Allow yaml file to specify default compression for images

utility/bmpblk_utility.cc

Index: utility/bmpblk_utility.cc
diff --git a/utility/bmpblk_utility.cc b/utility/bmpblk_utility.cc
index 8605dde046fa4d699197a7d238ef4ea5db69875b..078a5cebbe8fab423e83c3f955fbaeeb5300aae0 100644
--- a/utility/bmpblk_utility.cc
+++ b/utility/bmpblk_utility.cc
@@ -139,6 +139,8 @@ void BmpBlockUtil::parse_first_layer(yaml_parser_t *parser) {
         keyword = (char*)event.data.scalar.value;
         if (keyword == "bmpblock") {
           parse_bmpblock(parser);
+        } else if (keyword == "compression") {
+          parse_compression(parser);
         } else if (keyword == "images") {
           parse_images(parser);
         } else if (keyword == "screens") {
@@ -174,6 +176,24 @@ void BmpBlockUtil::parse_bmpblock(yaml_parser_t *parser) {
   yaml_event_delete(&event);
 }
 
+void BmpBlockUtil::parse_compression(yaml_parser_t *parser) {
+  yaml_event_t event;
+  yaml_parser_parse(parser, &event);
+  if (event.type != YAML_SCALAR_EVENT) {
+    error("Syntax error in parsing bmpblock.\n");
+  }
+  char *comp_str = (char *)event.data.scalar.value;
+  char *e = 0;
+  uint32_t comp = (uint32_t)strtoul(comp_str, &e, 0);
+  if (!*comp_str || (e && *e) || comp >= MAX_COMPRESS) {
+    error("Invalid compression specified in config file\n");
+  }
+  if (!set_compression_) {
+    compression_ = comp;
+  }
+  yaml_event_delete(&event);
+}
+
 void BmpBlockUtil::parse_images(yaml_parser_t *parser) {
   yaml_event_t event;
   string image_name, image_filename;