modem: cmux: Implement Modem Status Command #97569
Open
+211
−22
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Implement Modem Status Command(MSC) and a per DLC flow control by using it. Send flow control signals when our input buffer don't fit full frame anymore. Stop TX if we have received from controls on MSC. Signed-off-by: Seppo Takalo <[email protected]>
zephyrbot
added
area: Tests
|
bjarki-andreasen
requested changes
Oct 15, 2025
Comment on lines
+86
to
+94
| struct modem_cmux_msc_signals { | ||
| uint8_t ea: 1; /**< Last octet, always 1 */ | ||
| uint8_t fc: 1; /**< Flow Control */ | ||
| uint8_t rtc: 1; /**< Ready to Communicate */ | ||
| uint8_t rtr: 1; /**< Ready to Transmit */ | ||
| uint8_t res_0: 2; /**< Reserved, set to zero */ | ||
| uint8_t ic: 1; /**< Incoming call indicator */ | ||
| uint8_t dv: 1; /**< Data Valid */ | ||
| }; |
There was a problem hiding this comment.
We can not serialize data using bitfields, the order of bitfields is compiler specific, so one compiler may put ea at bit 0, another at bit 7. We can store the bits in a struct like this, but when serializing them, we need explicit bitshifting
There was a problem hiding this comment.
I see.
I had to check from C11 standard section 6.7.2.1
11 An implementation may allocate any addressable storage unit large enough to hold a bitfield.
If enough space remains, a bit-field that immediately follows another bit-field in a
structure shall be packed into adjacent bits of the same unit. If insufficient space remains,
whether a bit-field that does not fit is put into the next unit or overlaps adjacent units is
implementation-defined. The order of allocation of bit-fields within a unit (high-order to
low-order or low-order to high-order) is implementation-defined. The alignment of the
addressable storage unit is unspecified.
So you are right, this "implementation defined" might change between CPU targets even within the same compiler, so I'll rework this PR.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Implement Modem Status Command(MSC) and a per DLC flow control by using it.
Send flow control signals when our input buffer don't fit full frame anymore.
Stop TX if we have received from controls on MSC.