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lib: move some functions from vfs5011.c into img.c

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This commit is contained in:
Vasily Khoruzhick 2016-02-09 17:19:39 -08:00
parent 49a46668ad
commit 5e29695969
3 changed files with 40 additions and 35 deletions
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37
libfprint/drivers/vfs5011.c
View file

@ -252,39 +252,6 @@ static void usb_exchange_async(struct fpi_ssm *ssm,
/* ====================== utils ======================= */ /* ====================== 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 */ /* Calculade squared standand deviation of sum of two lines */
static int vfs5011_get_deviation2(struct fpi_line_asmbl_ctx *ctx, GSList *row1, GSList *row2) 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 unsigned char *linebuf = data->capture_buffer
+ i * VFS5011_LINE_SIZE; + i * VFS5011_LINE_SIZE;
if (get_deviation(linebuf + 8, VFS5011_IMAGE_WIDTH) if (fpi_std_sq_dev(linebuf + 8, VFS5011_IMAGE_WIDTH)
< DEVIATION_THRESHOLD) { < DEVIATION_THRESHOLD) {
if (data->lines_captured == 0) if (data->lines_captured == 0)
continue; continue;
@ -417,7 +384,7 @@ static int process_chunk(struct vfs5011_data *data, int transferred)
} }
if ((data->lastline == NULL) if ((data->lastline == NULL)
|| (get_diff_norm( || (fpi_mean_sq_diff_norm(
data->lastline + 8, data->lastline + 8,
linebuf + 8, linebuf + 8,
VFS5011_IMAGE_WIDTH) >= DIFFERENCE_THRESHOLD)) { VFS5011_IMAGE_WIDTH) >= DIFFERENCE_THRESHOLD)) {

4
libfprint/fp_internal.h
View file

@ -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_abort_scan(struct fp_img_dev *imgdev, int result);
void fpi_imgdev_session_error(struct fp_img_dev *imgdev, int error); 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 #endif

34
libfprint/img.c
View file

@ -511,3 +511,37 @@ API_EXPORTED struct fp_minutia **fp_img_get_minutiae(struct fp_img *img,
return img->minutiae->list; 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;
}