STRUCT COMEDI_RANGEINFO(9)

💖 STRUCT COMEDI_RANGEINFO(9) 💖

okay so this is the kernel API manual page for struct comedi_rangeinfo, and bestie, it's literally the little struct that goes and fetches the range table for a channel. that's the whole vibe. iykyk 🦋

---

✨ NAME ✨

struct comedi_rangeinfo — used to retrieve the range table for a channel 💅

---

🌸 SYNOPSIS 🌸

struct comedi_rangeinfo {
    unsigned int range_type;
    void __user *range_ptr;
 };

that's it, that's the struct, two members, main character energy only 🎀

---

🧚 MEMBERS 🧚

• range_type — okay so this one's doing a whole lot of encoding, no cap. it packs the subdevice index into bits 31:24, the channel index into bits 23:16, and the range table length into bits 15:0. three things, one unsigned int, she's efficient ✨
• range_ptr — a pointer to an array of struct comedi_krange that's gonna get filled in with the range table for the channel or subdevice. it's giving "bring your own buffer" 🫶

---

💜 DESCRIPTION 💜

so this struct is what you use with the COMEDI_RANGEINFO ioctl to retrieve the range table — either for one specific channel (when the subdevice has the SDF_RANGETYPE flag set, which is the signal that the range table depends on the channel), or for the subdevice as a whole (when the SDF_RANGETYPE flag is clear, meaning the range table is shared by all the channels). two modes, one struct, iconic honestly 👑

the range_type value is an input to the ioctl, and where does it come from? from a previous use of the COMEDI_SUBDINFO ioctl if the SDF_RANGETYPE flag is clear, or from the COMEDI_CHANINFO ioctl if the SDF_RANGETYPE flag is set. so like, you don't just make this number up, bestie — go get it from the right place first 💀

fr fr, keep track of which flag is set before you go picking your source ioctl, because range_type is an input here, not an output 🙈

---

🌈 SEE ALSO 🌈

• Kernel file ./include/uapi/linux/comedi.h 🌸
• enum comedi_subdevice_type(9)
• enum comedi_io_direction(9)
• enum configuration_ids(9)
• enum comedi_digital_trig_op(9)
• enum comedi_support_level(9)
• enum comedi_counter_status_flags(9)
• struct comedi_insn(9)
• struct comedi_insnlist(9)
• struct comedi_cmd(9)
• struct comedi_chaninfo(9)
• struct comedi_krange(9)
• struct comedi_subdinfo(9)
• struct comedi_devinfo(9)
• struct comedi_devconfig(9)
• struct comedi_bufconfig(9)
• struct comedi_bufinfo(9)

like, the whole comedi friend group, we love a linked list of besties 🫶✨

---

✨ and that's the page!! ✨ this one lives in ./include/uapi/linux, dated October 2026 — slay, go read the other comedi pages, ily, bye 💖🎀🦋