CRC big endian support (#97)

Author: DmitriyMusatkin

.github/workflows/ci.yml

@@ -232,6 +232,7 @@ jobs:
         id: test
         uses: cross-platform-actions/[email protected]
         with:
+          #note: sanitizer seems to be broken on s390x (fails trying to allocate several tbs of mem) and package manager works slightly differently that on regular ubuntu
           operating_system: freebsd
           architecture: x86-64
           version: '14.0'
@@ -243,6 +244,30 @@ jobs:
             chmod a+x builder
             ./builder build -p ${{ env.PACKAGE_NAME }}
 
+  s390x: #big-endian
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: uraimo/run-on-arch-action@v2
+        name: Run commands
+        id: runcmd
+        with:
+          arch: s390x
+          distro: ubuntu22.04
+          install: |
+            apt-get update -q -y
+            apt-get -y install sudo
+            apt-get -y install cmake
+            apt-get -y install make
+            apt-get -y install g++
+            apt-get -y install python3
+            apt-get -y install git
+          run: |
+            lscpu | grep Endian
+            python3 -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_SOURCE }}/${{ env.BUILDER_VERSION }}/builder.pyz?run=${{ env.RUN }}', 'builder')"
+            chmod a+x builder
+            ./builder build -p ${{ env.PACKAGE_NAME }} --variant s390x --cmake-extra=-DENABLE_SANITIZERS=OFF
+
   openbsd:
     runs-on: ubuntu-24.04 # latest
     strategy:

builder.json

@@ -10,5 +10,15 @@
     "test_steps": [
         "test",
         "{install_dir}/bin/checksum-profile{exe}"
-    ]
+    ],
+
+    "variants": {
+        "s390x": {
+            "hosts": {
+                "ubuntu": {
+                    "!pkg_setup": []
+                }
+            }
+        }
+    }
 }

include/aws/checksums/private/crc_util.h

@@ -5,8 +5,10 @@
  * SPDX-License-Identifier: Apache-2.0.
  */
 
+#include <aws/common/byte_order.h>
 #include <aws/common/stdint.h>
 #include <limits.h>
+#include <stdlib.h>
 
 #define large_buffer_apply_impl(Name, T)                                                                               \
     static T aws_large_buffer_apply_##Name(                                                                            \
@@ -21,4 +23,38 @@
         return val;                                                                                                    \
     }
 
+/* helper function to reverse byte order on big-endian platforms*/
+static inline uint32_t aws_bswap32_if_be(uint32_t x) {
+    if (!aws_is_big_endian()) {
+        return x;
+    }
+
+#if _MSC_VER
+    return _byteswap_ulong(x);
+#elif defined(__GNUC__) || defined(__clang__)
+    return __builtin_bswap32(x);
+#else
+    return (
+        ((x & 0xff000000u) >> 24) | ((x & 0x00ff0000u) >> 8) | ((x & 0x0000ff00u) << 8) | ((x & 0x000000ffu) << 24));
+#endif
+}
+
+/* Reverse the bytes in a 64-bit word. */
+static inline uint64_t aws_bswap64_if_be(uint64_t x) {
+    if (!aws_is_big_endian()) {
+        return x;
+    }
+
+#if _MSC_VER
+    return _byteswap_uint64(x);
+#elif defined(__GNUC__) || defined(__clang__)
+    return __builtin_bswap64(x);
+#else
+    return ((x << 56) & 0xff00000000000000ULL) | ((x << 40) & 0x00ff000000000000ULL) |
+           ((x << 24) & 0x0000ff0000000000ULL) | ((x << 8) & 0x000000ff00000000ULL) |
+           ((x >> 8) & 0x00000000ff000000ULL) | ((x >> 24) & 0x0000000000ff0000ULL) |
+           ((x >> 40) & 0x000000000000ff00ULL) | ((x >> 56) & 0x00000000000000ffULL);
+#endif
+}
+
 #endif /* AWS_CHECKSUMS_PRIVATE_CRC_UTIL_H */