This patch includes the changes for compression algorithm and the compression is carried out using T.4 run length coding and the code words used are based on 3GPP 44.060 --- include/osmocom/core/bitcomp.h | 7 +++ src/bitcomp.c | 129 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 136 insertions(+)
diff --git a/include/osmocom/core/bitcomp.h b/include/osmocom/core/bitcomp.h index 89eccbc..c5c223c 100644 --- a/include/osmocom/core/bitcomp.h +++ b/include/osmocom/core/bitcomp.h @@ -39,4 +39,11 @@ int osmo_t4_encode(struct bitvec *bv); int osmo_t4_decode(const struct bitvec *in, bool cc, struct bitvec *out);
+#define MOD64(X) ((X + 64) & 0x3F) +int osmo_bitmap_compress( + struct bitvec *rbb_vec, + uint16_t *ucmp_bmplen, //Uncompressed bitmap len + uint8_t *cmp_bmplen, //Compressed bitmap len + uint8_t *crbb_bitmap //Compressed bitmap + ); /*! @} */ diff --git a/src/bitcomp.c b/src/bitcomp.c index bf35927..f3326b2 100644 --- a/src/bitcomp.c +++ b/src/bitcomp.c @@ -476,5 +476,134 @@ int osmo_t4_encode(struct bitvec *bv) } return -1; } +void compress_bitmap( + uint16_t *run_len_cnt, /* cnt: run length count */ + uint16_t *codewrd_bitmap, /* code word */ + uint8_t *codewrd_len, /* number of bits in the code word */ + uint8_t *cbmbuf, /* bitmap buffer to put code word in */ + uint16_t *cstrtbits, /* start bits to put codeword. start from + * 0, the first bit in the first octets + * and increment without octets + * consideration. i.e. can be more than 7. + */ + uint8_t *cstrtocts, /* start octets to put codeword. start from 0*/ + uint8_t clr_code) +{ + int i = 0; + uint16_t bitsleft = 0; + uint16_t temp = 0; + *codewrd_bitmap = 0; + *codewrd_len = 0; + + if ((*run_len_cnt) >= 64) { + for (i = 0; i < 15; i++) { + if (t4_make_up_ind[i] == *run_len_cnt) { + *codewrd_bitmap = t4_make_up[clr_code][i]; + *codewrd_len = t4_make_up_length[clr_code][i]; + } + } + } else { + *codewrd_bitmap = t4_term[clr_code][*run_len_cnt]; + *codewrd_len = t4_term_length[clr_code][*run_len_cnt]; + } + bitsleft = *codewrd_len; + /* Move the codeword_bitmap to left in two bytes*/ + (*codewrd_bitmap) = (*codewrd_bitmap)<<(16-(*codewrd_len)); + + while (bitsleft != 0) { + /* Bring left most bits to right and start shifting by cstrtbits, + * we get each bit to update in compressed buffer + */ + temp = (((*codewrd_bitmap) & 0x8000)>>15)<<(7-(*cstrtbits)); + cbmbuf[*cstrtocts] = cbmbuf[*cstrtocts]|temp; + + (*codewrd_bitmap) = (*codewrd_bitmap)<<1; + (*cstrtbits)++; + bitsleft--; + if ((*cstrtbits) >= 8) { + (*cstrtbits) = (*cstrtbits)-8; + (*cstrtocts)++; + /* init buf */ + cbmbuf[*cstrtocts] = 0x00; + } + } +} + +int osmo_bitmap_compress( + struct bitvec *rbb_vec, + uint16_t *ucmp_bmplen, /* Uncompressed bitmap len */ + uint8_t *cmp_bmplen, /* Compressed bitmap len */ + uint8_t *crbb_bitmap /* Compressed bitmap */ + ) +{
+ char run_len_bit; + int buflen = *ucmp_bmplen; + uint16_t rlen; + uint16_t temprl = 0; + uint16_t cbmap; /* Compressed code word */ + uint8_t nbits; /* Length of code word */ + uint16_t cstrtbits = 0; + uint8_t cstrtocts = 0; + uint16_t uclen = 0; + uint8_t clen = 0; + uint8_t clr_code = 0; + + run_len_bit = (rbb_vec->data[0] & 0x80)>>7; + while (buflen > 0) { + temprl = 0; + /* Find Run length */ + if (run_len_bit == 1) + rlen = bitvec_rl(rbb_vec, true); + else + rlen = bitvec_rl(rbb_vec, false); + + buflen = buflen - rlen; + /* if rlen> 64 need 2 code words */ + //Compress the bits + if (run_len_bit == 0) { + if (rlen >= 64) { + temprl = (rlen/64)*64; + compress_bitmap(&temprl, &cbmap, &nbits, + crbb_bitmap, &cstrtbits, + &cstrtocts, clr_code); + } + temprl = MOD64(rlen); + compress_bitmap(&temprl, + &cbmap, &nbits, crbb_bitmap, + &cstrtbits, &cstrtocts, clr_code); + + /* next time the run length will be Ones */ + run_len_bit = 1; + } else { + if (rlen >= 64) { + temprl = (rlen/64)*64; + clr_code = 1; + compress_bitmap(&temprl, &cbmap, + &nbits, crbb_bitmap, + &cstrtbits, &cstrtocts, + clr_code); + } + temprl = MOD64(rlen); + compress_bitmap(&temprl, &cbmap, + &nbits, crbb_bitmap, + &cstrtbits, &cstrtocts, clr_code); + + /* next time the run length will be Zeros */ + run_len_bit = 0; + } + uclen = uclen + (rlen); + clen = clen + nbits; + } + *cmp_bmplen = clen;
+ if (clen >= uclen) { + /* No Gain is observed, So no need to compress, copy original + * bitmap in uncompressed bitmap + */ + return 0; + } else { + /* Add compressed bitmap to final buffer */ + return 1; + } +}
Hi.
Thanks for your contribution. Could you please elaborate on the intent of this function? Can we replace existing osmo_t4_encode() with it? Having couple of test cases would be helpful in understanding what this function do and how it's supposed to be used.
On 04/11/2016 02:48 PM, sangamesh sajjan wrote:
This patch includes the changes for compression algorithm and the compression is carried out using T.4 run length coding and the code words used are based on 3GPP 44.060
include/osmocom/core/bitcomp.h | 7 +++ src/bitcomp.c | 129 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 136 insertions(+)
diff --git a/include/osmocom/core/bitcomp.h b/include/osmocom/core/bitcomp.h index 89eccbc..c5c223c 100644 --- a/include/osmocom/core/bitcomp.h +++ b/include/osmocom/core/bitcomp.h @@ -39,4 +39,11 @@ int osmo_t4_encode(struct bitvec *bv); int osmo_t4_decode(const struct bitvec *in, bool cc, struct bitvec *out);
+#define MOD64(X) ((X + 64) & 0x3F) +int osmo_bitmap_compress(
struct bitvec *rbb_vec,uint16_t *ucmp_bmplen, //Uncompressed bitmap lenuint8_t *cmp_bmplen, //Compressed bitmap lenuint8_t *crbb_bitmap //Compressed bitmap);/*! @} */ diff --git a/src/bitcomp.c b/src/bitcomp.c index bf35927..f3326b2 100644 --- a/src/bitcomp.c +++ b/src/bitcomp.c @@ -476,5 +476,134 @@ int osmo_t4_encode(struct bitvec *bv) } return -1; } +void compress_bitmap(
uint16_t *run_len_cnt, /* cnt: run length count */uint16_t *codewrd_bitmap, /* code word */uint8_t *codewrd_len, /* number of bits in the code word */uint8_t *cbmbuf, /* bitmap buffer to put code word in */uint16_t *cstrtbits, /* start bits to put codeword. start from* 0, the first bit in the first octets* and increment without octets* consideration. i.e. can be more than 7.*/uint8_t *cstrtocts, /* start octets to put codeword. start from 0*/uint8_t clr_code)+{
- int i = 0;
- uint16_t bitsleft = 0;
- uint16_t temp = 0;
- *codewrd_bitmap = 0;
- *codewrd_len = 0;
- if ((*run_len_cnt) >= 64) {
for (i = 0; i < 15; i++) {if (t4_make_up_ind[i] == *run_len_cnt) {*codewrd_bitmap = t4_make_up[clr_code][i];*codewrd_len = t4_make_up_length[clr_code][i];}}- } else {
*codewrd_bitmap = t4_term[clr_code][*run_len_cnt];*codewrd_len = t4_term_length[clr_code][*run_len_cnt];- }
- bitsleft = *codewrd_len;
- /* Move the codeword_bitmap to left in two bytes*/
- (*codewrd_bitmap) = (*codewrd_bitmap)<<(16-(*codewrd_len));
- while (bitsleft != 0) {
/* Bring left most bits to right and start shifting by cstrtbits,* we get each bit to update in compressed buffer*/temp = (((*codewrd_bitmap) & 0x8000)>>15)<<(7-(*cstrtbits));cbmbuf[*cstrtocts] = cbmbuf[*cstrtocts]|temp;(*codewrd_bitmap) = (*codewrd_bitmap)<<1;(*cstrtbits)++;bitsleft--;if ((*cstrtbits) >= 8) {(*cstrtbits) = (*cstrtbits)-8;(*cstrtocts)++;/* init buf */cbmbuf[*cstrtocts] = 0x00;}- }
+}
+int osmo_bitmap_compress(
struct bitvec *rbb_vec,uint16_t *ucmp_bmplen, /* Uncompressed bitmap len */uint8_t *cmp_bmplen, /* Compressed bitmap len */uint8_t *crbb_bitmap /* Compressed bitmap */)+{
char run_len_bit;
int buflen = *ucmp_bmplen;
uint16_t rlen;
uint16_t temprl = 0;
uint16_t cbmap; /* Compressed code word */
uint8_t nbits; /* Length of code word */
uint16_t cstrtbits = 0;
uint8_t cstrtocts = 0;
uint16_t uclen = 0;
uint8_t clen = 0;
uint8_t clr_code = 0;
run_len_bit = (rbb_vec->data[0] & 0x80)>>7;
while (buflen > 0) {
temprl = 0;/* Find Run length */if (run_len_bit == 1)rlen = bitvec_rl(rbb_vec, true);elserlen = bitvec_rl(rbb_vec, false);buflen = buflen - rlen;/* if rlen> 64 need 2 code words *///Compress the bitsif (run_len_bit == 0) {if (rlen >= 64) {temprl = (rlen/64)*64;compress_bitmap(&temprl, &cbmap, &nbits,crbb_bitmap, &cstrtbits,&cstrtocts, clr_code);}temprl = MOD64(rlen);compress_bitmap(&temprl,&cbmap, &nbits, crbb_bitmap,&cstrtbits, &cstrtocts, clr_code);/* next time the run length will be Ones */run_len_bit = 1;} else {if (rlen >= 64) {temprl = (rlen/64)*64;clr_code = 1;compress_bitmap(&temprl, &cbmap,&nbits, crbb_bitmap,&cstrtbits, &cstrtocts,clr_code);}temprl = MOD64(rlen);compress_bitmap(&temprl, &cbmap,&nbits, crbb_bitmap,&cstrtbits, &cstrtocts, clr_code);/* next time the run length will be Zeros */run_len_bit = 0;}uclen = uclen + (rlen);clen = clen + nbits;}
*cmp_bmplen = clen;
if (clen >= uclen) {
/* No Gain is observed, So no need to compress, copy original* bitmap in uncompressed bitmap*/return 0;} else {
/* Add compressed bitmap to final buffer */return 1;}
+}
osmocom-net-gprs@lists.osmocom.org
-
Max -
sangamesh sajjan