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Heap management for small microcontrollers

by Isaac Marino Bavaresco

This is file "free.asm", it is an optional substitution for the file "free.c". It is much more optimized, but works only for PIC18 in extended mode with Microchip MPLAB-C18. 

;===============================================================================
; This file is part of "Heap Management For Small Microcontrollers".
; v1.05 (2009-06-29)
; isaacbavaresco@yahoo.com.br
;===============================================================================
; Copyright (c) 2007-2009, Isaac Marino Bavaresco
; All rights reserved.
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions are met:
;     * Redistributions of source code must retain the above copyright
;       notice, this list of conditions and the following disclaimer.
;     * Neither the name of the author 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 AUTHOR ''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 AUTHOR 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.
;===============================================================================
#include <P18CXXX.INC>
;===============================================================================
		radix	decimal
;===============================================================================
#include <heap_config.h>
;===============================================================================
#if	  USING_FREE_RTOS == 1
;-------------------------------------------------------------------------------
		extern	vTaskSuspendAll
		extern	xTaskResumeAll
#define	LOCALS_SIZE	6
DISABLE_INTERRUPTS macro
		call	vTaskSuspendAll
		endm

RESTORE_INTERRUPTS macro
		call	xTaskResumeAll
		endm
;-------------------------------------------------------------------------------
#else	; USING_FREE_RTOS == 1
;-------------------------------------------------------------------------------
#define	LOCALS_SIZE	7
DISABLE_INTERRUPTS macro
;			Aux	 = INTCON & 0xc0;
		movlw	0xc0
		andwf	INTCON,w,ACCESS
		movwf	[Aux+0]
;			INTCON	&= 0x3f;
		movlw	0x3f
		andwf	INTCON,f,ACCESS
		endm

RESTORE_INTERRUPTS macro
;			INTCON	|= Aux;
		movf	[Aux+0],w
		iorwf	INTCON,f,ACCESS
		endm
;-------------------------------------------------------------------------------
#endif	; USING_FREE_RTOS == 1
;===============================================================================
ALLOC		code
;===============================================================================
#define	r	0
#define	p	4
#define	q	6
#define Aux2	8
#define Aux	10

		extern	__freelist
;===============================================================================
		global	free
;15:		void free( void ram *r )

free:		movff	FSR2L, POSTINC1
		movff	FSR2H, POSTINC1
		movff	FSR1L,FSR2L
		movff	FSR1H,FSR2H

		subfsr	2,4

;16:			{
;17:			struct _AllocBlock ram	*p, *q;
;			unsigned short		Aux2;
;			unsigned char		Aux;

		addfsr	1,LOCALS_SIZE
;18:
;19:			if( r == NULL )

		movf	[r+0],w
		iorwf	[r+1],w
;20:				return;
		bnz	NotNULL
		bra	Finish
;21:		
;22:			r = (unsigned char *)r - 2;
NotNULL:	movlw	0x02
 		subwf	[r+0],f
		movlw	0
		subwfb	[r+1],f

		DISABLE_INTERRUPTS
;23:		
;24:			
;25:			for( p = __freelist.Next, q = &__freelist; p != NULL && p < (struct _AllocBlock ram *)r; q = p, p = p->Next )

		movlw	low __freelist
		movwf	[q+0]
		movlw	high __freelist
		movwf	[q+1]

		movff	__freelist+2,FSR0L	; p = __freelist.Next;
		movff	__freelist+3,FSR0H

Loop:		movf	FSR0L,w,ACCESS		; p != NULL
		iorwf	FSR0H,w,ACCESS
		bz	xa630

		movf	[r+0],w			; && p < (struct _AllocBlock ram *)r;
		subwf	FSR0L,w,ACCESS
		movf	[r+1],w
		subwfb	FSR0H,w,ACCESS
		bc	xa630

		movf	FSR0L,w,ACCESS		; q = p;
		movwf	[q+0]
		movf	FSR0H,w,ACCESS
		movwf	[q+1]

		addfsr	0,2			; p = p->Next );
		movf	POSTINC0,w,ACCESS
		movff	INDF0,FSR0H
		movwf	FSR0L,ACCESS

		bra	Loop
;26:				;	/* Empty statement */

xa630:		movf	FSR0L,w
		movwf	[p+0]
		movf	FSR0H,w
		movwf	[p+1]

;29:			q->Next					= r;
		movsf	[q+0],FSR0L
		movsf	[q+1],FSR0H
		addfsr	0,2
		movsf	[r+0],POSTINC0
		movsf	[r+1],POSTDEC0

;28:			((struct _AllocBlock ram *)r)->Next	= p;
		movsf	[r+0],FSR0L
		movsf	[r+1],FSR0H
		addfsr	0,2
		movsf	[p+0],POSTINC0
		movsf	[p+1],POSTDEC0

;31:			if( (unsigned short)r + ((struct _AllocBlock ram *)r)->Length + 2 == (unsigned short)p )

		;movsf	[r+0],FSR0L
		;movsf	[r+1],FSR0H
		subfsr	0,2

		movf	POSTINC0,w,ACCESS
		addwf	[r+0],w
		movwf	PRODL,ACCESS
		movf	POSTDEC0,w,ACCESS
		addwfc	[r+1],w
		movwf	PRODH,ACCESS

		movlw	0x02
		addwf	PRODL,w,ACCESS
		xorwf	[p+0],w
		bnz	xa68e

		movlw	0x00
		addwfc	PRODH,w,ACCESS
		xorwf	[p+1],w
		bnz	xa68e

;32:				{
;34:				((struct _AllocBlock ram *)r)->Length	+= p->Length + 2;
;33:				((struct _AllocBlock ram *)r)->Next	 = p->Next;

		movsf	[p+0],FSR0L		; FSR0 = p;
		movsf	[p+1],FSR0H

		movlw	0x02			; Aux2 = p->Length + 2;
		addwf	POSTINC0,w,ACCESS
		movwf	[Aux2+0]
		movlw	0x00
		addwfc	POSTINC0,w,ACCESS
		movwf	[Aux2+1]

		movff	POSTINC0,PRODL		; PROD = p->Next;
		movff	POSTINC0,PRODH

		movsf	[r+0],FSR0L		; FSR = r;
		movsf	[r+1],FSR0H

		movf	[Aux2+0],w		; r->Length += Aux2;
		addwf	POSTINC0,f,ACCESS
		movf	[Aux2+1],w
		addwfc	POSTINC0,f,ACCESS

		movff	PRODL,POSTINC0		; r->Next = PROD;
		movff	PRODH,POSTINC0
;35:				}
;36:		
;37:			if( (unsigned short)q + ((struct _AllocBlock ram *)q)->Length + 2 == (unsigned short)r )

xa68e:		movsf	[q+0],FSR0L		; FSR0 = q;
		movsf	[q+1],FSR0H

		movf	POSTINC0,w,ACCESS	; PROD = q->Length;
		addwf	[q+0],w
		movwf	PRODL,ACCESS
		movf	POSTDEC0,w,ACCESS
		addwfc	[q+1],w
		movwf	PRODH,ACCESS

		movlw	0x02			; if( PROD + 2 == r )
		addwf	PRODL,w,ACCESS		;    {
		xorwf	[r+0],w
		bnz	Epilog

		movlw	0x00
		addwfc	PRODH,w,ACCESS
		xorwf	[r+1],w
		bnz	Epilog

;38:				{

;40:				((struct _AllocBlock ram *)q)->Length	+= ((struct _AllocBlock ram *)r)->Length + 2;
;39:				((struct _AllocBlock ram *)q)->Next	 = ((struct _AllocBlock ram *)r)->Next;

		movsf	[r+0],FSR0L		; FSR0 = r;
		movsf	[r+1],FSR0H

		movlw	0x02			; Aux2 = r->Length + 2;
		addwf	POSTINC0,w,ACCESS
		movwf	[Aux2+0]
		movlw	0x00
		addwfc	POSTINC0,w,ACCESS
		movwf	[Aux2+1]

		movff	POSTINC0,PRODL		; PROD = r->Next;
		movff	POSTINC0,PRODH

		movsf	[q+0],FSR0L		; FSR0 = q;
		movsf	[q+1],FSR0H

		movf	[Aux2+0],w		; q->Length += Aux2;
		addwf	POSTINC0,f,ACCESS
		movf	[Aux2+1],w
		addwfc	POSTINC0,f,ACCESS

		movff	PRODL,POSTINC0		; q->Next = PROD;
		movff	PRODH,POSTINC0
;41:				}
;42:			}


Epilog:		RESTORE_INTERRUPTS
Finish:		subfsr	1,LOCALS_SIZE + 1

		movff	POSTDEC1,FSR2H
		movff	INDF1,FSR2L
		return	0
;===============================================================================
		end
;===============================================================================
file: /Techref/member/IMB-yahoo-J86/free.asm.htm, 8KB, , updated: 2010/4/14 14:59, local time: 2025/5/11 18:51, owner: IMB-yahoo-J86,
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