+#ifndef _IDCT_REFERENCE_H
+#define _IDCT_REFERENCE_H
+
+#include "idct.h"
+
+// Non-factorized reference version (section A.3.3 of the JPEG standard).
+void* idct_reference_alloc(const uint32_t* quant_table);
+void idct_reference_free(void* userdata);
+void idct_reference(const int16_t* input, const void* userdata, uint8_t* output);
+
+#endif /* !defined(_IDCT_REFERENCE_H) */