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#include <stdint.h>
#include <stdio.h>
#include <osmocom/core/crc8gen.h>
#include <osmocom/core/crc16gen.h>
static const struct osmo_crc8gen_code iuup_hdr_crc_code = {
.bits = 6,
.poly = 47,
.init = 0,
.remainder = 0,
};
static const struct osmo_crc16gen_code iuup_data_crc_code = {
.bits = 10,
.poly = 563,
.init = 0,
.remainder = 0,
};
static int iuup_get_payload_offset(const uint8_t *iuup_pdu)
{
uint8_t pdu_type = iuup_pdu[0] >> 4;
switch (pdu_type) {
case 0:
case 14:
return 4;
case 1:
return 3;
default:
return -1;
}
}
int osmo_iuup_compute_payload_crc(const uint8_t *iuup_pdu, unsigned int pdu_len)
{
ubit_t buf[1024*8];
uint8_t pdu_type;
int offset, payload_len_bytes;
if (pdu_len < 1)
return -1;
pdu_type = iuup_pdu[0] >> 4;
/* Type 1 has no CRC */
if (pdu_type == 1)
return 0;
offset = iuup_get_payload_offset(iuup_pdu, pdu_len);
if (offset < 0)
return offset;
if (pdu_len < offset)
return -1;
payload_len_bytes = pdu_eln - offset;
osmo_pbit2ubit(buf, iuup_pdu+offset, payload_len_bytes*8);
return osmo_crc16gen_compute_bits(&iuup_data_crc_code, buf, payload_len_bytes*8);
}
int osmo_iuup_compute_header_crc(const uint8_t *iuup_pdu, unsigned int pdu_len)
{
ubit_t buf[2*8];
if (pdu_len < 2)
return -1;
osmo_pbit2ubit(buf, iuup_pdu, 2*8);
return osmo_crc8gen_compute_bits(&iuup_hdr_crc_code, buf, 2*8);
}
#if 0
/* Frame 29 of MobileOriginatingCall_AMR.cap */
const uint8_t iuup_frame29[] = {
0x02, 0x00, 0x7d, 0x27, 0x55, 0x00, 0x88, 0xb6, 0x66, 0x79, 0xe1, 0xe0,
0x01, 0xe7, 0xcf, 0xf0, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
int main(int argc, char **argv)
{
ubit_t buf[1024*8];
int rc;
osmo_pbit2ubit(buf, iuup_frame29, 2*8);
rc = osmo_crc8gen_compute_bits(&iuup_hdr_crc_code, buf, 2*8);
printf("Header CRC = 0x%02x\n", rc);
osmo_pbit2ubit(buf, iuup_frame29+4, 31*8);
rc = osmo_crc16gen_compute_bits(&iuup_data_crc_code, buf, 31*8);
printf("Payload CRC = 0x%03x\n", rc);
}
#endif
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