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modbus: Get rid of custom CRC16 function

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In previous commits the crc16_ansi() function has been made compliant
with the CRC-16-ANSI aka CRC-16-MODBUS standard. Use that standard
function instead of a custom one.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This commit is contained in:
Carles Cufi 2022-02-03 16:51:46 +01:00 • committed by Anas Nashif
commit d0ebeee0aa
1 changed files with 4 additions and 35 deletions
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39
subsys/modbus/modbus_serial.c
View file

@ -26,6 +26,7 @@ LOG_MODULE_REGISTER(modbus_serial, CONFIG_MODBUS_LOG_LEVEL);
#include <kernel.h>
#include <string.h>
#include <sys/byteorder.h>
#include <sys/crc.h>
#include <modbus_internal.h>
static void modbus_serial_tx_on(struct modbus_context *ctx)
@ -238,37 +239,6 @@ static void modbus_ascii_tx_adu(struct modbus_context *ctx)
}
#endif
static uint16_t modbus_rtu_crc16(uint8_t *src, size_t length)
{
uint16_t crc = 0xFFFF;
uint8_t shiftctr;
bool flag;
uint8_t *pblock = src;
while (length > 0) {
length--;
crc ^= (uint16_t)*pblock++;
shiftctr = 8;
do {
/* Determine if the shift out of rightmost bit is 1 */
flag = (crc & 0x0001) ? true : false;
/* Shift CRC to the right one bit. */
crc >>= 1;
/*
* If bit shifted out of rightmost bit was a 1
* exclusive OR the CRC with the generating polynomial.
*/
if (flag == true) {
crc ^= MODBUS_CRC16_POLY;
}
shiftctr--;
} while (shiftctr > 0);
}
return crc;
}
/* Copy Modbus RTU frame and check if the CRC is valid. */
static int modbus_rtu_rx_adu(struct modbus_context *ctx)
{
@ -296,8 +266,8 @@ static int modbus_rtu_rx_adu(struct modbus_context *ctx)
ctx->rx_adu.crc = sys_get_le16(&cfg->uart_buf[crc_idx]);
/* Calculate CRC over address, function code, and payload */
calc_crc = modbus_rtu_crc16(&cfg->uart_buf[0],
cfg->uart_buf_ctr - sizeof(ctx->rx_adu.crc));
calc_crc = crc16_ansi(&cfg->uart_buf[0],
cfg->uart_buf_ctr - sizeof(ctx->rx_adu.crc));
if (ctx->rx_adu.crc != calc_crc) {
LOG_WRN("Calculated CRC does not match received CRC");
@ -320,8 +290,7 @@ static void rtu_tx_adu(struct modbus_context *ctx)
memcpy(data_ptr, ctx->tx_adu.data, ctx->tx_adu.length);
ctx->tx_adu.crc = modbus_rtu_crc16(&cfg->uart_buf[0],
ctx->tx_adu.length + 2);
ctx->tx_adu.crc = crc16_ansi(&cfg->uart_buf[0], ctx->tx_adu.length + 2);
sys_put_le16(ctx->tx_adu.crc,
&cfg->uart_buf[ctx->tx_adu.length + 2]);
tx_bytes += 2;