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Holger Freyther gerrit-no-reply at lists.osmocom.org
Review at https://gerrit.osmocom.org/1176
bitcomp: Remove the t4 decoding from libosmocore
As outlined 13.07.2016 the tree based approach in the PCU
is magnitude more quick in decoding. Instead of having a
slow one in the library and a quick one in the app, let's
have a quick one in the app and at some point (after it has
matured) move it to libosmocore.
Execute the plan and remove t4_decode.
Change-Id: I021424444625a097560d086c217c81eac4a5ee44
---
M include/osmocom/core/bitcomp.h
M src/bitcomp.c
M tests/bits/bitcomp_test.c
M tests/bits/bitcomp_test.ok
4 files changed, 0 insertions(+), 151 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/76/1176/1
diff --git a/include/osmocom/core/bitcomp.h b/include/osmocom/core/bitcomp.h
index 89eccbc..e87c0e1 100644
--- a/include/osmocom/core/bitcomp.h
+++ b/include/osmocom/core/bitcomp.h
@@ -37,6 +37,5 @@
int osmo_t4_encode(struct bitvec *bv);
-int osmo_t4_decode(const struct bitvec *in, bool cc, struct bitvec *out);
/*! @} */
diff --git a/src/bitcomp.c b/src/bitcomp.c
index 8b3090e..9c01246 100644
--- a/src/bitcomp.c
+++ b/src/bitcomp.c
@@ -180,18 +180,10 @@
{8, 6, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}
};
-static const unsigned t4_min_term_length[] = {2, 4};
-static const unsigned t4_min_make_up_length[] = {10, 5};
-
-static const unsigned t4_max_term_length[] = {12, 8};
-static const unsigned t4_max_make_up_length[] = {13, 9};
-
static const unsigned t4_make_up_length[2][15] = {
{10, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13},
{5, 5, 6, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9}
};
-
-static const unsigned t4_make_up_ind[15] = {64, 128, 192, 256, 320, 384, 448, 512, 576, 640, 704, 768, 832, 896, 960};
static const unsigned t4_make_up[2][15] = {
{
@@ -229,30 +221,6 @@
0b011010100
}
};
-
-/*! \brief Attempt to decode compressed bit vector
- *
- * \return length of RLE according to modified ITU-T T.4 from TS 44.060
- * Table 9.1.10.2 or -1 if no applicable RLE found N. B: we need
- * explicit bit length to make decoding unambiguous
-*/
-static inline int t4_rle_term(unsigned w, bool b, unsigned bits)
-{
- unsigned i;
- for (i = 0; i < 64; i++)
- if (w == t4_term[b][i] && bits == t4_term_length[b][i])
- return i;
- return -1;
-}
-
-static inline int t4_rle_makeup(unsigned w, bool b, unsigned bits)
-{
- unsigned i;
- for (i = 0; i < 15; i++)
- if (w == t4_make_up[b][i] && bits == t4_make_up_length[b][i])
- return t4_make_up_ind[i];
- return -1;
-}
/*! \brief Make-up codes for a given length
*
@@ -337,102 +305,6 @@
}
return bitvec_set_uint(bv, t4_term[b][len], t4_term_length[b][len]);
-}
-
-enum dec_state {
- EXPECT_TERM,
- TOO_LONG,
- NEED_MORE_BITS,
- CORRUPT,
- OK
-};
-
-static inline enum dec_state _t4_step(struct bitvec *v, uint16_t w, bool b, unsigned bits, bool term_only)
-{
- if (bits > t4_max_make_up_length[b])
- return TOO_LONG;
- if (bits < t4_min_term_length[b])
- return NEED_MORE_BITS;
-
- if (term_only) {
- if (bits > t4_max_term_length[b])
- return CORRUPT;
- int t = t4_rle_term(w, b, bits);
- if (-1 != t) {
- bitvec_fill(v, t, b ? ONE : ZERO);
- return OK;
- }
- return NEED_MORE_BITS;
- }
-
- int m = t4_rle_makeup(w, b, bits);
- if (-1 != m) {
- bitvec_fill(v, m, b ? ONE : ZERO);
- return EXPECT_TERM;
- }
-
- m = t4_rle_term(w, b, bits);
- if (-1 != m) {
- bitvec_fill(v, m, b ? ONE : ZERO);
- return OK;
- }
-
- return NEED_MORE_BITS;
-}
-
-/*! \brief decode T4-encoded bit vector
- * Assumes MSB first encoding.
- * \param[in] in bit vector with encoded data
- * \param[in] cc color code (whether decoding should start with 1 or 0)
- * \param[out] out the bit vector to store result into
- * \return 0 on success, negative value otherwise
- */
-int osmo_t4_decode(const struct bitvec *in, bool cc, struct bitvec *out)
-{
- uint8_t orig[in->data_len];
- struct bitvec vec;
- vec.data = orig;
- vec.data_len = in->data_len;
- bitvec_zero(&vec);
- memcpy(vec.data, in->data, in->data_len);
- vec.cur_bit = in->cur_bit;
-
- /* init decoder using known color code: */
- unsigned bits = t4_min_term_length[cc];
- enum dec_state d;
- int16_t w = bitvec_get_int16_msb(&vec, bits);
- bool b = cc;
- bool term_only = false;
-
- while (vec.cur_bit > 0) {
- d = _t4_step(out, w, b, bits, term_only);
-
- switch (d) {
- case EXPECT_TERM:
- bitvec_shiftl(&vec, bits);
- bits = t4_min_term_length[b];
- w = bitvec_get_int16_msb(&vec, bits);
- term_only = true;
- break;
- case OK:
- bitvec_shiftl(&vec, bits);
- bits = t4_min_term_length[!b];
- w = bitvec_get_int16_msb(&vec, bits);
- b = !b;
- term_only = false;
- break;
- case NEED_MORE_BITS:
- bits++;
- w = bitvec_get_int16_msb(&vec, bits);
- break;
- case TOO_LONG:
- return -E2BIG;
- case CORRUPT:
- return -EINVAL;
- }
- }
-
- return 0;
}
/*! \brief encode bit vector in-place using T4 encoding
diff --git a/tests/bits/bitcomp_test.c b/tests/bits/bitcomp_test.c
index f6895cf..587dd72 100644
--- a/tests/bits/bitcomp_test.c
+++ b/tests/bits/bitcomp_test.c
@@ -41,11 +41,6 @@
bitvec_set_uint(&bv, 4, 3);
bitvec_to_string_r(&bv, lol);
printf(" %s [%d]\n", lol, bv.cur_bit);
- int d = osmo_t4_decode(&bv, 0, &out);
- printf("\nDecoded:\n%d", d);
- bitvec_to_string_r(&out, lol);
- printf("%s [%d]\n", lol, out.cur_bit);
- printf("Expected:\n 00110111 01000111 10000001 1111 \n");
printf("\nTEST2:\n 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00\n");
bitvec_zero(&bv);
@@ -54,13 +49,6 @@
bitvec_set_uint(&bv, 0xFFFFFC00, 26); bitvec_to_string_r(&bv, lol); printf("%s", lol);
printf("\nEncoded:\n%d", osmo_t4_encode(&bv)); bitvec_to_string_r(&bv, lol); printf("%s", lol);
printf(" [%d]\nExpected:\n1 11011101 01000001 00 [18]\n", bv.cur_bit);
-
- bitvec_zero(&out);
- d = osmo_t4_decode(&bv, 1, &out);
- printf("\nDecoded:\n%d", d);
- bitvec_to_string_r(&out, lol);
- printf("%s [%d]\n", lol, out.cur_bit);
- printf("Expected:\n 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00\n");
return 0;
}
diff --git a/tests/bits/bitcomp_test.ok b/tests/bits/bitcomp_test.ok
index 238f3c4..d2ac16a 100644
--- a/tests/bits/bitcomp_test.ok
+++ b/tests/bits/bitcomp_test.ok
@@ -10,11 +10,6 @@
0 11011110 10001000 01110101 01100101 100 [35]
11011110 10001000 01110101 01100101 100 [35]
-Decoded:
-0 00110111 01000111 10000001 1111 [28]
-Expected:
- 00110111 01000111 10000001 1111
-
TEST2:
11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00
11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00
@@ -22,8 +17,3 @@
1 11011101 01000001 00 [18]
Expected:
1 11011101 01000001 00 [18]
-
-Decoded:
-0 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00 [90]
-Expected:
- 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 00000000 00
--
To view, visit https://gerrit.osmocom.org/1176
To unsubscribe, visit https://gerrit.osmocom.org/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I021424444625a097560d086c217c81eac4a5ee44
Gerrit-PatchSet: 1
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Holger Freyther <holger at freyther.de>