return -1;
}
+/* Compute the number of octets from the number of septets, for instance: 47 septets needs 41,125 = 42 octets */
+uint8_t gsm_get_octet_len(const uint8_t sept_len){
+ int octet_len = (sept_len * 7) / 8;
+ if ((sept_len * 7) % 8 != 0)
+ octet_len++;
+
+ return octet_len;
+}
+
/* GSM 03.38 6.2.1 Character unpacking */
-int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length)
+int gsm_7bit_decode_hdr(char *text, const uint8_t *user_data, uint8_t septet_l, uint8_t ud_hdr_ind)
{
int i = 0;
- int l = 0;
- int septet_l = (length * 8) / 7;
+ int shift = 0;
+
uint8_t *rtext = calloc(septet_l, sizeof(uint8_t));
uint8_t tmp;
- /* FIXME: We need to account for user data headers here */
- i += l;
- for (; i < septet_l; i++){
+ /* skip the user data header */
+ if (ud_hdr_ind) {
+ /* get user data header length + 1 (for the 'user data header length'-field) */
+ shift = ((user_data[0] + 1) * 8) / 7;
+ if ((((user_data[0] + 1) * 8) % 7) != 0)
+ shift++;
+ septet_l = septet_l - shift;
+ }
+
+ for (i = 0; i < septet_l; i++) {
rtext[i] =
- ((user_data[(i * 7 + 7) >> 3] <<
- (7 - ((i * 7 + 7) & 7))) |
- (user_data[(i * 7) >> 3] >>
- ((i * 7) & 7))) & 0x7f;
+ ((user_data[((i + shift) * 7 + 7) >> 3] <<
+ (7 - (((i + shift) * 7 + 7) & 7))) |
+ (user_data[((i + shift) * 7) >> 3] >>
+ (((i + shift) * 7) & 7))) & 0x7f;
}
for(i = 0; i < septet_l; i++){
/* this is an extension character */
- if(rtext[i] == 0x1b && i + 1 < length){
+ if(rtext[i] == 0x1b && i + 1 < septet_l){
tmp = rtext[i+1];
*(text++) = gsm_7bit_alphabet[0x7f + tmp];
i++;
*(text++) = gsm_septet_lookup(rtext[i]);
}
+ if (ud_hdr_ind)
+ i += shift;
*text = '\0';
free(rtext);
return i;
}
+int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t septet_l)
+{
+ return gsm_7bit_decode_hdr(text, user_data, septet_l, 0);
+}
+
/* GSM 03.38 6.2.1 Prepare character packing */
-static int gsm_septet_encode(uint8_t *result, const char *data)
+int gsm_septet_encode(uint8_t *result, const char *data)
{
int i, y = 0;
uint8_t ch;
return y;
}
-/* GSM 03.38 6.2.1 Character packing */
-int gsm_7bit_encode(uint8_t *result, const char *data)
-{
- 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));
+/* 7bit to octet packing */
+int gsm_septets2octets(uint8_t *result, uint8_t *rdata, uint8_t septet_len, uint8_t padding){
+ int i = 0, z = 0;
uint8_t cb, nb;
int shift = 0;
+ uint8_t *data = calloc(septet_len + 1, sizeof(uint8_t));
- y = gsm_septet_encode(rdata, data);
-
- for(i = 0; i < y; i++) {
- if(shift == 7 && i + 1 < y){
- shift = 0;
- continue;
+ if (padding) {
+ shift = 7 - padding;
+ /* the first zero is needed for padding */
+ memcpy(data + 1, rdata, septet_len);
+ septet_len++;
+ } else
+ memcpy(data, rdata, septet_len);
+
+ for(i = 0; i < septet_len; i++) {
+ if (shift == 7) {
+ /*
+ * special end case with the. This is necessary if the
+ * last septet fits into the previous octet. E.g. 48
+ * non-extension characters:
+ * ....ag ( a = 1100001, g = 1100111)
+ * result[40] = 100001 XX, result[41] = 1100111 1 */
+ if (i + 1 < septet_len) {
+ shift = 0;
+ continue;
+ } else if (i + 1 == septet_len)
+ break;
}
- cb = (rdata[i] & 0x7f) >> shift;
- if(i + 1 < y){
- nb = (rdata[i + 1] & 0x7f) << (7 - shift);
+ cb = (data[i] & 0x7f) >> shift;
+ if (i + 1 < septet_len) {
+ nb = (data[i + 1] & 0x7f) << (7 - shift);
cb = cb | nb;
}
result[z++] = cb;
-
shift++;
}
- free(rdata);
+ free(data);
+
return z;
}
+/* GSM 03.38 6.2.1 Character packing */
+int gsm_7bit_encode(uint8_t *result, const char *data)
+{
+ int y = 0, z = 0;
+ /* prepare for the worst case, every character expanding to two bytes */
+ uint8_t *rdata = calloc(strlen(data) * 2, sizeof(uint8_t));
+ y = gsm_septet_encode(rdata, data);
+ z = gsm_septets2octets(result, rdata, y, 0);
+
+ free(rdata);
+
+ /*
+ * We don't care about the number of octets (z), because they are not
+ * unique. E.g.:
+ * 1.) 46 non-extension characters + 1 extension character
+ * => (46 * 7 bit + (1 * (2 * 7 bit))) / 8 bit = 42 octets
+ * 2.) 47 non-extension characters
+ * => (47 * 7 bit) / 8 bit = 41,125 = 42 octets
+ * 3.) 48 non-extension characters
+ * => (48 * 7 bit) / 8 bit = 42 octects
+ */
+ return y;
+}
+
/* convert power class to dBm according to GSM TS 05.05 */
unsigned int ms_class_gmsk_dbm(enum gsm_band band, int class)
{
projects / osmocom-bb.git / blobdiff