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Sensix
Wireless Sensor Network Middleware |
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/home/brennan/Software/sensix/source/sense_endian.h
Go to the documentation of this file.00001 /* 00002 * \file sensix/source/sensix_endian.h 00003 * \brief Run-time endianness detection and byte swapping 00004 * 00005 * $Revision: 1.4 $ 00006 * $Author: sean_m_brennan $ 00007 * $Date: 2009/07/13 01:37:01 $ 00008 */ 00009 00010 /* 00011 * Copyright 2008. Los Alamos National Security, LLC. This material 00012 * was produced under U.S. Government contract DE-AC52-06NA25396 for 00013 * Los Alamos National Laboratory (LANL), which is operated by Los 00014 * Alamos National Security, LLC, for the Department of Energy. The 00015 * U.S. Government has rights to use, reproduce, and distribute this 00016 * software. NEITHER THE GOVERNMENT NOR LOS ALAMOS NATIONAL SECURITY, 00017 * LLC, MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LEGAL 00018 * LIABILITY FOR THE USE OF THIS SOFTWARE. If software is modified to 00019 * produce derivative works, such modified software should be clearly 00020 * marked, so as not to confuse it with the version available from LANL. 00021 * 00022 * Additionally, this program is free software; you can redistribute 00023 * it and/or modify it under the terms of the GNU General Public 00024 * License as published by the Free Software Foundation; version 2 of 00025 * the License. Accordingly, this program is distributed in the hope 00026 * it will be useful, but WITHOUT ANY WARRANTY; without even the 00027 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 00028 * PURPOSE. See the GNU General Public License for more details. 00029 * 00030 * You should have received a copy of the GNU General Public License 00031 * along with this program; if not, write to the Free Software 00032 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. 00033 */ 00034 00035 #ifndef _ENDIAN_H_ 00036 #define _ENDIAN_H_ 00037 00038 #ifdef MOTE 00039 # include "mote_types.h" 00040 #else 00041 # include <stdint.h> 00042 #endif 00043 00044 00045 #ifndef WORDSIZE 00046 # ifdef __WORDSIZE 00047 # if __WORDSIZE == 64 00048 # define WORDSIZE 8 00049 # define WORD int64_t 00050 # elif __WORDSIZE == 16 00051 # define WORDSIZE 2 00052 # define WORD int16_t 00053 # elif __WORDSIZE == 8 00054 # define WORDSIZE 1 00055 # define WORD int8_t 00056 # else 00057 # define WORDSIZE 4 00058 # define WORD int32_t 00059 # endif 00060 # else // no __WORDSIZE 00061 # define WORDSIZE 4 00062 # define WORD int32_t 00063 # endif 00064 #endif 00065 00066 #ifndef WORD 00067 # define WORD int32_t 00068 #endif 00069 00070 00071 00072 static inline uint8_t little_endian(void) 00073 { 00074 uint16_t word = 0x0001; 00075 uint8_t *byte = (uint8_t*)&word; 00076 return byte[0]; // BE->0x00, LE->0x01 00077 } 00078 00079 00080 static inline void swap(uint8_t *a, uint8_t *b) 00081 { 00082 uint8_t tmp; 00083 tmp = *a; 00084 *a = *b; 00085 *b = tmp; 00086 } 00087 00088 00089 static inline void _byte_swap(uint8_t *bytes, size_t size) 00090 { 00091 if (little_endian()) { 00092 size_t i, j; 00093 for (i = 0, j = size - 1; i < j; i++, j--) 00094 swap(&bytes[i], &bytes[j]); 00095 } 00096 // otherwise, already network byte order, do nothing 00097 } 00098 00099 00100 00101 00102 00103 static inline unsigned twos_complement(void) 00104 { 00105 int8_t value = -1; 00106 uint8_t rep = 0xff; 00107 uint8_t word = value; 00108 return (rep == word); 00109 } 00110 00111 00112 static inline unsigned ones_complement(void) 00113 { 00114 int8_t value = -1; 00115 uint8_t rep = 0xfe; 00116 uint8_t word = value; 00117 return (rep == word); 00118 } 00119 00120 00121 static inline unsigned signed_magnitude(void) 00122 { 00123 int8_t value = -1; 00124 uint8_t rep = 0x81; 00125 uint8_t word = value; 00126 return (rep == word); 00127 } 00128 00129 00130 00131 #define host_rep(x) \ 00132 do { \ 00133 if (ones_complement()) \ 00134 (x) -= 1; \ 00135 else if (signed_magnitude()) { \ 00136 uint8_t *ptr = (uint8_t*)&(x); \ 00137 (x) -= 1; \ 00138 (x) = ~(x); \ 00139 ptr[0] |= 0x80; \ 00140 } \ 00141 } while(0) 00142 00143 00144 static inline void host_order(WORD *var, uint8_t *bytes, 00145 size_t size, uint8_t convert, uint8_t sign) 00146 { 00147 uint8_t msb = little_endian() ? size - 1 : 0; 00148 uint8_t neg; 00149 00150 if (convert) 00151 _byte_swap(bytes, size); 00152 neg = bytes[msb] & 0x80; 00153 00154 if (size == 1) { 00155 if (sign) { 00156 int8_t val = *((int8_t*)bytes); 00157 if (neg) { 00158 host_rep(val); 00159 } 00160 *var = val; 00161 } else { 00162 uint8_t val = *((uint8_t*)bytes); 00163 *var = val; 00164 } 00165 } 00166 else if (size == 2) { 00167 if (sign) { 00168 int16_t val = *((int16_t*)bytes); 00169 if (neg) { 00170 host_rep(val); 00171 } 00172 *var = val; 00173 } else { 00174 uint16_t val = *((uint16_t*)bytes); 00175 *var = val; 00176 } 00177 } 00178 else if (size == 4) { 00179 if (sign) { 00180 int32_t val = *((int32_t*)bytes); 00181 if (neg) { 00182 host_rep(val); 00183 } 00184 *var = val; 00185 } else { 00186 uint32_t val = *((uint32_t*)bytes); 00187 *var = val; 00188 } 00189 } 00190 else if (size == 8) { 00191 if (sign) { 00192 int64_t val = *((int64_t*)bytes); 00193 if (neg) { 00194 host_rep(val); 00195 } 00196 *var = val; 00197 } else { 00198 uint64_t val = *((uint64_t*)bytes); 00199 *var = val; 00200 } 00201 } 00202 } 00203 00204 00205 00206 static inline void network_order(uint8_t *bytes, WORD var) 00207 { 00208 uint8_t sign = var < 0 ? 1: 0; 00209 uint8_t *ptr = (uint8_t*)&var; 00210 uint8_t msb = little_endian() ? WORDSIZE - 1 : 0; 00211 uint8_t neg = ptr[msb] & 0x80; 00212 00213 if (sign && neg) { // translate to CORBA-compliant 2s complement 00214 if (ones_complement()) { 00215 var++; 00216 } 00217 else if (signed_magnitude()) { 00218 ptr[msb] &= ~0x80; 00219 var = ~var; 00220 var++; 00221 } 00222 } 00223 memcpy(bytes, &var, WORDSIZE); 00224 } 00225 00226 00227 #endif // _ENDIAN_H_