14  *     Copyright (c) 1998-2000 Dag Brattli <dagb@cs.uit.no>,
16  *     Copyright (c) 2000-2002 Jean Tourrilhes <jt@hpl.hp.com>
25  *     provided "AS-IS" and at no charge.
41 /************************** FRAME WRAPPING **************************/
52  *    Byte stuff one single byte and put the result in buffer pointed to by
53  *    buf. The buffer must at all times be able to have two bytes inserted.
56  * (2000 bytes on P6 200MHz, non-inlined ~370us, inline ~170us) - Jean II
70 		 /* Non-special value, no transparency required */  in stuff_byte()
80  *    Makes a new buffer with wrapping and stuffing, should check that
81  *    we don't get tx buffer overflow.
85 	struct irda_skb_cb *cb = (struct irda_skb_cb *) skb->cb;  in async_wrap_skb()
103 	if (cb->magic != LAP_MAGIC) {  in async_wrap_skb()
105 		 * This will happen for all frames sent from user-space.  in async_wrap_skb()
112 		xbofs = cb->xbofs + cb->xbofs_delay;  in async_wrap_skb()
129 	/* Insert frame and calc CRC */  in async_wrap_skb()
130 	for (i=0; i < skb->len; i++) {  in async_wrap_skb()
132 		 *  Check for the possibility of tx buffer overflow. We use  in async_wrap_skb()
133 		 *  bufsize-5 since the maximum number of bytes that can be  in async_wrap_skb()
136 		if(n >= (buffsize-5)) {  in async_wrap_skb()
137 			IRDA_ERROR("%s(), tx buffer overflow (n=%d)\n",  in async_wrap_skb()
142 		n += stuff_byte(skb->data[i], tx_buff+n);  in async_wrap_skb()
143 		fcs.value = irda_fcs(fcs.value, skb->data[i]);  in async_wrap_skb()
161 /************************* FRAME UNWRAPPING *************************/
170  * And reduce wrapper.o by ~900B in the process ;-)
174  * (2005 B frame + EOF on P6 200MHz, without 30 to 50 us, with 10 to 25 us)
183  * receiving the End-Of-Frame.
187  * (2005 B frame on P6 200MHz, inlined 10 to 25 us, postponed 140 to 180 us)
189  * (2005 B frame on P6 200MHz, inlined 30 to 50 us, postponed 150 to 180 us)
204  *    Got a frame, make a copy of it, and pass it up the stack! We can try
219 	 * skb. But, if the frame is small, it is more efficient to  in async_bump()
220 	 * copy it to save memory (copy will be fast anyway - that's  in async_bump()
221 	 * called Rx-copy-break). Jean II */  in async_bump()
222 	docopy = ((rx_buff->skb == NULL) ||  in async_bump()
223 		  (rx_buff->len < IRDA_RX_COPY_THRESHOLD));  in async_bump()
226 	newskb = dev_alloc_skb(docopy ? rx_buff->len + 1 : rx_buff->truesize);  in async_bump()
228 		stats->rx_dropped++;  in async_bump()
235 	/* Align IP header to 20 bytes (i.e. increase skb->data)  in async_bump()
237 	 * header size (2 or 1 bytes) - Jean II */  in async_bump()
242 		skb_copy_to_linear_data(newskb, rx_buff->data,  in async_bump()
243 					rx_buff->len - 2);  in async_bump()
248 		dataskb = rx_buff->skb;  in async_bump()
250 		rx_buff->skb = newskb;  in async_bump()
251 		rx_buff->head = newskb->data;	/* NOT newskb->head */  in async_bump()
252 …//printk(KERN_DEBUG "ZeroCopy : len = %d, dataskb = %p, newskb = %p\n", rx_buff->len, dataskb, new…  in async_bump()
256 	skb_put(dataskb, rx_buff->len - 2);  in async_bump()
259 	dataskb->dev = dev;  in async_bump()
261 	dataskb->protocol = htons(ETH_P_IRDA);  in async_bump()
265 	stats->rx_packets++;  in async_bump()
266 	stats->rx_bytes += rx_buff->len;  in async_bump()
269 	rx_buff->data = rx_buff->head;  in async_bump()
270 	rx_buff->len = 0;  in async_bump()
276  *    Handle Beginning Of Frame character received within a frame
284 	switch(rx_buff->state) {  in async_unwrap_bof()
287 		/* Not supposed to happen, the previous frame is not  in async_unwrap_bof()
288 		 * finished - Jean II */  in async_unwrap_bof()
289 		IRDA_DEBUG(1, "%s(), Discarding incomplete frame\n",  in async_unwrap_bof()
291 		stats->rx_errors++;  in async_unwrap_bof()
292 		stats->rx_missed_errors++;  in async_unwrap_bof()
299 		/* We may receive multiple BOF at the start of frame */  in async_unwrap_bof()
303 	/* Now receiving frame */  in async_unwrap_bof()
304 	rx_buff->state = BEGIN_FRAME;  in async_unwrap_bof()
305 	rx_buff->in_frame = TRUE;  in async_unwrap_bof()
307 	/* Time to initialize receive buffer */  in async_unwrap_bof()
308 	rx_buff->data = rx_buff->head;  in async_unwrap_bof()
309 	rx_buff->len = 0;  in async_unwrap_bof()
310 	rx_buff->fcs = INIT_FCS;  in async_unwrap_bof()
316  *    Handle End Of Frame character received within a frame
328 	switch(rx_buff->state) {  in async_unwrap_eof()
331 		stats->rx_errors++;  in async_unwrap_eof()
332 		stats->rx_missed_errors++;  in async_unwrap_eof()
342 		 * error, as expected - Jean II */  in async_unwrap_eof()
343 		rx_buff->state = OUTSIDE_FRAME;  in async_unwrap_eof()
344 		rx_buff->in_frame = FALSE;  in async_unwrap_eof()
349 		for(i = 0; i < rx_buff->len; i++)  in async_unwrap_eof()
350 			rx_buff->fcs = irda_fcs(rx_buff->fcs,  in async_unwrap_eof()
351 						rx_buff->data[i]);  in async_unwrap_eof()
354 		/* Test FCS and signal success if the frame is good */  in async_unwrap_eof()
355 		if (rx_buff->fcs == GOOD_FCS) {  in async_unwrap_eof()
356 			/* Deliver frame */  in async_unwrap_eof()
360 			/* Wrong CRC, discard frame!  */  in async_unwrap_eof()
364 			stats->rx_errors++;  in async_unwrap_eof()
365 			stats->rx_crc_errors++;  in async_unwrap_eof()
374  *    Handle Character Escape character received within a frame
382 	switch(rx_buff->state) {  in async_unwrap_ce()
396 		rx_buff->state = LINK_ESCAPE;  in async_unwrap_ce()
404  *    Handle other characters received within a frame
412 	switch(rx_buff->state) {  in async_unwrap_other()
414 		 * probability (most frequent first) - Jean II */  in async_unwrap_other()
416 		/* Must be the next byte of the frame */  in async_unwrap_other()
417 		if (rx_buff->len < rx_buff->truesize)  {  in async_unwrap_other()
418 			rx_buff->data[rx_buff->len++] = byte;  in async_unwrap_other()
420 			rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);  in async_unwrap_other()
423 			IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n",  in async_unwrap_other()
425 			rx_buff->state = OUTSIDE_FRAME;  in async_unwrap_other()
435 		if (rx_buff->len < rx_buff->truesize)  {  in async_unwrap_other()
436 			rx_buff->data[rx_buff->len++] = byte;  in async_unwrap_other()
438 			rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);  in async_unwrap_other()
440 			rx_buff->state = INSIDE_FRAME;  in async_unwrap_other()
442 			IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n",  in async_unwrap_other()
444 			rx_buff->state = OUTSIDE_FRAME;  in async_unwrap_other()
456 		rx_buff->data[rx_buff->len++] = byte;  in async_unwrap_other()
458 		rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);  in async_unwrap_other()
460 		rx_buff->state = INSIDE_FRAME;  in async_unwrap_other()
468  *    Parse and de-stuff frame received from the IrDA-port