judsonupchurch/nanoMODBUS
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Expose the function that calculates CRC

Browse Source 
Having access to this function is useful in a variety of cases:

- hand-crafting PDUs for unit tests
- implementing extensions of the protocol
- reusing the code for other purposes (e.g. firmware integrity check)
This commit is contained in:
jonath.re@gmail.com 2022-06-25 17:17:34 +02:00
parent ca0dd3bab3
commit f22b06082e
2 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
nanomodbus.c
View File

@ -175,7 +175,7 @@ void nmbs_set_platform_arg(nmbs_t* nmbs, void* arg) {
}
static uint16_t crc_calc(const uint8_t* data, uint32_t length) {
uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length) {
uint16_t crc = 0xFFFF;
for (uint32_t i = 0; i < length; i++) {
crc ^= (uint16_t) data[i];
@ -232,7 +232,7 @@ static nmbs_error recv_msg_footer(nmbs_t* nmbs) {
DEBUG("\n");
if (nmbs->platform.transport == NMBS_TRANSPORT_RTU) {
uint16_t crc = crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
uint16_t crc = nmbs_crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
nmbs_error err = recv(nmbs, 2);
if (err != NMBS_ERROR_NONE)
@ -402,7 +402,7 @@ static nmbs_error send_msg(nmbs_t* nmbs) {
DEBUG("\n");
if (nmbs->platform.transport == NMBS_TRANSPORT_RTU) {
uint16_t crc = crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
uint16_t crc = nmbs_crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
put_2(nmbs, crc);
}

6
nanomodbus.h
View File

@ -226,6 +226,12 @@ void nmbs_set_byte_timeout(nmbs_t* nmbs, int32_t timeout_ms);
*/
void nmbs_set_platform_arg(nmbs_t* nmbs, void* arg);
/** Calculate the Modbus CRC of some data.
* @param data Data
* @param length Length of the data
*/
uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length);
#ifndef NMBS_CLIENT_DISABLED
/** Set the recipient server address of the next request on RTU transport.
* @param nmbs pointer to the nmbs_t instance