avr-libc
2.1.0
Standard C library for AVR-GCC
AVR Libc Home Page
AVR Libc Development Pages
Main Page
User Manual
Library Reference
FAQ
Example Projects
include
util
parity.h
Go to the documentation of this file.
1
/* Copyright (c) 2002, Marek Michalkiewicz
2
Copyright (c) 2004,2005,2007 Joerg Wunsch
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
11
* Redistributions in binary form must reproduce the above copyright
12
notice, this list of conditions and the following disclaimer in
13
the documentation and/or other materials provided with the
14
distribution.
15
16
* Neither the name of the copyright holders nor the names of
17
contributors may be used to endorse or promote products derived
18
from this software without specific prior written permission.
19
20
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30
POSSIBILITY OF SUCH DAMAGE. */
31
32
/* $Id: parity_8h_source.html,v 1.1.1.7 2022/01/29 09:21:59 joerg_wunsch Exp $ */
33
34
#ifndef _UTIL_PARITY_H_
35
#define _UTIL_PARITY_H_
36
37
/** \file */
38
/** \defgroup util_parity <util/parity.h>: Parity bit generation
39
\code #include <util/parity.h> \endcode
40
41
This header file contains optimized assembler code to calculate
42
the parity bit for a byte.
43
*/
44
/** \def parity_even_bit
45
\ingroup util_parity
46
\returns 1 if \c val has an odd number of bits set. */
47
#define parity_even_bit(val) \
48
(__extension__({ \
49
unsigned char __t; \
50
__asm__ ( \
51
"mov __tmp_reg__,%0" "\n\t" \
52
"swap %0" "\n\t" \
53
"eor %0,__tmp_reg__" "\n\t" \
54
"mov __tmp_reg__,%0" "\n\t" \
55
"lsr %0" "\n\t" \
56
"lsr %0" "\n\t" \
57
"eor %0,__tmp_reg__" \
58
: "=r" (__t) \
59
: "0" ((unsigned char)(val)) \
60
: "r0" \
61
); \
62
(((__t + 1) >> 1) & 1); \
63
}))
64
65
#endif
/* _UTIL_PARITY_H_ */
Generated on Sat Jan 29 2022 00:24:03 for avr-libc by
1.8.14