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/* Copyright (c) 2002 Michael Stumpf <mistumpf@de.pepperl-fuchs.com>
Copyright (c) 2006 Dmitry Xmelkov
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
* Neither the name of the copyright holders nor the names of
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE. */
/* $Id: acos.S,v 1.5 2007/01/14 15:05:14 dmix Exp $ */
/* float acos (float x);
The acos() function calculates the arc cosine of x; that is the value
whose cosine is x.
*/
#include "fp32def.h"
#include "asmdef.h"
#define HI40_PI 0x40490FDA /* Pi */
#define LO40_PI 0xA2
ENTRY acos
; save A sign
push rA3
; A = arccos(fabs(A))
andi rA3, 0x7f
rcall _U(__fp_arccos)
; check sign
pop r0
tst r0
brpl 1f
; for negative x: arccos(x) = Pi - arccos(-x)
subi rA3, 0x80
ldi rBE, LO40_PI
ldi rB0, lo8(HI40_PI)
ldi rB1, hi8(HI40_PI)
ldi rB2, hlo8(HI40_PI)
ldi rB3, hhi8(HI40_PI)
rcall _U(__addsf3x)
; round
1: rjmp _U(__fp_round)
ENDFUNC
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