Adding sbrk, and fixing a couple of other makefile problems.

2 files changed, 49 insertions, 1 deletions

diff --git a/os/Makefile b/os/Makefile
index 6f6ce2e..070566d 100644
--- a/os/Makefile
+++ b/os/Makefile
@@ -4,8 +4,9 @@ all: $(TARGET_LIB)
 
 include $(ROOTDIR)/common.mk
 include config.mk
+include $(ROOTDIR)/FreeRTOS/config.mk
 
-TARGET_SRCS = src/init.c
+TARGET_SRCS = src/init.c src/sbrk.c
 
 include $(ROOTDIR)/target-rules.mk
 
diff --git a/os/src/sbrk.c b/os/src/sbrk.c
new file mode 100644
index 0000000..3c674ba
--- /dev/null
+++ b/os/src/sbrk.c
@@ -0,0 +1,47 @@
+#include <reent.h>
+#include <errno.h>
+#include <stdlib.h>
+
+#include "FreeRTOS.h"
+#include "task.h"
+#include "mpu_wrappers.h"
+
+// Mostly stolen from mbed-freertos
+
+extern unsigned int __cs3_heap_start, __cs3_heap_end;
+
+/* Low-level bulk RAM allocator -- used by Newlib's Malloc */
+void *heap_end = NULL;
+PRIVILEGED_FUNCTION void *_sbrk_r(struct _reent *ptr, ptrdiff_t incr)
+{
+    void *prev_heap_end, *next_heap_end, *ret;
+
+    taskENTER_CRITICAL();
+    {
+        /* Initialize on first call */
+        if (heap_end == NULL)
+        {
+            heap_end = (void *)&__cs3_heap_start;
+        }
+
+        prev_heap_end = heap_end;
+
+        /* Align to always be on 8-byte boundaries */
+        next_heap_end = (void *)((((unsigned int)heap_end + incr) + 7) & ~7);
+
+        /* Check if this allocation would exceed the end of the ram - would probably get into the stack first however */
+        if (next_heap_end > (void *)&__cs3_heap_end)
+        {
+            ptr->_errno = ENOMEM;
+            ret = NULL;
+        }
+        else
+        {
+            heap_end = next_heap_end;
+            ret = (void *)prev_heap_end;
+        }
+    }
+    taskEXIT_CRITICAL();
+    return ret;
+}
+