Handle MBEDTLS_SHA256_USE_A64_* on Windows on ARM64 too

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index a645819..5734500 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -610,7 +610,8 @@
 #endif
 #endif
 
-#if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY) && !defined(__aarch64__)
+#if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY) && \
+    !defined(__aarch64__) && !defined(_M_ARM64)
 #error "MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY defined on non-Aarch64 system"
 #endif
 
diff --git a/library/sha256.c b/library/sha256.c
index 0db5f4d..307887b 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -52,6 +52,11 @@
 #  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT) && defined(__linux__)
 #    include <sys/auxv.h>
 #  endif
+#elif defined(_M_ARM64)
+#  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT) || \
+      defined(MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY)
+#    include <arm64_neon.h>
+#  endif
 #else
 #  undef MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY
 #  undef MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT
@@ -72,6 +77,16 @@
 {
     return( 1 );
 }
+#elif defined(_M_ARM64)
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+#include <processthreadsapi.h>
+
+static int mbedtls_a64_crypto_sha256_check_support( void )
+{
+    return( IsProcessorFeaturePresent( PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE ) ?
+            1 : 0 );
+}
 #elif defined(__unix__) && defined(SIG_SETMASK)
 /* Detection with SIGILL, setjmp() and longjmp() */
 #include <signal.h>