context.s

eCos1.31版

// #=============================================================================
// #
// #	context.S
// #
// #	ARM context switch code
// #
// #=============================================================================
// ####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
// ####COPYRIGHTEND####
// #=============================================================================
// ######DESCRIPTIONBEGIN####
// #
// # Author(s): 	nickg, gthomas
// # Contributors:	nickg, gthomas
// # Date:	1998-09-15
// # Purpose:	ARM context switch code
// # Description:	This file contains implementations of the thread context 
// #		switch routines. It also contains the longjmp() and setjmp()
// #              routines.
// #
// #####DESCRIPTIONEND####
// #
// #=============================================================================

#include <pkgconf/hal.h>

#include "arm.inc"

	.text

// ------------------------------------------------------------------------------
//  function declaration macro
		
#define FUNC_START(name) \
        .globl name; \
name:	
		
// ------------------------------------------------------------------------------
//  hal_thread_switch_context
//  Switch thread contexts
//  R0 = address of sp of next thread to execute
//  R1 = address of sp save location of current thread

// Need to save/restore R4..R12, R13 (sp), R14 (lr)

// Note: this is a little wasteful since r0..r3 don't need to be saved.
// They are saved here though so that the information can match the HAL_SavedRegisters
	
#ifdef __thumb__
	.code	16	
	.thumb_func
#endif
FUNC_START(hal_thread_switch_context)
#ifdef __thumb__
	ldr	r2,=hal_thread_switch_context_ARM
	bx	r2
	.code	32
FUNC_START(hal_thread_switch_context_ARM)
#endif
	mov	ip,sp			// saved stack pointer
        stmfd   sp!,{fp,ip,lr,pc}       // filler
	stmfd	sp!,{r0-r10,fp,ip,lr,pc}
	mrs	r2,cpsr
	str	r2,[sp,#armreg_cpsr]
	str	sp,[r1]			// return new stack pointer
#ifdef __thumb__
	b	hal_thread_load_context_ARM	// skip mode switch stuff
#endif

	# Now load the destination thread by dropping through
	# to hal_thread_load_context
	
// ------------------------------------------------------------------------------
//  hal_thread_load_context
//  Load thread context
//  R0 = address of sp of next thread to execute
//  Note that this function is also the second half of hal_thread_switch_context
//  and is simply dropped into from it.
	
#ifdef __thumb__
	.code	16	
	.thumb_func
#endif
FUNC_START(hal_thread_load_context)
#ifdef __thumb__
	ldr	r2,=hal_thread_load_context_ARM
	bx	r2
	.code	32
FUNC_START(hal_thread_load_context_ARM)
#endif
	ldr	fp,[r0]			// get context to restore
	mrs	r0,cpsr			// disable IRQ's
	orr	r0,r0,#CPSR_IRQ_DISABLE|CPSR_FIQ_DISABLE
	msr	cpsr,r0
	ldr	r0,[fp,#armreg_cpsr]
	msr	spsr,r0
	ldmfd	fp,{r0-r10,fp,sp,lr}
#ifdef __thumb__
	mrs	r1,spsr			// r1 is scratch 
                                        // [r0 holds initial thread arg]
	msr	cpsr,r1			// hopefully no mode switch here!
	bx	lr
#else
	movs	pc,lr	                // also restores saved PSR
#endif

// ------------------------------------------------------------------------------
//  HAL longjmp, setjmp implementations
//  hal_setjmp saves only to callee save registers 4-14
//  and lr into buffer supplied in r0[arg0]

#ifdef __thumb__
	.code	16	
	.thumb_func
#endif
FUNC_START(hal_setjmp)
#ifdef __thumb__
	ldr	r2,=hal_setjmp_ARM
	bx	r2
	.code	32
FUNC_START(hal_setjmp_ARM)
#endif
	stmea	r0,{r4-r14}
	mov	r0,#0
#ifdef __thumb__
	bx	lr
#else
	mov	pc,lr;		# return
#endif

//  hal_longjmp loads state from r0[arg0] and returns
	
#ifdef __thumb__
	.code	16	
	.thumb_func
#endif
FUNC_START(hal_longjmp)
#ifdef __thumb__
	ldr	r2,=hal_longjmp_ARM
	bx	r2
	.code	32
FUNC_START(hal_longjmp_ARM)
#endif
	ldmfd	r0,{r4-r14}
	mov	r0,r1;		# return [arg1]
#ifdef __thumb__
	bx	lr
#else
	mov	pc,lr
#endif

// ------------------------------------------------------------------------------
//  end of context.S