Send minimal amount of data

Send just the needed amount of data when writing to RAM and copying to Flash.

lpc.c

@@ -92,12 +92,14 @@ void lpc_init(struct lpc_device *dev) {
 }
 
 void lpc_write(struct lpc_device *dev, const struct sprog_data *d) {
-  static const int chunk_sizes[] = {256, 512, 1024, 4096, 0};
+  static const int chunk_sizes[] = {256, 512, 1024, 4096, 0}; /* keep it sorted! */
   struct sprog_data chunk;
   int i;
   int j;
+  int status;
   int offset;
   int chunk_size;
+  int max_chunk_index;
   int data_size;
   offset = 0;
   
@@ -134,14 +136,25 @@ void lpc_write(struct lpc_device *dev, const struct sprog_data *d) {
       }
     }
     
+    if(chunk_sizes[i]==0)
+      i--;
+    
     chunk_size = chunk_sizes[i];
-    if(chunk_size==0)
-      chunk_size = chunk_sizes[i-1];
-    sprog_alloc_data(&chunk, chunk_size);
+    max_chunk_index = i;
     
     data_size = chunk_size;
-    if(data_size > d->size-offset)
+    
+    if(data_size > d->size-offset) {
       data_size = d->size - offset;
+      /* we assume that all of the available chunk sizes are divisible by the first one */
+      /* TODO: Optimize the following code, assuming that the chunk sizes are powers of 2 */
+      chunk_size = data_size - data_size % chunk_sizes[0];
+      if(data_size % chunk_sizes[0])
+	chunk_size += chunk_sizes[0];
+    }
+    
+      
+    sprog_alloc_data(&chunk, chunk_size);
     
     for(i=0; i<data_size; i++)
       chunk.data[i] = d->data[offset+i];
@@ -166,10 +179,21 @@ void lpc_write(struct lpc_device *dev, const struct sprog_data *d) {
     lpc_write_ram(dev, &chunk, 0x10000400);
     
     sprog_info("Copying to Flash...\n");
-    if(lpc_command(dev, "C %d %u %d\r\n", offset, 0x10000400, chunk_size))
-      sprog_error("Error while copying to flash\n");
-    else
+    
+    j = max_chunk_index;
+    status = 1;
+    for(i=chunk_size; i>0; i-=chunk_sizes[j]) {
+      for(j=j; j>0; j--)
+	if(chunk_sizes[j]<=i)
+	  break;
+      if(lpc_command(dev, "C %d %u %d\r\n", offset+(chunk_size-i), 0x10000400+(chunk_size-i), chunk_sizes[j]))
+	status = 0;
+    }
+    
+    if(status)
       sprog_info("Done!\n");
+    else
+      sprog_info("Error\n");
     
     offset += data_size;
   }