On 18.04.25 18:48, Jocelyn Falempe wrote:
> On 32bits ARM, u64/u64 is not supported [1], so change the algorithm
> to use a simple fifo with decimal digits as u8 instead.
> This is slower but should compile on all architecture.
>
> Link:
> https://lore.kernel.org/dri-devel/caniq72ke45eowckmhwhvmwxc03dxr4rnxxkvx+hvwdblopz...@mail.gmail.com/
> [1]
> Signed-off-by: Jocelyn Falempe <jfale...@redhat.com>
> ---
> drivers/gpu/drm/drm_panic_qr.rs | 71 ++++++++++++++++++++++-----------
> 1 file changed, 48 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs
> index 6025a705530e..dd55b1cb764d 100644
> --- a/drivers/gpu/drm/drm_panic_qr.rs
> +++ b/drivers/gpu/drm/drm_panic_qr.rs
> @@ -366,8 +366,48 @@ fn iter(&self) -> SegmentIterator<'_> {
> SegmentIterator {
> segment: self,
> offset: 0,
> - carry: 0,
> - carry_len: 0,
> + decfifo: Default::default(),
> + }
> + }
> +}
> +
> +/// Max fifo size is 17 (max push) + 2 (max remaining)
> +const MAX_FIFO_SIZE: usize = 19;
> +
> +/// A simple Decimal digit FIFO
> +#[derive(Default)]
> +struct DecFifo {
> + decimals: [u8; MAX_FIFO_SIZE],
> + len: usize,
> +}
> +
> +impl DecFifo {
> + fn push(&mut self, data: u64, len: usize) {
> + let mut chunk = data;
> + for i in (0..self.len).rev() {
> + self.decimals[i + len] = self.decimals[i];
> + }
> + for i in 0..len {
> + self.decimals[i] = (chunk % 10) as u8;
> + chunk /= 10;
> + }
> + self.len += len;
> + }
> +
> + /// Pop 3 decimal digits from the FIFO
> + fn pop3(&mut self) -> Option<(u16, usize)> {
> + if self.len == 0 {
> + None
> + } else {
> + let poplen = 3.min(self.len);
> + self.len -= poplen;
> + let mut out = 0;
> + let mut exp = 1;
> + for i in 0..poplen {
> + out += self.decimals[self.len + i] as u16 * exp;
> + exp *= 10;
> + }
> + Some((out, NUM_CHARS_BITS[poplen]))
> }
> }
> }
> @@ -375,8 +415,7 @@ fn iter(&self) -> SegmentIterator<'_> {
> struct SegmentIterator<'a> {
> segment: &'a Segment<'a>,
> offset: usize,
> - carry: u64,
> - carry_len: usize,
> + decfifo: DecFifo,
> }
>
> impl Iterator for SegmentIterator<'_> {
> @@ -394,31 +433,17 @@ fn next(&mut self) -> Option<Self::Item> {
> }
> }
> Segment::Numeric(data) => {
> - if self.carry_len < 3 && self.offset < data.len() {
> - // If there are less than 3 decimal digits in the carry,
> - // take the next 7 bytes of input, and add them to the
> carry.
> + if self.decfifo.len < 3 && self.offset < data.len() {
> + // If there are less than 3 decimal digits in the fifo,
> + // take the next 7 bytes of input, and push them to the
> fifo.
> let mut buf = [0u8; 8];
> let len = 7.min(data.len() - self.offset);
>
> buf[..len].copy_from_slice(&data[self.offset..self.offset + len]);
> let chunk = u64::from_le_bytes(buf);
> - let pow = u64::pow(10, BYTES_TO_DIGITS[len] as u32);
> - self.carry = chunk + self.carry * pow;
> + self.decfifo.push(chunk, BYTES_TO_DIGITS[len]);
> self.offset += len;
> - self.carry_len += BYTES_TO_DIGITS[len];
> - }
> - match self.carry_len {
> - 0 => None,
> - len => {
> - // take the next 3 decimal digits of the carry
> - // and return 10bits of numeric data.
> - let out_len = 3.min(len);
> - self.carry_len -= out_len;
> - let pow = u64::pow(10, self.carry_len as u32);
> - let out = (self.carry / pow) as u16;
> - self.carry %= pow;
> - Some((out, NUM_CHARS_BITS[out_len]))
> - }
> }
> + self.decfifo.pop3()
> }
> }
> }
>
> base-commit: 74757ad1c105c8fc00b4cac0b7918fe3262cdb18
Hi Jocelyn,
Apologies for reviving this old thread, but I'm still encountering
the same issue with the latest master (78f4e737a53e).
When compiling this module for ARM32 (multi_v7_defconfig),
I get the following error:
ld.lld: error: undefined symbol: __aeabi_uldivmod
>>> referenced by drm_panic_qr.rs:392 (drivers/gpu/drm/drm_panic_qr.rs:392)
>>>
drivers/gpu/drm/drm_panic_qr.o:(<drm_panic_qr::SegmentIterator as
core::iter::traits::iterator::Iterator>::next) in archive vmlinux.a
>>> referenced by drm_panic_qr.rs:392 (drivers/gpu/drm/drm_panic_qr.rs:392)
>>>
drivers/gpu/drm/drm_panic_qr.o:(<drm_panic_qr::SegmentIterator as
core::iter::traits::iterator::Iterator>::next) in archive vmlinux.a
>>> referenced by drm_panic_qr.rs:392 (drivers/gpu/drm/drm_panic_qr.rs:392)
>>>
drivers/gpu/drm/drm_panic_qr.o:(<drm_panic_qr::SegmentIterator as
core::iter::traits::iterator::Iterator>::next) in archive vmlinux.a
>>> referenced 14 more times
>>> did you mean: __aeabi_uidivmod
>>> defined in: vmlinux.a(arch/arm/lib/lib1funcs.o)
Since no one else has reported this in two months, I’m wondering
if this might be a configuration issue on my end.
Thanks a lot!
--
Best regards,
Andrei Lalaev
