kolibrios/kernel/branches/net/network/queue.inc

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;; Copyright (C) KolibriOS team 2004-2010. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
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;;  queue.inc                                                   ;;
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;;    Written by hidnplayr@kolibrios.org                        ;;
;;                                                              ;;
;;          GNU GENERAL PUBLIC LICENSE                          ;;
;;             Version 2, June 1991                             ;;
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$Revision$

; The Queues implemented by these macros form a ring-buffer.
; The data to these queue's always looks like this:
;
; At top, you have the queue struct, wich has the size (number of currently queued packets, read and write pointers.
; This struct is followed by a number of slots wich you can read and write to using the macros.
; How these slots look like is up to you to chose, normally they should have at least a pointer to where the real data is.
; (you can see some examples below)


struct	queue

	size	       dd ?    ; number of queued packets in this queue
	w_ptr	       dd ?    ; current writing pointer in queue
	r_ptr	       dd ?    ; current reading pointer

ends

; The following macros share these inputs:

; ptr           = pointer to where the queue data is located
; size          = number of slots/entrys in the queue
; entry_size    = size of one slot, in bytes
; failaddr      = the address where macro will jump to when there is no data in the queue

; additionally, add_to_queue requires you to set esi to the data wich you want to queue
; get_from_queue on the other hand will return a pointer in esi, to the entry you're interessed in
; PS: macros WILL destroy ecx and edi

macro add_to_queue ptr, size, entry_size, failaddr {

	cmp	[ptr + queue.size], size	; Check if queue isnt full
	jae	failaddr

	inc	[ptr + queue.size]		; if not full, queue one more

	mov	edi, [ptr + queue.w_ptr]	; Current write pointer (FIFO!)
	mov	ecx, entry_size/4		; Write the queue entry
	rep	movsd				;

	lea	ecx, [size*entry_size+ptr+sizeof.queue]
	cmp	edi, ecx			; entry size
	jb	.no_wrap

	sub	edi, size*entry_size

  .no_wrap:
	mov	[ptr + queue.w_ptr], edi

}



macro get_from_queue ptr, size, entry_size,  failaddr {

	cmp	[ptr + queue.size], 0		; any packets queued?
	je	failaddr

	dec	[ptr + queue.size]		; if so, dequeue one

	mov	esi, [ptr + queue.r_ptr]
	push	esi

	add	esi, entry_size

	lea	ecx, [size*entry_size+ptr+sizeof.queue]
	cmp	esi, ecx			; entry size
	jb	.no_wrap

	sub	esi, size*entry_size

  .no_wrap:
	mov	dword [ptr + queue.r_ptr], esi

	pop	esi

}

macro init_queue ptr {

	mov	[ptr + queue.size] , 0
	lea	edi, [ptr + sizeof.queue]
	mov	[ptr + queue.w_ptr], edi
	mov	[ptr + queue.r_ptr], edi
}