Sat Aug 6 00:39:32 2011

Asterisk developer's documentation


unaligned.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief Handle unaligned data access
00021  */
00022 
00023 #ifndef _ASTERISK_UNALIGNED_H
00024 #define _ASTERISK_UNALIGNED_H
00025 
00026 #if defined(__cplusplus) || defined(c_plusplus)
00027 extern "C" {
00028 #endif
00029 
00030 #ifdef __GNUC__
00031 /* If we just tell GCC what's going on, we can trust it to behave optimally */
00032 static inline unsigned int get_unaligned_uint32(void *p)
00033 {
00034    struct { unsigned int d; } __attribute__((packed)) *pp = (void *)p;
00035 
00036    return pp->d;
00037 }
00038 static inline unsigned short get_unaligned_uint16(void *p)
00039 {
00040    struct { unsigned short d; } __attribute__((packed)) *pp = (void *)p;
00041 
00042    return pp->d;
00043 }
00044 
00045 static inline void put_unaligned_uint32(void *p, unsigned int datum)
00046 {
00047    struct { unsigned int d; } __attribute__((packed)) *pp = (void *)p;
00048 
00049    pp->d = datum;
00050 }
00051 
00052 static inline void put_unaligned_uint16(void *p, unsigned short datum)
00053 {
00054    struct { unsigned short d; } __attribute__((packed)) *pp = (void *)p;
00055 
00056    pp->d = datum;
00057 }
00058 #elif defined(SOLARIS) && defined(__sparc__)
00059 static inline unsigned int get_unaligned_uint32(void *p)
00060 {
00061    unsigned char *cp = p;
00062 
00063    return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | cp[3];
00064 }
00065 
00066 static inline unsigned short get_unaligned_uint16(void *p)
00067 {
00068    unsigned char *cp = p;
00069 
00070    return (cp[0] << 8) | cp[1] ;
00071 }
00072 
00073 static inline void put_unaligned_uint32(void *p, unsigned int datum)
00074 {
00075    unsigned char *cp = p;
00076 
00077    cp[0] = datum >> 24;
00078    cp[1] = datum >> 16;
00079    cp[2] = datum >> 8;
00080    cp[3] = datum;
00081 }
00082 
00083 static inline void put_unaligned_uint16(void *p, unsigned int datum)
00084 {
00085    unsigned char *cp = p;
00086 
00087    cp[0] = datum >> 8;
00088    cp[1] = datum;
00089 }
00090 #else /* Not GCC, not Solaris/SPARC. Assume we can handle direct load/store. */
00091 #define get_unaligned_uint32(p) (*((unsigned int *)(p)))
00092 #define get_unaligned_uint16(p) (*((unsigned short *)(p)))
00093 #define put_unaligned_uint32(p,d) do { unsigned int *__P = (p); *__P = d; } while(0)
00094 #define put_unaligned_uint16(p,d) do { unsigned short *__P = (p); *__P = d; } while(0)
00095 #endif
00096 
00097 #if defined(__cplusplus) || defined(c_plusplus)
00098 }
00099 #endif
00100 
00101 
00102 #endif /* _ASTERISK_UNALIGNED_H */

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