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Re: Microcontroller software stacks (was Re: this girl calls c ugly)

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  Re: Microcontroller software stacks (was Re: this girl calls c ugly) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-06-21 14:13 -0700
    Re: Microcontroller software stacks (was Re: this girl calls c ugly) David Brown <david.brown@hesbynett.no> - 2026-06-22 08:58 +0200
      Re: Microcontroller software stacks (was Re: this girl calls c ugly) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-22 03:35 -0700
        Re: Microcontroller software stacks (was Re: this girl calls c ugly) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-06-22 10:50 +0000
        Re: Microcontroller software stacks (was Re: this girl calls c ugly) David Brown <david.brown@hesbynett.no> - 2026-06-22 12:59 +0200
        Storage needed when there are bit-field members Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-06-28 09:42 -0700
          Re: Storage needed when there are bit-field members Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-28 18:06 -0700
            Re: Storage needed when there are bit-field members Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-28 20:20 -0700
              Re: Storage needed when there are bit-field members Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-14 14:56 -0700
                Re: Storage needed when there are bit-field members scott@slp53.sl.home (Scott Lurndal) - 2026-08-14 22:30 +0000
                  Re: Storage needed when there are bit-field members Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-15 16:10 -0700
                    Re: Storage needed when there are bit-field members scott@slp53.sl.home (Scott Lurndal) - 2026-08-16 15:20 +0000
            Re: Storage needed when there are bit-field members Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-14 14:19 -0700
    Re: Microcontroller software stacks (was Re: this girl calls c ugly) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-06-22 10:45 +0000
      Re: Microcontroller software stacks (was Re: this girl calls c ugly) scott@slp53.sl.home (Scott Lurndal) - 2026-06-22 15:23 +0000
      Re: Microcontroller software stacks (was Re: this girl calls c ugly) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-14 13:23 -0700
        Re: Microcontroller software stacks (was Re: this girl calls c ugly) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-18 20:32 +0000
    Re: Microcontroller software stacks (was Re: this girl calls c ugly) scott@slp53.sl.home (Scott Lurndal) - 2026-06-22 15:04 +0000
      Re: Microcontroller software stacks (was Re: this girl calls c ugly) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-06-22 13:02 -0700
      Re: Microcontroller software stacks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-14 12:51 -0700
        Re: Microcontroller software stacks Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-15 05:02 +0800
          Re: Microcontroller software stacks bart <bc@freeuk.com> - 2026-08-15 01:18 +0100
            Re: Microcontroller software stacks Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-16 13:52 +0800
        Re: Microcontroller software stacks Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-14 14:06 -0700
        Re: Microcontroller software stacks scott@slp53.sl.home (Scott Lurndal) - 2026-08-14 21:42 +0000
          Re: Microcontroller software stacks Michael S <already5chosen@yahoo.com> - 2026-08-15 22:13 +0300
            Re: Microcontroller software stacks scott@slp53.sl.home (Scott Lurndal) - 2026-08-15 19:39 +0000
              Re: Microcontroller software stacks Michael S <already5chosen@yahoo.com> - 2026-08-15 23:22 +0300
                Re: Microcontroller software stacks scott@slp53.sl.home (Scott Lurndal) - 2026-08-16 14:38 +0000
                  Re: Microcontroller software stacks Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-16 16:11 -0700
          Re: Microcontroller software stacks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-15 16:16 -0700
            Re: Microcontroller software stacks cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-18 20:34 +0000
          Re: Microcontroller software stacks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-15 17:31 -0700

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#401184 — Re: Microcontroller software stacks

On 15/08/2026 3:51 AM, Tim Rentsch wrote:
> scott@slp53.sl.home (Scott Lurndal) writes:
> 
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>
>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>
>>>> One might also define data structures for control and status
>>>> registers using bitfield structs.
>>>
>>> Yeah.  This kind of application (among others) I consider one of
>>> the motivating forces behind bitfields.
>>>
>>> [Some whitespace trimming done in the excerpt below.]
>>>
>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>
>>>> union UAHC_GBL_OOBR {
>>>>    uint32_t u;
>>>>    struct UAHC_GBL_OOBR_s {
>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>      uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>      uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>      uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>      uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>      uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>> #else
>>>>      uint32_t cimax  :  8;
>>>>      uint32_t cimin  :  8;
>>>>      uint32_t cwmax  :  8;
>>>>      uint32_t cwmin  :  7;
>>>>      uint32_t we     :  1;
>>>> #endif
>>>>    } s;
>>>> };
>>>
>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>> I would just use unsigned, which is just as sure to work as intended,
>>> isn't it?
>>
>> The SATA hardware register is defined as a 32-bit register in the
>> SATA specification.  Therefore we explicitly declare it as such.
> 
> I understand the motivation for using uint32_t for the union member
> u.  My question is only about the type used for the bitfields.  Do
> you know of any platform, or even suspect that there might be a
> platform, where using 'unsigned' rather than 'uint32_t' for the type
> of the bitfields makes any difference at all?

Yes, people still code real mode DOS for fun and amusement.  Not to
mention boot strapping code for /real operating systems/, for some value
of /real/.

On 6502, int is 16bit, I believe, for reasons.  And I also believe it
makes total sense to keep int 16bit on a 68000.

> 
>> There are other hardware registers in our implementation of the SATA
>> controller that are defined as 64-bit registers, for those we use
>> uint64_t (rather than relying on 'unsigned long' for 64-bit linux
>> or 'unsigned long long' for 32-bit OS - and this code was designed
>> to be compiled for both 32-bit and 64-bit targets originally).
> 
> Sure, for the non-bitfield member.  My question is only about
> (unsigned) bitfields all of width 8 or less.

I'm ignorant of the prior discussion, so I'll stop now; happy retro-
coding!
-- 
Johann | email: invalid -> com | http://www.myrkraverk.com/blog/
I'm not from the Internet, I just work there. | via Easynews.com
https://bsky.app/profile/myrkraverk.bsky.social | for ( ;; ) _:;

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#401193 — Re: Microcontroller software stacks

On 14/08/2026 22:02, Johann 'Myrkraverk' Oskarsson wrote:
> On 15/08/2026 3:51 AM, Tim Rentsch wrote:
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>
>>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>>
>>>>> One might also define data structures for control and status
>>>>> registers using bitfield structs.
>>>>
>>>> Yeah.  This kind of application (among others) I consider one of
>>>> the motivating forces behind bitfields.
>>>>
>>>> [Some whitespace trimming done in the excerpt below.]
>>>>
>>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>>
>>>>> union UAHC_GBL_OOBR {
>>>>>    uint32_t u;
>>>>>    struct UAHC_GBL_OOBR_s {
>>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>>      uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>>      uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>>      uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>>      uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>>      uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>>> #else
>>>>>      uint32_t cimax  :  8;
>>>>>      uint32_t cimin  :  8;
>>>>>      uint32_t cwmax  :  8;
>>>>>      uint32_t cwmin  :  7;
>>>>>      uint32_t we     :  1;
>>>>> #endif
>>>>>    } s;
>>>>> };
>>>>
>>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>>> I would just use unsigned, which is just as sure to work as intended,
>>>> isn't it?
>>>
>>> The SATA hardware register is defined as a 32-bit register in the
>>> SATA specification.  Therefore we explicitly declare it as such.
>>
>> I understand the motivation for using uint32_t for the union member
>> u.  My question is only about the type used for the bitfields.  Do
>> you know of any platform, or even suspect that there might be a
>> platform, where using 'unsigned' rather than 'uint32_t' for the type
>> of the bitfields makes any difference at all?
> 
> Yes, people still code real mode DOS for fun and amusement.  Not to
> mention boot strapping code for /real operating systems/, for some value
> of /real/.
> 
> On 6502, int is 16bit, I believe, for reasons.  And I also believe it
> makes total sense to keep int 16bit on a 68000.
> 

WTF are you on about? If you're an actual human then I suggest getting 
some help. If not then where the hell does all this bilge come from?


>>> There are other hardware registers in our implementation of the SATA
>>> controller that are defined as 64-bit registers, for those we use
>>> uint64_t (rather than relying on 'unsigned long' for 64-bit linux
>>> or 'unsigned long long' for 32-bit OS - and this code was designed
>>> to be compiled for both 32-bit and 64-bit targets originally).
>>
>> Sure, for the non-bitfield member.  My question is only about
>> (unsigned) bitfields all of width 8 or less.
> 
> I'm ignorant of the prior discussion, so I'll stop now; happy retro-
> coding!

'Happy' - OK, CMT has finally convinced me!

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#401228 — Re: Microcontroller software stacks

On 15/08/2026 8:18 AM, bart wrote:
> On 14/08/2026 22:02, Johann 'Myrkraverk' Oskarsson wrote:
>> On 15/08/2026 3:51 AM, Tim Rentsch wrote:
>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>
>>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>>
>>>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>>>
>>>>>> One might also define data structures for control and status
>>>>>> registers using bitfield structs.
>>>>>
>>>>> Yeah.  This kind of application (among others) I consider one of
>>>>> the motivating forces behind bitfields.
>>>>>
>>>>> [Some whitespace trimming done in the excerpt below.]
>>>>>
>>>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>>>
>>>>>> union UAHC_GBL_OOBR {
>>>>>>    uint32_t u;
>>>>>>    struct UAHC_GBL_OOBR_s {
>>>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>>>      uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>>>      uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value 
>>>>>> [...] */
>>>>>>      uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value 
>>>>>> [...] */
>>>>>>      uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value 
>>>>>> [...] */
>>>>>>      uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value 
>>>>>> [...] */
>>>>>> #else
>>>>>>      uint32_t cimax  :  8;
>>>>>>      uint32_t cimin  :  8;
>>>>>>      uint32_t cwmax  :  8;
>>>>>>      uint32_t cwmin  :  7;
>>>>>>      uint32_t we     :  1;
>>>>>> #endif
>>>>>>    } s;
>>>>>> };
>>>>>
>>>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>>>> I would just use unsigned, which is just as sure to work as intended,
>>>>> isn't it?
>>>>
>>>> The SATA hardware register is defined as a 32-bit register in the
>>>> SATA specification.  Therefore we explicitly declare it as such.
>>>
>>> I understand the motivation for using uint32_t for the union member
>>> u.  My question is only about the type used for the bitfields.  Do
>>> you know of any platform, or even suspect that there might be a
>>> platform, where using 'unsigned' rather than 'uint32_t' for the type
>>> of the bitfields makes any difference at all?
>>
>> Yes, people still code real mode DOS for fun and amusement.  Not to
>> mention boot strapping code for /real operating systems/, for some value
>> of /real/.
>>
>> On 6502, int is 16bit, I believe, for reasons.  And I also believe it
>> makes total sense to keep int 16bit on a 68000.
>>
> 
> WTF are you on about? If you're an actual human then I suggest getting 
> some help. If not then where the hell does all this bilge come from?


Hey bart!  You fucking piece of shit asshole.  Tim asked a question.  I
answered it.  There is a difference between 'unsigned' and 'uint32_t' on
DOS, you fucking piece of shit know-nothing slob burger.

Now, if Tim decides real mode DOS is not a target for his own question,
then he should be answering with a polite followup, or spew his own
hatred, and not you, you miserable psychopath!


>>>> There are other hardware registers in our implementation of the SATA
>>>> controller that are defined as 64-bit registers, for those we use
>>>> uint64_t (rather than relying on 'unsigned long' for 64-bit linux
>>>> or 'unsigned long long' for 32-bit OS - and this code was designed
>>>> to be compiled for both 32-bit and 64-bit targets originally).
>>>
>>> Sure, for the non-bitfield member.  My question is only about
>>> (unsigned) bitfields all of width 8 or less.
>>
>> I'm ignorant of the prior discussion, so I'll stop now; happy retro-
>> coding!
> 
> 'Happy' - OK, CMT has finally convinced me!

Happy living in alt.fantasy, you fucking piece of shit!
-- 
Johann | email: invalid -> com | http://www.myrkraverk.com/blog/
I'm not from the Internet, I just work there. | via Easynews.com
https://bsky.app/profile/myrkraverk.bsky.social | for ( ;; ) _:;

[toc] | [prev] | [next] | [standalone]

#401186 — Re: Microcontroller software stacks

Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
[...]
> I understand the motivation for using uint32_t for the union member
> u.  My question is only about the type used for the bitfields.  Do
> you know of any platform, or even suspect that there might be a
> platform, where using 'unsigned' rather than 'uint32_t' for the type
> of the bitfields makes any difference at all?

On platforms where unsigned int is 32 bits, I'd be very surprised
if it made any difference.  If unsigned it is, say, 16 or 64 bits,
it can make a difference.

As I wrote here a while ago, "Implementions commonly use the declared
type of a bit-field to affect the layout, not necessarily of the
bit-field itself, but of the containing structure."  This was in
a thread with the subject "Storage needed when there are bit-field
members", in a followup to your post a few days after the article
to which you've just replied.

On the other hand, the standard only requires support for
bitfields of declared types int, signed int, unsigned int, and bool
(and bit-precise integer types in C23 and later); a conforming
implementation might not support bit-fields of type uint32_t.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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#401190 — Re: Microcontroller software stacks

Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>scott@slp53.sl.home (Scott Lurndal) writes:
>
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>
>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>
>>>> One might also define data structures for control and status
>>>> registers using bitfield structs.
>>>
>>> Yeah.  This kind of application (among others) I consider one of
>>> the motivating forces behind bitfields.
>>>
>>> [Some whitespace trimming done in the excerpt below.]
>>>
>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>
>>>> union UAHC_GBL_OOBR {
>>>>   uint32_t u;
>>>>   struct UAHC_GBL_OOBR_s {
>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>     uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>     uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>     uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>> #else
>>>>     uint32_t cimax  :  8;
>>>>     uint32_t cimin  :  8;
>>>>     uint32_t cwmax  :  8;
>>>>     uint32_t cwmin  :  7;
>>>>     uint32_t we     :  1;
>>>> #endif
>>>>   } s;
>>>> };
>>>
>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>> I would just use unsigned, which is just as sure to work as intended,
>>> isn't it?
>>
>> The SATA hardware register is defined as a 32-bit register in the
>> SATA specification.  Therefore we explicitly declare it as such.
>
>I understand the motivation for using uint32_t for the union member
>u.  My question is only about the type used for the bitfields.  Do
>you know of any platform, or even suspect that there might be a
>platform, where using 'unsigned' rather than 'uint32_t' for the type
>of the bitfields makes any difference at all?

I haven't canvassed all the available platforms, and don't have
any desire so to do.  In my opinion, using the same type for the
bitfield members as was used for the corresponding union
element is simply logical.   If we declare the integer part
of the union as uint64_t,  we use the same time for the
bitfields (and yes, we could have used unsigned long
(or unsigned long long on the micky OS) - uint64_t
is less typing.

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#401217 — Re: Microcontroller software stacks

On Fri, 14 Aug 2026 21:42:38 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> >scott@slp53.sl.home (Scott Lurndal) writes:
> >  
> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> >>  
> >>> scott@slp53.sl.home (Scott Lurndal) writes:
> >>>  
> >>>> One might also define data structures for control and status
> >>>> registers using bitfield structs.  
> >>>
> >>> Yeah.  This kind of application (among others) I consider one of
> >>> the motivating forces behind bitfields.
> >>>
> >>> [Some whitespace trimming done in the excerpt below.]
> >>>  
> >>>> e.g. for the SATA UAHC_GLB_OOBR register:
> >>>>
> >>>> union UAHC_GBL_OOBR {
> >>>>   uint32_t u;
> >>>>   struct UAHC_GBL_OOBR_s {
> >>>> #if __BYTE_ORDER == __BIG_ENDIAN
> >>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
> >>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value
> >>>> [...] */ uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum
> >>>> value [...] */ uint32_t cimin  :  8; /**< R/W/H - COMINIT
> >>>> minimum value [...] */ uint32_t cimax  :  8; /**< R/W/H -
> >>>> COMINIT maximum value [...] */ #else
> >>>>     uint32_t cimax  :  8;
> >>>>     uint32_t cimin  :  8;
> >>>>     uint32_t cwmax  :  8;
> >>>>     uint32_t cwmin  :  7;
> >>>>     uint32_t we     :  1;
> >>>> #endif
> >>>>   } s;
> >>>> };  
> >>>
> >>> To me it seems kind of goofy to use uint32_t for the bitfields
> >>> type. I would just use unsigned, which is just as sure to work as
> >>> intended, isn't it?  
> >>
> >> The SATA hardware register is defined as a 32-bit register in the
> >> SATA specification.  Therefore we explicitly declare it as such.  
> >
> >I understand the motivation for using uint32_t for the union member
> >u.  My question is only about the type used for the bitfields.  Do
> >you know of any platform, or even suspect that there might be a
> >platform, where using 'unsigned' rather than 'uint32_t' for the type
> >of the bitfields makes any difference at all?  
> 
> I haven't canvassed all the available platforms, and don't have
> any desire so to do.  In my opinion, using the same type for the
> bitfield members as was used for the corresponding union
> element is simply logical.   If we declare the integer part
> of the union as uint64_t,  we use the same time for the
> bitfields (and yes, we could have used unsigned long
> (or unsigned long long on the micky OS) - uint64_t
> is less typing.
> 

Why not plain 'unsigned' ?

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#401218 — Re: Microcontroller software stacks

Michael S <already5chosen@yahoo.com> writes:
>On Fri, 14 Aug 2026 21:42:38 GMT
>scott@slp53.sl.home (Scott Lurndal) wrote:
>
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>> >scott@slp53.sl.home (Scott Lurndal) writes:
>> >  
>> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>> >>  
>> >>> scott@slp53.sl.home (Scott Lurndal) writes:
>> >>>  
>> >>>> One might also define data structures for control and status
>> >>>> registers using bitfield structs.  
>> >>>
>> >>> Yeah.  This kind of application (among others) I consider one of
>> >>> the motivating forces behind bitfields.
>> >>>
>> >>> [Some whitespace trimming done in the excerpt below.]
>> >>>  
>> >>>> e.g. for the SATA UAHC_GLB_OOBR register:
>> >>>>
>> >>>> union UAHC_GBL_OOBR {
>> >>>>   uint32_t u;
>> >>>>   struct UAHC_GBL_OOBR_s {
>> >>>> #if __BYTE_ORDER == __BIG_ENDIAN
>> >>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>> >>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value
>> >>>> [...] */ uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum
>> >>>> value [...] */ uint32_t cimin  :  8; /**< R/W/H - COMINIT
>> >>>> minimum value [...] */ uint32_t cimax  :  8; /**< R/W/H -
>> >>>> COMINIT maximum value [...] */ #else
>> >>>>     uint32_t cimax  :  8;
>> >>>>     uint32_t cimin  :  8;
>> >>>>     uint32_t cwmax  :  8;
>> >>>>     uint32_t cwmin  :  7;
>> >>>>     uint32_t we     :  1;
>> >>>> #endif
>> >>>>   } s;
>> >>>> };  
>> >>>
>> >>> To me it seems kind of goofy to use uint32_t for the bitfields
>> >>> type. I would just use unsigned, which is just as sure to work as
>> >>> intended, isn't it?  
>> >>
>> >> The SATA hardware register is defined as a 32-bit register in the
>> >> SATA specification.  Therefore we explicitly declare it as such.  
>> >
>> >I understand the motivation for using uint32_t for the union member
>> >u.  My question is only about the type used for the bitfields.  Do
>> >you know of any platform, or even suspect that there might be a
>> >platform, where using 'unsigned' rather than 'uint32_t' for the type
>> >of the bitfields makes any difference at all?  
>> 
>> I haven't canvassed all the available platforms, and don't have
>> any desire so to do.  In my opinion, using the same type for the
>> bitfield members as was used for the corresponding union
>> element is simply logical.   If we declare the integer part
>> of the union as uint64_t,  we use the same time for the
>> bitfields (and yes, we could have used unsigned long
>> (or unsigned long long on the micky OS) - uint64_t
>> is less typing.
>> 
>
>Why not plain 'unsigned' ?
>

Did you not read the paragraph you are responding to?

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#401221 — Re: Microcontroller software stacks

On Sat, 15 Aug 2026 19:39:54 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:

> Michael S <already5chosen@yahoo.com> writes:
> >On Fri, 14 Aug 2026 21:42:38 GMT
> >scott@slp53.sl.home (Scott Lurndal) wrote:
> >  
> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:  
> >> >scott@slp53.sl.home (Scott Lurndal) writes:
> >> >    
> >> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> >> >>    
> >> >>> scott@slp53.sl.home (Scott Lurndal) writes:
> >> >>>    
> >> >>>> One might also define data structures for control and status
> >> >>>> registers using bitfield structs.    
> >> >>>
> >> >>> Yeah.  This kind of application (among others) I consider one
> >> >>> of the motivating forces behind bitfields.
> >> >>>
> >> >>> [Some whitespace trimming done in the excerpt below.]
> >> >>>    
> >> >>>> e.g. for the SATA UAHC_GLB_OOBR register:
> >> >>>>
> >> >>>> union UAHC_GBL_OOBR {
> >> >>>>   uint32_t u;
> >> >>>>   struct UAHC_GBL_OOBR_s {
> >> >>>> #if __BYTE_ORDER == __BIG_ENDIAN
> >> >>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
> >> >>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value
> >> >>>> [...] */ uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum
> >> >>>> value [...] */ uint32_t cimin  :  8; /**< R/W/H - COMINIT
> >> >>>> minimum value [...] */ uint32_t cimax  :  8; /**< R/W/H -
> >> >>>> COMINIT maximum value [...] */ #else
> >> >>>>     uint32_t cimax  :  8;
> >> >>>>     uint32_t cimin  :  8;
> >> >>>>     uint32_t cwmax  :  8;
> >> >>>>     uint32_t cwmin  :  7;
> >> >>>>     uint32_t we     :  1;
> >> >>>> #endif
> >> >>>>   } s;
> >> >>>> };    
> >> >>>
> >> >>> To me it seems kind of goofy to use uint32_t for the bitfields
> >> >>> type. I would just use unsigned, which is just as sure to work
> >> >>> as intended, isn't it?    
> >> >>
> >> >> The SATA hardware register is defined as a 32-bit register in
> >> >> the SATA specification.  Therefore we explicitly declare it as
> >> >> such.    
> >> >
> >> >I understand the motivation for using uint32_t for the union
> >> >member u.  My question is only about the type used for the
> >> >bitfields.  Do you know of any platform, or even suspect that
> >> >there might be a platform, where using 'unsigned' rather than
> >> >'uint32_t' for the type of the bitfields makes any difference at
> >> >all?    
> >> 
> >> I haven't canvassed all the available platforms, and don't have
> >> any desire so to do.  In my opinion, using the same type for the
> >> bitfield members as was used for the corresponding union
> >> element is simply logical.   If we declare the integer part
> >> of the union as uint64_t,  we use the same time for the
> >> bitfields (and yes, we could have used unsigned long
> >> (or unsigned long long on the micky OS) - uint64_t
> >> is less typing.
> >>   
> >
> >Why not plain 'unsigned' ?
> >  
> 
> Did you not read the paragraph you are responding to?

I missed the part about "using the same type". Sorry.
Now, when I read it ... no, I don't think that it is logical.

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#401230 — Re: Microcontroller software stacks

Michael S <already5chosen@yahoo.com> writes:
>On Sat, 15 Aug 2026 19:39:54 GMT
>scott@slp53.sl.home (Scott Lurndal) wrote:
>
>> Michael S <already5chosen@yahoo.com> writes:
>> >On Fri, 14 Aug 2026 21:42:38 GMT
>> >scott@slp53.sl.home (Scott Lurndal) wrote:
>> >  
>> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:  
>> >> >scott@slp53.sl.home (Scott Lurndal) writes:
>> >> >    
>> >> >> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>> >> >>    
>> >> >>> scott@slp53.sl.home (Scott Lurndal) writes:
>> >> >>>    
>> >> >>>> One might also define data structures for control and status
>> >> >>>> registers using bitfield structs.    
>> >> >>>
>> >> >>> Yeah.  This kind of application (among others) I consider one
>> >> >>> of the motivating forces behind bitfields.
>> >> >>>
>> >> >>> [Some whitespace trimming done in the excerpt below.]
>> >> >>>    
>> >> >>>> e.g. for the SATA UAHC_GLB_OOBR register:
>> >> >>>>
>> >> >>>> union UAHC_GBL_OOBR {
>> >> >>>>   uint32_t u;
>> >> >>>>   struct UAHC_GBL_OOBR_s {
>> >> >>>> #if __BYTE_ORDER == __BIG_ENDIAN
>> >> >>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>> >> >>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value
>> >> >>>> [...] */ uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum
>> >> >>>> value [...] */ uint32_t cimin  :  8; /**< R/W/H - COMINIT
>> >> >>>> minimum value [...] */ uint32_t cimax  :  8; /**< R/W/H -
>> >> >>>> COMINIT maximum value [...] */ #else
>> >> >>>>     uint32_t cimax  :  8;
>> >> >>>>     uint32_t cimin  :  8;
>> >> >>>>     uint32_t cwmax  :  8;
>> >> >>>>     uint32_t cwmin  :  7;
>> >> >>>>     uint32_t we     :  1;
>> >> >>>> #endif
>> >> >>>>   } s;
>> >> >>>> };    
>> >> >>>
>> >> >>> To me it seems kind of goofy to use uint32_t for the bitfields
>> >> >>> type. I would just use unsigned, which is just as sure to work
>> >> >>> as intended, isn't it?    
>> >> >>
>> >> >> The SATA hardware register is defined as a 32-bit register in
>> >> >> the SATA specification.  Therefore we explicitly declare it as
>> >> >> such.    
>> >> >
>> >> >I understand the motivation for using uint32_t for the union
>> >> >member u.  My question is only about the type used for the
>> >> >bitfields.  Do you know of any platform, or even suspect that
>> >> >there might be a platform, where using 'unsigned' rather than
>> >> >'uint32_t' for the type of the bitfields makes any difference at
>> >> >all?    
>> >> 
>> >> I haven't canvassed all the available platforms, and don't have
>> >> any desire so to do.  In my opinion, using the same type for the
>> >> bitfield members as was used for the corresponding union
>> >> element is simply logical.   If we declare the integer part
>> >> of the union as uint64_t,  we use the same time for the
>> >> bitfields (and yes, we could have used unsigned long
>> >> (or unsigned long long on the micky OS) - uint64_t
>> >> is less typing.
>> >>   
>> >
>> >Why not plain 'unsigned' ?
>> >  
>> 
>> Did you not read the paragraph you are responding to?
>
>I missed the part about "using the same type". Sorry.
>Now, when I read it ... no, I don't think that it is logical.
>

Using unsigned for the bitfields wouldn't work properly
if the modeled register is 64 bits and any of the fields
are more than 32 bits in size.

I've never liked using unadorned 'unsigned' in C.  

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#401242 — Re: Microcontroller software stacks

scott@slp53.sl.home (Scott Lurndal) writes:
> Michael S <already5chosen@yahoo.com> writes:
>>On Sat, 15 Aug 2026 19:39:54 GMT
>>scott@slp53.sl.home (Scott Lurndal) wrote:
>>> Michael S <already5chosen@yahoo.com> writes:
[...]
>>> >Why not plain 'unsigned' ?
>>> 
>>> Did you not read the paragraph you are responding to?
>>
>>I missed the part about "using the same type". Sorry.
>>Now, when I read it ... no, I don't think that it is logical.
>
> Using unsigned for the bitfields wouldn't work properly
> if the modeled register is 64 bits and any of the fields
> are more than 32 bits in size.

If you need a bitfield wider than the width of int, of course you
have to use some implementation-defined type.  There's no way to
do that portably unless you have C23.  (C23 requires support for
bit-fields of bit-precise integer types, so up to at least 64 bits,
but still doesn't require support for bit-fields of type unsigned
long.)

> I've never liked using unadorned 'unsigned' in C.  

I think that by "plain 'unsigned'", Michael was referring to the type,
not necessarily to how it's named.  ("unsigned", "unsigned int", and
"int unsigned" are all the same type.)

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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#401224 — Re: Microcontroller software stacks

scott@slp53.sl.home (Scott Lurndal) writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>
>>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>>
>>>>> One might also define data structures for control and status
>>>>> registers using bitfield structs.
>>>>
>>>> Yeah.  This kind of application (among others) I consider one of
>>>> the motivating forces behind bitfields.
>>>>
>>>> [Some whitespace trimming done in the excerpt below.]
>>>>
>>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>>
>>>>> union UAHC_GBL_OOBR {
>>>>>   uint32_t u;
>>>>>   struct UAHC_GBL_OOBR_s {
>>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>>     uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>>     uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>>     uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>>> #else
>>>>>     uint32_t cimax  :  8;
>>>>>     uint32_t cimin  :  8;
>>>>>     uint32_t cwmax  :  8;
>>>>>     uint32_t cwmin  :  7;
>>>>>     uint32_t we     :  1;
>>>>> #endif
>>>>>   } s;
>>>>> };
>>>>
>>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>>> I would just use unsigned, which is just as sure to work as intended,
>>>> isn't it?
>>>
>>> The SATA hardware register is defined as a 32-bit register in the
>>> SATA specification.  Therefore we explicitly declare it as such.
>>
>> I understand the motivation for using uint32_t for the union member
>> u.  My question is only about the type used for the bitfields.  Do
>> you know of any platform, or even suspect that there might be a
>> platform, where using 'unsigned' rather than 'uint32_t' for the type
>> of the bitfields makes any difference at all?
>
> I haven't canvassed all the available platforms, and don't have
> any desire so to do.  In my opinion, using the same type for the
> bitfield members as was used for the corresponding union
> element is simply logical.   If we declare the integer part
> of the union as uint64_t,  we use the same time for the
> bitfields (and yes, we could have used unsigned long
> (or unsigned long long on the micky OS) - uint64_t
> is less typing.

To me it seems more logical to use the smallest basic type that
suffices for the width of the associated bit-field, assuming
the compiler allows it, or 'unsigned' for compilers that don't
provide those extensions.

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#401311 — Re: Microcontroller software stacks

In article <868q673rft.fsf@linuxsc.com>,
Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>scott@slp53.sl.home (Scott Lurndal) writes:
>
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>
>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>
>>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>>
>>>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>>>
>>>>>> One might also define data structures for control and status
>>>>>> registers using bitfield structs.
>>>>>
>>>>> Yeah.  This kind of application (among others) I consider one of
>>>>> the motivating forces behind bitfields.
>>>>>
>>>>> [Some whitespace trimming done in the excerpt below.]
>>>>>
>>>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>>>
>>>>>> union UAHC_GBL_OOBR {
>>>>>>   uint32_t u;
>>>>>>   struct UAHC_GBL_OOBR_s {
>>>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>>>     uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>>>     uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>>>     uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>>>> #else
>>>>>>     uint32_t cimax  :  8;
>>>>>>     uint32_t cimin  :  8;
>>>>>>     uint32_t cwmax  :  8;
>>>>>>     uint32_t cwmin  :  7;
>>>>>>     uint32_t we     :  1;
>>>>>> #endif
>>>>>>   } s;
>>>>>> };
>>>>>
>>>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>>>> I would just use unsigned, which is just as sure to work as intended,
>>>>> isn't it?
>>>>
>>>> The SATA hardware register is defined as a 32-bit register in the
>>>> SATA specification.  Therefore we explicitly declare it as such.
>>>
>>> I understand the motivation for using uint32_t for the union member
>>> u.  My question is only about the type used for the bitfields.  Do
>>> you know of any platform, or even suspect that there might be a
>>> platform, where using 'unsigned' rather than 'uint32_t' for the type
>>> of the bitfields makes any difference at all?
>>
>> I haven't canvassed all the available platforms, and don't have
>> any desire so to do.  In my opinion, using the same type for the
>> bitfield members as was used for the corresponding union
>> element is simply logical.   If we declare the integer part
>> of the union as uint64_t,  we use the same time for the
>> bitfields (and yes, we could have used unsigned long
>> (or unsigned long long on the micky OS) - uint64_t
>> is less typing.
>
>To me it seems more logical to use the smallest basic type that
>suffices for the width of the associated bit-field, assuming
>the compiler allows it, or 'unsigned' for compilers that don't
>provide those extensions.

You do not appear to actually write software that interfaces
directly with hardware in the manner that Scott and I (among
others) do.

	- Dan C.

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#401227 — Re: Microcontroller software stacks

scott@slp53.sl.home (Scott Lurndal) writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>
>>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>>
>>>>> One might also define data structures for control and status
>>>>> registers using bitfield structs.
>>>>
>>>> Yeah.  This kind of application (among others) I consider one of
>>>> the motivating forces behind bitfields.
>>>>
>>>> [Some whitespace trimming done in the excerpt below.]
>>>>
>>>>> e.g. for the SATA UAHC_GLB_OOBR register:
>>>>>
>>>>> union UAHC_GBL_OOBR {
>>>>>   uint32_t u;
>>>>>   struct UAHC_GBL_OOBR_s {
>>>>> #if __BYTE_ORDER == __BIG_ENDIAN
>>>>>     uint32_t we     :  1; /**< R/W/H - Write enable. */
>>>>>     uint32_t cwmin  :  7; /**< R/W/H - COMWAKE minimum value [...] */
>>>>>     uint32_t cwmax  :  8; /**< R/W/H - COMWAKE maximum value [...] */
>>>>>     uint32_t cimin  :  8; /**< R/W/H - COMINIT minimum value [...] */
>>>>>     uint32_t cimax  :  8; /**< R/W/H - COMINIT maximum value [...] */
>>>>> #else
>>>>>     uint32_t cimax  :  8;
>>>>>     uint32_t cimin  :  8;
>>>>>     uint32_t cwmax  :  8;
>>>>>     uint32_t cwmin  :  7;
>>>>>     uint32_t we     :  1;
>>>>> #endif
>>>>>   } s;
>>>>> };
>>>>
>>>> To me it seems kind of goofy to use uint32_t for the bitfields type.
>>>> I would just use unsigned, which is just as sure to work as intended,
>>>> isn't it?
>>>
>>> The SATA hardware register is defined as a 32-bit register in the
>>> SATA specification.  Therefore we explicitly declare it as such.
>>
>> I understand the motivation for using uint32_t for the union member
>> u.  My question is only about the type used for the bitfields.  Do
>> you know of any platform, or even suspect that there might be a
>> platform, where using 'unsigned' rather than 'uint32_t' for the type
>> of the bitfields makes any difference at all?
>
> I haven't canvassed all the available platforms, and don't have
> any desire so to do.  In my opinion, using the same type for the
> bitfield members as was used for the corresponding union
> element is simply logical.   If we declare the integer part
> of the union as uint64_t,  we use the same time for the
> bitfields (and yes, we could have used unsigned long
> (or unsigned long long on the micky OS) - uint64_t
> is less typing.

Out of curiosity I put together a short program to explore how
bit-field types are understood by the compiler.  Here is the
program:

    #include <stdio.h>
    #include <stdint.h>

    typedef struct {
      _Bool                 ub  : 1;
      unsigned char         uc  : 8;
      unsigned short        us  :16;
      unsigned int          ui  :32;
      unsigned long         ul  :64;
      unsigned long long    ull :64;

      uint8_t               u1  : 1;
      uint8_t               u8  : 8;
      uint16_t              u16 :16;
      uint32_t              u32 :32;
      uint64_t              u64 :64;

      uint64_t              x1  : 1;
      uint64_t              x8  : 8;
      uint64_t              x16 :16;
      uint64_t              x32 :32;
      uint64_t              x64 :64;
    } Bitfields;

    #define whatkind(e) (                                           \
      _Generic( e,                                                  \
        _Bool               : "_Bool",                              \
        unsigned char       : "unsigned char",                      \
        unsigned short      : "unsigned short",                     \
        unsigned int        : "unsigned int",                       \
        unsigned long       : "unsigned long",                      \
        unsigned long long  : "unsigned long long",                 \
        default             : "<something else>"                    \
      )                                                             \
    )

    int
    main(){
      Bitfields bf;
        printf( " whatkind( bf.ub  ) is %s\n", whatkind( bf.ub  ) );
        printf( " whatkind( bf.uc  ) is %s\n", whatkind( bf.uc  ) );
        printf( " whatkind( bf.us  ) is %s\n", whatkind( bf.us  ) );
        printf( " whatkind( bf.ui  ) is %s\n", whatkind( bf.ui  ) );
        printf( " whatkind( bf.ul  ) is %s\n", whatkind( bf.ul  ) );
        printf( " whatkind( bf.ull ) is %s\n", whatkind( bf.ull ) );
        printf( "\n" );

        printf( " whatkind( bf.u1  ) is %s\n", whatkind( bf.u1  ) );
        printf( " whatkind( bf.u8  ) is %s\n", whatkind( bf.u8  ) );
        printf( " whatkind( bf.u16 ) is %s\n", whatkind( bf.u16 ) );
        printf( " whatkind( bf.u32 ) is %s\n", whatkind( bf.u32 ) );
        printf( " whatkind( bf.u64 ) is %s\n", whatkind( bf.u64 ) );
        printf( "\n" );

        printf( " whatkind( bf.x1  ) is %s\n", whatkind( bf.x1  ) );
        printf( " whatkind( bf.x8  ) is %s\n", whatkind( bf.x8  ) );
        printf( " whatkind( bf.x16 ) is %s\n", whatkind( bf.x16 ) );
        printf( " whatkind( bf.x32 ) is %s\n", whatkind( bf.x32 ) );
        printf( " whatkind( bf.x64 ) is %s\n", whatkind( bf.x64 ) );
    }

and the output (using gcc)

     whatkind( bf.ub  ) is _Bool
     whatkind( bf.uc  ) is unsigned char
     whatkind( bf.us  ) is unsigned short
     whatkind( bf.ui  ) is unsigned int
     whatkind( bf.ul  ) is unsigned long
     whatkind( bf.ull ) is unsigned long long

     whatkind( bf.u1  ) is <something else>
     whatkind( bf.u8  ) is unsigned char
     whatkind( bf.u16 ) is unsigned short
     whatkind( bf.u32 ) is unsigned int
     whatkind( bf.u64 ) is unsigned long

     whatkind( bf.x1  ) is <something else>
     whatkind( bf.x8  ) is unsigned char
     whatkind( bf.x16 ) is unsigned short
     whatkind( bf.x32 ) is unsigned int
     whatkind( bf.x64 ) is unsigned long

and the output (using clang)

     whatkind( bf.ub  ) is _Bool
     whatkind( bf.uc  ) is unsigned char
     whatkind( bf.us  ) is unsigned short
     whatkind( bf.ui  ) is unsigned int
     whatkind( bf.ul  ) is unsigned long
     whatkind( bf.ull ) is unsigned long long

     whatkind( bf.u1  ) is unsigned char
     whatkind( bf.u8  ) is unsigned char
     whatkind( bf.u16 ) is unsigned short
     whatkind( bf.u32 ) is unsigned int
     whatkind( bf.u64 ) is unsigned long

     whatkind( bf.x1  ) is unsigned long
     whatkind( bf.x8  ) is unsigned long
     whatkind( bf.x16 ) is unsigned long
     whatkind( bf.x32 ) is unsigned long
     whatkind( bf.x64 ) is unsigned long

which serves to reinforce my view that bit-field types should be
chosen from the basic types, and should be the narrowest type that
covers the width of the corresponding bit-field member (with
possible adjustment for widths that match two types, as for example
unsigned long and unsigned long long).

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