/*
 *      Copyright (C) 1994-1996 Bas Laarhoven,
 *                (C) 1996-1997 Claus 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-bsm.c,v $
 * $Revision: 1.3 $
 * $Date: 1997/10/05 19:15:15 $
 *
 *      This file contains the bad-sector map handling code for
 *      the QIC-117 floppy tape driver for Linux.
 *      QIC-40, QIC-80, QIC-3010 and QIC-3020 maps are implemented.
 */

#include <linux/string.h>

#include <linux/ftape.h>
#include "../lowlevel/ftape-tracing.h"
#include "../lowlevel/ftape-bsm.h"
#include "../lowlevel/ftape-ctl.h"
#include "../lowlevel/ftape-rw.h"

/*      Global vars.
 */

/*      Local vars.
 */
static __u8 *bad_sector_map;
static SectorCount *bsm_hash_ptr; 

typedef enum {
        forward, backward
} mode_type;

#if 0
/*  fix_tape converts a normal QIC-80 tape into a 'wide' tape.
 *  For testing purposes only !
 */
void fix_tape(__u8 * buffer, ft_format_type new_code)
{
        static __u8 list[BAD_SECTOR_MAP_SIZE];
        SectorMap *src_ptr = (SectorMap *) list;
        __u8 *dst_ptr = bad_sector_map;
        SectorMap map;
        unsigned int sector = 1;
        int i;

        if (format_code != fmt_var && format_code != fmt_big) {
                memcpy(list, bad_sector_map, sizeof(list));
                memset(bad_sector_map, 0, sizeof(bad_sector_map));
                while ((__u8 *) src_ptr - list < sizeof(list)) {
                        map = *src_ptr++;
                        if (map == EMPTY_SEGMENT) {
                                *(SectorMap *) dst_ptr = 0x800000 + sector;
                                dst_ptr += 3;
                                sector += SECTORS_PER_SEGMENT;
                        } else {
                                for (i = 0; i < SECTORS_PER_SEGMENT; ++i) {
                                        if (map & 1) {
                                                *(SewctorMap *) dst_ptr = sector;
                                                dst_ptr += 3;
                                        }
                                        map >>= 1;
                                        ++sector;
                                }
                        }
                }
        }
        bad_sector_map_changed = 1;
        *(buffer + 4) = new_code;       /* put new format code */
        if (format_code != fmt_var && new_code == fmt_big) {
                PUT4(buffer, FT_6_HSEG_1,   (__u32)GET2(buffer, 6));
                PUT4(buffer, FT_6_HSEG_2,   (__u32)GET2(buffer, 8));
                PUT4(buffer, FT_6_FRST_SEG, (__u32)GET2(buffer, 10));
                PUT4(buffer, FT_6_LAST_SEG, (__u32)GET2(buffer, 12));
                memset(buffer+6, '\0', 8);
        }
        format_code = new_code;
}

#endif

/*   given buffer that contains a header segment, find the end of
 *   of the bsm list
 */
__u8 * ftape_find_end_of_bsm_list(__u8 * address)
{
        __u8 *ptr   = address + FT_HEADER_END; /* start of bsm list */
        __u8 *limit = address + FT_SEGMENT_SIZE;
        while (ptr + 2 < limit) {
                if (ptr[0] || ptr[1] || ptr[2]) {
                        ptr += 3;
                } else {
                        return ptr;
                }
        }
        return NULL;
}

static inline void put_sector(SectorCount *ptr, unsigned int sector)
{
        ptr->bytes[0] = sector & 0xff;
        sector >>= 8;
        ptr->bytes[1] = sector & 0xff;
        sector >>= 8;
        ptr->bytes[2] = sector & 0xff;
}

static inline unsigned int get_sector(SectorCount *ptr)
{
#if 1
        unsigned int sector;

        sector  = ptr->bytes[0];
        sector += ptr->bytes[1] <<  8;
        sector += ptr->bytes[2] << 16;

        return sector;
#else
        /*  GET4 gets the next four bytes in Intel little endian order
         *  and converts them to host byte order and handles unaligned
         *  access.
         */
        return (GET4(ptr, 0) & 0x00ffffff); /* back to host byte order */
#endif
}

static void bsm_debug_fake(void)
{
        /* for testing of bad sector handling at end of tape
         */
#if 0
        ftape_put_bad_sector_entry(segments_per_track * tracks_per_tape - 3,
                                   0x000003e0;
        ftape_put_bad_sector_entry(segments_per_track * tracks_per_tape - 2,
                                   0xff3fffff;
        ftape_put_bad_sector_entry(segments_per_track * tracks_per_tape - 1,
                                   0xffffe000;
#endif
        /*  Enable to test bad sector handling
         */
#if 0
        ftape_put_bad_sector_entry(30, 0xfffffffe)
        ftape_put_bad_sector_entry(32, 0x7fffffff);
        ftape_put_bad_sector_entry(34, 0xfffeffff);
        ftape_put_bad_sector_entry(36, 0x55555555);
        ftape_put_bad_sector_entry(38, 0xffffffff);
        ftape_put_bad_sector_entry(50, 0xffff0000);
        ftape_put_bad_sector_entry(51, 0xffffffff);
        ftape_put_bad_sector_entry(52, 0xffffffff);
        ftape_put_bad_sector_entry(53, 0x0000ffff);
#endif
        /*  Enable when testing multiple volume tar dumps.
         */
#if 0
        {
                int i;

                for (i = ft_first_data_segment;
                     i <= ft_last_data_segment - 7; ++i) {
                        ftape_put_bad_sector_entry(i, EMPTY_SEGMENT);
                }
        }
#endif
        /*  Enable when testing bit positions in *_error_map
         */
#if 0
        {
                int i;
                
                for (i = first_data_segment; i <= last_data_segment; ++i) {
                        ftape_put_bad_sector_entry(i,
                                           ftape_get_bad_sector_entry(i) 
                                           | 0x00ff00ff);
                }
        }
#endif
}

static void print_bad_sector_map(void)
{
        unsigned int good_sectors;
        unsigned int total_bad = 0;
        int i;
        TRACE_FUN(ft_t_flow);

        if (ft_format_code == fmt_big || 
            ft_format_code == fmt_var || 
            ft_format_code == fmt_1100ft) {
                SectorCount *ptr = (SectorCount *)bad_sector_map;
                unsigned int sector;

                while((sector = get_sector(ptr++)) != 0) {
                        if ((ft_format_code == fmt_big || 
                             ft_format_code == fmt_var) &&
                            sector & 0x800000) {
                                total_bad += FT_SECTORS_PER_SEGMENT - 3;
                                TRACE(ft_t_noise, "bad segment at sector: %6d",
                                      sector & 0x7fffff);
                        } else {
                                ++total_bad;
                                TRACE(ft_t_noise, "bad sector: %6d", sector);
                        }
                }
                /*  Display old ftape's end-of-file marks
                 */
                while ((sector = get_unaligned(((__u16*)ptr)++)) != 0) {
                        TRACE(ft_t_noise, "Old ftape eof mark: %4d/%2d",
                              sector, get_unaligned(((__u16*)ptr)++));
                }
        } else { /* fixed size format */
                for (i = ft_first_data_segment;
                     i < (int)(ft_segments_per_track * ft_tracks_per_tape); ++i) {
                        SectorMap map = ((SectorMap *) bad_sector_map)[i];

                        if (map) {
                                TRACE(ft_t_noise,
                                      "bsm for segment %4d: 0x%08x", i, (unsigned int)map);
                                total_bad += ((map == EMPTY_SEGMENT)
                                               ? FT_SECTORS_PER_SEGMENT - 3
                                               : count_ones(map));
                        }
                }
        }
        good_sectors =
                ((ft_segments_per_track * ft_tracks_per_tape - ft_first_data_segment)
                 * (FT_SECTORS_PER_SEGMENT - 3)) - total_bad;
        TRACE(ft_t_info, "%d Kb usable on this tape", good_sectors);
        if (total_bad == 0) {
                TRACE(ft_t_info,
                      "WARNING: this tape has no bad blocks registered !");
        } else {
                TRACE(ft_t_info, "%d bad sectors", total_bad);
        }
        TRACE_EXIT;
}


void ftape_extract_bad_sector_map(__u8 * buffer)
{
        TRACE_FUN(ft_t_any);

        /*  Fill the bad sector map with the contents of buffer.
         */
        if (ft_format_code == fmt_var || ft_format_code == fmt_big) {
                /* QIC-3010/3020 and wide QIC-80 tapes no longer have a failed
                 * sector log but use this area to extend the bad sector map.
                 */
                bad_sector_map = &buffer[FT_HEADER_END];
        } else {
                /* non-wide QIC-80 tapes have a failed sector log area that
                 * mustn't be included in the bad sector map.
                 */
                bad_sector_map = &buffer[FT_FSL + FT_FSL_SIZE];
        }
        if (ft_format_code == fmt_1100ft || 
            ft_format_code == fmt_var    ||
            ft_format_code == fmt_big) {
                bsm_hash_ptr = (SectorCount *)bad_sector_map;
        } else {
                bsm_hash_ptr = NULL;
        }
        bsm_debug_fake();
        if (TRACE_LEVEL >= ft_t_info) {
                print_bad_sector_map();
        }
        TRACE_EXIT;
}

static inline SectorMap cvt2map(unsigned int sector)
{
        return 1 << (((sector & 0x7fffff) - 1) % FT_SECTORS_PER_SEGMENT);
}

static inline int cvt2segment(unsigned int sector)
{
        return ((sector & 0x7fffff) - 1) / FT_SECTORS_PER_SEGMENT;
}

static int forward_seek_entry(int segment_id, 
                              SectorCount **ptr, 
                              SectorMap *map)
{
        unsigned int sector;
        int segment;

        do {
                sector = get_sector((*ptr)++);
                segment = cvt2segment(sector);
        } while (sector != 0 && segment < segment_id);
        (*ptr) --; /* point to first sector >= segment_id */
        /*  Get all sectors in segment_id
         */
        if (sector == 0 || segment != segment_id) {
                *map = 0;
                return 0;
        } else if ((sector & 0x800000) &&
                   (ft_format_code == fmt_var || ft_format_code == fmt_big)) {
                *map = EMPTY_SEGMENT;
                return FT_SECTORS_PER_SEGMENT;
        } else {
                int count = 1;
                SectorCount *tmp_ptr = (*ptr) + 1;
                
                *map = cvt2map(sector);
                while ((sector = get_sector(tmp_ptr++)) != 0 &&
                       (segment = cvt2segment(sector)) == segment_id) {
                        *map |= cvt2map(sector);
                        ++count;
                }
                return count;
        }
}

static int backwards_seek_entry(int segment_id,
                                SectorCount **ptr,
                                SectorMap *map)
{
        unsigned int sector;
        int segment; /* max unsigned int */

        if (*ptr <= (SectorCount *)bad_sector_map) {
                *map = 0;
                return 0;
        }
        do {
                sector  = get_sector(--(*ptr));
                segment = cvt2segment(sector);
        } while (*ptr > (SectorCount *)bad_sector_map && segment > segment_id);
        if (segment > segment_id) { /*  at start of list, no entry found */
                *map = 0;
                return 0;
        } else if (segment < segment_id) {
                /*  before smaller entry, adjust for overshoot */
                (*ptr) ++;
                *map = 0;
                return 0;
        } else if ((sector & 0x800000) &&
                   (ft_format_code == fmt_big || ft_format_code == fmt_var)) {
                *map = EMPTY_SEGMENT;
                return FT_SECTORS_PER_SEGMENT;
        } else { /*  get all sectors in segment_id */
                int count = 1;

                *map = cvt2map(sector);
                while(*ptr > (SectorCount *)bad_sector_map) {
                        sector = get_sector(--(*ptr));
                        segment = cvt2segment(sector);
                        if (segment != segment_id) {
                                break;
                        }
                        *map |= cvt2map(sector);
                        ++count;
                }
                if (segment < segment_id) {
                        (*ptr) ++;
                }
                return count;
        }
}

void ftape_put_bad_sector_entry(int segment_id, SectorMap new_map)
{
        SectorCount *ptr = (SectorCount *)bad_sector_map;
        int count;
        int new_count;
        SectorMap map;
        TRACE_FUN(ft_t_any);

        if (ft_format_code == fmt_1100ft || 
            ft_format_code == fmt_var || 
            ft_format_code == fmt_big) {
                count = forward_seek_entry(segment_id, &ptr, &map);
                new_count = count_ones(new_map);
                /* If format code == 4 put empty segment instead of 32
                 * bad sectors.
                 */
                if (ft_format_code == fmt_var || ft_format_code == fmt_big) {
                        if (new_count == FT_SECTORS_PER_SEGMENT) {
                                new_count = 1;
                        }
                        if (count == FT_SECTORS_PER_SEGMENT) {
                                count = 1;
                        }
                }
                if (count != new_count) {
                        /* insert (or delete if < 0) new_count - count
                         * entries.  Move trailing part of list
                         * including terminating 0.
                         */
                        SectorCount *hi_ptr = ptr;

                        do {
                        } while (get_sector(hi_ptr++) != 0);
                        /*  Note: ptr is of type byte *, and each bad sector
                         *  consumes 3 bytes.
                         */
                        memmove(ptr + new_count, ptr + count,
                                (size_t)(hi_ptr - (ptr + count))*sizeof(SectorCount));
                }
                TRACE(ft_t_noise, "putting map 0x%08x at %p, segment %d",
                      (unsigned int)new_map, ptr, segment_id);
                if (new_count == 1 && new_map == EMPTY_SEGMENT) {
                        put_sector(ptr++, (0x800001 + 
                                          segment_id * 
                                          FT_SECTORS_PER_SEGMENT));
                } else {
                        int i = 0;

                        while (new_map) {
                                if (new_map & 1) {
                                        put_sector(ptr++, 
                                                   1 + segment_id * 
                                                   FT_SECTORS_PER_SEGMENT + i);
                                }
                                ++i;
                                new_map >>= 1;
                        }
                }
        } else {
                ((SectorMap *) bad_sector_map)[segment_id] = new_map;
        }
        TRACE_EXIT;
}

SectorMap ftape_get_bad_sector_entry(int segment_id)
{
        if (ft_used_header_segment == -1) {
                /*  When reading header segment we'll need a blank map.
                 */
                return 0;
        } else if (bsm_hash_ptr != NULL) {
                /*  Invariants:
                 *    map - mask value returned on last call.
                 *    bsm_hash_ptr - points to first sector greater or equal to
                 *          first sector in last_referenced segment.
                 *    last_referenced - segment id used in the last call,
                 *                      sector and map belong to this id.
                 *  This code is designed for sequential access and retries.
                 *  For true random access it may have to be redesigned.
                 */
                static int last_reference = -1;
                static SectorMap map;

                if (segment_id > last_reference) {
                        /*  Skip all sectors before segment_id
                         */
                        forward_seek_entry(segment_id, &bsm_hash_ptr, &map);
                } else if (segment_id < last_reference) {
                        /* Skip backwards until begin of buffer or
                         * first sector in segment_id 
                         */
                        backwards_seek_entry(segment_id, &bsm_hash_ptr, &map);
                }               /* segment_id == last_reference : keep map */
                last_reference = segment_id;
                return map;
        } else {
                return ((SectorMap *) bad_sector_map)[segment_id];
        }
}

/*  This is simply here to prevent us from overwriting other kernel
 *  data. Writes will result in NULL Pointer dereference.
 */
void ftape_init_bsm(void)
{
        bad_sector_map = NULL;
        bsm_hash_ptr   = NULL;
}