Zepp-Hanzj opened a new pull request, #19246:
URL: https://github.com/apache/nuttx/pull/19246
## Summary
Fixes #14532
The existing crc32() uses init=0 with no final XOR, which differs from the
Linux/zlib standard CRC32 (init=0xFFFFFFFF, final XOR 0xFFFFFFFF). This causes
interoperability issues when exchanging CRC32 values between NuttX and Linux
systems (e.g., UART protocols, file integrity checks).
Add two new functions following the crc8/crc16 variant naming convention:
- crc32_ieee(src, len) — full CRC, Linux/zlib compatible
- crc32_ieeepart(src, len, crcval) — incremental CRC, Linux/zlib compatible
The existing crc32() and crc32part() are unchanged to avoid breaking
existing callers (bbsram, sbram, etc.).
## Verification
Built and tested on sim:nsh. Used known Linux zlib CRC32 test vectors.
Build command:
make distclean
tools/configure.sh sim:nsh
make -j$(nproc)
Run command:
printf 'hello\npoweroff\n' | timeout 30 ./nuttx 2>/dev/null
Test output:
NuttShell (NSH) NuttX-13.0.0-RC0
nsh> hello
=== crc32_ieee compatibility test ===
crc32("hello") = 0xf032519b (old, init=0)
crc32_ieee("hello") = 0x3610a686 (expected 0x3610a686)
PASS
crc32("123456789") = 0x2dfd2d88
crc32_ieee("123456789") = 0xcbf43926 (expected 0xcbf43926)
PASS
crc32("") = 0x00000000
crc32_ieee("") = 0x00000000 (expected 0x00000000)
PASS
crc32_ieeepart incremental("123456789") = 0xcbf43926 (expected 0xcbf43926)
PASS
crc32("hello") = 0xf032519b (should be unchanged from before)
(old crc32 backward compatible - no reference value needed)
=== Results: 5 pass, 0 fail ===
nsh> poweroff
Test vectors verified against Linux zlib crc32():
crc32_ieee("hello") = 0x3610a686 — matches Linux
crc32_ieee("123456789") = 0xcbf43926 — matches Linux
crc32_ieee("") = 0x00000000 — matches Linux
crc32_ieeepart incremental — matches one-shot crc32_ieee
crc32("hello") = 0xf032519b — unchanged, backward compatible
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