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/*
libffm - Free, pretty fast replacement for some math (libm) routines
on Linux/AXP, optimized for the 21164
Copyright (C) 1998 Joachim Wesner <joachim.wesner@frankfurt.netsurf.de>
and Kazushige Goto <goto@statabo.rim.or.jp>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library (see file COPYING.LIB); if not, write
to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge,
MA 02139, USA.
*/
/*
Fast atan approximation including range reduction by Joachim Wesner,
<joachim.wesner@frankfurt.netsurf.de>, see also mc 8/1991 p. 78-93.
Done in June/July 1998.
No special handling of illegal arguments or NANs, yet !!!
*/
/*
improved and modified by Kazushige Goto <goto@statabo.rim.or.jp>
*/
.set noreorder
.set noat
#ifdef __ELF__
.section .rodata
#else
.rdata
#endif
.align 5
.type K,@object
K:
.t_floating 2.67949192431122695801e-1
.t_floating 1.73205080756887741522e0
.t_floating 5.77350269189625842081e-1
.t_floating 1.00000000000000000000e0
.t_floating 3.73205080756887719318e0
.t_floating 1.57079632679489655800e0
.t_floating 5.23598775598298815659e-1
.t_floating 1.04719755119659763132e0
.t_floating 4.43895157186999997356e-2
.t_floating 7.67936869066000032946e-2
.t_floating 1.11110978980510477498e-1
.t_floating 1.99999999987294480031e-1
.t_floating -6.48319351030299945160e-2
.t_floating -9.09037114191073997160e-2
.t_floating -1.42857141028255446580e-1
.t_floating -3.33333333333299286494e-1
.text
.align 5
.globl atan
.ent atan
atan:
fabs $f16, $f17
ldgp $29,.-atan($27)
lda $1,K
.frame $30,0,$26,0
#ifdef PROF
lda $28, _mcount
jsr $28, ($28), _mcount
unop
unop
#endif
.prologue 1
ldt $f18, 0($1) # K[0]
ldt $f19, 8($1) # K[1]
ldt $f20, 16($1) # K[2]
ldt $f21, 24($1) # K[3]
ldt $f22, 32($1) # K[4]
cmptlt $f18, $f17, $f18
mult $f19, $f17, $f14
lda $3, 40($1) # c_addr = &K[5]
cmptle $f17, $f21, $f13 # $f1 = (xa<=K[3])
ldt $f23, 64($1) # K[8]
mult $f20, $f17, $f12
ldt $f24, 72($1) # K[9]
cmptle $f17, $f22, $f22
ldt $f25, 80($1) # K[10]
fclr $f0 # corr = 0.0
ldt $f26, 88($1) # K[11]
ldt $f27, 96($1) # K[12]
ldt $f28,104($1) # K[13]
ldt $f29,112($1) # K[14]
fbeq $f18, $L6
fneg $f17, $f15 # y7 = -xa
fbeq $f13, $L7
addt $f19,$f17,$f15 # y7 = K[1] + xa
lda $3, 48($1) # c_addr = &K[6]
subt $f14,$f21,$f21 # y5 = y3 - y5
br $31,$L8
$L7:
fbeq $f22,$L8
addt $f20,$f17,$f15 # y7 = K[2] + xa
lda $3, 56($1) # c_addr = &K[7]
subt $f12,$f21,$f21 # y5 = y4 - y5
$L8:
divt $f21,$f15,$f17 # xa = y5/y7
ldt $f0, 0($3) # load corr
.align 4
$L6:
ldt $f30,120($1) # K[15]
mult $f17, $f17, $f10 # y1 = xa * xa
mult $f10, $f10, $f11 # y2 = y1 * y1
mult $f23, $f10, $f23 # r1 = K[8] * y1
mult $f24, $f10, $f24 # r2 = K[9] * y1
mult $f25, $f10, $f25 # r3 = K[10] * y1
mult $f10, $f11, $f12 # y3 = y1 * y2
mult $f11, $f11, $f13 # y4 = y2 * y2
addt $f23, $f27, $f23 # r1 = r1 + K[12]
addt $f24, $f28, $f24 # r2 = r2 + K[13]
mult $f26, $f10, $f26 # r4 = K[11] * y1
addt $f25, $f29, $f25 # r3 = r3 + K[14]
mult $f11, $f12, $f14 # y5 = y3 * y2
mult $f12, $f13, $f15 # y7 = y4 * y3
addt $f26, $f30, $f26 # r4 = r4 + K[15]
mult $f25, $f12, $f25 # r3 = r3 * y3
mult $f24, $f14, $f24 # r2 = r2 * y5
mult $f23, $f15, $f23 # r1 = r1 * y7
mult $f26, $f10, $f26 # r4 = r4 * y1
addt $f23, $f24, $f23 # r1 = r1 + r2
addt $f25, $f26, $f25 # r3 = r3 + r4
addt $f23, $f25, $f23 # r1 = r1 + r3
mult $f23, $f17, $f23 # r1 = r1 * xa
addt $f23, $f17, $f23 # r1 = r1 + xa
addt $f23, $f0, $f0 # r1 = r1 + corr
fblt $f16, $L12
ret $31,($26),1
$L12:
fneg $f0, $f0
ret $31,($26),1
.end atan
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