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lib: add support for Classic CAN raw DLC values

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ISO 11898-1 Chapter 8.4.2.3 defines a 4 bit data length code (DLC) table which
maps the DLC to the payload length of the CAN frame in bytes:

    DLC      ->  payload length
    0 .. 8   ->  0 .. 8
    9 .. 15  ->  8

To access the raw DLC values 9 .. 15 the len8_dlc element is introduced, which
is only valid when the payload length 'len' is 8 and the DLC is greater than 8.

The extension for len8_dlc has been implemented for the Classic CAN frame
representation in the log file format and for the standard output for
candump where the raw DLC value is printed in 'unusual' curly braces {}.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
This commit is contained in:
Oliver Hartkopp
2020-11-22 18:59:53 +01:00
parent c398e56afb
commit b70d8c050f
2 changed files with 76 additions and 12 deletions
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lib.c
+63 -5
View File
@@ -53,6 +53,7 @@
#include "lib.h"
#define CANID_DELIM '#'
#define CC_DLC_DELIM '_'
#define DATA_SEPERATOR '.'
const char hex_asc_upper[] = "0123456789ABCDEF";
@@ -195,9 +196,19 @@ int parse_canframe(char *cs, struct canfd_frame *cf) {
cf->can_id |= CAN_RTR_FLAG;
/* check for optional DLC value for CAN 2.0B frames */
if(cs[++idx] && (tmp = asc2nibble(cs[idx])) <= CAN_MAX_DLC)
if(cs[++idx] && (tmp = asc2nibble(cs[idx++])) <= CAN_MAX_DLEN) {
cf->len = tmp;
/* check for optional raw DLC value for CAN 2.0B frames */
if ((tmp == CAN_MAX_DLEN) && (cs[idx++] == CC_DLC_DELIM)) {
tmp = asc2nibble(cs[idx]);
if ((tmp > CAN_MAX_DLEN) && (tmp <= CAN_MAX_RAW_DLC)) {
struct can_frame *ccf = (struct can_frame *)cf;
ccf->len8_dlc = tmp;
}
}
}
return ret;
}
@@ -232,6 +243,17 @@ int parse_canframe(char *cs, struct canfd_frame *cf) {
}
cf->len = dlen;
/* check for extra DLC when having a Classic CAN with 8 bytes payload */
if ((maxdlen == CAN_MAX_DLEN) && (dlen == CAN_MAX_DLEN) && (cs[idx++] == CC_DLC_DELIM)) {
unsigned char dlc = asc2nibble(cs[idx]);
if ((dlc > CAN_MAX_DLEN) && (dlc <= CAN_MAX_RAW_DLC)) {
struct can_frame *ccf = (struct can_frame *)cf;
ccf->len8_dlc = dlc;
}
}
return ret;
}
@@ -270,9 +292,20 @@ void sprint_canframe(char *buf , struct canfd_frame *cf, int sep, int maxdlen) {
if (maxdlen == CAN_MAX_DLEN && cf->can_id & CAN_RTR_FLAG) {
buf[offset++] = 'R';
/* print a given CAN 2.0B DLC if it's not zero */
if (cf->len && cf->len <= CAN_MAX_DLC)
if (cf->len && cf->len <= CAN_MAX_DLEN) {
buf[offset++] = hex_asc_upper_lo(cf->len);
/* check for optional raw DLC value for CAN 2.0B frames */
if (cf->len == CAN_MAX_DLEN) {
struct can_frame *ccf = (struct can_frame *)cf;
if ((ccf->len8_dlc > CAN_MAX_DLEN) && (ccf->len8_dlc <= CAN_MAX_RAW_DLC)) {
buf[offset++] = CC_DLC_DELIM;
buf[offset++] = hex_asc_upper_lo(ccf->len8_dlc);
}
}
}
buf[offset] = 0;
return;
}
@@ -292,6 +325,17 @@ void sprint_canframe(char *buf , struct canfd_frame *cf, int sep, int maxdlen) {
buf[offset++] = '.';
}
/* check for extra DLC when having a Classic CAN with 8 bytes payload */
if ((maxdlen == CAN_MAX_DLEN) && (len == CAN_MAX_DLEN)) {
struct can_frame *ccf = (struct can_frame *)cf;
unsigned char dlc = ccf->len8_dlc;
if ((dlc > CAN_MAX_DLEN) && (dlc <= CAN_MAX_RAW_DLC)) {
buf[offset++] = CC_DLC_DELIM;
buf[offset++] = hex_asc_upper_lo(dlc);
}
}
buf[offset] = 0;
}
@@ -337,9 +381,23 @@ void sprint_long_canframe(char *buf , struct canfd_frame *cf, int view, int maxd
/* The len value is sanitized by maxdlen (see above) */
if (maxdlen == CAN_MAX_DLEN) {
buf[offset + 1] = '[';
buf[offset + 2] = len + '0';
buf[offset + 3] = ']';
if (view & CANLIB_VIEW_LEN8_DLC) {
struct can_frame *ccf = (struct can_frame *)cf;
unsigned char dlc = ccf->len8_dlc;
/* fall back to len if we don't have a valid DLC > 8 */
if (!((len == CAN_MAX_DLEN) && (dlc > CAN_MAX_DLEN) &&
(dlc <= CAN_MAX_RAW_DLC)))
dlc = len;
buf[offset + 1] = '{';
buf[offset + 2] = hex_asc_upper[dlc];
buf[offset + 3] = '}';
} else {
buf[offset + 1] = '[';
buf[offset + 2] = len + '0';
buf[offset + 3] = ']';
}
/* standard CAN frames may have RTR enabled */
if (cf->can_id & CAN_RTR_FLAG) {