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/*************************************************************************
* arch/z16/src/z16f/z16f_saveusercontext.asm
*
* Copyright (C) 2008 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 <arch/irq.h>
#include "chip/chip.h"
/*************************************************************************
* External References / External Definitions
*************************************************************************/
xdef _up_saveusercontext
/*************************************************************************
* Data Allocation
*************************************************************************/
define CODESEG, SPACE=EROM
segment CODESEG
/*************************************************************************
* Code
*************************************************************************/
/*************************************************************************
* Name: up_saveusercontext
*
* Description:
* Save the current user context.
* r0-r7: These are caller saved registers and do not need to be stored
* here
* r8-r13: There callee saved registers must be preserved
* r14: Frame pointer
* r15: Stack pointer (with return address on stack)
*
* Parameters:
* r1: pointer to the register save array in the XCPT structure
*
*************************************************************************/
_up_saveusercontext:
/* Save the flags (needed to restore the interrupt state) */
ld.ub r3, Z16F_CNTRL_FLAGS /* Fetch the flags register (zero padded) */
ld.w 2*REG_FLAGS(r1), r3 /* Save 16-bit value */
/* Save r8-R13 */
ld 2*REG_R8(r1), r8 /* Save r8 */
ld 2*REG_R9(r1), r9 /* Save r9 */
ld 2*REG_R10(r1), r10 /* Save r10 */
ld 2*REG_R11(r1), r11 /* Save r11 */
ld 2*REG_R12(r1), r12 /* Save r12 */
ld 2*REG_R13(r1), r13 /* Save r13 */
/* Save the stack pointer and the frame pointer */
ld 2*REG_FP(r1), fp /* Save the frame pointer */
ld r0, #4 /* 4 bytes of return address on stack */
add r0, sp /* Value of stack pointer on return */
ld 2*REG_SP(r1), r0 /* Save the stack pointer value on return */
/* Save the return address at the top of the stack */
ld r0, (sp) /* Save the return address */
ld 2*REG_PC(r1), r0
/* Set the return value so that if when the task is restarted
* (via z16f_restoreusercontext() or via interrupt handling return),
* the returned value will be 1
*/
ld r0, #1
ld 2*REG_R0(r1), r0
/* But always return 0 when returning from this function. The
* apparent return value tells the higher level logic whether the
* user context was saved or restored (in the spirit of setjmp and longjmp)
*/
clr r0 /* Always returns 0 */
ret
end
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