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The following commit(s) were added to refs/heads/master by this push:
new a01518ce6 util/crc: Add option for crc16_ccitt without table
a01518ce6 is described below
commit a01518ce681b89b5925233c762920474acdb1c5c
Author: Jerzy Kasenberg <[email protected]>
AuthorDate: Sun Jun 30 12:58:30 2024 +0200
util/crc: Add option for crc16_ccitt without table
This adds crc16_ccitt() version without table.
It makes it slower but can reduce flash usage
about 512 bytes.
Default still uses table but can be disabled
with UTIL_CRC_CRC16_CCITT_USE_TABLE: 0
Signed-off-by: Jerzy Kasenberg <[email protected]>
---
util/crc/src/crc16.c | 24 +++++++++++++++++++++++-
util/crc/syscfg.yml | 23 +++++++++++++++++++++++
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/util/crc/src/crc16.c b/util/crc/src/crc16.c
index 6ece41909..fce23a068 100644
--- a/util/crc/src/crc16.c
+++ b/util/crc/src/crc16.c
@@ -26,10 +26,12 @@
*/
#include <inttypes.h>
+#include <syscfg/syscfg.h>
#include "crc/crc16.h"
-/* CRC16 implementation acording to CCITT standards */
+/* CRC16 implementation according to CCITT standards */
+#if MYNEWT_VAL(UTIL_CRC_CRC16_CCITT_USE_TABLE)
static const uint16_t crc16tab[256]= {
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
@@ -81,3 +83,23 @@ crc16_ccitt(uint16_t initial_crc, const void *buf, int len)
return crc;
}
+
+#else
+
+uint16_t
+crc16_ccitt(uint16_t initial_crc, const void *buf, int len)
+{
+ uint8_t x;
+ uint16_t crc = initial_crc;
+ const uint8_t *ptr = buf;
+ int i;
+
+ for (i = 0; i < len; ++i) {
+ x = (crc >> 8) ^ ptr[i];
+ x ^= x >> 4;
+ crc = (crc << 8) ^ ((uint16_t)(x << 12)) ^ ((uint16_t)(x << 5)) ^
((uint16_t)x);
+ }
+ return crc;
+}
+
+#endif
diff --git a/util/crc/syscfg.yml b/util/crc/syscfg.yml
new file mode 100644
index 000000000..e6231abd8
--- /dev/null
+++ b/util/crc/syscfg.yml
@@ -0,0 +1,23 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+syscfg.defs:
+ UTIL_CRC_CRC16_CCITT_USE_TABLE:
+ description: >
+ Use table for calculation CRC to make it faster.
+ Set it 0 to reduce code size.
+ value: 1
