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/* egprs_rlc_compression.h
* Routines for EGPRS RLC bitmap compression handling
*/
#include <errno.h>
#include <decoding.h>
#include <arpa/inet.h>
#include <string.h>
#include <gprs_debug.h>
#include <gprs_rlcmac.h>
#include <egprs_rlc_compression.h>
extern "C" {
#include <osmocom/core/talloc.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/stats.h>
}
#define EGPRS_CODEWORDS 79 /* total number of codewords */
struct egprs_compress_node{
struct egprs_compress_node *left;
struct egprs_compress_node *right;
int run_length;
};
extern void *tall_pcu_ctx;
egprs_compress *egprs_compress::s_instance = 0;
egprs_compress_node *egprs_compress::create_tree_node(void *parent)
{
egprs_compress_node *new_node;
new_node = talloc_zero(parent, egprs_compress_node);
new_node->left = NULL;
new_node->right = NULL;
new_node->run_length = -1;
return new_node;
}
egprs_compress *egprs_compress::instance()
{
if (!egprs_compress::s_instance)
egprs_compress::s_instance = new egprs_compress;
return egprs_compress::s_instance;
}
/* Expands the given tree by incorporating
* the given codewords.
* \param root[in] Root of ones or zeros tree
* \param cdwd[in] Array of code words
* number of codewords is EGPRS_CODEWORDS
*/
void egprs_compress::build_codewords(egprs_compress_node *root, const char *cdwd[])
{
egprs_compress_node *iter;
int len;
int i;
int idx;
for (idx = 0; idx < EGPRS_CODEWORDS; idx++) {
len = strlen((const char *)cdwd[idx]);
iter = root;
for (i = 0; i < len; i++) {
if (cdwd[idx][i] == '0') {
if (!iter->left)
iter->left = create_tree_node(root);
iter = iter->left;
} else {
if (!iter->right)
iter->right = create_tree_node(root);
iter = iter->right;
}
}
if (iter) {
/* The first 64 run lengths are 0, 1, 2, ..., 63
* and the following ones are 64, 128, 192 described in
* section 9.1.10 of 3gpp 44.060 */
if (idx < 64)
iter->run_length = idx;
else
iter->run_length = (idx - 63) * 64;
}
}
}
/* The code words for one run length and zero run length are described in
* table 9.1.10.1 of 3gpp 44.060
*/
const char *one_run_len_code_list[EGPRS_CODEWORDS] = {
"00110101",
"000111",
"0111",
"1000",
"1011",
"1100",
"1110",
"1111",
"10011",
"10100",
"00111",
"01000",
"001000",
"000011",
"110100",
"110101",
"101010",
"101011",
"0100111",
"0001100",
"0001000",
"0010111",
"0000011",
"0000100",
"0101000",
"0101011",
"0010011",
"0100100",
"0011000",
"00000010",
"00000011",
"00011010",
"00011011",
"00010010",
"00010011",
"00010100",
"00010101",
"00010110",
"00010111",
"00101000",
"00101001",
"00101010",
"00101011",
"00101100",
"00101101",
"00000100",
"00000101",
"00001010",
"00001011",
"01010010",
"01010011",
"01010100",
"01010101",
"00100100",
"00100101",
"01011000",
"01011001",
"01011010",
"01011011",
"01001010",
"01001011",
"00110010",
"00110011",
"00110100",
"11011",
"10010",
"010111",
"0110111",
"00110110",
"00110111",
"01100100",
"01100101",
"01101000",
"01100111",
"011001100",
"011001101",
"011010010",
"011010011",
"011010100"
};
const char *zero_run_len_code_list[EGPRS_CODEWORDS] = {
"0000110111",
"10",
"11",
"010",
"011",
"0011",
"0010",
"00011",
"000101",
"000100",
"0000100",
"0000101",
"0000111",
"00000100",
"00000111",
"000011000",
"0000010111",
"0000011000",
"0000001000",
"00001100111",
"00001101000",
"00001101100",
"00000110111",
"00000101000",
"00000010111",
"00000011000",
"000011001010",
"000011001011",
"000011001100",
"000011001101",
"000001101000",
"000001101001",
"000001101010",
"000001101011",
"000011010010",
"000011010011",
"000011010100",
"000011010101",
"000011010110",
"000011010111",
"000001101100",
"000001101101",
"000011011010",
"000011011011",
"000001010100",
"000001010101",
"000001010110",
"000001010111",
"000001100100",
"000001100101",
"000001010010",
"000001010011",
"000000100100",
"000000110111",
"000000111000",
"000000100111",
"000000101000",
"000001011000",
"000001011001",
"000000101011",
"000000101100",
"000001011010",
"000001100110",
"000001100111",
"0000001111",
"000011001000",
"000011001001",
"000001011011",
"000000110011",
"000000110100",
"000000110101",
"0000001101100",
"0000001101101",
"0000001001010",
"0000001001011",
"0000001001100",
"0000001001101",
"0000001110010",
"0000001110011"
};
/* Calculate runlength of a codeword
* \param root[in] Root of Ones or Zeros tree
* \param bmbuf[in] Received compressed bitmap buf
* \param bit_pos[in] The start bit pos to read codeword
* \param len_codewd[in] Length of code word
* \param rlen[out] Calculated run length
*/
static int search_runlen(
egprs_compress_node *root,
const uint8_t *bmbuf,
uint8_t bit_pos,
uint8_t *len_codewd,
uint16_t *rlen)
{
egprs_compress_node *iter;
uint8_t dir;
iter = root;
*len_codewd = 0;
while (iter->run_length == -1) {
if ((!iter->left) && (!iter->right))
return -1;
/* get the bit value at the bitpos and put it in right most of dir */
dir = (bmbuf[bit_pos/8] >> (7 - (bit_pos & 0x07))) & 0x01;
bit_pos++;
(*len_codewd)++;
if (!dir && (iter->left != NULL))
iter = iter->left;
else if (dir && (iter->right != NULL))
iter = iter->right;
else
return -1;
}
LOGP(DRLCMACUL, LOGL_DEBUG, "Run_length = %d\n", iter->run_length);
*rlen = iter->run_length;
return 1;
}
/* Decompress received block bitmap
* \param compress_bmap_len[in] Compressed bitmap length
* \param start[in] Starting Color Code, true if bitmap starts with a run
* length of ones, false if zeros; see 9.1.10, 3GPP 44.060.
* \param orig_crbb_buf[in] Received block crbb bitmap
* \param dest[out] Uncompressed bitvector
*/
int egprs_compress::decompress_crbb(
int8_t compress_bmap_len,
bool start,
const uint8_t *orig_crbb_buf,
bitvec *dest)
{
uint8_t bit_pos = 0;
uint8_t data;
egprs_compress_node *list = NULL;
uint8_t nbits = 0; /* number of bits of codeword */
uint16_t run_length = 0;
uint16_t cbmaplen = 0; /* compressed bitmap part after decompression */
unsigned wp = dest->cur_bit;
int rc = 0;
egprs_compress *compress = instance();
while (compress_bmap_len > 0) {
if (start) {
data = 0xff;
list = compress->ones_list;
} else {
data = 0x00;
list = compress->zeros_list;
}
rc = search_runlen(list, orig_crbb_buf,
bit_pos, &nbits, &run_length);
if (rc == -1)
return -1;
/* If run length > 64, need makeup and terminating code */
if (run_length < 64)
start = !start;
cbmaplen = cbmaplen + run_length;
/* put run length of Ones in uncompressed bitmap */
while (run_length != 0) {
if (run_length > 8) {
bitvec_write_field(dest, wp, data, 8);
run_length = run_length - 8;
} else {
bitvec_write_field(dest, wp, data, run_length);
run_length = 0;
}
}
bit_pos = bit_pos + nbits;
compress_bmap_len = compress_bmap_len - nbits;
}
return 0;
}
void egprs_compress::decode_tree_init()
{
ones_list = create_tree_node(tall_pcu_ctx);
zeros_list = create_tree_node(tall_pcu_ctx);
build_codewords(ones_list, one_run_len_code_list);
build_codewords(zeros_list, zero_run_len_code_list);
}
egprs_compress::egprs_compress()
{
decode_tree_init();
}
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