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 (VR4131)
 *	CPU-Dependant Task Start Processing
 */

#ifndef _CPU_TASK_
#define _CPU_TASK_

#include "cpu_insn.h"

IMPORT TCB	*fpu_ctxtsk;		/* Task including FPU context */

/*
 * System stack configuration at task startup
 */
typedef struct {
	struct rng0_3 {			/* RNG 0-3 common */
		DW	hi, lo;
		DW	at;
		DW	v[2];		/* v0-v1 */
		DW	a[4];		/* a0-a3 */
		DW	t[8];		/* t0-t7 */
		DW	s[8];		/* s0-s7 */
		DW	fp, ra, gp;
		DW	t8, t9;
		DW	epc;
		UW	taskmode;
		UW	psr;
	} rng0_3;
	struct rng1_3 {			/* Only RNG 1-3 */
		DW	usp;
	} rng1_3;
} SStackFrame;

#define	SizeofSS0	( sizeof(struct rng0_3) )	/* RNG 0 */
#define	SizeofSS1_3	( sizeof(SStackFrame) )		/* RNG 1-3 */

/* Stack consumption by function arguments */
#define	SizeofFUNCPARA	( sizeof(DW) * 4 )

/*
 * 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(DW) * 6 )	/* To 'gp' */

/*
 * Size of area kept for special use from system stack
 */
#if TA_FPU
#define	RESERVE_SSTACK(tskatr)	\
		( ( ((tskatr) & TA_FPU) != 0 )? sizeof(T_COP0REGS): 0 )
#else
#define	RESERVE_SSTACK(tskatr)	0
#endif

/*
 * Initial value for task startup
 */
#if USE_MMU
#define	INIT_KSU(rng)	( ( (rng) == 3 )? SR_USR: SR_KNL )
#else
#define	INIT_KSU(rng)	( SR_KNL )
#endif

IMPORT UW	initPSR;
#define	_INIT_IM	(SR_IMMSK & ~SR_IM(7))
#define	_INIT_PSR	(_INIT_IM|SR_XX|SR_KX|SR_SX|SR_UX)
#define	INIT_PSR(rng)	( initPSR | _INIT_PSR|SR_EXL|SR_IE|INIT_KSU(rng) )
#define	INIT_TMF(rng)	( TMF_PPL(rng) | TMF_CPL(rng) )

#define	INIT_FCR31	0x01000000	/* FS=1 */

/*
 * Switch task space
 */
Inline void change_space( INT lsid )
{
	/* Set ASID for entry Hi register */
	Asm("dmtc0 %0, $10":: "r"(lsid));
}

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

	rng = (tcb->tskatr & TA_RNG3) >> 8;
	ssp = tcb->isstack;
	(UB*)ssp -= ( rng == 0 )? SizeofSS0 + SizeofFUNCPARA: SizeofSS1_3;

#if TA_FPU
	if ( (tcb->tskatr & TA_FPU) != 0 ) {
		/* FPU context initialization */
		T_COP0REGS	*fpu;

		fpu = tcb->isstack;
		fpu->fcr31 = INIT_FCR31;
	}
#endif

	/* CPU context initialization */
	SetDW(&ssp->rng0_3.gp,  (INT)tcb->gp);	/* Global pointer */
	SetDW(&ssp->rng0_3.epc, (INT)tcb->task);/* Task startup address */
	ssp->rng0_3.taskmode = INIT_TMF(rng);	/* Initial taskmode */
	ssp->rng0_3.psr      = INIT_PSR(rng);	/* Initial SR */
	SetDW(&tcb->tskctxb.ssp, (INT)ssp);	/* System stack */

	if ( rng > 0 ) {
		SetDW(&ssp->rng1_3.usp, (INT)tcb->istack - SizeofFUNCPARA);
						/* User stack */
	}
}

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

	SetDW(&ssp->rng0_3.a[0], stacd);
	SetDW(&ssp->rng0_3.a[1], (INT)tcb->exinf);
}

/*
 * Delete task contexts
 */
Inline void cleanup_context( TCB *tcb )
{
#if TA_FPU
	/* If the current FPU context belongs to 'tcb',
	   Disable the FPU context */
	if ( fpu_ctxtsk == tcb ) fpu_ctxtsk = NULL;
#endif
}

#endif /* _CPU_TASK_ */