path: root/drivers/char/ftape/lowlevel/ftape-rw.c

/*
 *      Copyright (C) 1993-1996 Bas Laarhoven,
 *                (C) 1996-1997 Claus-Justus Heine.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; see the file COPYING.  If not, write to
 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

 *
 * $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-rw.c,v $
 * $Revision: 1.7 $
 * $Date: 1997/10/28 14:26:49 $
 *
 *      This file contains some common code for the segment read and
 *      segment write routines for the QIC-117 floppy-tape driver for
 *      Linux.
 */

#include <linux/string.h>
#include <linux/errno.h>

#include <linux/ftape.h>
#include <linux/qic117.h>
#include "../lowlevel/ftape-tracing.h"
#include "../lowlevel/ftape-rw.h"
#include "../lowlevel/fdc-io.h"
#include "../lowlevel/ftape-init.h"
#include "../lowlevel/ftape-io.h"
#include "../lowlevel/ftape-ctl.h"
#include "../lowlevel/ftape-read.h"
#include "../lowlevel/ftape-ecc.h"
#include "../lowlevel/ftape-bsm.h"

/*      Global vars.
 */
int ft_nr_buffers;
buffer_struct *ft_buffer[FT_MAX_NR_BUFFERS];
static volatile int ft_head;
static volatile int ft_tail;	/* not volatile but need same type as head */
int fdc_setup_error;
location_record ft_location = {-1, 0};
volatile int ftape_tape_running;

/*      Local vars.
 */
static int overrun_count_offset;
static int inhibit_correction;

/*  maxmimal allowed overshoot when fast seeking
 */
#define OVERSHOOT_LIMIT 10

/*      Increment cyclic buffer nr.
 */
buffer_struct *ftape_next_buffer(ft_buffer_queue_t pos)
{
	switch (pos) {
	case ft_queue_head:
		if (++ft_head >= ft_nr_buffers) {
			ft_head = 0;
		}
		return ft_buffer[ft_head];
	case ft_queue_tail:
		if (++ft_tail >= ft_nr_buffers) {
			ft_tail = 0;
		}
		return ft_buffer[ft_tail];
	default:
		return NULL;
	}
}
int ftape_buffer_id(ft_buffer_queue_t pos)
{
	switch(pos) {
	case ft_queue_head: return ft_head;
	case ft_queue_tail: return ft_tail;
	default: return -1;
	}
}
buffer_struct *ftape_get_buffer(ft_buffer_queue_t pos)
{
	switch(pos) {
	case ft_queue_head: return ft_buffer[ft_head];
	case ft_queue_tail: return ft_buffer[ft_tail];
	default: return NULL;
	}
}
void ftape_reset_buffer(void)
{
	ft_head = ft_tail = 0;
}

buffer_state_enum ftape_set_state(buffer_state_enum new_state)
{
	buffer_state_enum old_state = ft_driver_state;

	ft_driver_state = new_state;
	return old_state;
}
/*      Calculate Floppy Disk Controller and DMA parameters for a segment.
 *      head:   selects buffer struct in array.
 *      offset: number of physical sectors to skip (including bad ones).
 *      count:  number of physical sectors to handle (including bad ones).
 */
static int setup_segment(buffer_struct * buff, 
			 int segment_id,
			 unsigned int sector_offset, 
			 unsigned int sector_count, 
			 int retry)
{
	SectorMap offset_mask;
	SectorMap mask;
	TRACE_FUN(ft_t_any);

	buff->segment_id = segment_id;
	buff->sector_offset = sector_offset;
	buff->remaining = sector_count;
	buff->head = segment_id / ftape_segments_per_head;
	buff->cyl = (segment_id % ftape_segments_per_head) / ftape_segments_per_cylinder;
	buff->sect = (segment_id % ftape_segments_per_cylinder) * FT_SECTORS_PER_SEGMENT + 1;
	buff->deleted = 0;
	offset_mask = (1 << buff->sector_offset) - 1;
	mask = ftape_get_bad_sector_entry(segment_id) & offset_mask;
	while (mask) {
		if (mask & 1) {
			offset_mask >>= 1;	/* don't count bad sector */
		}
		mask >>= 1;
	}
	buff->data_offset = count_ones(offset_mask);	/* good sectors to skip */
	buff->ptr = buff->address + buff->data_offset * FT_SECTOR_SIZE;
	TRACE(ft_t_flow, "data offset = %d sectors", buff->data_offset);