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/**************************************************************************
* arch/z80/src/z8/z8_saveusercontext.S
* Save the state of the current user thread
*
* 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 <ez8.inc>
/**************************************************************************
* Pre-processor Definitions
**************************************************************************/
xdef _z8_restorecontext
/**************************************************************************
* Code
**************************************************************************/
segment CODE
/****************************************************************************
* Name: _z8_restorecontext
*
* Description:
* Restore the task context that was previously saved via
* _z8_saveusercontext() or by interrupt handling. Unlike the
* _z8_saveusercontext() counterpart, we do not know the context of the
* restored task and, hence, we must handle the worst case -- restore
* everythihng.
*
* Parameters:
* On entry, the following stack organization is assumed:
*
* Pointer to the context save structure
* TOS -> Return address (2)
*
* Assumptions:
* Large model, dynamic frames
*
**************************************************************************/
_z8_restorecontext:
/* Disable all interrupts because we are going to be using
* the IRQ register set.
*/
di
/* Switch to IRQ register set */
srp #%f0
/* Get the rr0 = the current value of the stack pointer */
ldx r0, sph /* rr0 = stack pointer */
ldx r1, spl
/* Get rr6 = the pointer to the context save structure */
ldx r6, 2(rr0) /* rr6 = pointer to context structure */
ldx r7, 3(rr0)
/* Copy all registers into the user register area. NOTE: we
* use the saved RP value to determine the destination adress.
*/
clr r0 /* rr0 = destination address */
ldx r1, XCPT_RP_OFFS(rr6)
ld r2, r6 /* rr2 = source address */
ld r3, r7
ld r4, #16 /* r4 = number of bytes to copy */
_z8_restore:
ldx r5, @rr2
ldx @rr0, r5
incw rr0
incw rr2
djnz r4, _z8_restore
/* Set the new stack pointer */
ldx r0, XCPT_SPH_OFFS(rr6)
ldx r1, XCPT_SPL_OFFS(rr6)
ldx sph, r0
ldx spl, r1
/* Push the return address onto the stack */
ldx r0, XCPT_PCH_OFFS(rr6)
ldx r1, XCPT_PCL_OFFS(rr6)
push r1
push r0
/* Recover the flags and RP settings.. but don't restore them yet */
ldx r1, XCPT_FLAGS_OFFS(rr6)
ldx r2, XCPT_RP_OFFS(rr6)
/* Determine whether interrupts must be enabled on return. This
* would be nicer to do below, but later we will need to preserve
* the condition codes in the flags.
*/
ldx r0, XCPT_IRQCTL_OFFS(rr6)
tm r0, #%80
jr nz, _z8_returnenabled
/* Restore the flag settings */
ldx flags, r1
/* Restore the user register page and return with interrupts disabled */
ldx rp, r2 /* Does not effect flags */
ret /* Does not effect flags */
_z8_returnenabled:
/* Restore the flag settings */
ldx flags, r1
/* Restore the user register page, re-enable interrupts and return */
ldx rp, r2 /* Does not effect flags */
ei /* Does not effect flags */
ret /* Does not effect flags */
end
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