Merge pull request #156 from systec-ms/memory_2048_368_fix

Fix RAM address and add ITCM and DTCM sections

Author: hannobraun

memory_2048_368.x

@@ -3,9 +3,32 @@ MEMORY
 {
   /* NOTE K = KiBi = 1024 bytes */
   FLASH : ORIGIN = 0x08000000, LENGTH = 2M
-  RAM : ORIGIN = 0x20000000, LENGTH = 368K + 16K
+  RAM : ORIGIN = 0x20020000, LENGTH = 368K + 16K
+  ITCM : ORIGIN = 0x00000000, LENGTH = 16K /* Instruction Tighly Coupled Memory */
+  DTCM : ORIGIN = 0x20000000, LENGTH = 128K /* Data Tighly Coupled Memory */
 }
 
+SECTIONS
+{
+    .itcm : ALIGN(4)
+    {
+        *(.itcm .itcm.*);
+        . = ALIGN(4);
+    } > ITCM
+
+    .dtcm : ALIGN(4)
+    {
+        *(.dtcm .dtcm.*);
+        . = ALIGN(4);
+    } > DTCM
+}
+
+/* You can then use something like this to place a variable into a specific section of memory:
+ *  #[link_section = ".dtcm.BUFFER"]
+ *  static mut BUF: [u8; 1024] = [3u8; 1024];
+ *  Verifiable with: cargo size --release --example hello_world -- -A
+ */
+
 /* This is where the call stack will be allocated. */
 /* The stack is of the full descending type. */
 /* NOTE Do NOT modify `_stack_start` unless you know what you are doing */