1 files changed, 84 insertions, 0 deletions
diff --git a/src/blind-skip-pattern.c b/src/blind-skip-pattern.c
new file mode 100644
index 0000000..1debeca
--- /dev/null
+++ b/src/blind-skip-pattern.c
@@ -0,0 +1,84 @@
+/* See LICENSE file for copyright and license details. */
+#include "stream.h"
+#include "util.h"
+
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+
+USAGE("(skipped-frames | +included-frames) ...")
+
+static int
+process_frame(struct stream *stream, int include, size_t rown)
+{
+	size_t h, n;
+	int anything = 0;
+
+	for (h = stream->height; h;) {
+		h--;
+		for (n = rown; n; n -= stream->ptr) {
+			stream->ptr = 0;
+			if (!eread_stream(stream, n))
+				goto done;
+			anything = 1;
+			if (include)
+				ewriteall(STDOUT_FILENO, stream->buf, stream->ptr, "<stdout>");
+		}
+	}
+done:
+
+	if (anything && (h || n || stream->frames))
+		eprintf("%s: is shorted than expected\n", stream->file);
+
+	return !anything;
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct stream stream;
+	int i, include;
+	size_t f, n, rown, total = 0;
+	char *includes;
+	size_t *ns;
+
+	UNOFLAGS(!argc);
+
+	stream.fd = STDIN_FILENO;
+	stream.file = "<stdin>";
+	einit_stream(&stream);
+
+	includes = emalloc((size_t)argc);
+	ns = ecalloc((size_t)argc, sizeof(*ns));
+
+	for (i = 0; i < argc; i++) {
+		include = argv[i][0] == '+';
+		n = etozu_arg(include ? "included frame count" : "skipped frame count",
+			      argv[i] + include, 0, SIZE_MAX);
+		ns[i] = n;
+		includes[i] = (char)include;
+	}
+	if (!total)
+		eprintf("null pattern is not allowed");
+
+	for (i = 0, total = 0, f = stream.frames;; i = (i + 1) % argc) {
+		include = (int)includes[i];
+		for (n = ns[i]; n-- && f--;)
+			total += (size_t)include;
+	}
+
+	stream.frames = total;
+	fprint_stream_head(stdout, &stream);
+	efflush(stdout, "<stdout>");
+
+	rown = stream.width * stream.pixel_size;
+	for (i = 0;; i = (i + 1) % argc) {
+		include = (int)includes[i];
+		n = ns[i];
+		while (n-- && process_frame(&stream, include, rown));
+	}
+
+	free(includes);
+	free(ns);
+	return 0;
+}