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/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
 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 48|	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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
 82	faddx		%fp0,%fp0		| ...2Y
 83	fadds		#0x3F800000,%fp1	| ...1-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