comedi_sample_shift(9)

✨ comedi_sample_shift(9) ✨

okay so bestie, welcome to the comedi_sample_shift(9) page — yes it's a section 9 Kernel API Manual situation, and yes it's exactly as cute as it sounds (it's a tiny little helper function, honestly iconic of it). 💅

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🌸 SYNOPSIS 🌸

unsigned int comedi_sample_shift (struct comedi_subdevice *s );

like, that's the whole function signature, no notes, she's simple and she works 🫶

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🎀 ARGUMENTS 🎀

• s — your COMEDI subdevice. your blorbo. the subdevice in question. that's the whole arg, one (1) subdevice, and she has to be a struct comedi_subdevice *.

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🦋 DESCRIPTION 🦋

okay so here's the vibe: your sample size is gonna be 4 (sizeof int) or 2 (sizeof short), and which one it is depends entirely on whether the SDF_LSAMPL subdevice flag is set or not. like, flag set → one size, flag not set → the other. the way that it hinges on one single flag?? highkey elegant.

so the log2 of that sample size is gonna be 2 or 1 respectively, and here's the slay part: you can use that number as the right operand of a bit-shift operator to multiply or divide something by the sample size. shifting instead of multiplying, no cap, it's giving optimization main character energy 🔥

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👑 RETURN 👑

returns the log2 of the subdevice sample size. that's it. that's the return value. unsigned int, log2, sample size, periodt. ✨

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💖 SEE ALSO 💖

• the kernel file ./include/linux/comedi/comedidev.h (specifically struct comedi_subdevice(9))
• struct comedi_buf_page(9)
• struct comedi_buf_map(9)
• struct comedi_async(9)
• enum comedi_cb(9)
• struct comedi_driver(9)
• struct comedi_device(9)
• struct comedi_lrange(9)
• comedi_range_is_bipolar(9)
• comedi_range_is_unipolar(9)
• comedi_range_is_external(9)
• comedi_chan_range_is_bipolar(9)
• comedi_chan_range_is_unipolar(9)
• comedi_chan_range_is_external(9)
• comedi_offset_munge(9)
• comedi_bytes_per_sample(9)
• comedi_bytes_to_samples(9)
• comedi_samples_to_bytes(9)
• comedi_check_trigger_src(9)
• comedi_check_trigger_is_unique(9)
• comedi_check_trigger_arg_is(9)
• comedi_check_trigger_arg_min(9)
• comedi_check_trigger_arg_max(9)
• comedi_buf_n_bytes_ready(9)
• __comedi_request_region(9)
• comedi_request_region(9)
• module_comedi_driver(9)

like that's the whole friend group, read up on all of them, iykyk 💜

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lowkey a reminder that this page is from <pink>./include/linux/comedi</pink>, dropped in October 2026, living in the Kernel API Manual, and it is, always and forever, the comedi_sample_shift(9) page. mwah 💋 🧚‍♀️🌸