[PATCH RFC 3/6] libv4lconvert: SDR conversion from S8 to FLOAT

[Antti Palosaari]

SDR I/Q data conversion from signed 8-bit to [-1 to +1] float.

Signed-off-by: Antti Palosaari <cr...@iki.fi>
---
 contrib/freebsd/include/linux/videodev2.h |  1 +
 include/linux/videodev2.h                 |  1 +
 lib/libv4lconvert/libv4lconvert.c         | 12 ++++++++++++
 3 files changed, 14 insertions(+)

diff --git a/contrib/freebsd/include/linux/videodev2.h 
b/contrib/freebsd/include/linux/videodev2.h
index 05cc19b..d433a45 100644
--- a/contrib/freebsd/include/linux/videodev2.h
+++ b/contrib/freebsd/include/linux/videodev2.h
@@ -468,6 +468,7 @@ struct v4l2_pix_format {
 /* SDR */
 #define V4L2_PIX_FMT_SDR_FLOAT  v4l2_fourcc('D', 'F', '3', '2') /* float 
32-bit */
 #define V4L2_PIX_FMT_SDR_U8     v4l2_fourcc('D', 'U', '0', '8') /* unsigned 
8-bit */
+#define V4L2_PIX_FMT_SDR_S8     v4l2_fourcc('D', 'S', '0', '8') /* signed 
8-bit */
 
 /*
  *     F O R M A T   E N U M E R A T I O N
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index ba2a173..35b5731 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -434,6 +434,7 @@ struct v4l2_pix_format {
 /* SDR */
 #define V4L2_PIX_FMT_SDR_FLOAT  v4l2_fourcc('D', 'F', '3', '2') /* float 
32-bit */
 #define V4L2_PIX_FMT_SDR_U8     v4l2_fourcc('D', 'U', '0', '8') /* unsigned 
8-bit */
+#define V4L2_PIX_FMT_SDR_S8     v4l2_fourcc('D', 'S', '0', '8') /* signed 
8-bit */
 
 /*
  *     F O R M A T   E N U M E R A T I O N
diff --git a/lib/libv4lconvert/libv4lconvert.c 
b/lib/libv4lconvert/libv4lconvert.c
index b7cc0e1..421a8f1 100644
--- a/lib/libv4lconvert/libv4lconvert.c
+++ b/lib/libv4lconvert/libv4lconvert.c
@@ -447,6 +447,7 @@ static int v4lconvert_do_try_format_sdr(struct 
v4lconvert_data *data,
        static const unsigned int supported_src_pixfmts_sdr[] = {
                V4L2_PIX_FMT_SDR_FLOAT,
                V4L2_PIX_FMT_SDR_U8,
+               V4L2_PIX_FMT_SDR_S8,
        };
 
        for (i = 0; i < ARRAY_SIZE(supported_src_pixfmts_sdr); i++) {
@@ -1334,6 +1335,7 @@ static int v4lconvert_convert_sdr(struct v4lconvert_data 
*data,
        int i, dest_needed;
        unsigned int src_pix_fmt = fmt->fmt.pix.pixelformat;
        float *fptr = (float *) dest;
+       int8_t *s8ptr;
 
        switch (src_pix_fmt) {
        case V4L2_PIX_FMT_SDR_U8:
@@ -1345,6 +1347,16 @@ static int v4lconvert_convert_sdr(struct v4lconvert_data 
*data,
                for (i = 0; i < src_size; i++)
                        *fptr++ = (*src++ - 127.5f) / 127.5f;
                break;
+       case V4L2_PIX_FMT_SDR_S8:
+               s8ptr = (int8_t *) src;
+               /* 8-bit signed to 32-bit float */
+               dest_needed = src_size * sizeof(float);
+               if (dest_size < dest_needed)
+                       goto err_buf_too_small;
+
+               for (i = 0; i < src_size; i++)
+                       *fptr++ = (*s8ptr++ + 0.5f) / 127.5f;
+               break;
        default:
                V4LCONVERT_ERR("Unknown src format in conversion\n");
                errno = EINVAL;
-- 
1.8.4.2

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