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Diffstat (limited to 'openbsc/src/gsm_utils.c')
-rw-r--r-- | openbsc/src/gsm_utils.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/openbsc/src/gsm_utils.c b/openbsc/src/gsm_utils.c new file mode 100644 index 000000000..0c25b28c6 --- /dev/null +++ b/openbsc/src/gsm_utils.c @@ -0,0 +1,73 @@ +/* + * (C) 2008 by Daniel Willmann <daniel@totalueberwachung.de> + * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org> + * (C) 2009 by Harald Welte <laforge@gnumonks.org> + * + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + */ + +#include <openbsc/gsm_utils.h> +#include <stdlib.h> +#include <string.h> + +/* GSM 03.38 6.2.1 Charachter packing */ +int gsm_7bit_decode(char *text, const u_int8_t *user_data, u_int8_t length) +{ + u_int8_t d_off = 0, b_off = 0; + u_int8_t i; + + for (i=0;i<length;i++) { + text[i] = ((user_data[d_off] + (user_data[d_off+1]<<8)) & (0x7f<<b_off))>>b_off; + b_off += 7; + if (b_off >= 8) { + d_off += 1; + b_off -= 8; + } + } + text[i] = '\0'; + return 0; +} + +/* GSM 03.38 6.2.1 Charachter packing */ +int gsm_7bit_encode(u_int8_t *result, const char *data) +{ + int i; + u_int8_t d_off = 0, b_off = 0; + const int length = strlen(data); + int out_length = (length * 8)/7; + + memset(result, 0, out_length); + + for (i = 0; i < length; ++i) { + u_int8_t first = (data[i] & 0x7f) << b_off; + u_int8_t second = (data[i] & 0x7f) >> (8 - b_off); + + result[d_off] |= first; + if (second != 0) + result[d_off + 1] = second; + + b_off += 7; + + if (b_off >= 8) { + d_off += 1; + b_off -= 8; + } + } + + return out_length; +} |