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

1 files changed, 361 insertions, 0 deletions

diff --git a/src/egprs_rlc_compression.cpp b/src/egprs_rlc_compression.cpp
new file mode 100644
index 00000000..f4e6bdee
--- /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();
+}
+