[PATCH] * rewrite gsm_7bit_encode() based on a lookup table as the previous code produced wrong encodings for certain characters.

--- include/osmocore/gsm_utils.h | 28 ++++++++++++++++++ src/gsm_utils.c | 64 ++++++++++++++++++++++++++++++++---------- 2 files changed, 77 insertions(+), 15 deletions(-) diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h index 7dc2388..661846a 100644 --- a/include/osmocore/gsm_utils.h +++ b/include/osmocore/gsm_utils.h @@ -3,6 +3,7 @@ * (C) 2008 by Daniel Willmann &lt;daniel(a)totalueberwachung.de&gt; * (C) 2009 by Holger Hans Peter Freyther &lt;zecke(a)selfish.org&gt; * (C) 2009-2010 by Harald Welte &lt;laforge(a)gnumonks.org&gt; + * (C) 2010 by Nico Golde &lt;nico(a)ngolde.de&gt; * * All Rights Reserved * @@ -53,6 +54,33 @@ enum gsm_band { GSM_BAND_810 = 0x80, }; +/* ETSI GSM 03.38 6.2.1 and 6.2.1.1 default alphabet + * Greek symbols at hex positions 0x10 and 0x12-0x1a + * left out as they can't be handled with a char and + * since most phones don't display or write these + * characters this would only needlessly make the code + * more complex +*/ +unsigned char gsm_7bit_alphabet[] = { + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0a, 0xff, 0x0a, 0x0d, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0x20, 0x21, 0x22, 0x23, 0x02, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, + 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, + 0x3c, 0x3d, 0x3e, 0x3f, 0x00, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, + 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, + 0x5a, 0x3c, 0x2f, 0x3e, 0x14, 0x11, 0xff, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, + 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, + 0x78, 0x79, 0x7a, 0x28, 0x40, 0x29, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x24, + 0x03, 0xff, 0x5f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x60, 0xff, 0xff, 0xff, + 0xff, 0x5b, 0x0e, 0x1c, 0x09, 0xff, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5d, + 0xff, 0xff, 0xff, 0xff, 0x5c, 0xff, 0x0b, 0xff, 0xff, 0xff, 0x5e, 0xff, 0xff, 0x1e, 0x7f, + 0xff, 0xff, 0xff, 0x7b, 0x0f, 0x1d, 0xff, 0x04, 0x05, 0xff, 0xff, 0x07, 0xff, 0xff, 0xff, + 0xff, 0x7d, 0x08, 0xff, 0xff, 0xff, 0x7c, 0xff, 0x0c, 0x06, 0xff, 0xff, 0x7e, 0xff, 0xff +}; + const char *gsm_band_name(enum gsm_band band); enum gsm_band gsm_band_parse(const char *mhz); diff --git a/src/gsm_utils.c b/src/gsm_utils.c index dc97cef..ce5cefd 100644 --- a/src/gsm_utils.c +++ b/src/gsm_utils.c @@ -2,6 +2,7 @@ * (C) 2008 by Daniel Willmann &lt;daniel(a)totalueberwachung.de&gt; * (C) 2009 by Holger Hans Peter Freyther &lt;zecke(a)selfish.org&gt; * (C) 2009-2010 by Harald Welte &lt;laforge(a)gnumonks.org&gt; + * (C) 2010 by Nico Golde &lt;nico(a)ngolde.de&gt; * * All Rights Reserved * @@ -53,33 +54,66 @@ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length) return i - l; } +/* GSM 03.38 6.2.1 Prepare character packing */ +static int gsm_septet_encode(uint8_t *result, const char *data) +{ + int i, y = 0; + uint8_t ch; + for(i = 0; i < strlen(data); i++){ + ch = data[i]; + switch(ch){ + case 0x0c: + case 0x5e: + case 0x7b: + case 0x7d: + case 0x5c: + case 0x5b: + case 0x7e: + case 0x5d: + case 0x7c: + result[y] = 0x1b; + result[y + 1] = gsm_7bit_alphabet[ch]; + y++; + break; + default: + result[y] = gsm_7bit_alphabet[ch]; + break; + } + y++; + } -/* GSM 03.38 6.2.1 Charachter packing */ + return y; +} + +/* GSM 03.38 6.2.1 Character packing */ int gsm_7bit_encode(uint8_t *result, const char *data) { - int i,j = 0; - unsigned char ch1, ch2; + int i,y,z = 0; + /* prepare for the worst case, every character expanding to two bytes */ + uint8_t *rdata = calloc(strlen(data) * 2, sizeof(uint8_t)); + uint8_t cb, nb; int shift = 0; - for ( i=0; i<strlen(data); i++ ) { + y = gsm_septet_encode(rdata, data); - ch1 = data[i] & 0x7F; - ch1 = ch1 >> shift; - ch2 = data[(i+1)] & 0x7F; - ch2 = ch2 << (7-shift); + for(i = 0; i < y; i++) { + if(shift == 7 && i + 1 < y){ + shift = 0; + continue; + } - ch1 = ch1 | ch2; + cb = (rdata[i] & 0x7f) >> shift; + if(i + 1 < y){ + nb = (rdata[i + 1] & 0x7f) << (7 - shift); + cb = cb | nb; + } - result[j++] = ch1; + result[z++] = cb; shift++; - - if ((shift == 7) && (i+1<strlen(data))) { - shift = 0; - i++; - } } + free(rdata); return i; } -- 1.7.1 --liOOAslEiF7prFVr--