types/ci: scope 16-bit word64 to WIDE_BYTE and add portable split-64 Keccak host test

.github/workflows/ti-c2000-compile.yml

@@ -19,7 +19,7 @@ on:
       - '.github/workflows/ti-c2000-compile.yml'
   pull_request:
     types: [opened, synchronize, reopened, ready_for_review]
-    branches: [ '*' ]
+    branches: [ '**' ]
     paths:
       - 'wolfcrypt/src/**'
       - 'wolfssl/wolfcrypt/**'
@@ -105,3 +105,25 @@ jobs:
         run: |
           CGT_ROOT="${{ steps.find-cl.outputs.cgt_root }}" \
             IDE/C2000/compile.sh
+
+  # Portable regression guard for the WC_SHA3_SPLIT64 Keccak permutation added
+  # for CHAR_BIT != 8 targets.  It is pure C and runs on any host, so force it
+  # on a normal x86-64 build and run the crypto KATs (SHA-3/SHAKE plus the
+  # SHAKE-heavy ML-DSA/ML-KEM) that exercise it.  No hardware or TI CGT needed,
+  # so unlike the compile-only guard above this always runs.
+  sha3_split64_host:
+    name: SHA-3 split-64 host test
+    if: ${{ github.event_name != 'pull_request' || github.event.pull_request.draft == false }}
+    runs-on: ubuntu-22.04
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+        name: Checkout wolfSSL
+
+      - name: Build + run crypto KATs with WC_SHA3_SPLIT64 forced
+        run: |
+          ./autogen.sh
+          ./configure --enable-dilithium --enable-mlkem --enable-experimental \
+              --enable-shake128 --enable-shake256 CPPFLAGS="-DWC_SHA3_SPLIT64"
+          make
+          ./wolfcrypt/test/testwolfcrypt

wolfssl/wolfcrypt/types.h

@@ -443,15 +443,18 @@ typedef const char wcchar[];
 
 #elif defined(WC_16BIT_CPU)
     /* WC_16BIT_CPU selects 16-bit int (word16=unsigned int, word32=unsigned
-     * long).  It historically also assumes no native 64-bit type, but targets
-     * like the TI C2000 C28x are 16-bit-int yet have a 64-bit long long, so
-     * keep WORD64_AVAILABLE when one genuinely exists.  Porting note: any other
-     * 16-bit-int target with a 64-bit long/long long now keeps the 64-bit paths
-     * (SHA-512, word64 rotates) that were previously force-disabled here. */
+     * long).  Historically every WC_16BIT_CPU build (except MICROCHIP_PIC24)
+     * force-disabled WORD64_AVAILABLE.  The TI C2000 C28x is 16-bit-int yet has
+     * a 64-bit long long and needs the 64-bit paths (SHA-512, ML-DSA/ML-KEM),
+     * so keep WORD64_AVAILABLE for CHAR_BIT != 8 (WOLFSSL_WIDE_BYTE) targets
+     * that genuinely have a 64-bit type.  All other 16-bit-int targets (e.g.
+     * MSP430) retain the historical behavior, so this is not a silent ABI or
+     * code-path change for existing non-C28x ports. */
     #if !defined(MICROCHIP_PIC24) && \
-        !(defined(SIZEOF_LONG) && (SIZEOF_LONG == 8)) && \
-        !(defined(SIZEOF_LONG_LONG) && (SIZEOF_LONG_LONG == 8)) && \
-        !(defined(__SIZEOF_LONG_LONG__) && (__SIZEOF_LONG_LONG__ == 8))
+        !(defined(WOLFSSL_WIDE_BYTE) && \
+          ((defined(SIZEOF_LONG) && (SIZEOF_LONG == 8)) || \
+           (defined(SIZEOF_LONG_LONG) && (SIZEOF_LONG_LONG == 8)) || \
+           (defined(__SIZEOF_LONG_LONG__) && (__SIZEOF_LONG_LONG__ == 8))))
         #undef WORD64_AVAILABLE
     #endif
     typedef word16 wolfssl_word;