Software crc32c produces wrong results on big endian CPUs

[crisidev]

I am trying to run some code which uses crc32c on powerpc 32 and 64 bit and I noticed it produces incorrect results.

I have tried to run the test suite of this crate using cross and they indeed fail:

❯❯❯ ~/github/crc32c ❯ cross test --target powerpc-unknown-linux-gnu
warning: unused manifest key: target.aarch64-unknown-linux-gnu.linker
    Finished test [unoptimized + debuginfo] target(s) in 0.15s
     Running unittests src/lib.rs (/target/powerpc-unknown-linux-gnu/debug/deps/crc32c-06d60a5bbd004a3e)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running tests/simple.rs (/target/powerpc-unknown-linux-gnu/debug/deps/simple-63febc81630ac4ff)

running 6 tests
test crc ... ok
test crc_append ... ok
test crc_combine ... FAILED
test long_string ... FAILED
test very_big ... FAILED
test very_small ... ok

failures:

---- crc_combine stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `689410915`,
 right: `3475076554`', tests/simple.rs:25:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- long_string stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `550182489`,
 right: `372323125`', tests/simple.rs:55:5

---- very_big stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `314413457`,
 right: `1410821608`', tests/simple.rs:63:5


failures:
    crc_combine
    long_string
    very_big

test result: FAILED. 3 passed; 3 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s

error: test failed, to rerun pass '--test simple'

❯❯❯ ~/github/crc32c ❯ cross test --target powerpc64-unknown-linux-gnu
warning: unused manifest key: target.aarch64-unknown-linux-gnu.linker
    Finished test [unoptimized + debuginfo] target(s) in 0.14s
     Running unittests src/lib.rs (/target/powerpc64-unknown-linux-gnu/debug/deps/crc32c-d3c4704dfac2e462)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running tests/simple.rs (/target/powerpc64-unknown-linux-gnu/debug/deps/simple-7936969e39a66f78)

running 6 tests
test crc ... ok
test crc_append ... ok
test crc_combine ... FAILED
test long_string ... FAILED
test very_big ... FAILED
test very_small ... ok

failures:

---- crc_combine stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `2861399345`,
 right: `3645618169`', tests/simple.rs:25:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- long_string stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `550182489`,
 right: `372323125`', tests/simple.rs:55:5

---- very_big stdout ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `314413457`,
 right: `1410821608`', tests/simple.rs:63:5


failures:
    crc_combine
    long_string
    very_big

test result: FAILED. 3 passed; 3 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.04s

error: test failed, to rerun pass '--test simple'