edge: Add Encoding::rlc_data_to_dl_append
This function appends a single chunk to an RLC downlink data block.
The implementation is basically taken from the
gprs_rlcmac_dl_tbf::create_new_bsn method without the TBF related
functionality and any side effects.
Note that it still only supports GRPS.
Sponsored-by: On-Waves ehf
diff --git a/src/encoding.cpp b/src/encoding.cpp
index 0756ffc..eb424cb 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -751,3 +751,124 @@
return rdbi->data_len;
}
+
+Encoding::AppendResult Encoding::rlc_data_to_dl_append(
+ struct gprs_rlc_data_block_info *rdbi,
+ gprs_llc *llc, int *offset, int *num_chunks,
+ uint8_t *data_block,
+ bool is_final)
+{
+ int chunk;
+ int space;
+ struct rlc_li_field *li;
+ uint8_t *delimiter, *data, *e_pointer;
+
+ data = data_block + *offset;
+ delimiter = data_block + *num_chunks;
+ e_pointer = (*num_chunks ? delimiter - 1 : NULL);
+
+ chunk = llc->chunk_size();
+ space = rdbi->data_len - *offset;
+
+ /* if chunk will exceed block limit */
+ if (chunk > space) {
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+ "larger than space (%d) left in block: copy "
+ "only remaining space, and we are done\n",
+ chunk, space);
+ /* block is filled, so there is no extension */
+ if (e_pointer)
+ *e_pointer |= 0x01;
+ /* fill only space */
+ llc->consume(data, space);
+ /* return data block as message */
+ *offset = rdbi->data_len;
+ (*num_chunks)++;
+ return AR_NEED_MORE_BLOCKS;
+ }
+ /* if FINAL chunk would fit precisely in space left */
+ if (chunk == space && is_final)
+ {
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+ "would exactly fit into space (%d): because "
+ "this is a final block, we don't add length "
+ "header, and we are done\n", chunk, space);
+ /* block is filled, so there is no extension */
+ if (e_pointer)
+ *e_pointer |= 0x01;
+ /* fill space */
+ llc->consume(data, space);
+ *offset = rdbi->data_len;
+ (*num_chunks)++;
+ rdbi->cv = 0;
+ return AR_COMPLETED_BLOCK_FILLED;
+ }
+ /* if chunk would fit exactly in space left */
+ if (chunk == space) {
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+ "would exactly fit into space (%d): add length "
+ "header with LI=0, to make frame extend to "
+ "next block, and we are done\n", chunk, space);
+ /* make space for delimiter */
+ if (delimiter != data)
+ memmove(delimiter + 1, delimiter,
+ data - delimiter);
+ data++;
+ (*offset)++;
+ space--;
+ /* add LI with 0 length */
+ li = (struct rlc_li_field *)delimiter;
+ li->e = 1; /* not more extension */
+ li->m = 0; /* shall be set to 0, in case of li = 0 */
+ li->li = 0; /* chunk fills the complete space */
+ rdbi->e = 0; /* 0: extensions present */
+ // no need to set e_pointer nor increase delimiter
+ /* fill only space, which is 1 octet less than chunk */
+ llc->consume(data, space);
+ /* return data block as message */
+ *offset = rdbi->data_len;
+ (*num_chunks)++;
+ return AR_NEED_MORE_BLOCKS;
+ }
+
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d is less "
+ "than remaining space (%d): add length header to "
+ "to delimit LLC frame\n", chunk, space);
+ /* the LLC frame chunk ends in this block */
+ /* make space for delimiter */
+ if (delimiter != data)
+ memmove(delimiter + 1, delimiter, data - delimiter);
+ data++;
+ (*offset)++;
+ space--;
+ /* add LI to delimit frame */
+ li = (struct rlc_li_field *)delimiter;
+ li->e = 0; /* Extension bit, maybe set later */
+ li->m = 0; /* will be set later, if there is more LLC data */
+ li->li = chunk; /* length of chunk */
+ rdbi->e = 0; /* 0: extensions present */
+ (*num_chunks)++;
+ /* copy (rest of) LLC frame to space and reset later */
+ llc->consume(data, chunk);
+ data += chunk;
+ space -= chunk;
+ (*offset) += chunk;
+ /* if we have more data and we have space left */
+ if (space > 0 && !is_final) {
+ li->m = 1; /* we indicate more frames to follow */
+ return AR_COMPLETED_SPACE_LEFT;
+ }
+ /* if we don't have more LLC frames */
+ if (is_final) {
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- Final block, so we "
+ "done.\n");
+ li->e = 1; /* we cannot extend */
+ rdbi->cv = 0;
+ return AR_COMPLETED_BLOCK_FILLED;
+ }
+ /* we have no space left */
+ LOGP(DRLCMACDL, LOGL_DEBUG, "-- No space left, so we are "
+ "done.\n");
+ li->e = 1; /* we cannot extend */
+ return AR_COMPLETED_BLOCK_FILLED;
+}