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authorPravin Kumarvel <pmanohar@radisys.com>2016-10-17 11:00:57 +0530
committerPravin Kumarvel <pmanohar@radisys.com>2016-10-17 11:00:57 +0530
commit0a4a6c120040c8dd0744f745e08f24624df62647 (patch)
treebb26bcb0e1127248a86f246a13ac177b27f88a94 /src
parent6348aea6a2cdc753021e5324a0dd2aecf8791f10 (diff)
EGPRS: Add EPDAN CRBB Tree based decoding
Implemented tree based algorithm to decode compressed bitmap in EPDAN as described in section 9.1.10 of 3GPP 44.060. This algorithm intends to improve the performance over existing method. New Regression test is added under bitcomp directory. Test case is added to validate decompressed result of the bitmap Present in EPDAN. Test is done for multiple bitmaps of varying length. Invalid inputs are also part of the test vector. Change-Id: Ieae1992ed4b02bb1e09eec2d3de1a030eabd16ce
Diffstat (limited to 'src')
-rw-r--r--src/Makefile.am6
-rw-r--r--src/decoding.cpp21
-rw-r--r--src/egprs_rlc_compression.cpp361
-rw-r--r--src/egprs_rlc_compression.h29
4 files changed, 403 insertions, 14 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index 9bdec2f..9b047e7 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -62,7 +62,8 @@ libgprs_la_SOURCES = \
rlc.cpp \
osmobts_sock.cpp \
gprs_codel.c \
- gprs_coding_scheme.cpp
+ gprs_coding_scheme.cpp \
+ egprs_rlc_compression.cpp
bin_PROGRAMS = \
osmo-pcu
@@ -94,7 +95,8 @@ noinst_HEADERS = \
pcu_utils.h \
cxx_linuxlist.h \
gprs_codel.h \
- gprs_coding_scheme.h
+ gprs_coding_scheme.h \
+ egprs_rlc_compression.h
osmo_pcu_SOURCES = pcu_main.cpp
diff --git a/src/decoding.cpp b/src/decoding.cpp
index 3f5c4d2..6ae4b16 100644
--- a/src/decoding.cpp
+++ b/src/decoding.cpp
@@ -20,6 +20,7 @@
#include <decoding.h>
#include <rlc.h>
#include <gprs_debug.h>
+#include <egprs_rlc_compression.h>
extern "C" {
#include <osmocom/core/utils.h>
@@ -692,21 +693,17 @@ int Decoding::decode_egprs_acknack_bits(const EGPRS_AckNack_Desc_t *desc,
if (crbb_len > 0) {
int old_len = bits->cur_bit;
- struct bitvec crbb;
-
- crbb.data = (uint8_t *)desc->CRBB;
- crbb.data_len = sizeof(desc->CRBB);
- crbb.cur_bit = desc->CRBB_LENGTH;
-
- rc = osmo_t4_decode(&crbb, desc->CRBB_STARTING_COLOR_CODE,
- bits);
+ LOGP(DRLCMACDL, LOGL_DEBUG, "Compress bitmap exists, "
+ "CRBB LEN = %d and Starting color code = %d",
+ desc->CRBB_LENGTH, desc->CRBB_STARTING_COLOR_CODE);
+ rc = egprs_compress::decompress_crbb(desc->CRBB_LENGTH,
+ desc->CRBB_STARTING_COLOR_CODE, desc->CRBB, bits);
if (rc < 0) {
LOGP(DRLCMACUL, LOGL_NOTICE,
- "Failed to decode CRBB: "
- "length %d, data '%s'\n",
- desc->CRBB_LENGTH,
- osmo_hexdump(crbb.data, crbb.data_len));
+ "Failed to decode CRBB: length %d, data '%s'\n",
+ desc->CRBB_LENGTH, osmo_hexdump(
+ desc->CRBB, (desc->CRBB_LENGTH + 7)/8));
/* We don't know the SSN offset for the URBB,
* return what we have so far and assume the
* bitmap has stopped here */
diff --git a/src/egprs_rlc_compression.cpp b/src/egprs_rlc_compression.cpp
new file mode 100644
index 0000000..f4e6bde
--- /dev/null
+++ b/src/egprs_rlc_compression.cpp
@@ -0,0 +1,361 @@
+/* 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();
+}
+
diff --git a/src/egprs_rlc_compression.h b/src/egprs_rlc_compression.h
new file mode 100644
index 0000000..c5f0f1a
--- /dev/null
+++ b/src/egprs_rlc_compression.h
@@ -0,0 +1,29 @@
+/* egprs_rlc_compression.h
+ * Routines for EGPRS RLC bitmap compression handling
+ */
+
+#pragma once
+
+struct egprs_compress_node;
+
+/* Singleton to manage the EGPRS compression algorithm. */
+class egprs_compress
+{
+public:
+ static int decompress_crbb(int8_t compress_bmap_len,
+ bool start, const uint8_t *orig_buf,
+ bitvec *dest);
+ egprs_compress();
+
+private:
+ egprs_compress_node *ones_list;
+ egprs_compress_node *zeros_list;
+
+ void decode_tree_init(void);
+ static egprs_compress *s_instance;
+ static egprs_compress*instance();
+ egprs_compress_node *create_tree_node(void *);
+ void build_codewords(egprs_compress_node *root, const char *cdwd[]);
+ /* singleton class, so this private destructor is left unimplemented. */
+ ~egprs_compress();
+};