First cut at support for Cortex-M0

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5655 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 144 insertions, 0 deletions

diff --git a/nuttx/arch/arm/src/armv6-m/vfork.S b/nuttx/arch/arm/src/armv6-m/vfork.S
new file mode 100644
index 000000000..0e9b9790d
--- /dev/null
+++ b/nuttx/arch/arm/src/armv6-m/vfork.S
@@ -0,0 +1,144 @@
+/************************************************************************************
+ * arch/arm/src/armv6-m/vfork.S
+ *
+ *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 "up_vfork.h"
+
+/************************************************************************************
+ * Pre-processor Definitions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Global Symbols
+ ************************************************************************************/
+
+	.cpu	cortex-m0
+	.file	"vfork.S"
+	.globl	up_vfork
+
+/************************************************************************************
+ * Public Functions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Name: vfork
+ *
+ * Description:
+ *   The vfork() function has the same effect as fork(), except that the behavior is
+ *   undefined if the process created by vfork() either modifies any data other than
+ *   a variable of type pid_t used to store the return value from vfork(), or returns
+ *   from the function in which vfork() was called, or calls any other function before
+ *   successfully calling _exit() or one of the exec family of functions. 
+ *
+ *   This thin layer implements vfork by simply calling up_vfork() with the vfork()
+ *   context as an argument.  The overall sequence is:
+ *
+ *   1) User code calls vfork().  vfork() collects context information and
+ *      transfers control up up_vfork().
+ *   2) up_vfork()and calls task_vforksetup().
+ *   3) task_vforksetup() allocates and configures the child task's TCB.  This
+ *      consists of:
+ *      - Allocation of the child task's TCB.
+ *      - Initialization of file descriptors and streams
+ *      - Configuration of environment variables
+ *      - Setup the intput parameters for the task.
+ *      - Initialization of the TCB (including call to up_initial_state()
+ *   4) up_vfork() provides any additional operating context. up_vfork must:
+ *      - Allocate and initialize the stack
+ *      - Initialize special values in any CPU registers that were not
+ *        already configured by up_initial_state()
+ *   5) up_vfork() then calls task_vforkstart()
+ *   6) task_vforkstart() then executes the child thread.
+ *
+ * Input Paremeters:
+ *   None
+ *
+ * Return:
+ *   Upon successful completion, vfork() returns 0 to the child process and returns
+ *   the process ID of the child process to the parent process. Otherwise, -1 is
+ *   returned to the parent, no child process is created, and errno is set to
+ *   indicate the error. 
+ *
+ ************************************************************************************/
+
+	.align	2
+	.code	16
+	.thumb_func
+	.globl	vfork
+	.type	vfork, function
+vfork:
+	/* Create a stack frame */
+
+	mov		r0, sp					/* Save the value of the stack on entry */
+	sub		sp, sp, #VFORK_SIZEOF	/* Allocate the structure on the stack */
+
+	/* CPU registers */
+	/* Save the volatile registers */
+
+	mov		r1, sp
+	stmia	r1!, {r4-r7}			/* Save r4-r7 in the structure */
+	mov		r4, r8					/* Copy high registers to low registers */
+	mov		r5, r9
+	mov		r6, r10
+	mov		r7, fp
+	stmia	r1!, {r4-r7}			/* Save r8-r10 and fp in the structure */
+	str		r0, [r1, #0]			/* Save the stack pointer in the structure */
+	mov		r0, r14					/* Copy lr to a low registers */
+	str		r0, [r1, #0]			/* Save the stack pointer in the structure */
+
+	/* Then, call up_vfork(), passing it a pointer to the stack structure */
+
+	mov		r0, sp
+	bl		up_vfork
+
+	/* Recover r4-r7 that were destroyed before up_vfork was called */
+
+	mov		r1, sp
+	ldmia	r1!, {r4-r7}
+
+	/* Release the stack data and return the value returned by up_vfork */
+
+	ldr		r1, [sp, #VFORK_LR_OFFSET]
+	mov		r14, r1
+	add		sp, sp, #VFORK_SIZEOF
+	bx		lr
+	.size	vfork, .-vfork
+	.end
+