/************************************************************************************
* arch/z80/src/z8/switch.h
* arch/z80/src/chip/switch.h
*
* Copyright (C) 2008-2009, 2011-2012 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.
*
************************************************************************************/
#ifndef __Z80_SWITCH_H
#define __Z80_SWITCH_H
/************************************************************************************
* Included Files
************************************************************************************/
#ifndef __ASSEMBLY__
# include <stdint.h>
# include <nuttx/sched.h>
# include <nuttx/arch.h>
#endif
#include "common/up_internal.h"
/************************************************************************************
* Pre-processor Definitions
************************************************************************************/
/* Z8_IRQSTATE_* definitions ********************************************************
* These are used in the state field of 'struct z8_irqstate_s' structure to define
* the current state of the interrupt handling. These definition support "lazy"
* interrupt context saving. See comments below associated with s'truct z8_irqstate_s'.
*/
#define Z8_IRQSTATE_NONE 0 /* Not handling an interrupt */
#define Z8_IRQSTATE_ENTRY 1 /* In interrupt, context has not been saved */
#define Z8_IRQSTATE_SAVED 2 /* In interrupt, context has been saved */
/* The information saved on interrupt entry can be retained in a array of two
* uint24_t values. These are
*
* value[0] = RP (MS byte) and Flags (LS) byte
* value[1] = PC
*
* The pointer to the save structure is a stack pointer at the time that up_doirq()
* was called:
*
* PC[7:0]
* PC[15:8]
* Flags Register
* SP -> RP
*
* The stack pointer on return from interrupt can be obtained by adding 4 to the
* pointer to the save structure.
*/
#define Z8_IRQSAVE_RPFLAGS (0) /* Index 10: RP (MS) and FLAGS (LS) */
#define Z8_IRQSAVE_PC (1) /* Index 2: PC[8:15] */
#define Z8_IRQSAVE_REGS (2) /* Number 16-bit values saved */
/* Byte offsets */
#define Z8_IRQSAVE_RP_OFFS (2*Z8_IRQSAVE_RPFLAGS) /* Offset 0: RP */
#define Z8_IRQSAVE_FLAGS_OFFS (2*Z8_IRQSAVE_RPFLAGS+1) /* Offset 1: FLAGS */
#define Z8_IRQSAVE_PCH_OFFS (2*Z8_IRQSAVE_PC) /* Offset 2: PC[8:15] */
#define Z8_IRQSAVE_PCL_OFFS (2*Z8_IRQSAVE_PC+1) /* Offset 3: PC[0:7] */
#define Z8_IRQSAVE_SIZE (2*Z8_IRQSAVE_REGS) /* Number 8-bit values saved */
/* Macros for portability ***********************************************************
*
* Common logic in arch/z80/src/common is customized for the z8 context switching
* logic via the following macros.
*/
/* Initialize the IRQ state */
#define INIT_IRQCONTEXT() \
do { \
g_z8irqstate.state = Z8_IRQSTATE_NONE; \
} while (0)
/* IN_INTERRUPT returns true if the system is currently operating in the interrupt
* context. IN_INTERRUPT is the inline equivalent of up_interrupt_context().
*/
#define IN_INTERRUPT() \
(g_z8irqstate.state != Z8_IRQSTATE_NONE)
/* The following macro is used when the system enters interrupt handling logic
*
* NOTE: Nested interrupts are not supported in this implementation. If you want
* to implement nested interrupts, you would have to change the way that
* current_regs is handled. The savestate variable would not work for
* that purpose as implemented here because only the outermost nested
* interrupt can result in a context switch (it can probably be deleted).
*/
#define DECL_SAVESTATE() \
struct z8_irqstate_s savestate
#define IRQ_ENTER(irq, regs) \
do { \
savestate.state = g_z8irqstate.state; \
savestate.regs = g_z8irqstate.regs; \
g_z8irqstate.state = Z8_IRQSTATE_ENTRY; \
g_z8irqstate.regs = (regs); \
up_ack_irq(irq); \
} while (0)
/* The following macro is used when the system exits interrupt handling logic */
#define IRQ_LEAVE(irq) \
do { \
g_z8irqstate.state = savestate.state; \
g_z8irqstate.regs = savestate.regs; \
} while (0)
/* The following macro is used to sample the interrupt state (as a opaque handle) */
#define IRQ_STATE() \
(g_z8irqstate.regs)
/* Save the current IRQ context in the specified TCB */
#define SAVE_IRQCONTEXT(tcb) \
z8_saveirqcontext((tcb)->xcp.regs)
/* Set the current IRQ context to the state specified in the TCB */
#define SET_IRQCONTEXT(tcb) \
do { \
g_z8irqstate.state = Z8_IRQSTATE_SAVED; \
g_z8irqstate.regs = (tcb)->xcp.regs; \
} while (0)
/* Save the user context in the specified TCB. User context saves can be simpler
* because only those registers normally saved in a C called need be stored.
*/
#define SAVE_USERCONTEXT(tcb) \
z8_saveusercontext((tcb)->xcp.regs)
/* Restore the full context -- either a simple user state save or the full,
* IRQ state save.
*/
#define RESTORE_USERCONTEXT(tcb) \
z8_restorecontext((tcb)->xcp.regs)
/* Dump the current machine registers */
#define _REGISTER_DUMP() \
z8_registerdump()
/************************************************************************************
* Public Types
************************************************************************************/
/* In order to provide faster interrupt handling, the interrupt logic does "lazy"
* context saving as described below:
*
* (1) At the time of the interrupt, minimum information is saved and the register
* pointer is changed so that the interrupt logic does not alter the state of
* the interrupted task's registers.
* (2) If no context switch occurs during the interrupt processing, then the return
* from interrupt is also simple.
* (3) If a context switch occurs during interrupt processing, then
* (a) The full context of the interrupt task is saved, and
* (b) A full context switch is performed when the interrupt exits (see
* z8_vector.S).
*
* The following structure is used to manage this "lazy" context saving.
*/
#ifndef __ASSEMBLY__
struct z8_irqstate_s
{
uint8_t state; /* See Z8_IRQSTATE_* definitions above */
chipreg_t *regs; /* Saved register information */
};
#endif
/************************************************************************************
* Public Variables
************************************************************************************/
#ifndef __ASSEMBLY__
/* This structure holds information about the current interrupt processing state */
extern struct z8_irqstate_s g_z8irqstate;
#endif
/************************************************************************************
* Public Function Prototypes
************************************************************************************/
#ifndef __ASSEMBLY__
#ifdef __cplusplus
extern "C"
{
#endif
/* Defined in z8_irq.c */
void up_ack_irq(int irq);
/* Defined in z8_saveusercontext.asm */
int z8_saveusercontext(FAR chipreg_t *regs);
/* Defined in z8_saveirqcontext.c */
void z8_saveirqcontext(FAR chipreg_t *regs);
/* Defined in z8_restorecontext.asm */
void z8_restorecontext(FAR chipreg_t *regs);
/* Defined in z8_sigsetup.c */
void z8_sigsetup(FAR struct tcb_s *tcb, sig_deliver_t sigdeliver, FAR chipreg_t *regs);
/* Defined in z8_registerdump.c */
void z8_registerdump(void);
#ifdef __cplusplus
}
#endif
#endif
#endif /* __Z80_SWITCH_H */
