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94 lines
2.1 KiB
94 lines
2.1 KiB
/*
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* |-----------------------------------------------------------|
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* | Copyright (c) 1991, 1990 MIPS Computer Systems, Inc. |
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* | All Rights Reserved |
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* |-----------------------------------------------------------|
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* | Restricted Rights Legend |
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* | Use, duplication, or disclosure by the Government is |
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* | subject to restrictions as set forth in |
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* | subparagraph (c)(1)(ii) of the Rights in Technical |
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* | Data and Computer Software Clause of DFARS 252.227-7013. |
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* | MIPS Computer Systems, Inc. |
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* | 950 DeGuigne Avenue |
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* | Sunnyvale, California 94088-3650, USA |
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* |-----------------------------------------------------------|
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*/
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/* $Header: ftan.s,v 3000.5.1.2 91/05/31 14:44:46 bettina Exp $ */
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/* Algorithm from Cody and Waite. */
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#include <kxmips.h>
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#define _RM_MASK 3
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#define pio4 0.78539816339744830961
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#define pio2 1.57079632679489661923132
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#define ymax 6433.0
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#define twoopi 0.63661977236758134308
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#define p0 -0.958017723e-1
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#define q1 0.971685835e-2
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#define q0 -0.429135777e+0
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#define one 1.0
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.text
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.globl ftan
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.globl tanf
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.ent ftan
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.aent tanf
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ftan:
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tanf:
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.frame sp, 0, ra
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.prologue 0
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li.s $f8, pio4
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abs.s $f0, $f12
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c.olt.s $f0, $f8
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cfc1 t1, $31
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cvt.d.s $f14, $f12
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li t0, 0
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bc1t ftan0
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and t2, t1, ~_RM_MASK
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li.s $f8, ymax
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c.olt.s $f0, $f8
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li.s $f8, twoopi
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bc1f ftan2
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mul.s $f2, $f12, $f8
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// convert to integer using round-to-nearest
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ctc1 t2, $31
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cvt.w.s $f2
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mfc1 t0, $f2
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and t0, 1
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// argument reduction
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cvt.d.w $f2
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li.d $f6, pio2
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mul.d $f2, $f6
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sub.d $f14, $f2
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ftan0:
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// rational approximation
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mul.d $f2, $f14, $f14
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li.d $f8, q1
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li.d $f6, p0
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mul.d $f10, $f2, $f8
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li.d $f8, q0
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mul.d $f4, $f2, $f6
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add.d $f10, $f8
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mul.d $f10, $f2
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li.d $f8, one
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mul.d $f4, $f14
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add.d $f10, $f8
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add.d $f14, $f4
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ctc1 t1, $31
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bne t0, 0, ftan1
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div.d $f0, $f14, $f10
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cvt.s.d $f0
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j ra
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ftan1: div.d $f0, $f10, $f14
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neg.d $f0
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cvt.s.d $f0
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j ra
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ftan2:
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li.s $f0, 0.0
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div.s $f0, $f0
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j ra
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.end ftan
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