preparations for >255byte patterns

the rest of the code (display etc.) isn't well-tested yet and will follow
in another commit

3 files changed, 34 insertions, 4 deletions

diff --git a/src/static_patterns.h b/src/static_patterns.h
index 5df47a0..e91c219 100644
--- a/src/static_patterns.h
+++ b/src/static_patterns.h
@@ -13,6 +13,10 @@
 
 #include <avr/pgmspace.h>
 
+/*
+ * Note: Static patterns must not be longer than 128 bytes (headers excluded)
+ */
+
 const uint8_t PROGMEM shutdownPattern[] = {
 	0x20, 0x40,
 	0x01, 0x0f,
diff --git a/src/storage.cc b/src/storage.cc
index bd35780..e965589 100644
--- a/src/storage.cc
+++ b/src/storage.cc
@@ -260,12 +260,27 @@ bool Storage::hasData()
 
 void Storage::load(uint8_t idx, uint8_t *data)
 {
-	uint8_t page_offset;
-	uint8_t header[2];
 	i2c_read(0, 1 + idx, 1, &page_offset);
 
-	i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32,  2, header);
-	i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32, header[1] + 4, data);
+	// always read headers
+	i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32,  4, data);
+
+	header[0] = data[0];
+	header[1] = data[1];
+
+	if (header[0] & 0x0f) {
+		// read whole byte block
+		i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32 + 4, 128, data + 4);
+		i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32 + 4 + 128, 128, data + 4 + 128);
+	} else {
+		i2c_read(1 + (page_offset / 8), (page_offset % 8) * 32 + 4, header[1], data + 4);
+	}
+}
+
+void Storage::loadChunk(uint8_t chunk, uint8_t *data)
+{
+	uint8_t this_page_offset = page_offset + (4 * chunk);
+	i2c_read(1 + (this_page_offset / 8), (this_page_offset % 8) * 32 + 4, 128, data);
 }
 
 void Storage::save(uint8_t *data)
diff --git a/src/storage.h b/src/storage.h
index cb99afd..e7feedb 100644
--- a/src/storage.h
+++ b/src/storage.h
@@ -15,6 +15,8 @@
 class Storage {
 	private:
 		uint8_t num_anims;
+		uint8_t page_offset;
+		uint8_t header[2];
 		uint8_t first_free_page;
 		uint8_t i2c_start_write(void);
 		uint8_t i2c_start_read(void);
@@ -83,6 +85,15 @@ class Storage {
 		void load(uint8_t idx, uint8_t *data);
 
 		/**
+		 * Load partial pattern chunk (without header) from EEPROM.
+		 *
+		 * @param chunk 128 byte-offset inside pattern (starting with 0)
+		 * @param data pointer to data structure for the pattern. Must be
+		 *        at least 128 bytes
+		 */
+		void loadChunk(uint8_t chunk, uint8_t *data);
+
+		/**
 		 * Save (possibly partial) pattern on the EEPROM. 32 bytes of
 		 * dattern data will be read and stored, regardless of the
 		 * pattern header.