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diff --git a/sys/vops/ak/acnvs.x b/sys/vops/ak/acnvs.x
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# ACNV -- Vector convolution.  The output vector is equal to the sum of its
+# initial value and the convolution of the input vector with the kernel.
+# This routine assumes boundary extension on the input vector has been provided.
+# For short kernels, we unroll the inner do loop into a single statement to
+# reduce loop overhead.
+#
+# Example: npix=10, kpix=5, 2 pixels out of bounds on either end.
+# in[1] corresponds to x = -1
+#
+#	-1  0  1  2  3  4  5  6  7  8  9 10 11 12	(x coord)
+#	 1  2  3  4  5
+#	    1  2  3  4  5
+#			...
+#				    1  2  3  4  5
+
+procedure acnvs (in, out, npix, kernel, knpix)
+
+short	in[npix+knpix-1]	# input vector, including boundary pixels
+short	out[ARB]		# output vector
+int	npix			# length of output vector
+short	kernel[knpix]		# convolution kernel
+int	knpix			# size of convolution kernel
+
+int	i, j
+short	sum, k1, k2, k3, k4, k5
+
+begin
+	switch (knpix) {
+	case 3:
+	    k1 = kernel[1]
+	    k2 = kernel[2]
+	    k3 = kernel[3]
+	    do i = 1, npix
+	        out[i] = out[i] + k1 * in[i] + k2 * in[i+1] + k3 * in[i+2]
+	case 5:
+	    k1 = kernel[1]
+	    k2 = kernel[2]
+	    k3 = kernel[3]
+	    k4 = kernel[4]
+	    k5 = kernel[5]
+	    do i = 1, npix
+	        out[i] = out[i] + k1 * in[i] + k2 * in[i+1] + k3 * in[i+2] +
+		    k4 * in[i+3] + k5 * in[i+4]
+	default:
+	    do i = 1, npix {
+	        sum = out[i]
+	        do j = 1, knpix
+		    sum = sum + (kernel[j] * in[i+j-1])
+	        out[i] = sum
+	    }
+	}
+end