This commit was manufactured by cvs2svn to create branch 'rtems-4-6-branch'.

Cherrypick from master 2003-09-26 20:43:22 UTC Joel Sherrill <joel.sherrill@OARcorp.com> '2003-09-26	Till Strauman <strauman@slac.stanford.edu>':
    c/src/lib/libbsp/powerpc/shared/startup/sbrk.c

1 files changed, 64 insertions, 0 deletions

diff --git a/c/src/lib/libbsp/powerpc/shared/startup/sbrk.c b/c/src/lib/libbsp/powerpc/shared/startup/sbrk.c
new file mode 100644
index 0000000000..276433a5da
--- /dev/null
+++ b/c/src/lib/libbsp/powerpc/shared/startup/sbrk.c
@@ -0,0 +1,64 @@
+/* $Id$ */
+
+/*
+ *  sbrk.c
+ *
+ *  Author: Till Straumann <strauman@slac.stanford.edu>, 2002
+ *
+ *  Hack around the 32bit powerpc 32M problem:
+ *
+ *  GCC by default uses relative branches which can not jump
+ *  farther than 32M. Hence all program text is confined to
+ *  a single 32M segment.
+ *  This hack gives the RTEMS malloc region all memory below
+ *  32M at startup. Only when this region is exhausted will sbrk
+ *  add more memory. Loading modules may fail at that point, hence
+ *  the user is expected to load all modules at startup _prior_
+ *  to malloc()ing lots of memory...
+ *
+ *  NOTE: it would probably be better to have a separate region
+ *        for module code.
+ */
+
+#include <rtems.h>
+
+#include <signal.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static rtems_unsigned32 remaining_start=0;
+static rtems_unsigned32 remaining_size=0;
+
+#define LIMIT_32M  0x02000000
+
+rtems_unsigned32
+_bsp_sbrk_init(rtems_unsigned32 heap_start, rtems_unsigned32 *heap_size_p)
+{
+  rtems_unsigned32 rval=0;
+
+  remaining_start =  heap_start;
+  remaining_size  =*  heap_size_p;
+  if (remaining_start < LIMIT_32M &&
+      remaining_start + remaining_size > LIMIT_32M) {
+    /* clip at LIMIT_32M */
+    rval = remaining_start + remaining_size - LIMIT_32M;
+    *heap_size_p = LIMIT_32M - remaining_start;
+  }
+  return rval;
+}
+
+void * sbrk(ptrdiff_t incr)
+{
+  void *rval=(void*)-1;
+
+  if (incr <= remaining_size) {
+    remaining_size-=incr;
+    rval = (void*)remaining_start;
+    remaining_start += incr;
+  } else {
+    errno = ENOMEM;
+  }
+  return rval;
+}
+