cta: add support for video data blocks

Report the SVDs inside the video data block.

We'll need to add additional APIs to get detailed SVD mode info
in the future (with a SVD table).

Signed-off-by: Simon Ser <contact@emersion.fr>

cta.c

@@ -43,6 +43,47 @@ add_failure_until(struct di_edid_cta *cta, int revision, const char fmt[], ...)
 	va_end(args);
 }
 
+static bool
+parse_video_block(struct di_edid_cta *cta, struct di_cta_video_block *video,
+		  const uint8_t *data, size_t size)
+{
+	size_t i;
+	uint8_t raw;
+	struct di_cta_svd svd, *svd_ptr;
+
+	if (size == 0)
+		add_failure(cta, "Video Data Block: Empty Data Block");
+
+	for (i = 0; i < size; i++) {
+		raw = data[i];
+
+		if (raw == 0 || raw == 128 || raw >= 254) {
+			/* Reserved */
+			add_failure_until(cta, 3,
+					  "Video Data Block: Unknown VIC %" PRIu8 ".",
+					  raw);
+			continue;
+		} else if (raw <= 127 || raw >= 193) {
+			svd = (struct di_cta_svd) {
+				.vic = raw,
+			};
+		} else {
+			svd = (struct di_cta_svd) {
+				.vic = get_bit_range(raw, 6, 0),
+				.native = true,
+			};
+		}
+
+		svd_ptr = calloc(1, sizeof(*svd_ptr));
+		if (!svd_ptr)
+			return false;
+		*svd_ptr = svd;
+		video->svds[video->svds_len++] = svd_ptr;
+	}
+
+	return true;
+}
+
 static bool
 parse_colorimetry_block(struct di_edid_cta *cta,
 			struct di_cta_colorimetry_block *colorimetry,
@@ -133,6 +174,25 @@ parse_hdr_static_metadata_block(struct di_edid_cta *cta,
 	return true;
 }
 
+static void
+destroy_data_block(struct di_cta_data_block *data_block)
+{
+	size_t i;
+	struct di_cta_video_block *video;
+
+	switch (data_block->tag) {
+	case DI_CTA_DATA_BLOCK_VIDEO:
+		video = &data_block->video;
+		for (i = 0; i < video->svds_len; i++)
+			free(video->svds[i]);
+		break;
+	default:
+		break; /* Nothing to do */
+	}
+
+	free(data_block);
+}
+
 static bool
 parse_data_block(struct di_edid_cta *cta, uint8_t raw_tag, const uint8_t *data, size_t size)
 {
@@ -151,6 +211,8 @@ parse_data_block(struct di_edid_cta *cta, uint8_t raw_tag, const uint8_t *data,
 		break;
 	case 2:
 		tag = DI_CTA_DATA_BLOCK_VIDEO;
+		if (!parse_video_block(cta, &data_block->video, data, size))
+			goto error;
 		break;
 	case 3:
 		/* Vendor-Specific Data Block */
@@ -257,6 +319,10 @@ parse_data_block(struct di_edid_cta *cta, uint8_t raw_tag, const uint8_t *data,
 skip:
 	free(data_block);
 	return true;
+
+error:
+	destroy_data_block(data_block);
+	return false;
 }
 
 bool
@@ -352,7 +418,7 @@ _di_edid_cta_finish(struct di_edid_cta *cta)
 	size_t i;
 
 	for (i = 0; i < cta->data_blocks_len; i++) {
-		free(cta->data_blocks[i]);
+		destroy_data_block(cta->data_blocks[i]);
 	}
 
 	for (i = 0; i < cta->detailed_timing_defs_len; i++) {
@@ -384,6 +450,15 @@ di_cta_data_block_get_tag(const struct di_cta_data_block *block)
 	return block->tag;
 }
 
+const struct di_cta_svd *const *
+di_cta_data_block_get_svds(const struct di_cta_data_block *block)
+{
+	if (block->tag != DI_CTA_DATA_BLOCK_VIDEO) {
+		return NULL;
+	}
+	return (const struct di_cta_svd *const *) block->video.svds;
+}
+
 const struct di_cta_colorimetry_block *
 di_cta_data_block_get_colorimetry(const struct di_cta_data_block *block)
 {

di-edid-decode.c

@@ -474,6 +474,24 @@ display_color_type_name(enum di_edid_display_color_type type)
 	abort();
 }
 
+static void
+printf_cta_svds(const struct di_cta_svd *const *svds)
+{
+	size_t i;
+	const struct di_cta_svd *svd;
+
+	for (i = 0; svds[i] != NULL; i++) {
+		svd = svds[i];
+
+		printf("    VIC %3" PRIu8, svd->vic);
+		if (svd->native)
+			printf(" (native)");
+		printf("\n");
+
+		// TODO: print detailed mode info
+	}
+}
+
 static uint8_t
 encode_max_luminance(float max)
 {
@@ -580,6 +598,7 @@ print_cta(const struct di_edid_cta *cta)
 	const struct di_cta_data_block *const *data_blocks;
 	const struct di_cta_data_block *data_block;
 	enum di_cta_data_block_tag data_block_tag;
+	const struct di_cta_svd *const *svds;
 	const struct di_cta_colorimetry_block *colorimetry;
 	const struct di_cta_hdr_static_metadata_block *hdr_static_metadata;
 	size_t i;
@@ -610,6 +629,10 @@ print_cta(const struct di_edid_cta *cta)
 		printf("  %s:\n", cta_data_block_tag_name(data_block_tag));
 
 		switch (data_block_tag) {
+		case DI_CTA_DATA_BLOCK_VIDEO:
+			svds = di_cta_data_block_get_svds(data_block);
+			printf_cta_svds(svds);
+			break;
 		case DI_CTA_DATA_BLOCK_COLORIMETRY:
 			colorimetry = di_cta_data_block_get_colorimetry(data_block);
 			if (colorimetry->xvycc_601)

include/cta.h

@@ -19,6 +19,13 @@
  * 18 bytes.
  */
 #define EDID_CTA_MAX_DETAILED_TIMING_DEFS 6
+/**
+ * The maximum number of SVD entries in a video data block.
+ *
+ * Each data block has its size described in a 5-bit field, so its maximum size
+ * is 63 bytes, and each SVD uses 1 byte.
+ */
+#define EDID_CTA_MAX_VIDEO_BLOCK_ENTRIES 63
 
 struct di_edid_cta {
 	int revision;
@@ -41,9 +48,17 @@ struct di_cta_hdr_static_metadata_block_priv {
 	struct di_cta_hdr_static_metadata_block_descriptors descriptors;
 };
 
+struct di_cta_video_block {
+	/* NULL-terminated */
+	struct di_cta_svd *svds[EDID_CTA_MAX_VIDEO_BLOCK_ENTRIES + 1];
+	size_t svds_len;
+};
+
 struct di_cta_data_block {
 	enum di_cta_data_block_tag tag;
 
+	/* Used for DI_CTA_DATA_BLOCK_VIDEO */
+	struct di_cta_video_block video;
 	/* Used for DI_CTA_DATA_BLOCK_COLORIMETRY */
 	struct di_cta_colorimetry_block colorimetry;
 	/* Used for DI_CTA_DATA_BLOCK_HDR_STATIC_METADATA */

include/libdisplay-info/cta.h

@@ -199,6 +199,26 @@ struct di_cta_hdr_static_metadata_block {
 const struct di_cta_hdr_static_metadata_block *
 di_cta_data_block_get_hdr_static_metadata(const struct di_cta_data_block *block);
 
+/**
+ * A Short Video Descriptor (SVD).
+ */
+struct di_cta_svd {
+	/* Video Identification Code (VIC) */
+	uint8_t vic;
+	/* Whether this is a native video format */
+	bool native;
+};
+
+/**
+ * Get an array of short video descriptors from a CTA data block.
+ *
+ * Returns NULL if the data block tag is not DI_CTA_DATA_BLOCK_VIDEO.
+ *
+ * The returned array is NULL-terminated.
+ */
+const struct di_cta_svd *const *
+di_cta_data_block_get_svds(const struct di_cta_data_block *block);
+
 /**
  * Get a list of EDID detailed timing definitions.
  *

test/data/hp-5dq99aa-hdmi.diff

@@ -23,7 +23,7 @@
    Detailed Timing Descriptors:
      DTD 1:  2560x1440   59.950550 Hz  16:9     88.787 kHz    241.500000 MHz (597 mm x 339 mm)
                   Hfront   48 Hsync  32 Hback   80 Hpol P
-@@ -51,32 +51,7 @@
+@@ -51,32 +51,16 @@
    Supports YCbCr 4:2:2
    Native detailed modes: 1
    Video Data Block:
@@ -42,6 +42,15 @@
 -    DC_30bit
 -    DC_Y444
 -    Maximum TMDS clock: 310 MHz
++    VIC  16
++    VIC   4
++    VIC   3
++    VIC   2
++    VIC  31
++    VIC  19
++    VIC  18
++    VIC  17
++    VIC   1
    Video Capability Data Block:
 -    YCbCr quantization: No Data
 -    RGB quantization: No Data
@@ -56,7 +65,7 @@
    Colorimetry Data Block:
      BT2020cYCC
      BT2020YCC
-@@ -104,20 +79,8 @@
+@@ -104,20 +88,8 @@
      DTD 5:  1920x1080   74.972503 Hz  16:9     83.894 kHz    174.500000 MHz (597 mm x 339 mm)
                   Hfront   48 Hsync  32 Hback   80 Hpol P
                   Vfront    3 Vsync   5 Vback   31 Vpol N