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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;                                                                 ;;

;;  RTL8139.INC                                                    ;;

;;                                                                 ;;

;;  Ethernet driver for Menuet OS                                  ;;

;;                                                                 ;;

;;  Version 0.2  11 August 2003                                    ;;

;;                                                                 ;;

;;  Driver for chips of RealTek 8139 family                        ;;

;;  References:                                                    ;;

;;    www.realtek.com.hw - data sheets                             ;;

;;    rtl8139.c - linux driver                                     ;;

;;    8139too.c - linux driver                                     ;;

;;    ethernet driver template by Mike Hibbett                     ;;

;;                                                                 ;;

;;  The copyright statement is                                     ;;

;;                                                                 ;;

;;          GNU GENERAL PUBLIC LICENSE                             ;;

;;             Version 2, June 1991                                ;;

;;                                                                 ;;

;;  Copyright 2003 Endre Kozma,                                    ;;

;;   endre.kozma@axelero.hu                                        ;;

;;                                                                 ;;

;;  See file COPYING for details                                   ;;

;;                                                                 ;;

;;                                                                 ;;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

	ETH_ALEN	       equ 6

	ETH_HLEN	       equ (2 * ETH_ALEN + 2)

	ETH_ZLEN	       equ 60 ; 60 + 4bytes auto payload for

				      ; mininmum 64bytes frame length

	PCI_REG_COMMAND        equ 0x04 ; command register

	PCI_BIT_PIO	       equ 0 ; bit0: io space control

	PCI_BIT_MMIO	       equ 1 ; bit1: memory space control

	PCI_BIT_MASTER	       equ 2 ; bit2: device acts as a PCI master

	RTL8139_REG_MAR0       equ 0x08 ; multicast filter register 0

	RTL8139_REG_MAR4       equ 0x0c ; multicast filter register 4

	RTL8139_REG_TSD0       equ 0x10 ; transmit status of descriptor

	RTL8139_REG_TSAD0      equ 0x20 ; transmit start address of descriptor

	RTL8139_REG_RBSTART    equ 0x30 ; RxBuffer start address

	RTL8139_REG_COMMAND    equ 0x37 ; command register

	RTL8139_REG_CAPR       equ 0x38 ; current address of packet read

	RTL8139_REG_IMR        equ 0x3c ; interrupt mask register

	RTL8139_REG_ISR        equ 0x3e ; interrupt status register

	RTL8139_REG_TXCONFIG   equ 0x40 ; transmit configuration register

	RTL8139_REG_TXCONFIG_0 equ 0x40 ; transmit configuration register 0

	RTL8139_REG_TXCONFIG_1 equ 0x41 ; transmit configuration register 1

	RTL8139_REG_TXCONFIG_2 equ 0x42 ; transmit configuration register 2

	RTL8139_REG_TXCONFIG_3 equ 0x43 ; transmit configuration register 3

	RTL8139_REG_RXCONFIG   equ 0x44 ; receive configuration register 0

	RTL8139_REG_RXCONFIG_0 equ 0x44 ; receive configuration register 0

	RTL8139_REG_RXCONFIG_1 equ 0x45 ; receive configuration register 1

	RTL8139_REG_RXCONFIG_2 equ 0x46 ; receive configuration register 2

	RTL8139_REG_RXCONFIG_3 equ 0x47 ; receive configuration register 3

	RTL8139_REG_MPC        equ 0x4c ; missed packet counter

	RTL8139_REG_9346CR     equ 0x50 ; serial eeprom 93C46 command register

	RTL8139_REG_CONFIG1    equ 0x52 ; configuration register 1

	RTL8139_REG_CONFIG4    equ 0x5a ; configuration register 4

	RTL8139_REG_HLTCLK     equ 0x5b ; undocumented halt clock register

	RTL8139_REG_BMCR       equ 0x62 ; basic mode control register

	RTL8139_REG_ANAR       equ 0x66 ; auto negotiation advertisement register

; 5.1 packet header

	RTL8139_BIT_RUNT       equ 4 ; total packet length < 64 bytes

	RTL8139_BIT_LONG       equ 3 ; total packet length > 4k

	RTL8139_BIT_CRC        equ 2 ; crc error occured

	RTL8139_BIT_FAE        equ 1 ; frame alignment error occured

	RTL8139_BIT_ROK        equ 0 ; received packet is ok

; 5.4 command register

	RTL8139_BIT_RST        equ 4 ; reset bit

	RTL8139_BIT_RE	       equ 3 ; receiver enabled

	RTL8139_BIT_TE	       equ 2 ; transmitter enabled

	RTL8139_BIT_BUFE       equ 0 ; rx buffer is empty, no packet stored

; 5.6 interrupt status register

	RTL8139_BIT_ISR_TOK    equ 2 ; transmit ok

	RTL8139_BIT_ISR_RER    equ 1 ; receive error interrupt

	RTL8139_BIT_ISR_ROK    equ 0 ; receive ok

; 5.7 transmit configyration register

	RTL8139_BIT_TX_MXDMA   equ 8 ; Max DMA burst size per Tx DMA burst

	RTL8139_BIT_TXRR       equ 4 ; Tx Retry count 16+(TXRR*16)

; 5.8 receive configuration register

	RTL8139_BIT_RXFTH      equ 13 ; Rx fifo threshold

	RTL8139_BIT_RBLEN      equ 11 ; Ring buffer length indicator

	RTL8139_BIT_RX_MXDMA   equ 8 ; Max DMA burst size per Rx DMA burst

	RTL8139_BIT_NOWRAP     equ 7 ; transfered data wrapping

	RTL8139_BIT_9356SEL    equ 6 ; eeprom selector 9346/9356

	RTL8139_BIT_AER        equ 5 ; accept error packets

	RTL8139_BIT_AR	       equ 4 ; accept runt packets

	RTL8139_BIT_AB	       equ 3 ; accept broadcast packets

	RTL8139_BIT_AM	       equ 2 ; accept multicast packets

	RTL8139_BIT_APM        equ 1 ; accept physical match packets

	RTL8139_BIT_AAP        equ 0 ; accept all packets

; 5.9 93C46/93C56 command register

	RTL8139_BIT_93C46_EEM1 equ 7 ; RTL8139 eeprom operating mode1

	RTL8139_BIT_93C46_EEM0 equ 6 ; RTL8139 eeprom operating mode0

	RTL8139_BIT_93C46_EECS equ 3 ; chip select

	RTL8139_BIT_93C46_EESK equ 2 ; serial data clock

	RTL8139_BIT_93C46_EEDI equ 1 ; serial data input

	RTL8139_BIT_93C46_EEDO equ 0 ; serial data output

; 5.11 configuration register 1

	RTL8139_BIT_LWACT      equ 4 ; see RTL8139_REG_CONFIG1

	RTL8139_BIT_SLEEP      equ 1 ; sleep bit at older chips

	RTL8139_BIT_PWRDWN     equ 0 ; power down bit at older chips

	RTL8139_BIT_PMEn       equ 0 ; power management enabled

; 5.14 configuration register 4

	RTL8139_BIT_LWPTN      equ 2 ; see RTL8139_REG_CONFIG4

; 6.2 transmit status register

	RTL8139_BIT_ERTXTH     equ 16 ; early TX threshold

	RTL8139_BIT_TOK        equ 15 ; transmit ok

	RTL8139_BIT_OWN        equ 13 ; tx DMA operation is completed

; 6.18 basic mode control register

	RTL8139_BIT_ANE        equ 12 ; auto negotiation enable

; 6.20 auto negotiation advertisement register

	RTL8139_BIT_TXFD       equ 8 ; 100base-T full duplex

	RTL8139_BIT_TX	       equ 7 ; 100base-T

	RTL8139_BIT_10FD       equ 6 ; 10base-T full duplex

	RTL8139_BIT_10	       equ 5 ; 10base-T

	RTL8139_BIT_SELECTOR   equ 0 ; binary encoded selector CSMA/CD=00001

; RX/TX buffer size

	RTL8139_RBLEN	       equ 0 ; 0==8K 1==16k 2==32k 3==64k

	RTL8139_RX_BUFFER_SIZE equ (8192 shl RTL8139_RBLEN)

	MAX_ETH_FRAME_SIZE     equ 1516 ; exactly 1514 wthout CRC

	RTL8139_NUM_TX_DESC    equ 4

	RTL8139_TX_BUFFER_SIZE equ (MAX_ETH_FRAME_SIZE * RTL8139_NUM_TX_DESC)

	RTL8139_TXRR	       equ 8 ; total retries = 16+(TXRR*16)

	RTL8139_TX_MXDMA       equ 6 ; 0==16 1==32 2==64 3==128

				     ; 4==256 5==512 6==1024 7==2048

	RTL8139_ERTXTH	       equ 8 ; in unit of 32 bytes e.g:(8*32)=256

	RTL8139_RX_MXDMA       equ 7 ; 0==16 1==32 2==64 3==128

				     ; 4==256 5==512 6==1024 7==unlimited

	RTL8139_RXFTH	       equ 7 ; 0==16 1==32 2==64 3==128

				     ; 4==256 5==512 6==1024 7==no threshold

	RTL8139_RX_CONFIG      equ ((RTL8139_RBLEN shl RTL8139_BIT_RBLEN) \

				    or (RTL8139_RX_MXDMA shl RTL8139_BIT_RX_MXDMA) \

				    or (1 shl RTL8139_BIT_NOWRAP) \

				    or (RTL8139_RXFTH shl RTL8139_BIT_RXFTH) \

				    or (1 shl RTL8139_BIT_AB) or (1 shl RTL8139_BIT_APM) \

				    or (1 shl RTL8139_BIT_AER) or (1 shl RTL8139_BIT_AR) \

				    or (1 shl RTL8139_BIT_AM))

	RTL8139_TX_TIMEOUT     equ 30 ; 300 milliseconds timeout

	EE_93C46_REG_ETH_ID    equ 7 ; MAC offset

	EE_93C46_READ_CMD      equ (6 shl 6) ; 110b + 6bit address

	EE_93C56_READ_CMD      equ (6 shl 8) ; 110b + 8bit address

	EE_93C46_CMD_LENGTH    equ 9 ; start bit + cmd + 6bit address

	EE_93C56_CMD_LENGTH    equ 11 ; start bit + cmd + 8bit ddress

	VER_RTL8139	       equ 1100000b

	VER_RTL8139A	       equ 1110000b

;       VER_RTL8139AG          equ 1110100b

	VER_RTL8139B	       equ 1111000b

	VER_RTL8130	       equ VER_RTL8139B

	VER_RTL8139C	       equ 1110100b

	VER_RTL8100	       equ 1111010b

	VER_RTL8100B	       equ 1110101b

	VER_RTL8139D	       equ VER_RTL8100B

	VER_RTL8139CP	       equ 1110110b

	VER_RTL8101	       equ 1110111b

	IDX_RTL8139	       equ 0

	IDX_RTL8139A	       equ 1

	IDX_RTL8139B	       equ 2

	IDX_RTL8139C	       equ 3

	IDX_RTL8100	       equ 4

	IDX_RTL8139D	       equ 5

	IDX_RTL8139D	       equ 6

	IDX_RTL8101	       equ 7

; These two must be 4 byte aligned ( which they are )

rtl8139_rx_buff     equ     eth_data_start

rtl8139_tx_buff     equ     rtl8139_rx_buff + (RTL8139_RX_BUFFER_SIZE + MAX_ETH_FRAME_SIZE)

uglobal

	align	4

rtl8139_rx_buff_offset: dd 0

curr_tx_desc: dd 0

endg

iglobal

hw_ver_array: db VER_RTL8139, VER_RTL8139A, VER_RTL8139B, VER_RTL8139C

	      db VER_RTL8100, VER_RTL8139D, VER_RTL8139CP, VER_RTL8101

HW_VER_ARRAY_SIZE = $-hw_ver_array

endg

uglobal

hw_ver_id: db 0

endg

;***************************************************************************

;   Function

;      rtl8139_probe

;   Description

;      Searches for an ethernet card, enables it and clears the rx buffer

;      If a card was found, it enables the ethernet -> TCPIP link

;   Destroyed registers

;      eax, ebx, ecx, edx

;

;***************************************************************************

rtl8139_probe:

; enable the device

	mov	al, 2

	mov	ah, [pci_bus]

	mov	bh, [pci_dev]

	mov	bl, PCI_REG_COMMAND

	call	pci_read_reg

	mov	cx, ax

	or	cl, (1 shl PCI_BIT_MASTER) or (1 shl PCI_BIT_PIO)

	and	cl, not (1 shl PCI_BIT_MMIO)

	mov	al, 2

	mov	ah, [pci_bus]

	mov	bh, [pci_dev]

	mov	bl, PCI_REG_COMMAND

	call	pci_write_reg

; get chip version

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_TXCONFIG_2

	in	ax, dx

	shr	ah, 2

	shr	ax, 6

	and	al, 01111111b

	mov	ecx, HW_VER_ARRAY_SIZE-1

.chip_ver_loop:

	cmp	al, [hw_ver_array+ecx]

	je	.chip_ver_found

	dec	ecx

	jns	.chip_ver_loop

	xor	cl, cl ; default RTL8139

.chip_ver_found:

	mov	[hw_ver_id], cl

; wake up the chip

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_HLTCLK

	mov	al, 'R' ; run the clock

	out	dx, al

; unlock config and BMCR registers

	add	edx, RTL8139_REG_9346CR - RTL8139_REG_HLTCLK

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) or (1 shl RTL8139_BIT_93C46_EEM0)

	out	dx, al

; enable power management

	add	edx, RTL8139_REG_CONFIG1 - RTL8139_REG_9346CR

	in	al, dx

	cmp	byte [hw_ver_id], IDX_RTL8139B

	jl	.old_chip

; set LWAKE pin to active high (default value).

; it is for Wake-On-LAN functionality of some motherboards.

; this signal is used to inform the motherboard to execute a wake-up process.

; only at newer chips.

	or	al, (1 shl RTL8139_BIT_PMEn)

	and	al, not (1 shl RTL8139_BIT_LWACT)

	out	dx, al

	add	edx, RTL8139_REG_CONFIG4 - RTL8139_REG_CONFIG1

	in	al, dx

	and	al, not (1 shl RTL8139_BIT_LWPTN)

	out	dx, al

	jmp	.finish_wake_up

.old_chip:

; wake up older chips

	and	al, not ((1 shl RTL8139_BIT_SLEEP) or (1 shl RTL8139_BIT_PWRDWN))

	out	dx, al

.finish_wake_up:

; lock config and BMCR registers

	xor	al, al

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_9346CR

	out	dx, al

;***************************************************************************

;   Function

;      rt8139_reset

;   Description

;      Place the chip (ie, the ethernet card) into a virgin state

;   Destroyed registers

;      eax, ebx, ecx, edx

;

;***************************************************************************

rtl8139_reset:

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_COMMAND

	mov	al, 1 shl RTL8139_BIT_RST

	out	dx, al

	mov	cx, 1000 ; wait no longer for the reset

.wait_for_reset:

	in	al, dx

	test	al, 1 shl RTL8139_BIT_RST

	jz	.reset_completed ; RST remains 1 during reset

	dec	cx

	jns	.wait_for_reset

.reset_completed:

; get MAC (hardware address)

	mov	ecx, 2

.mac_read_loop:

	lea	eax, [EE_93C46_REG_ETH_ID+ecx]

	push	ecx

	call	rtl8139_read_eeprom

	pop	ecx

	mov	[node_addr+ecx*2], ax

	dec	ecx

	jns	.mac_read_loop

; unlock config and BMCR registers

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_9346CR

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) or (1 shl RTL8139_BIT_93C46_EEM0)

	out	dx, al

; initialize multicast registers (no filtering)

	mov	eax, 0xffffffff

	add	edx, RTL8139_REG_MAR0 - RTL8139_REG_9346CR

	out	dx, eax

	add	edx, RTL8139_REG_MAR4 - RTL8139_REG_MAR0

	out	dx, eax

; enable Rx/Tx

	mov	al, (1 shl RTL8139_BIT_RE) or (1 shl RTL8139_BIT_TE)

	add	edx, RTL8139_REG_COMMAND - RTL8139_REG_MAR4

	out	dx, al

; 32k Rxbuffer, unlimited dma burst, no wrapping, no rx threshold

; accept broadcast packets, accept physical match packets

	mov	ax, RTL8139_RX_CONFIG

	add	edx, RTL8139_REG_RXCONFIG - RTL8139_REG_COMMAND

	out	dx, ax

; 1024 bytes DMA burst, total retries = 16 + 8 * 16 = 144

	mov	ax, (RTL8139_TX_MXDMA shl RTL8139_BIT_TX_MXDMA) \

		    or (RTL8139_TXRR shl RTL8139_BIT_TXRR)

	add	edx, RTL8139_REG_TXCONFIG - RTL8139_REG_RXCONFIG

	out	dx, ax

; enable auto negotiation

	add	edx, RTL8139_REG_BMCR - RTL8139_REG_TXCONFIG

	in	ax, dx

	or	ax, (1 shl RTL8139_BIT_ANE)

	out	dx, ax

; set auto negotiation advertisement

	add	edx, RTL8139_REG_ANAR - RTL8139_REG_BMCR

	in	ax, dx

	or	ax, (1 shl RTL8139_BIT_SELECTOR) or (1 shl RTL8139_BIT_10) \

		    or (1 shl RTL8139_BIT_10FD) or (1 shl RTL8139_BIT_TX) \

		    or (1 shl RTL8139_BIT_TXFD)

	out	dx, ax

; lock config and BMCR registers

	xor	eax, eax

	add	edx, RTL8139_REG_9346CR - RTL8139_REG_ANAR

	out	dx, al

; init RX/TX pointers

	mov	[rtl8139_rx_buff_offset], eax

	mov	[curr_tx_desc], eax

; clear missing packet counter

	add	edx, RTL8139_REG_MPC - RTL8139_REG_9346CR

	out	dx, eax

; disable all interrupts

	add	edx, RTL8139_REG_IMR - RTL8139_REG_MPC

	out	dx, ax

; set RxBuffer address, init RX buffer offset, init TX ring

	mov	eax, rtl8139_rx_buff

	add	edx, RTL8139_REG_RBSTART - RTL8139_REG_IMR

	out	dx, eax

; Indicate that we have successfully reset the card

	mov	eax, [pci_data]

	mov	[eth_status], eax

	ret

;***************************************************************************

;   Function

;      rtl8139_read_eeprom

;   Description

;      reads eeprom type 93c46 and 93c56

;   Parameters

;      al - word to be read (6bit in case of 93c46 and 8bit otherwise)

;   Return value

;      ax - word read in

;   Destroyed register(s)

;      eax, cx, ebx, edx

;

;***************************************************************************

rtl8139_read_eeprom:

	movzx	ebx, al

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_RXCONFIG

	in	al, dx

	test	al, (1 shl RTL8139_BIT_9356SEL)

	jz	.type_93c46

;       and     bl, 01111111b ; don't care first bit

	or	bx, EE_93C56_READ_CMD ; it contains start bit

	mov	cx, EE_93C56_CMD_LENGTH-1 ; cmd_loop counter

	jmp	.read_eeprom

.type_93c46:

	and	bl, 00111111b

	or	bx, EE_93C46_READ_CMD ; it contains start bit

	mov	cx, EE_93C46_CMD_LENGTH-1 ; cmd_loop counter

.read_eeprom:

	add	edx, RTL8139_REG_9346CR - RTL8139_REG_RXCONFIG_0

;       mov     al, (1 shl RTL8139_BIT_93C46_EEM1)

;       out     dx, al

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) \

		    or (1 shl RTL8139_BIT_93C46_EECS) ; wake up the eeprom

	out	dx, al

.cmd_loop:

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) or (1 shl RTL8139_BIT_93C46_EECS)

	bt	bx, cx

	jnc	.zero_bit

	or	al, (1 shl RTL8139_BIT_93C46_EEDI)

.zero_bit:

	out	dx, al

;       push    eax

;       in      eax, dx ; eeprom delay

;       pop     eax

	or	al, (1 shl RTL8139_BIT_93C46_EESK)

	out	dx, al

;       in      eax, dx ; eeprom delay

	dec	cx

	jns	.cmd_loop

;       in      eax, dx ; eeprom delay

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) or (1 shl RTL8139_BIT_93C46_EECS)

	out	dx, al

	mov	cl, 0xf

.read_loop:

	shl	ebx, 1

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) \

		    or (1 shl RTL8139_BIT_93C46_EECS) \

		    or (1 shl RTL8139_BIT_93C46_EESK)

	out	dx, al

;       in      eax, dx ; eeprom delay

	in	al, dx

	and	al, (1 shl RTL8139_BIT_93C46_EEDO)

	jz	.dont_set

	inc	ebx

.dont_set:

	mov	al, (1 shl RTL8139_BIT_93C46_EEM1) \

		    or (1 shl RTL8139_BIT_93C46_EECS)

	out	dx, al

;       in      eax, dx ; eeprom delay

	dec	cl

	jns	.read_loop

	xor	al, al

	out	dx, al

	mov	ax, bx

	ret

;***************************************************************************

;   Function

;      rtl8139_transmit

;   Description

;      Transmits a packet of data via the ethernet card

;         Pointer to 48 bit destination address in edi

;         Type of packet in bx

;         size of packet in ecx

;         pointer to packet data in esi

;   Destroyed registers

;      eax, edx, esi, edi

;   ToDo

;      for waiting of timeout the rtl8139 internal timer

;      should be used

;

;***************************************************************************

rtl8139_transmit:

	cmp	ecx, MAX_ETH_FRAME_SIZE

	jg	.finish ; packet is too long

	push	ecx

; check descriptor

	mov	ecx, [curr_tx_desc]

	mov	edx, [io_addr]

	lea	edx, [edx+ecx*4+RTL8139_REG_TSD0]

	push	edx ebx

	in	ax, dx

	and	ax, (1 shl RTL8139_BIT_TOK) or (1 shl RTL8139_BIT_OWN)

	cmp	ax, (1 shl RTL8139_BIT_TOK) or (1 shl RTL8139_BIT_OWN)

	jz	.send_packet

	test	ax, 0x1fff ; or no size given

	jz	.send_packet

; wait for timeout

	mov	ebx, RTL8139_TX_TIMEOUT

	mov	eax, 0x5 ; delay x/100 secs

	int	0x40

	in	ax, dx

	and	ax, (1 shl RTL8139_BIT_TOK) or (1 shl RTL8139_BIT_OWN)

	cmp	ax, (1 shl RTL8139_BIT_TOK) or (1 shl RTL8139_BIT_OWN)

	jz	.send_packet

; chip hung, reset it

	call	rtl8139_reset

; reset the card

.send_packet:

; calculate tx_buffer address

	pop	ebx

	push	esi

	mov	eax, MAX_ETH_FRAME_SIZE

	mul	dword [curr_tx_desc]

	mov	esi, edi

	lea	edi, [rtl8139_tx_buff+eax]

	mov	eax, edi

	cld

; copy destination address

	movsd

	movsw

; copy source address

	mov	esi, node_addr

	movsd

	movsw

; copy packet type

	mov	[edi], bx

	add	edi, 2

; copy the packet data

	pop	esi edx ecx

	push	ecx

	shr	ecx, 2

	rep	movsd

	pop	ecx

	push	ecx

	and	ecx, 3

	rep	movsb

; set address

	add	edx, RTL8139_REG_TSAD0 - RTL8139_REG_TSD0

	out	dx, eax

; set size and early threshold

	pop	eax ; pick up the size

	add	eax, ETH_HLEN

	cmp	eax, ETH_ZLEN

	jnc	.no_pad

	mov	eax, ETH_ZLEN

.no_pad:

	or	eax, (RTL8139_ERTXTH shl RTL8139_BIT_ERTXTH)

	add	edx, RTL8139_REG_TSD0 - RTL8139_REG_TSAD0

	out	dx, eax

; get next descriptor 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, ...

	inc	dword [curr_tx_desc]

	and	dword [curr_tx_desc], 3

.finish:

	ret

;***************************************************************************

; Function

;    rtl8139_poll

;

; Description

;    Polls the ethernet card for a received packet

;    Received data, if any, ends up in Ether_buffer

; Destroyed register(s)

;    eax, edx, ecx

;

;***************************************************************************

rtl8139_poll:

	mov	word [eth_rx_data_len], 0

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_COMMAND

	in	al, dx

	test	al, (1 shl RTL8139_BIT_BUFE)

	jnz	.finish

; new packet received copy it from rx_buffer into Ether_buffer

	mov	eax, rtl8139_rx_buff

	add	eax, [rtl8139_rx_buff_offset]

; check if packet is ok

	test	byte [eax], (1 shl RTL8139_BIT_ROK)

	jz	.reset_rx

; packet is ok copy it into the Ether_buffer

	movzx	ecx, word [eax+2] ; packet length

	sub	ecx, 4 ; don't copy CRC

	mov	word [eth_rx_data_len], cx

	push	ecx

	shr	ecx, 2 ; first copy dword-wise

	lea	esi, [eax+4] ; don't copy the packet header

	mov	edi, Ether_buffer

	cld

	rep	movsd ; copy the dwords

	pop	ecx

	and	ecx, 3

	rep	movsb ; copy the rest bytes

; update rtl8139_rx_buff_offset

	movzx	eax, word [eax+2] ; packet length

	add	eax, [rtl8139_rx_buff_offset]

	add	eax, 4+3 ; packet header is 4 bytes long + dword alignment

	and	eax, not 3 ; dword alignment

	cmp	eax, RTL8139_RX_BUFFER_SIZE

	jl	.no_wrap

	sub	eax, RTL8139_RX_BUFFER_SIZE

.no_wrap:

	mov	[rtl8139_rx_buff_offset], eax

; update CAPR register

	sub	eax, 0x10 ; value 0x10 is a constant for CAPR

	add	edx, RTL8139_REG_CAPR - RTL8139_REG_COMMAND

	out	dx, ax

.finish:

; clear active interrupt sources

	mov	edx, [io_addr]

	add	edx, RTL8139_REG_ISR

	in	ax, dx

	out	dx, ax

	ret

.reset_rx:

	in	al, dx ; read command register

	push	eax

	and	al, not (1 shl RTL8139_BIT_RE)

	out	dx, al

	pop	eax

	out	dx, al

	add	edx, RTL8139_REG_RXCONFIG - RTL8139_REG_COMMAND

	mov	ax, RTL8139_RX_CONFIG

	out	dx, ax

	ret

rtl8139_cable:

	pusha

	mov	edx, [io_addr]

	add	edx, 0x58

	in	al,dx

	test	al,1 SHL 2

	jnz	.notconnected

	popa

	xor	al,al

	inc	al

	ret

       .notconnected:

	popa

	xor	al,al

	ret