1/* Copyright (c) 2002  Michael Stumpf  <mistumpf@de.pepperl-fuchs.com>
2   Copyright (c) 2006  Dmitry Xmelkov
3   All rights reserved.
4
5   Redistribution and use in source and binary forms, with or without
6   modification, are permitted provided that the following conditions are met:
7
8   * Redistributions of source code must retain the above copyright
9     notice, this list of conditions and the following disclaimer.
10   * Redistributions in binary form must reproduce the above copyright
11     notice, this list of conditions and the following disclaimer in
12     the documentation and/or other materials provided with the
13     distribution.
14   * Neither the name of the copyright holders nor the names of
15     contributors may be used to endorse or promote products derived
16     from this software without specific prior written permission.
17
18   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28   POSSIBILITY OF SUCH DAMAGE. */
29
30/* $Id: fp_trunc.S 2473 2015-04-09 08:10:22Z pitchumani $ */
31
32
33#if !defined(__AVR_TINY__)
34
35#include "fp32def.h"
36#include "asmdef.h"
37
38/* <non_standart> __fp_trunc (float A);
39     This is an internal functions. __fp_trunc() splits argument and
40     truncates to zero direction. It is intended as first part of work
41     in floor(), ceil(), trunc() functions.
42
43   Return:
44     T	   - sign bit
45     C	   - set if A is not finite (A is splited)
46     rA3   - exponent:
47    		0	-  A is zero
48		1..126	-  fabs(A) < 1
49		127..	-  fabs(A) >= 1
50     rA2.rA1.rA0  - mantissa (with hidden bit)
51     rAE	  - flag of nonzero fraction
52
53   Notes:
54     * Return value is not a float value. Function, like __fp_mpack(),
55     is needed to merge a float.
56     * In case of 'fabs(A) < 1' rA2.rA1.rA0 and rAE are random.
57 */
58
59ENTRY __fp_trunc
60	XCALL	_U(__fp_splitA)
61	brcs	9f
62  ; A is finite
63	ldi	rAE, 126
64	cp	rAE, rA3
65	brsh	9f
66  ; fabs (A) >= 1.0
67	clr	rAE
683:	cpi	rA3, 127+23-7
69	brsh	5f		; shift by 1..7 positions or no shift
70  ; quick shift by 8
71	cp	r1, rA0
72	adc	rAE, r1
73	mov	rA0, rA1
74	mov	rA1, rA2
75	clr	rA2
76	subi	rA3, -8
77	rjmp	3b
78  ; slow shift
794:	lsr	rA2
80	ror	rA1
81	ror	rA0
82	adc	rAE, r1
83	inc	rA3
845:	cpi	rA3, 127+23
85	brlo	4b
869:	ret			; C == 0
87ENDFUNC
88
89#endif /* !defined(__AVR_TINY__) */
90