i didn't take into account partial writes, in io_args
this fixes it
unfortunately, this means i have to loosen the offset
check a bit, but it's fine
Signed-off-by: Leah Rowe <leah@libreboot.org>
re-check. very unlikely since the program doesn't run
for very long, but we have to check if the file has
changed. this is a basic check of file size.
we could probably check the contents too, but that
would be overkill.
Signed-off-by: Leah Rowe <leah@libreboot.org>
the time difference used here could go negative, which
would overflow in the xor op on mix, leading to a biased
entropy pool. we want to ensure that they numbers do
not overflow, because here they are cast to unsigned
which would then produce very large numbers.
Signed-off-by: Leah Rowe <leah@libreboot.org>
zero never occurs, because rw_file_once never returns zero,
but only rw_file_once determines that. rw_file_exact must
handle every possible error.
right now, if that call returns zero, rw_file_exact would
have an infinite loop.
this doesn't actually happen at the moment, so this is a
preventative bug fix.
Signed-off-by: Leah Rowe <leah@libreboot.org>
properly verify the value of the arguments, with
asserts.
add simpler runtime checks in-function, on prw,
rw_file_once and rw_file_exact.
variable names in english now, and the code is
cleaner, while being functionally equivalent.
Signed-off-by: Leah Rowe <leah@libreboot.org>
for pulses, we currently use amplitude detection.
edge detection is better, because weak / low gain
signals will be more reliable. if audio is coming
in on/from a system that does automatic gain
adjustment, this once again is more robust too.
microphones and speakers (which people often use
with spkmodem if nothing else available) often
clamp amplitude, to an extent that this software
may not detect those pulses reliably that way.
so we detect slope edges instead. this causes
very little performance penalty (use of abs(),
that's about it)
however, edge detection is inherently vulnerable
to noise, so we will also detect amplitude. this
acts as an effective noise filter, while still
improving pulse detection.
Signed-off-by: Leah Rowe <leah@libreboot.org>
this check no longer applies (never triggers)
is_signal_valid already guarantees that the separator
tone is valid.
Signed-off-by: Leah Rowe <leah@libreboot.org>
bits are currently assembled even on invalid frames. this
patch fixes that - the bug is also in the GNU version.
this reduces the chance of noise/calibration from creating
corrupt character output during operation.
Signed-off-by: Leah Rowe <leah@libreboot.org>
enforce at least two tones. this mitigates the
chance of random noise being treated as a real
tone, and reduces the chance of broken
thresholds versus freq min/max e.g.
freq min 31, max 32 and threshold 31
Signed-off-by: Leah Rowe <leah@libreboot.org>
we weren't actually using what we calculated. this patch
fixes that, thus preventing random noise / microphone
clicks, random artifacts and such from being treated
as real frames (the purpose of is_valid_signal is
partly noise suppression).
Signed-off-by: Leah Rowe <leah@libreboot.org>
in handle audio, i do the number of samples
per frame, and one more. e.g. 241 instead of
240. this bug is in the original GNU version
too. this patch fixes it.
this means that the output could slowly go
out of sync with calculated timings. the
patch fixes that. in practise, the decoder
is not that sensitive, and the code would
adjust anyway (automatic timing adjustment),
but ideally we want to not *cause* such
issues even if we mitigate them.
Signed-off-by: Leah Rowe <leah@libreboot.org>
assert integer sizes, important in this program because
we make several implicit assumptions about word sizes,
and integers need to be of a certain size.
Signed-off-by: Leah Rowe <leah@libreboot.org>
collect_separator should be select_separator, to bring
it in line with select_low_tone
this just makes the code a bit easier to read
Signed-off-by: Leah Rowe <leah@libreboot.org>
