Add bucket cache

Stores accumulation buckets. Use case: Run n seconds, check image noise
levels, run again (with cache and thus previous results), check image
agin, …

3 files changed, 81 insertions, 2 deletions

diff --git a/main.c b/main.c
index 7a699c3..6a17b3a 100644
--- a/main.c
+++ b/main.c
@@ -35,6 +35,7 @@ const char *argp_program_version =
 typedef struct {
 	unsigned int bpc;
 	float scale, time;
+	char *cache;
 } render_arguments;
 
 static error_t parse_render_opt (int key, char *arg,
@@ -68,6 +69,10 @@ static error_t parse_render_opt (int key, char *arg,
 			}
 			break;
 
+		case 'c':
+			arguments->cache = strdup (arg);
+			break;
+
 		case ARGP_KEY_ARG:
 			if (state->arg_num > 0) {
 				return ARGP_ERR_UNKNOWN;
@@ -112,8 +117,16 @@ static void do_render (const render_arguments * const arguments) {
 
 	bucket bucket;
 	bucket_init (&bucket, (uint2) { genome->width, genome->height });
+	if (arguments->cache != NULL) {
+		bucket_deserialize (&bucket, arguments->cache);
+	}
 
 	render_bucket (genome, &bucket, arguments->time);
+
+	if (arguments->cache != NULL) {
+		bucket_serialize (&bucket, arguments->cache);
+	}
+
 	fprintf (stderr, "%lu samples, %lu bad\n",
 			bucket.samples, bucket.badvals);
 	render_image (genome, &bucket, image, bytes_per_channel);
@@ -476,8 +489,7 @@ int main (int argc, char **argv) {
 				{"scale", 's', "factor", 0, "Scale image dimensions by factor (1.0)" },
 				{"bpc", 'b', "8|16", 0, "Bits per channel of output image (8)" },
 				{"time", 't', "seconds", 0, "Rendering time" },
-				{"width", 'w', "pixels", 0, "Output image width" },
-				{"height", 'h', "pixels", 0, "Output image height" },
+				{"cache", 'c', "path", 0, "Cache file" },
 				{ 0 },
 				};
 		const char doc[] = "vlame3-render -- a fractal flame renderer";
@@ -490,6 +502,7 @@ int main (int argc, char **argv) {
 				.bpc = 8,
 				.scale = 1.0,
 				.time = 1.0,
+				.cache = NULL,
 				};
 
 		argp_parse (&argp, argc, argv, 0, NULL, &arguments);
diff --git a/rect.c b/rect.c
index d988ed1..34bbc7e 100644
--- a/rect.c
+++ b/rect.c
@@ -194,9 +194,72 @@ void bucket_init (bucket * const b, const uint2 dim) {
 	int ret = posix_memalign ((void **) &b->data, sizeof (*b->data), size);
 	assert (ret == 0);
 	assert (b->data != NULL);
+
 	memset (b->data, 0, size);
 }
 
+/* just a random 32 bit value */
+#define BUCKET_CACHE_IDENT 0x252007d2
+
+/*	Read bucket from file
+ */
+bool bucket_deserialize (bucket * const b, const char *file) {
+	FILE *fd = fopen (file, "r");
+	if (fd == NULL) {
+		return false;
+	}
+
+	uint32_t ident;
+	size_t ret = fread (&ident, sizeof (ident), 1, fd);
+	assert (ret == 1);
+	assert (ident == BUCKET_CACHE_IDENT);
+
+	uint32_t w, h;
+	ret = fread (&w, sizeof (w), 1, fd);
+	assert (ret == 1);
+	ret = fread (&h, sizeof (h), 1, fd);
+	assert (ret == 1);
+	assert (b->dim[0] == w && b->dim[1] == h);
+
+	uint64_t samples, badvals;
+	ret = fread (&samples, sizeof (samples), 1, fd);
+	assert (ret == 1);
+	ret = fread (&badvals, sizeof (badvals), 1, fd);
+	assert (ret == 1);
+	b->samples = samples;
+	b->badvals = badvals;
+
+	ret = fread (b->data, sizeof (*b->data), w*h, fd);
+	assert (ret == w*h);
+
+	fclose (fd);
+
+	return true;
+}
+
+/*	Write bucket into a file
+ */
+void bucket_serialize (bucket * const b, const char *file) {
+	FILE *fd = fopen (file, "w");
+	assert (fd != NULL);
+
+	uint32_t ident = BUCKET_CACHE_IDENT;
+	fwrite (&ident, sizeof (ident), 1, fd);
+
+	assert (sizeof (b->dim[0]) >= sizeof (uint32_t));
+	fwrite (&b->dim[0], sizeof (uint32_t), 1, fd);
+	fwrite (&b->dim[1], sizeof (uint32_t), 1, fd);
+
+	assert (sizeof (b->samples) >= sizeof (uint64_t));
+	assert (sizeof (b->badvals) >= sizeof (uint64_t));
+	fwrite (&b->samples, sizeof (uint64_t), 1, fd);
+	fwrite (&b->badvals, sizeof (uint64_t), 1, fd);
+
+	fwrite (b->data, sizeof (*b->data), b->dim[0]*b->dim[1], fd);
+
+	fclose (fd);
+}
+
 static void compute_camera (const flam3_genome * const genome,
 		const bucket * const bucket, render_constants * const c) {
 	assert (genome != NULL);
diff --git a/rect.h b/rect.h
index 39c76cb..5b3dd62 100644
--- a/rect.h
+++ b/rect.h
@@ -11,6 +11,9 @@ typedef struct {
 } bucket;
 
 void bucket_init (bucket * const b, const uint2 dim);
+bool bucket_deserialize (bucket * const b, const char *file);
+void bucket_serialize (bucket * const b, const char *file);
+
 bool render_bucket (flam3_genome * const genome, bucket * const bucket,
 		const double timelimit);
 void render_image (const flam3_genome * const genome, const bucket * const b,