overwrite input
91	movel		%d1,-(%sp)
92	clrl		%d1
93	bsr		slognp1		| ...LOG1P(Z)
94	fmovel		(%sp)+,%fpcr
95	fmuls		(%sp)+,%fp0
96	bra		t_frcinx
97
98ATANHBIG:
99	fabsx		(%a0),%fp0	| ...|X|
100	fcmps		#0x3F800000,%fp0
101	fbgt		t_operr
102	bra		t_dz
103
104	|end
```