Added quantize_binary function

src/hnswscan.c

@@ -80,14 +80,7 @@ GetScanValue(IndexScanDesc scan)
 		int			dimensions = GetDimensions(scan->indexRelation);
 
 		if (typid == BITOID || typid == VARBITOID)
-		{
-			int			len = VARBITTOTALLEN(dimensions);
-			VarBit	   *v = (VarBit *) palloc0(len);
-
-			SET_VARSIZE(v, len);
-			VARBITLEN(v) = dimensions;
-			value = PointerGetDatum(v);
-		}
+			value = PointerGetDatum(InitBitVector(dimensions));
 		else
 			value = PointerGetDatum(InitVector(dimensions));
 	}

src/vector.c

@@ -1163,6 +1163,42 @@ vector_avg(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(result);
 }
 
+/*
+ * Allocate and initialize a new bit vector
+ */
+VarBit *
+InitBitVector(int dim)
+{
+	VarBit	   *result;
+	int			size;
+
+	size = VARBITTOTALLEN(dim);
+	result = (VarBit *) palloc0(size);
+	SET_VARSIZE(result, size);
+	VARBITLEN(result) = dim;
+
+	return result;
+}
+
+/*
+ * Quantize a vector
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(quantize_binary);
+Datum
+quantize_binary(PG_FUNCTION_ARGS)
+{
+	Vector	   *a = PG_GETARG_VECTOR_P(0);
+	float	   *ax = a->x;
+	VarBit	   *result = InitBitVector(a->dim);
+	unsigned char *rx = VARBITS(result);
+
+	/* TODO Improve */
+	for (int i = 0; i < a->dim; i++)
+		rx[i / 8] |= (ax[i] > 0) << (7 - (i % 8));
+
+	PG_RETURN_VARBIT_P(result);
+}
+
 /*
  * Ensure same number of bits
  */

src/vector.h

@@ -1,6 +1,8 @@
 #ifndef VECTOR_H
 #define VECTOR_H
 
+#include "utils/varbit.h"
+
 #define VECTOR_MAX_DIM 16000
 
 #define VECTOR_SIZE(_dim)		(offsetof(Vector, x) + sizeof(float)*(_dim))
@@ -17,6 +19,7 @@ typedef struct Vector
 }			Vector;
 
 Vector	   *InitVector(int dim);
+VarBit	   *InitBitVector(int dim);
 void		PrintVector(char *msg, Vector * vector);
 int			vector_cmp_internal(Vector * a, Vector * b);