fix: move RTL-SDR to userspace

programs/man/rtlsdr.3

@@ -0,0 +1,44 @@
+.TH RTLSDR 3
+.SH NAME
+rtlsdr.lib - userspace RTL2832U and R820T2 radio driver
+.SH SYNOPSIS
+.nf
+#include <rtlsdr/rtlsdr.h>
+.fi
+.SH DESCRIPTION
+The library at
+.B 0:/os/rtlsdr.lib
+drives supported Realtek RTL2832U USB receivers from userspace through the
+generic process-owned USB API. Supported USB product IDs are 0bda:2832 and
+0bda:2838. Samples are returned as interleaved unsigned 8-bit I/Q pairs.
+
+Applications load the library with libloader, resolve the
+.B rtlsdr_*
+symbols declared in the header, enumerate devices, open one, configure it,
+start bulk reception, read samples, stop, and close it. Claims are exclusive
+and are released by the kernel if the process exits or the device disconnects.
+.SH API
+.B rtlsdr_count
+and
+.B rtlsdr_get_device_info
+enumerate compatible unbound USB interfaces.
+.B rtlsdr_open
+claims an interface and returns an opaque device pointer.
+.B rtlsdr_set_center_freq,
+.B rtlsdr_set_sample_rate,
+.B rtlsdr_set_tuner_gain_mode,
+.B rtlsdr_set_tuner_gain,
+.B rtlsdr_set_freq_correction,
+.B rtlsdr_set_agc_mode,
+and
+.B rtlsdr_set_direct_sampling
+configure the receiver.
+.B rtlsdr_start,
+.B rtlsdr_read,
+and
+.B rtlsdr_stop
+control non-blocking reception.
+.SH NOTES
+Syscall numbers 140 through 148 are reserved former SDR slots and are not an
+API. Device-specific control and tuner programming live entirely in this
+library.