/**************************************************************************
* up_savecontext.c
*
* Copyright (C) 2007, 2009 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 <stdint.h>
#include <nuttx/irq.h>
#include "up_internal.h"
/**************************************************************************
* Private Definitions
**************************************************************************/
/**************************************************************************
* Private Types
**************************************************************************/
/**************************************************************************
* Private Function Prototypes
**************************************************************************/
/**************************************************************************
* Global Variables
**************************************************************************/
/**************************************************************************
* Private Variables
**************************************************************************/
/**************************************************************************
* Private Functions
**************************************************************************/
/**************************************************************************
* Name: up_savestack
*
* Description:
* Save the entire interrupt stack contents in the provided context
* structure.
*
* Inputs:
* context - the context structure in which to save the stack info
*
* Return:
* None
*
* Assumptions:
* - Interrupts are disabled
*
**************************************************************************/
static void up_savestack(FAR struct xcptcontext *context, uint8_t tos)
{
/* Copy the current stack frame from internal RAM to XRAM. */
uint8_t nbytes = tos - (STACK_BASE-1);
NEAR uint8_t *src = (NEAR uint8_t*)STACK_BASE;
FAR uint8_t *dest = context->stack;
context->nbytes = nbytes;
while (nbytes--)
{
*dest++ = *src++;
}
}
/**************************************************************************
* Name: up_saveregs
*
* Description:
* Save the interrupt registers into the TCB.
*
* Inputs:
* context - the context structure in which to save the register info
*
* Return:
* None
*
* Assumptions:
* - Interrupts are disabled
*
**************************************************************************/
static void up_saveregs(FAR struct xcptcontext *context, uint8_t tos)
{
/* Copy the irq register save area into the TCB */
FAR uint8_t *src = g_irqregs;
FAR uint8_t *dest = context->regs;
uint8_t nbytes = REGS_SIZE;
while (nbytes--)
{
*dest++ = *src++;
}
}
/**************************************************************************
* Public Functions
**************************************************************************/
/**************************************************************************
* Name: up_saveregisters
*
* Description:
* Save the current registers in the context save area. This function
* is called from up_savecontext (below) and also from interrupt
* handling logic.
*
* Note that this function does not save:
* a, dptr, ie - these are saved in the stack area
* sp - this can be inferred from g_irqtos or struct xcptontext.nbytes.
*
* Inputs:
* regs - the context register array in which to save the register info
*
* Return:
* None
*
**************************************************************************/
void up_saveregisters(FAR uint8_t *regs) _naked
{
_asm
mov a, b
movx @dptr, a
inc dptr
mov a, r2
movx @dptr, a
inc dptr
mov a, r3
movx @dptr, a
inc dptr
mov a, r4
movx @dptr, a
inc dptr
mov a, r5
movx @dptr, a
inc dptr
mov a, r6
movx @dptr, a
inc dptr
mov a, r7
movx @dptr, a
inc dptr
mov a, r0
movx @dptr, a
inc dptr
mov a, r1
movx @dptr, a
inc dptr
mov a, psw
movx @dptr, a
clr psw
inc dptr
mov a, _bp
movx @dptr, a
ret
_endasm;
}
/**************************************************************************
* Name: up_savecontext
*
* Description:
* Push the current execution context onto the stack, then save the
* entire stack contents in the provided context structure.
*
* Inputs:
* context - the context structure in which to save the stack info
*
* Return:
* 0 = Normal state save return
* 1 = This is the matching return from up_restorecontext()
*
**************************************************************************/
uint8_t up_savecontext(FAR struct xcptcontext *context) _naked
{
_asm
/* Create the stack frame that we want when it is time to restore
* this context. The return address will be the return address
* of this function, the return value will be zero.
*
* ...
* return address (2 bytes, already on the stack)
* register a=0 (1 byte)
* register ie (1 byte)
* register dptr (2 bytes)
*/
clr a
push acc /* ACC = 0 */
push ie
mov a, #1
push acc /* DPL = 1 */
clr a
push acc /* DPH = 0 */
/* Dump the stack contents before they are occupied into XRAM */
#ifdef CONFIG_SWITCH_FRAME_DUMP
push dpl
push dph
lcall _up_dumpstack
pop dph
pop dpl
#endif
/* Disable interrupts while we create a snapshot of the stack
* and registers. At this point, we have 5 bytes on the stack
* to account for.
*/
push ie
mov ea, 0
/* Save the registers in the context save area */
push dpl
push dph
mov a, #XCPT_REGS
add a, dpl
mov dpl, a
clr a
addc a, dph
mov dph, a
lcall _up_saveregisters
pop dph
pop dpl
#ifdef CONFIG_SWITCH_FRAME_DUMP
/* Save the address of the context structure. We will
* need this later to dump the saved frame. Now we have
* 7 bytes on the stack to account for.
*/
push dpl
push dph
/* Push the top of frame stack pointer. We need to
* decrement the current SP value by three to account
* for dptr+IE on the stack above the end of the frame.
*/
mov a, sp
subb a, #3
#else
/* Push the top of frame stack pointer. We need to
* decrement the current stack pointer by one to account
* for IE that we saved on the stack.
*/
mov a, sp
dec a
#endif
push acc
/* Copy the current stack frame from internal RAM to XRAM. */
lcall _up_savestack
pop acc
/* Dump the contents of the saved frame after it has been
* copied from memory/registers.
*/
#ifdef CONFIG_SWITCH_FRAME_DUMP
pop dph
pop dpl
push dpl
push dph
lcall _up_dumpframe
pop dph
pop dpl
lcall _up_dumpstack
#endif
/* Restore the interrupt state */
pop ie
/* Now that we have a snapshot of the desired stack frame saved,
* we can release the stack frame (all but the return address)
*/
mov a, sp
subb a, #4
mov sp, a
mov dpl,#0
ret
_endasm;
}
/**************************************************************************
* Name: up_saveirqcontext
*
* Description:
* The interrupt context was saved in g_irqtos and g_irqregs when the
* interrupt was taken. If a context switch from the interrupted task
* will be made at the interrupt level, then these saved values must be
* copied into the TCB.
*
* Inputs:
* context - the structure in which to save the context info
*
* Return:
* None
*
* Assumptions:
* - Interrupts are disabled
*
**************************************************************************/
void up_saveirqcontext(FAR struct xcptcontext *context)
{
/* Save the number of bytes in the stack */
context->nbytes = g_irqtos - (STACK_BASE-1);
/* Copy the current stack frame from internal RAM to XRAM. */
up_savestack(context, g_irqtos);
/* Copy the saved registers into the TCB */
up_saveregisters(context->regs);
}
