From 5e296959697643aab14feac709c8adda8726d582 Mon Sep 17 00:00:00 2001
From: Vasily Khoruzhick <anarsoul@gmail.com>
Date: Tue, 9 Feb 2016 17:19:39 -0800
Subject: [PATCH] lib: move some functions from vfs5011.c into img.c

---
 libfprint/drivers/vfs5011.c | 37 ++-----------------------------------
 libfprint/fp_internal.h     |  4 ++++
 libfprint/img.c             | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/libfprint/drivers/vfs5011.c b/libfprint/drivers/vfs5011.c
index fa1dcab..90947d3 100644
--- a/libfprint/drivers/vfs5011.c
+++ b/libfprint/drivers/vfs5011.c
@@ -252,39 +252,6 @@ static void usb_exchange_async(struct fpi_ssm *ssm,
 
 /* ====================== utils ======================= */
 
-#if VFS5011_LINE_SIZE > INT_MAX/(256*256)
-#error We might get integer overflow while computing standard deviation!
-#endif
-
-/* Calculade squared standand deviation */
-static int get_deviation(unsigned char *buf, int size)
-{
-	int res = 0, mean = 0, i;
-	for (i = 0; i < size; i++)
-		mean += buf[i];
-
-	mean /= size;
-
-	for (i = 0; i < size; i++) {
-		int dev = (int)buf[i] - mean;
-		res += dev*dev;
-	}
-
-	return res / size;
-}
-
-/* Calculate mean square difference of two lines */
-static int get_diff_norm(unsigned char *buf1, unsigned char *buf2, int size)
-{
-	int res = 0, i;
-	for (i = 0; i < size; i++) {
-		int dev = (int)buf1[i] - (int)buf2[i];
-		res += dev*dev;
-	}
-
-	return res / size;
-}
-
 /* Calculade squared standand deviation of sum of two lines */
 static int vfs5011_get_deviation2(struct fpi_line_asmbl_ctx *ctx, GSList *row1, GSList *row2)
 {
@@ -395,7 +362,7 @@ static int process_chunk(struct vfs5011_data *data, int transferred)
 		unsigned char *linebuf = data->capture_buffer
 					 + i * VFS5011_LINE_SIZE;
 
-		if (get_deviation(linebuf + 8, VFS5011_IMAGE_WIDTH)
+		if (fpi_std_sq_dev(linebuf + 8, VFS5011_IMAGE_WIDTH)
 				< DEVIATION_THRESHOLD) {
 			if (data->lines_captured == 0)
 				continue;
@@ -417,7 +384,7 @@ static int process_chunk(struct vfs5011_data *data, int transferred)
 		}
 
 		if ((data->lastline == NULL)
-			|| (get_diff_norm(
+			|| (fpi_mean_sq_diff_norm(
 				data->lastline + 8,
 				linebuf + 8,
 				VFS5011_IMAGE_WIDTH) >= DIFFERENCE_THRESHOLD)) {
diff --git a/libfprint/fp_internal.h b/libfprint/fp_internal.h
index 5970e31..e309ea9 100644
--- a/libfprint/fp_internal.h
+++ b/libfprint/fp_internal.h
@@ -489,5 +489,9 @@ void fpi_imgdev_image_captured(struct fp_img_dev *imgdev, struct fp_img *img);
 void fpi_imgdev_abort_scan(struct fp_img_dev *imgdev, int result);
 void fpi_imgdev_session_error(struct fp_img_dev *imgdev, int error);
 
+/* utils */
+int fpi_std_sq_dev(const unsigned char *buf, int size);
+int fpi_mean_sq_diff_norm(unsigned char *buf1, unsigned char *buf2, int size);
+
 #endif
 
diff --git a/libfprint/img.c b/libfprint/img.c
index f9545db..408dd56 100644
--- a/libfprint/img.c
+++ b/libfprint/img.c
@@ -511,3 +511,37 @@ API_EXPORTED struct fp_minutia **fp_img_get_minutiae(struct fp_img *img,
 	return img->minutiae->list;
 }
 
+/* Calculate squared standand deviation */
+int fpi_std_sq_dev(const unsigned char *buf, int size)
+{
+	int res = 0, mean = 0, i;
+
+	if (size > (INT_MAX / 65536)) {
+		fp_err("%s: we might get an overflow!", __func__);
+		return -EOVERFLOW;
+	}
+
+	for (i = 0; i < size; i++)
+		mean += buf[i];
+
+	mean /= size;
+
+	for (i = 0; i < size; i++) {
+		int dev = (int)buf[i] - mean;
+		res += dev*dev;
+	}
+
+	return res / size;
+}
+
+/* Calculate normalized mean square difference of two lines */
+int fpi_mean_sq_diff_norm(unsigned char *buf1, unsigned char *buf2, int size)
+{
+	int res = 0, i;
+	for (i = 0; i < size; i++) {
+		int dev = (int)buf1[i] - (int)buf2[i];
+		res += dev * dev;
+	}
+
+	return res / size;
+}