cpu_task.h

日本著名的的嵌入式实时操作系统T-Kernel的源码及用户手册。

/*
 *----------------------------------------------------------------------
 *    T-Kernel
 *
 *    Copyright (C) 2004 by Ken Sakamura. All rights reserved.
 *    T-Kernel is distributed under the T-License.
 *----------------------------------------------------------------------
 *
 *    Version:   1.01.00
 *    Released by T-Engine Forum(http://www.t-engine.org) at 2004/6/28.
 *
 *----------------------------------------------------------------------
 */

/*
 *	cpu_task.h (MC9328)
 *	CPU-Dependant Task Start Processing
 */

#ifndef _CPU_TASK_
#define _CPU_TASK_

#include "cpu_insn.h"

IMPORT	UW	*SystemUATB;	/* System page table UATB */
IMPORT	UW	*cur_uatb;	/* Current task space */

/*
 * System stack configuration at task startup
 */
typedef struct {
	VW	r[12];		/* R0-R11 */
	UW	taskmode;
	VP	usp;		/* R13_usr */
	VP	lr_usr;		/* R14_usr */
	VP	lr_svc;		/* R14_svc */
	VW	spsr_svc;
	VW	ip;		/* R12 */
	VP	pc;		/* R15 */
} SStackFrame;

/*
 * User stack configuration at task startup (only RNG 1-3)
 */
typedef struct {
	/* Empty */
} UStackFrame;

/*
 * Size of system stack area destroyed by 'make_dormant()'
 * In other words, the size of area required to write by 'setup_context().'
 */
#define	DORMANT_STACK_SIZE	( sizeof(VW) * 7 )	/* To 'taskmode' */

/*
 * Size of area kept for special use from system stack
 */
#define	RESERVE_SSTACK(tskatr)	0

/*
 * Initial value for task startup
 */
#if USE_MMU
#define	INIT_PSR(rng)	( ( (rng) == 0 )? PSR_SVC: \
			  ( (rng) == 3 )? PSR_USR: PSR_SYS )
#else
#define	INIT_PSR(rng)	( ( (rng) == 0 )? PSR_SVC: PSR_SYS )
#endif

#define	INIT_TMF(rng)	( TMF_PPL(rng) | TMF_CPL(rng) )

/*
 * Switch task space
 */
Inline void change_space( VP uatb )
{
IMPORT void FlushCache( VP laddr, INT len );

	UW	*sp, *dp, *ep;

	/* If there is no space in the switched target,
	   do not switch actually. */
	if ( uatb != NULL ) {
		FlushCache(NULL, 0);	/* Cache flash */

		/* UATB copy */
		sp = uatb;
		dp = SystemUATB;
		ep = SystemUATB + NUM_PDIR_ENTRIES;
		while ( dp < ep ) *dp++ = *sp++;

		PurgeTLB();	/* TLB invalidate */
	}
}

/*
 * Create stack frame for task startup
 *	Call from 'make_dormant()'
 */
Inline void setup_context( TCB *tcb )
{
	SStackFrame	*ssp;
	W		rng;
	UW		pc, spsr;

	rng = (tcb->tskatr & TA_RNG3) >> 8;
	ssp = tcb->isstack;
	ssp--;

	spsr = INIT_PSR(rng);
	pc = (UW)tcb->task;
	if ( (pc & 1) != 0 ) spsr |= PSR_T; /* Thumb mode */

	/* CPU context initialization */
	ssp->taskmode = INIT_TMF(rng);	/* Initial taskmode */
	ssp->spsr_svc = spsr;		/* Initial SR */
	ssp->pc = (VP)(pc & ~1);	/* Task startup address */
	tcb->tskctxb.ssp = ssp;		/* System stack */

	if ( rng > 0 ) {
		ssp->usp = tcb->istack;	/* User stack */
	}
}

/*
 * Set task startup code
 *	Called by 'tk_sta_tsk()' processing.
 */
Inline void setup_stacd( TCB *tcb, INT stacd )
{
	SStackFrame	*ssp = tcb->tskctxb.ssp;

	ssp->r[0] = stacd;
	ssp->r[1] = (VW)tcb->exinf;
}

/*
 * Delete task contexts
 */
Inline void cleanup_context( TCB *tcb )
{
EXPORT void FlushCache( VP laddr, INT len );

	UW	*p, *ep;

	/* If the current space belongs to 'tcb,' disable the space */
	if ( ctxtsk == tcb && cur_uatb == tcb->tskctxb.uatb ) {

		cur_uatb = NULL;

		FlushCache(NULL, 0);	/* Cache flash */

		/* Clear UATB */
		p =  SystemUATB;
		ep = SystemUATB + NUM_PDIR_ENTRIES;
		while ( p < ep ) *p++ = 0;

		PurgeTLB();	/* TLB invalidate */
	}
}

#endif /* _CPU_TASK_ */