1 files changed, 39 insertions, 0 deletions
diff --git a/code/fe310/gloss/sys_sbrk.c b/code/fe310/gloss/sys_sbrk.c
new file mode 100644
index 0000000..cc01c8f
--- /dev/null
+++ b/code/fe310/gloss/sys_sbrk.c
@@ -0,0 +1,39 @@
+#include <sys/types.h>
+
+/* brk is handled entirely within the C library.  This limits METAL programs that
+ * use the C library to be disallowed from dynamically allocating memory
+ * without talking to the C library, but that sounds like a sane way to go
+ * about it.  Note that there is no error checking anywhere in this file, users
+ * will simply get the relevant error when actually trying to use the memory
+ * that's been allocated. */
+extern char metal_segment_heap_target_start;
+extern char metal_segment_heap_target_end;
+static char *brk = &metal_segment_heap_target_start;
+
+int
+_brk(void *addr)
+{
+  brk = addr;
+  return 0;
+}
+
+char *
+_sbrk(ptrdiff_t incr)
+{
+  char *old = brk;
+
+  /* If __heap_size == 0, we can't allocate memory on the heap */
+  if(&metal_segment_heap_target_start == &metal_segment_heap_target_end) {
+    return (void *)-1;
+  }
+
+  /* Don't move the break past the end of the heap */
+  if ((brk + incr) < &metal_segment_heap_target_end) {
+    brk += incr;
+  } else {
+    brk = &metal_segment_heap_target_end;
+    return (void *)-1;
+  }
+
+  return old;
+}