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/*************************************************************************
* arch/z16/src/z16f/z16f_restoreusercontext.asm
*
* Copyright (C) 2008 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 <arch/irq.h>
#include "chip/chip.h"
/*************************************************************************
* External References / External Definitions
*************************************************************************/
xdef _up_restoreusercontext
/*************************************************************************
* Data Allocation
*************************************************************************/
define CODESEG, SPACE=EROM
segment CODESEG
/*************************************************************************
* Code
*************************************************************************/
/*************************************************************************
* Name: up_restoreusercontext
*
* Description:
* Restore the current user context.
*
* Parameters:
* r1: pointer to the register save array in the XCPT structure
*
*************************************************************************/
_up_restoreusercontext:
/* Disable interrupts while we are accessing the TCB's register
* save structure
*/
di
/* Set up the stack for return */
ld sp, 2*REG_SP(r1) /* sp=Value of SP on return */
ld r2, 2*REG_PC(r1) /* r2=return address */
push r2 /* Push the return address onto the stack */
ld r7, 2*REG_R7(r1) /* r7=saved value of r7 */
push r7 /* Save this so that we can use r7 */
ld r7, sp /* r7=saved SP value */
/* Retore r8-r14 */
ld sp, r1 /* sp=Points to register save structure */
popmhi <r8-r14> /* Restore r8-r14 */
add sp, #4 /* Skip over r15=sp */
/* Test if interrupts should be enabled upon return */
ld.w r2, 2*REG_FLAGS(r1) /* r2=padded flags value */
tm r2, #Z16F_CNTRL_FLAGS_IRQE /* Test IRQE bit (Z-bit == 0 if disabled) */
popmlo <r0-r6> /* Restore r0-r6 (retains Z-bit) */
ld sp, r7 /* Recover the correct SP value (retains Z-bit) */
pop r7 /* Get the saved value of r7 (retains Z-bit)*/
jp z, _up_returndisabled /* Jump if interrupts should remain disabled */
/* Return with interrupts enabled. Note that at this point in the logic,
* we are finished accessing the TCB. Therefore, any interrupt level context
* switches that may modify the TCB should be OK
*/
ei /* Enable interrupts */
_up_returndisabled:
ret
end
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