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_mintl.S 1173 2007-01-14 15:04:40Z dmix $ */
31
32#include "fp32def.h"
33#include "asmdef.h"
34
35/* float __fp_mintl (<non-standart>);
36     Normalize value by shifting to left (only left) and merge parts of
37     float value. Mainly, this function is intended for integral values,
38     as a last stage of functions floor(), floatsisf(). Its functionality
39     is very restricted: no subnormals, no rounding, no Inf/NaN.
40
41   Input:
42     T			- sign
43     rA3		- exponent
44     rA2.rA1.rA0	- mantissa
45   Output:
46     rA3.rA2.rA1.rA0	- float value
47
48   Notes:
49     * Underflow of exponent is NOT checked: result would undefined.
50     * In zero case mantissa must be 0.
51     * Sign bit is set in any case. -0.0 is possible.
52     * Shifts are optimized for speed.
53 */
54
55ENTRY __fp_mintl
56
57	tst	rA2
58	brne	.L_bm
59	tst	rA1
60	breq	1f
61  ; mantissa is 0x00XXXX
62	subi	rA3, 8
63	or	rA2, rA1	; to obtain N flag (rA2 was 0)
64	mov	rA1, rA0
65	rjmp	.L_a0
66  ; mantissa is 0x0000XX
671:	tst	rA0
68	brne	2f
69	clr	rA3
70	rjmp	.L_sign
71  ; low mantissa byte != 0
722:	subi	rA3, 16
73	or	rA2, rA0	; to obtain N flag (rA2 was 0)
74	ldi	rA1, 0
75.L_a0:	ldi	rA0, 0
76.L_bm:	brmi	.L_pack		; N flag is from rA2
77  ; shift to left (1..7 positions)
78.Loop:	dec	rA3
79	lsl	rA0
80	rol	rA1
81	rol	rA2
82	brpl	.Loop
83.L_pack:
84	lsl	rA2
85	lsr	rA3
86	ror	rA2
87.L_sign:
88	bld	rA3, 7		; sign
89	ret
90ENDFUNC
91