Initial SHA256 test harness

include/sha.h

@@ -0,0 +1,48 @@
+#ifndef SHA256_SHA_H
+#define SHA256_SHA_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef _WIN32
+  #ifdef SHA256_EXPORTS
+    #define SHA256_API __declspec(dllexport)
+  #else
+    #define SHA256_API __declspec(dllimport)
+  #endif
+#else
+  #define SHA256_API
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef uint32_t sha256_digest_t[8];
+
+SHA256_API int TestHello(void);
+
+/*
+ * Returns NULL (0) on success according to assembly comments.
+ * data_addr      - pointer to current data chunk.
+ * full_size      - total message/file size in bytes.
+ * current_size   - current chunk size in bytes.
+ * digest         - 32-byte state/result buffer (8 x uint32_t).
+ * is_last_chunk  - 1 if this is the last chunk, otherwise 0.
+ */
+SHA256_API void *Sha256(
+    const void *data_addr,
+    uint64_t full_size,
+    uint64_t current_size,
+    sha256_digest_t digest,
+    uint64_t is_last_chunk
+);
+
+/* Initializes digest and internal K constants. */
+SHA256_API void Sha256Init(sha256_digest_t digest);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SHA256_SHA_H */