1 files changed, 119 insertions, 0 deletions
diff --git a/nuttx/arch/x86/src/i486/up_usestack.c b/nuttx/arch/x86/src/i486/up_usestack.c
new file mode 100644
index 000000000..fb8ded0e1
--- /dev/null
+++ b/nuttx/arch/x86/src/i486/up_usestack.c
@@ -0,0 +1,119 @@
+/****************************************************************************
+ * arch/x86/src/common/up_usestack.c
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_use_stack
+ *
+ * Description:
+ *   Setup up stack-related information in the TCB using pre-allocated stack
+ *   memory
+ *
+ *   The following TCB fields must be initialized:
+ *   adj_stack_size: Stack size after adjustment for hardware, processor,
+ *     etc.  This value is retained only for debug purposes.
+ *   stack_alloc_ptr: Pointer to allocated stack
+ *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The initial value of
+ *     the stack pointer.
+ *
+ * Inputs:
+ *   tcb: The TCB of new task
+ *   stack_size:  The allocated stack size.
+ *
+ ****************************************************************************/
+
+int up_use_stack(_TCB *tcb, void *stack, size_t stack_size)
+{
+  size_t top_of_stack;
+  size_t size_of_stack;
+
+  if (tcb->stack_alloc_ptr)
+    {
+      sched_free(tcb->stack_alloc_ptr);
+    }
+
+  /* Save the stack allocation */
+
+  tcb->stack_alloc_ptr = stack;
+
+  /* The i486 uses a push-down stack:  the stack grows toward loweraddresses in
+   * memory.  The stack pointer register, points to the lowest, valid work
+   * address (the "top" of the stack).  Items on the stack are referenced as
+   * positive word offsets from sp.
+   */
+
+  top_of_stack = (uint32_t)tcb->stack_alloc_ptr + stack_size - 4;
+
+  /* The i486 stack must be aligned at word (4 byte) boundaries. If necessary
+   * top_of_stack must be rounded down to the next boundary
+   */
+
+  top_of_stack &= ~3;
+  size_of_stack = top_of_stack - (uint32_t)tcb->stack_alloc_ptr + 4;
+
+  /* Save the adjusted stack values in the _TCB */
+
+  tcb->adj_stack_ptr  = (uint32_t*)top_of_stack;
+  tcb->adj_stack_size = size_of_stack;
+
+  return OK;
+}