/*
 * 86Box    A hypervisor and IBM PC system emulator that specializes in
 *          running old operating systems and software designed for IBM
 *          PC systems and compatibles from 1981 through fairly recent
 *          system designs based on the PCI bus.
 *
 *          This file is part of the 86Box distribution.
 *
 *          FDI to raw bit stream converter
 *          FDI format created by Vincent "ApH" Joguin
 *          Tiny changes - function type fixes, multiple drives,
 *          addition of get_last_head and C++ callability by Thomas
 *          Harte.
 *
 * Authors: Toni Wilen, <twilen@arabuusimiehet.com>
 *          and Vincent Joguin,
 *          Thomas Harte, <T.Harte@excite.co.uk>
 *
 *          Copyright 2001-2004 Toni Wilen.
 *          Copyright 2001-2004 Vincent Joguin.
 *          Copyright 2001-2016 Thomas Harte.
 */
#define STATIC_INLINE
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <wchar.h>

#define xmalloc malloc
#define HAVE_STDARG_H
#include <86box/86box.h>
#include <fdi2raw.h>
#include <86box/plat_unused.h>

#ifdef DEBUG
#undef DEBUG
#endif
#define VERBOSE
#undef VERBOSE

#ifdef ENABLE_FDI2RAW_LOG
int fdi2raw_do_log = ENABLE_FDI2RAW_LOG;

static void
fdi2raw_log(const char *fmt, ...)
{
    va_list ap;

    if (fdi2raw_do_log) {
        va_start(ap, fmt);
        pclog_ex(fmt, ap);
        va_end(ap);
    }
}
#else
#    define fdi2raw_log(fmt, ...)
#endif

#ifdef ENABLE_FDI2RAW_LOG
#    ifdef DEBUG
static char *
datalog(uint8_t *src, int len)
{
    static char buf[1000];
    static int  offset;
    int         i = 0;
    int         offset2;

    offset2       = offset;
    buf[offset++] = '\'';
    while (len--) {
        sprintf(buf + offset, "%02.2X", src[i]);
        offset += 2;
        i++;
        if (i > 10)
            break;
    }
    buf[offset++] = '\'';
    buf[offset++] = 0;
    if (offset >= 900)
        offset = 0;
    return buf + offset2;
}
#    else
static char *
datalog(uint8_t *src, int len)
{
    return "";
}
#    endif

static int fdi_allocated;
#endif

#ifdef DEBUG
static void
fdi_free(void *priv)
{
    int size;
    if (!priv)
        return;
    size = ((int *) priv)[-1];
    fdi_allocated -= size;
    write_log("%d freed (%d)\n", size, fdi_allocated);
    free((int *) priv - 1);
}
static void *
fdi_malloc(int size)
{
    void *priv       = xmalloc(size + sizeof(int));
    ((int *) prv)[0] = size;
    fdi_allocated += size;
    write_log("%d allocated (%d)\n", size, fdi_allocated);
    return (int *) priv + 1;
}
#else
#    define fdi_free   free
#    define fdi_malloc xmalloc
#endif

#define MAX_SRC_BUFFER      4194304
#define MAX_DST_BUFFER      40000
#define MAX_MFM_SYNC_BUFFER 60000
#define MAX_TIMING_BUFFER   400000
#define MAX_TRACKS          166

struct fdi_cache {
    uint32_t *avgp, *minp, *maxp;
    uint8_t  *idxp;
    int       avg_free, idx_free, min_free, max_free;
    uint32_t  totalavg, pulses, maxidx, indexoffset;
    int       weakbits;
    int       lowlevel;
};

struct fdi {
    uint8_t  *track_src_buffer;
    uint8_t  *track_src;
    int32_t   track_src_len;
    uint8_t  *track_dst_buffer;
    uint8_t  *track_dst;
    uint16_t *track_dst_buffer_timing;
    uint8_t   track_len;
    uint8_t   track_type;
    int       current_track;
    int       last_track;
    int       last_head;
    int       rotation_speed;
    int       bit_rate;
    int       disk_type;
    bool      write_protect;
    int       reversed_side;
    int       err;
    uint8_t   header[2048];
    int32_t   track_offsets[MAX_TRACKS];
    FILE     *file;
    int       out;
    int       mfmsync_offset;
    int      *mfmsync_buffer;
    /* sector described only */
    int index_offset;
    int encoding_type;
    /* bit handling */
    int              nextdrop;
    struct fdi_cache cache[MAX_TRACKS];
};

#define get_u32(x) ((((x)[0]) << 24) | (((x)[1]) << 16) | (((x)[2]) << 8) | ((x)[3]))
#define get_u24(x) ((((x)[0]) << 16) | (((x)[1]) << 8) | ((x)[2]))
STATIC_INLINE void
put_u32(uint8_t *d, uint32_t v)
{
    d[0] = v >> 24;
    d[1] = v >> 16;
    d[2] = v >> 8;
    d[3] = v;
}

struct node {
    uint16_t     v;
    struct node *left;
    struct node *right;
};
typedef struct node NODE;

static uint8_t temp;
static uint8_t temp2;

static uint8_t *
expand_tree(uint8_t *stream, NODE *node)
{
    if (temp & temp2) {
        if (node->left) {
            fdi_free(node->left);
            node->left = 0;
        }
        if (node->right) {
            fdi_free(node->right);
            node->right = 0;
        }
        temp2 >>= 1;
        if (!temp2) {
            temp  = *stream++;
            temp2 = 0x80;
        }
        return stream;
    } else {
        uint8_t *stream_temp;
        temp2 >>= 1;
        if (!temp2) {
            temp  = *stream++;
            temp2 = 0x80;
        }
        node->left = fdi_malloc(sizeof(NODE));
        memset(node->left, 0, sizeof(NODE));
        stream_temp = expand_tree(stream, node->left);
        node->right = fdi_malloc(sizeof(NODE));
        memset(node->right, 0, sizeof(NODE));
        return expand_tree(stream_temp, node->right);
    }
}

static uint8_t *
values_tree8(uint8_t *stream, NODE *node)
{
    if (node->left == 0) {
        node->v = *stream++;
        return stream;
    } else {
        uint8_t *stream_temp = values_tree8(stream, node->left);
        return values_tree8(stream_temp, node->right);
    }
}

static uint8_t *
values_tree16(uint8_t *stream, NODE *node)
{
    if (node->left == 0) {
        uint16_t high_8_bits = (*stream++) << 8;
        node->v              = high_8_bits | (*stream++);
        return stream;
    } else {
        uint8_t *stream_temp = values_tree16(stream, node->left);
        return values_tree16(stream_temp, node->right);
    }
}

static void
free_nodes(NODE *node)
{
    if (node) {
        free_nodes(node->left);
        free_nodes(node->right);
        fdi_free(node);
    }
}

/// @returns the 32-bit sign extended version of the 16-bit value in the low part of @c v.
static uint32_t
sign_extend16(uint32_t v)
{
    if (v & 0x8000)
        v |= 0xffff0000;
    return v;
}

/// @returns the 32-bit sign extended version of the 8-bit value in the low part of @c v.
static uint32_t
sign_extend8(uint32_t v)
{
    if (v & 0x80)
        v |= 0xffffff00;
    return v;
}

static void
fdi_decode(uint8_t *stream, int size, uint8_t *out)
{
    uint8_t sign_extend;
    uint8_t sixteen_bit;
    uint8_t sub_stream_shift;
    NODE    root;
    NODE   *current_node;

    memset(out, 0, size * 4);
    sub_stream_shift = 1;
    while (sub_stream_shift) {

        /* sub-stream header decode */
        sign_extend      = *stream++;
        sub_stream_shift = sign_extend & 0x7f;
        sign_extend &= 0x80;
        sixteen_bit = (*stream++) & 0x80;

        /* huffman tree architecture decode */
        temp   = *stream++;
        temp2  = 0x80;
        stream = expand_tree(stream, &root);
        if (temp2 == 0x80)
            stream--;

        /* huffman output values decode */
        if (sixteen_bit)
            stream = values_tree16(stream, &root);
        else
            stream = values_tree8(stream, &root);

        /* sub-stream data decode */
        temp2 = 0;
        for (int i = 0; i < size; i++) {
            uint32_t v;
            uint8_t  decode = 1;
            current_node    = &root;
            while (decode) {
                if (current_node->left == 0) {
                    decode = 0;
                } else {
                    temp2 >>= 1;
                    if (!temp2) {
                        temp2 = 0x80;
                        temp  = *stream++;
                    }
                    if (temp & temp2)
                        current_node = current_node->right;
                    else
                        current_node = current_node->left;
                }
            }
            v = ((uint32_t *) out)[i];
            if (sign_extend) {
                if (sixteen_bit)
                    v |= sign_extend16(current_node->v) << sub_stream_shift;
                else
                    v |= sign_extend8(current_node->v) << sub_stream_shift;
            } else {
                v |= current_node->v << sub_stream_shift;
            }
            ((uint32_t *) out)[i] = v;
        }
        free_nodes(root.left);
        root.left = 0;
        free_nodes(root.right);
        root.right = 0;
    }
}

static int
decode_raw_track(FDI *fdi)
{
    int size = get_u32(fdi->track_src);
    memcpy(fdi->track_dst, fdi->track_src, (size + 7) >> 3);
    fdi->track_src += (size + 7) >> 3;
    return size;
}

/* unknown track */
static void
zxx(UNUSED(FDI *fdi))
{
    fdi2raw_log("track %d: unknown track type 0x%02.2X\n", fdi->current_track, fdi->track_type);
}
/* unsupported track */
#if 0
static void zyy (FDI *fdi)
{
    fdi2raw_log("track %d: unsupported track type 0x%02.2X\n", fdi->current_track, fdi->track_type);
}
#endif
/* empty track */
static void
track_empty(UNUSED(FDI *fdi))
{
    return;
}

/* unknown sector described type */
static void
dxx(FDI *fdi)
{
    fdi2raw_log("\ntrack %d: unknown sector described type 0x%02.2X\n", fdi->current_track, fdi->track_type);
    fdi->err = 1;
}
/* add position of mfm sync bit */
static void
add_mfm_sync_bit(FDI *fdi)
{
    if (fdi->nextdrop) {
        fdi->nextdrop = 0;
        return;
    }
    fdi->mfmsync_buffer[fdi->mfmsync_offset++] = fdi->out;
    if (fdi->out == 0) {
        fdi2raw_log("illegal position for mfm sync bit, offset=%d\n", fdi->out);
        fdi->err = 1;
    }
    if (fdi->mfmsync_offset >= MAX_MFM_SYNC_BUFFER) {
        fdi->mfmsync_offset = 0;
        fdi2raw_log("mfmsync buffer overflow\n");
        fdi->err = 1;
    }
    fdi->out++;
}

#define BIT_BYTEOFFSET ((fdi->out) >> 3)
#define BIT_BITOFFSET  (7 - ((fdi->out) & 7))

/* add one bit */
static void
bit_add(FDI *fdi, int bit)
{
    if (fdi->nextdrop) {
        fdi->nextdrop = 0;
        return;
    }
    fdi->track_dst[BIT_BYTEOFFSET] &= ~(1 << BIT_BITOFFSET);
    if (bit)
        fdi->track_dst[BIT_BYTEOFFSET] |= (1 << BIT_BITOFFSET);
    fdi->out++;
    if (fdi->out >= MAX_DST_BUFFER * 8) {
        fdi2raw_log("destination buffer overflow\n");
        fdi->err = 1;
        fdi->out = 1;
    }
}
/* add bit and mfm sync bit */
static void
bit_mfm_add(FDI *fdi, int bit)
{
    add_mfm_sync_bit(fdi);
    bit_add(fdi, bit);
}
/* remove following bit */
static void
bit_drop_next(FDI *fdi)
{
    if (fdi->nextdrop > 0) {
        fdi2raw_log("multiple bit_drop_next() called");
    } else if (fdi->nextdrop < 0) {
        fdi->nextdrop = 0;
        fdi2raw_log(":DNN:");
        return;
    }
    fdi2raw_log(":DN:");
    fdi->nextdrop = 1;
}

/* ignore next bit_drop_next() */
static void
bit_dedrop(FDI *fdi)
{
    if (fdi->nextdrop) {
        fdi2raw_log("bit_drop_next called before bit_dedrop");
    }
    fdi->nextdrop = -1;
    fdi2raw_log(":BDD:");
}

/* add one byte */
static void
byte_add(FDI *fdi, uint8_t v)
{
    for (int8_t i = 7; i >= 0; i--)
        bit_add(fdi, v & (1 << i));
}
/* add one word */
static void
word_add(FDI *fdi, uint16_t v)
{
    byte_add(fdi, (uint8_t) (v >> 8));
    byte_add(fdi, (uint8_t) v);
}
/* add one byte and mfm encode it */
static void
byte_mfm_add(FDI *fdi, uint8_t v)
{
    for (int8_t i = 7; i >= 0; i--)
        bit_mfm_add(fdi, v & (1 << i));
}
/* add multiple bytes and mfm encode them */
static void
bytes_mfm_add(FDI *fdi, uint8_t v, int len)
{
    for (int i = 0; i < len; i++)
        byte_mfm_add(fdi, v);
}
/* add one mfm encoded word and re-mfm encode it */
static void
word_post_mfm_add(FDI *fdi, uint16_t v)
{
    for (int8_t i = 14; i >= 0; i -= 2)
        bit_mfm_add(fdi, v & (1 << i));
}

/* bit 0 */
static void
s00(FDI *fdi)
{
    bit_add(fdi, 0);
}
/* bit 1*/
static void
s01(FDI *fdi)
{
    bit_add(fdi, 1);
}
/* 4489 */
static void
s02(FDI *fdi)
{
    word_add(fdi, 0x4489);
}
/* 5224 */
static void
s03(FDI *fdi)
{
    word_add(fdi, 0x5224);
}
/* mfm sync bit */
static void
s04(FDI *fdi)
{
    add_mfm_sync_bit(fdi);
}
/* RLE MFM-encoded data */
static void
s08(FDI *fdi)
{
    int     bytes = *fdi->track_src++;
    uint8_t byte  = *fdi->track_src++;
    if (bytes == 0)
        bytes = 256;
    fdi2raw_log("s08:len=%d,data=%02.2X", bytes, byte);
    while (bytes--)
        byte_add(fdi, byte);
}
/* RLE MFM-decoded data */
static void
s09(FDI *fdi)
{
    int     bytes = *fdi->track_src++;
    uint8_t byte  = *fdi->track_src++;
    if (bytes == 0)
        bytes = 256;
    bit_drop_next(fdi);
    fdi2raw_log("s09:len=%d,data=%02.2X", bytes, byte);
    while (bytes--)
        byte_mfm_add(fdi, byte);
}
/* MFM-encoded data */
static void
s0a(FDI *fdi)
{
    int     i;
    int     bits = (fdi->track_src[0] << 8) | fdi->track_src[1];
    uint8_t b;
    fdi->track_src += 2;
    fdi2raw_log("s0a:bits=%d,data=%s", bits, datalog(fdi->track_src, (bits + 7) / 8));
    while (bits >= 8) {
        byte_add(fdi, *fdi->track_src++);
        bits -= 8;
    }
    if (bits > 0) {
        i = 7;
        b = *fdi->track_src++;
        while (bits--) {
            bit_add(fdi, b & (1 << i));
            i--;
        }
    }
}
/* MFM-encoded data */
static void
s0b(FDI *fdi)
{
    int     i;
    int     bits = ((fdi->track_src[0] << 8) | fdi->track_src[1]) + 65536;
    uint8_t b;
    fdi->track_src += 2;
    fdi2raw_log("s0b:bits=%d,data=%s", bits, datalog(fdi->track_src, (bits + 7) / 8));
    while (bits >= 8) {
        byte_add(fdi, *fdi->track_src++);
        bits -= 8;
    }
    if (bits > 0) {
        i = 7;
        b = *fdi->track_src++;
        while (bits--) {
            bit_add(fdi, b & (1 << i));
            i--;
        }
    }
}
/* MFM-decoded data */
static void
s0c(FDI *fdi)
{
    int     i;
    int     bits = (fdi->track_src[0] << 8) | fdi->track_src[1];
    uint8_t b;
    fdi->track_src += 2;
    bit_drop_next(fdi);
    fdi2raw_log("s0c:bits=%d,data=%s", bits, datalog(fdi->track_src, (bits + 7) / 8));
    while (bits >= 8) {
        byte_mfm_add(fdi, *fdi->track_src++);
        bits -= 8;
    }
    if (bits > 0) {
        i = 7;
        b = *fdi->track_src++;
        while (bits--) {
            bit_mfm_add(fdi, b & (1 << i));
            i--;
        }
    }
}
/* MFM-decoded data */
static void
s0d(FDI *fdi)
{
    int     i;
    int     bits = ((fdi->track_src[0] << 8) | fdi->track_src[1]) + 65536;
    uint8_t b;
    fdi->track_src += 2;
    bit_drop_next(fdi);
    fdi2raw_log("s0d:bits=%d,data=%s", bits, datalog(fdi->track_src, (bits + 7) / 8));
    while (bits >= 8) {
        byte_mfm_add(fdi, *fdi->track_src++);
        bits -= 8;
    }
    if (bits > 0) {
        i = 7;
        b = *fdi->track_src++;
        while (bits--) {
            bit_mfm_add(fdi, b & (1 << i));
            i--;
        }
    }
}

/* ***** */
/* AMIGA */
/* ***** */

/* just for testing integrity of Amiga sectors */
#if 0
static void
rotateonebit (uint8_t *start, uint8_t *end, int shift)
{
        if (shift == 0)
                return;
        while (start <= end) {
                start[0] <<= shift;
                start[0] |= start[1] >> (8 - shift);
                start++;
        }
}

static uint16_t
getmfmword (uint8_t *mbuf)
{
        uint32_t v;

        v = (mbuf[0] << 8) | (mbuf[1] << 0);
        if (check_offset == 0)
                return (uint16_t)v;
        v <<= 8;
        v |= mbuf[2];
        v >>= check_offset;
        return (uint16_t)v;
}

#define MFMMASK 0x55555555
static uint32_t
getmfmlong (uint8_t * mbuf)
{
        return ((getmfmword (mbuf) << 16) | getmfmword (mbuf + 2)) & MFMMASK;
}
#endif

#if 0
static int amiga_check_track (FDI *fdi)
{
    int i, j, secwritten = 0;
    int fwlen = fdi->out / 8;
    int length = 2 * fwlen;
    int drvsec = 11;
    uint32_t odd, even, chksum, id, dlong;
    uint8_t *secdata;
    uint8_t secbuf[544];
    uint8_t bigmfmbuf[60000];
    uint8_t *mbuf, *mbuf2, *mend;
    char sectable[22];
    uint8_t *raw = fdi->track_dst_buffer;
    int slabel, off;
    int ok = 1;

    memset (bigmfmbuf, 0, sizeof (bigmfmbuf));
    mbuf = bigmfmbuf;
    check_offset = 0;
    for (i = 0; i < (fdi->out + 7) / 8; i++)
        *mbuf++ = raw[i];
    off = fdi->out & 7;
#    if 1
    if (off > 0) {
        mbuf--;
        *mbuf &= ~((1 << (8 - off)) - 1);
    }
    j = 0;
    while (i < (fdi->out + 7) / 8 + 600) {
        *mbuf++ |= (raw[j] >> off) | ((raw[j + 1]) << (8 - off));
        j++;
        i++;
    }
#    endif
    mbuf = bigmfmbuf;

    memset (sectable, 0, sizeof (sectable));
    mend = bigmfmbuf + length;
    mend -= (4 + 16 + 8 + 512);

    while (secwritten < drvsec) {
        int trackoffs;

        for (;;) {
            rotateonebit (bigmfmbuf, mend, 1);
            if (getmfmword (mbuf) == 0)
                break;
            if (secwritten == 10) {
                mbuf[0] = 0x44;
                mbuf[1] = 0x89;
            }
            if (check_offset > 7) {
                check_offset = 0;
                mbuf++;
                if (mbuf >= mend || *mbuf == 0)
                    break;
            }
            if (getmfmword (mbuf) == 0x4489)
                break;
        }
        if (mbuf >= mend || *mbuf == 0)
            break;

        rotateonebit (bigmfmbuf, mend, check_offset);
        check_offset = 0;

        while (getmfmword (mbuf) == 0x4489)
            mbuf+= 1 * 2;
        mbuf2 = mbuf + 8;

        odd = getmfmlong (mbuf);
        even = getmfmlong (mbuf + 2 * 2);
        mbuf += 4 * 2;
        id = (odd << 1) | even;

        trackoffs = (id & 0xff00) >> 8;
        if (trackoffs + 1 > drvsec) {
            fdi2raw_log("illegal sector offset %d\n",trackoffs);
            ok = 0;
            mbuf = mbuf2;
            continue;
        }
        if ((id >> 24) != 0xff) {
            fdi2raw_log("sector %d format type %02.2X?\n", trackoffs, id >> 24);
            ok = 0;
        }
        chksum = odd ^ even;
        slabel = 0;
        for (i = 0; i < 4; i++) {
            odd = getmfmlong (mbuf);
            even = getmfmlong (mbuf + 8 * 2);
            mbuf += 2* 2;

            dlong = (odd << 1) | even;
            if (dlong) slabel = 1;
                chksum ^= odd ^ even;
        }
        mbuf += 8 * 2;
        odd = getmfmlong (mbuf);
        even = getmfmlong (mbuf + 2 * 2);
        mbuf += 4 * 2;
        if (((odd << 1) | even) != chksum) {
            fdi2raw_log("sector %d header crc error\n", trackoffs);
            ok = 0;
            mbuf = mbuf2;
            continue;
        }
        fdi2raw_log("sector %d header crc ok\n", trackoffs);
        if (((id & 0x00ff0000) >> 16) != (uint32_t)fdi->current_track) {
            fdi2raw_log("illegal track number %d <> %d\n",fdi->current_track,(id & 0x00ff0000) >> 16);
            ok++;
            mbuf = mbuf2;
            continue;
        }
        odd = getmfmlong (mbuf);
        even = getmfmlong (mbuf + 2 * 2);
        mbuf += 4 * 2;
        chksum = (odd << 1) | even;
        secdata = secbuf + 32;
        for (i = 0; i < 128; i++) {
            odd = getmfmlong (mbuf);
            even = getmfmlong (mbuf + 256 * 2);
            mbuf += 2 * 2;
            dlong = (odd << 1) | even;
            *secdata++ = (uint8_t) (dlong >> 24);
            *secdata++ = (uint8_t) (dlong >> 16);
            *secdata++ = (uint8_t) (dlong >> 8);
            *secdata++ = (uint8_t) dlong;
            chksum ^= odd ^ even;
        }
        mbuf += 256 * 2;
        if (chksum) {
            fdi2raw_log("sector %d data checksum error\n",trackoffs);
            ok = 0;
        } else if (sectable[trackoffs]) {
            fdi2raw_log("sector %d already found?\n", trackoffs);
            mbuf = mbuf2;
        } else {
            fdi2raw_log("sector %d ok\n",trackoffs);
            if (slabel) fdi2raw_log("(non-empty sector header)\n");
            sectable[trackoffs] = 1;
            secwritten++;
            if (trackoffs == 9)
                mbuf += 0x228;
        }
    }
    for (i = 0; i < drvsec; i++) {
        if (!sectable[i]) {
            fdi2raw_log("sector %d missing\n", i);
            ok = 0;
        }
    }
    return ok;
}
#endif

static void
amiga_data_raw(FDI *fdi, uint8_t *secbuf, uint8_t *crc, int len)
{
    int     i;
    uint8_t crcbuf[4];

    if (!crc) {
        memset(crcbuf, 0, 4);
    } else {
        memcpy(crcbuf, crc, 4);
    }
    for (i = 0; i < 4; i++)
        byte_mfm_add(fdi, crcbuf[i]);
    for (i = 0; i < len; i++)
        byte_mfm_add(fdi, secbuf[i]);
}

static void
amiga_data(FDI *fdi, uint8_t *secbuf)
{
    uint16_t mfmbuf[4 + 512];
    uint32_t dodd;
    uint32_t deven;
    uint32_t dck;

    for (uint16_t i = 0; i < 512; i += 4) {
        deven = ((secbuf[i + 0] << 24) | (secbuf[i + 1] << 16)
                 | (secbuf[i + 2] << 8) | (secbuf[i + 3]));
        dodd  = deven >> 1;
        deven &= 0x55555555;
        dodd &= 0x55555555;
        mfmbuf[(i >> 1) + 4]       = (uint16_t) (dodd >> 16);
        mfmbuf[(i >> 1) + 5]       = (uint16_t) dodd;
        mfmbuf[(i >> 1) + 256 + 4] = (uint16_t) (deven >> 16);
        mfmbuf[(i >> 1) + 256 + 5] = (uint16_t) deven;
    }
    dck = 0;
    for (uint32_t i = 4; i < 4 + 512; i += 2)
        dck ^= (mfmbuf[i] << 16) | mfmbuf[i + 1];
    deven = dodd = dck;
    dodd >>= 1;
    deven &= 0x55555555;
    dodd &= 0x55555555;
    mfmbuf[0] = (uint16_t) (dodd >> 16);
    mfmbuf[1] = (uint16_t) dodd;
    mfmbuf[2] = (uint16_t) (deven >> 16);
    mfmbuf[3] = (uint16_t) deven;

    for (uint32_t i = 0; i < 4 + 512; i++)
        word_post_mfm_add(fdi, mfmbuf[i]);
}

static void
amiga_sector_header(FDI *fdi, uint8_t *header, uint8_t *data, int sector, int untilgap)
{
    uint8_t  headerbuf[4];
    uint8_t  databuf[16];
    uint32_t deven;
    uint32_t dodd;
    uint32_t hck;
    uint16_t mfmbuf[24];

    byte_mfm_add(fdi, 0);
    byte_mfm_add(fdi, 0);
    word_add(fdi, 0x4489);
    word_add(fdi, 0x4489);
    if (header) {
        memcpy(headerbuf, header, 4);
    } else {
        headerbuf[0] = 0xff;
        headerbuf[1] = (uint8_t) fdi->current_track;
        headerbuf[2] = (uint8_t) sector;
        headerbuf[3] = (uint8_t) untilgap;
    }
    if (data)
        memcpy(databuf, data, 16);
    else
        memset(databuf, 0, 16);

    deven = ((headerbuf[0] << 24) | (headerbuf[1] << 16)
             | (headerbuf[2] << 8) | (headerbuf[3]));
    dodd  = deven >> 1;
    deven &= 0x55555555;
    dodd &= 0x55555555;
    mfmbuf[0] = (uint16_t) (dodd >> 16);
    mfmbuf[1] = (uint16_t) dodd;
    mfmbuf[2] = (uint16_t) (deven >> 16);
    mfmbuf[3] = (uint16_t) deven;
    for (uint8_t i = 0; i < 16; i += 4) {
        deven = ((databuf[i] << 24) | (databuf[i + 1] << 16)
                 | (databuf[i + 2] << 8) | (databuf[i + 3]));
        dodd  = deven >> 1;
        deven &= 0x55555555;
        dodd &= 0x55555555;
        mfmbuf[(i >> 1) + 0 + 4] = (uint16_t) (dodd >> 16);
        mfmbuf[(i >> 1) + 0 + 5] = (uint16_t) dodd;
        mfmbuf[(i >> 1) + 8 + 4] = (uint16_t) (deven >> 16);
        mfmbuf[(i >> 1) + 8 + 5] = (uint16_t) deven;
    }
    hck = 0;
    for (uint32_t i = 0; i < 4 + 16; i += 2)
        hck ^= (mfmbuf[i] << 16) | mfmbuf[i + 1];
    deven = dodd = hck;
    dodd >>= 1;
    deven &= 0x55555555;
    dodd &= 0x55555555;
    mfmbuf[20] = (uint16_t) (dodd >> 16);
    mfmbuf[21] = (uint16_t) dodd;
    mfmbuf[22] = (uint16_t) (deven >> 16);
    mfmbuf[23] = (uint16_t) deven;

    for (uint32_t i = 0; i < 4 + 16 + 4; i++)
        word_post_mfm_add(fdi, mfmbuf[i]);
}

/* standard super-extended Amiga sector header */
static void
s20(FDI *fdi)
{
    bit_drop_next(fdi);
    fdi2raw_log("s20:header=%s,data=%s", datalog(fdi->track_src, 4), datalog(fdi->track_src + 4, 16));
    amiga_sector_header(fdi, fdi->track_src, fdi->track_src + 4, 0, 0);
    fdi->track_src += 4 + 16;
}
/* standard extended Amiga sector header */
static void
s21(FDI *fdi)
{
    bit_drop_next(fdi);
    fdi2raw_log("s21:header=%s", datalog(fdi->track_src, 4));
    amiga_sector_header(fdi, fdi->track_src, 0, 0, 0);
    fdi->track_src += 4;
}
/* standard Amiga sector header */
static void
s22(FDI *fdi)
{
    bit_drop_next(fdi);
    fdi2raw_log("s22:sector=%d,untilgap=%d", fdi->track_src[0], fdi->track_src[1]);
    amiga_sector_header(fdi, 0, 0, fdi->track_src[0], fdi->track_src[1]);
    fdi->track_src += 2;
}
/* standard 512-byte, CRC-correct Amiga data */
static void
s23(FDI *fdi)
{
    fdi2raw_log("s23:data=%s", datalog(fdi->track_src, 512));
    amiga_data(fdi, fdi->track_src);
    fdi->track_src += 512;
}
/* not-decoded, 128*2^x-byte, CRC-correct Amiga data */
static void
s24(FDI *fdi)
{
    int shift = *fdi->track_src++;
    fdi2raw_log("s24:shift=%d,data=%s", shift, datalog(fdi->track_src, 128 << shift));
    amiga_data_raw(fdi, fdi->track_src, 0, 128 << shift);
    fdi->track_src += 128 << shift;
}
/* not-decoded, 128*2^x-byte, CRC-incorrect Amiga data */
static void
s25(FDI *fdi)
{
    int shift = *fdi->track_src++;
    fdi2raw_log("s25:shift=%d,crc=%s,data=%s", shift, datalog(fdi->track_src, 4), datalog(fdi->track_src + 4, 128 << shift));
    amiga_data_raw(fdi, fdi->track_src + 4, fdi->track_src, 128 << shift);
    fdi->track_src += 4 + (128 << shift);
}
/* standard extended Amiga sector */
static void
s26(FDI *fdi)
{
    s21(fdi);
    fdi2raw_log("s26:data=%s", datalog(fdi->track_src, 512));
    amiga_data(fdi, fdi->track_src);
    fdi->track_src += 512;
}
/* standard short Amiga sector */
static void
s27(FDI *fdi)
{
    s22(fdi);
    fdi2raw_log("s27:data=%s", datalog(fdi->track_src, 512));
    amiga_data(fdi, fdi->track_src);
    fdi->track_src += 512;
}

/* *** */
/* IBM */
/* *** */

static uint16_t
ibm_crc(uint8_t byte, int reset)
{
    static uint16_t crc;

    if (reset)
        crc = 0xcdb4;
    for (uint8_t i = 0; i < 8; i++) {
        if (crc & 0x8000) {
            crc <<= 1;
            if (!(byte & 0x80))
                crc ^= 0x1021;
        } else {
            crc <<= 1;
            if (byte & 0x80)
                crc ^= 0x1021;
        }
        byte <<= 1;
    }
    return crc;
}

static void
ibm_data(FDI *fdi, uint8_t *data, uint8_t *crc, int len)
{
    uint8_t  crcbuf[2];
    uint16_t crcv = 0;

    word_add(fdi, 0x4489);
    word_add(fdi, 0x4489);
    word_add(fdi, 0x4489);
    byte_mfm_add(fdi, 0xfb);
    ibm_crc(0xfb, 1);
    for (int i = 0; i < len; i++) {
        byte_mfm_add(fdi, data[i]);
        crcv = ibm_crc(data[i], 0);
    }
    if (!crc) {
        crc    = crcbuf;
        crc[0] = (uint8_t) (crcv >> 8);
        crc[1] = (uint8_t) crcv;
    }
    byte_mfm_add(fdi, crc[0]);
    byte_mfm_add(fdi, crc[1]);
}

static void
ibm_sector_header(FDI *fdi, uint8_t *data, uint8_t *crc, int secnum, int pre)
{
    uint8_t  secbuf[5];
    uint8_t  crcbuf[2];
    uint16_t crcv;

    if (pre)
        bytes_mfm_add(fdi, 0, 12);
    word_add(fdi, 0x4489);
    word_add(fdi, 0x4489);
    word_add(fdi, 0x4489);
    secbuf[0] = 0xfe;
    if (secnum >= 0) {
        secbuf[1] = (uint8_t) (fdi->current_track / 2);
        secbuf[2] = (uint8_t) (fdi->current_track % 2);
        secbuf[3] = (uint8_t) secnum;
        secbuf[4] = 2;
    } else {
        memcpy(secbuf + 1, data, 4);
    }
    ibm_crc(secbuf[0], 1);
    ibm_crc(secbuf[1], 0);
    ibm_crc(secbuf[2], 0);
    ibm_crc(secbuf[3], 0);
    crcv = ibm_crc(secbuf[4], 0);
    if (crc) {
        memcpy(crcbuf, crc, 2);
    } else {
        crcbuf[0] = (uint8_t) (crcv >> 8);
        crcbuf[1] = (uint8_t) crcv;
    }
    /* data */
    for (uint8_t i = 0; i < 5; i++)
        byte_mfm_add(fdi, secbuf[i]);
    /* crc */
    byte_mfm_add(fdi, crcbuf[0]);
    byte_mfm_add(fdi, crcbuf[1]);
}

/* standard IBM index address mark */
static void
s10(FDI *fdi)
{
    bit_drop_next(fdi);
    bytes_mfm_add(fdi, 0, 12);
    word_add(fdi, 0x5224);
    word_add(fdi, 0x5224);
    word_add(fdi, 0x5224);
    byte_mfm_add(fdi, 0xfc);
}
/* standard IBM pre-gap */
static void
s11(FDI *fdi)
{
    bit_drop_next(fdi);
    bytes_mfm_add(fdi, 0x4e, 78);
    bit_dedrop(fdi);
    s10(fdi);
    bytes_mfm_add(fdi, 0x4e, 50);
}
/* standard ST pre-gap */
static void
s12(FDI *fdi)
{
    bit_drop_next(fdi);
    bytes_mfm_add(fdi, 0x4e, 78);
}
/* standard extended IBM sector header */
static void
s13(FDI *fdi)
{
    bit_drop_next(fdi);
    fdi2raw_log("s13:header=%s", datalog(fdi->track_src, 4));
    ibm_sector_header(fdi, fdi->track_src, 0, -1, 1);
    fdi->track_src += 4;
}
/* standard mini-extended IBM sector header */
static void
s14(FDI *fdi)
{
    fdi2raw_log("s14:header=%s", datalog(fdi->track_src, 4));
    ibm_sector_header(fdi, fdi->track_src, 0, -1, 0);
    fdi->track_src += 4;
}
/* standard short IBM sector header */
static void
s15(FDI *fdi)
{
    bit_drop_next(fdi);
    fdi2raw_log("s15:sector=%d", *fdi->track_src);
    ibm_sector_header(fdi, 0, 0, *fdi->track_src++, 1);
}
/* standard mini-short IBM sector header */
static void
s16(FDI *fdi)
{
    fdi2raw_log("s16:track=%d", *fdi->track_src);
    ibm_sector_header(fdi, 0, 0, *fdi->track_src++, 0);
}
/* standard CRC-incorrect mini-extended IBM sector header */
static void
s17(FDI *fdi)
{
    fdi2raw_log("s17:header=%s,crc=%s", datalog(fdi->track_src, 4), datalog(fdi->track_src + 4, 2));
    ibm_sector_header(fdi, fdi->track_src, fdi->track_src + 4, -1, 0);
    fdi->track_src += 4 + 2;
}
/* standard CRC-incorrect mini-short IBM sector header */
static void
s18(FDI *fdi)
{
    fdi2raw_log("s18:sector=%d,header=%s", *fdi->track_src, datalog(fdi->track_src + 1, 4));
    ibm_sector_header(fdi, 0, fdi->track_src + 1, *fdi->track_src, 0);
    fdi->track_src += 1 + 4;
}
/* standard 512-byte CRC-correct IBM data */
static void
s19(FDI *fdi)
{
    fdi2raw_log("s19:data=%s", datalog(fdi->track_src, 512));
    ibm_data(fdi, fdi->track_src, 0, 512);
    fdi->track_src += 512;
}
/* standard 128*2^x-byte-byte CRC-correct IBM data */
static void
s1a(FDI *fdi)
{
    int shift = *fdi->track_src++;
    fdi2raw_log("s1a:shift=%d,data=%s", shift, datalog(fdi->track_src, 128 << shift));
    ibm_data(fdi, fdi->track_src, 0, 128 << shift);
    fdi->track_src += 128 << shift;
}
/* standard 128*2^x-byte-byte CRC-incorrect IBM data */
static void
s1b(FDI *fdi)
{
    int shift = *fdi->track_src++;
    fdi2raw_log("s1b:shift=%d,crc=%s,data=%s", shift, datalog(fdi->track_src + (128 << shift), 2), datalog(fdi->track_src, 128 << shift));
    ibm_data(fdi, fdi->track_src, fdi->track_src + (128 << shift), 128 << shift);
    fdi->track_src += (128 << shift) + 2;
}
/* standard extended IBM sector */
static void
s1c(FDI *fdi)
{
    int shift = fdi->track_src[3];
    s13(fdi);
    bytes_mfm_add(fdi, 0x4e, 22);
    bytes_mfm_add(fdi, 0x00, 12);
    ibm_data(fdi, fdi->track_src, 0, 128 << shift);
    fdi->track_src += 128 << shift;
}
/* standard short IBM sector */
static void
s1d(FDI *fdi)
{
    s15(fdi);
    bytes_mfm_add(fdi, 0x4e, 22);
    bytes_mfm_add(fdi, 0x00, 12);
    s19(fdi);
}

/* end marker */
static void
sff(UNUSED(FDI *fdi))
{
}

typedef void (*decode_described_track_func)(FDI *);

static decode_described_track_func decode_sectors_described_track[] = {
    s00, s01, s02, s03, s04, dxx, dxx, dxx, s08, s09, s0a, s0b, s0c, s0d, dxx, dxx, /* 00-0F */
    s10, s11, s12, s13, s14, s15, s16, s17, s18, s19, s1a, s1b, s1c, s1d, dxx, dxx, /* 10-1F */
    s20, s21, s22, s23, s24, s25, s26, s27, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 20-2F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 30-3F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 40-4F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 50-5F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 60-6F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 70-7F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 80-8F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* 90-9F */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* A0-AF */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* B0-BF */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* C0-CF */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* D0-DF */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, /* E0-EF */
    dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, dxx, sff  /* F0-FF */
};

static void
track_amiga(struct fdi *fdi, int first_sector, int max_sector)
{
    bit_add(fdi, 0);
    bit_drop_next(fdi);
    for (int i = 0; i < max_sector; i++) {
        amiga_sector_header(fdi, 0, 0, first_sector, max_sector - i);
        amiga_data(fdi, fdi->track_src + first_sector * 512);
        first_sector++;
        if (first_sector >= max_sector)
            first_sector = 0;
    }
    bytes_mfm_add(fdi, 0, 260); /* gap */
}
static void
track_atari_st(struct fdi *fdi, int max_sector)
{
    int      gap3 = 0;
    uint8_t *p = fdi->track_src;

    switch (max_sector) {
        case 9:
            gap3 = 40;
            break;
        case 10:
            gap3 = 24;
            break;

        default:
            break;
    }
    s15(fdi);
    for (int i = 0; i < max_sector; i++) {
        byte_mfm_add(fdi, 0x4e);
        byte_mfm_add(fdi, 0x4e);
        ibm_sector_header(fdi, 0, 0, fdi->current_track, 1);
        ibm_data(fdi, p + i * 512, 0, 512);
        bytes_mfm_add(fdi, 0x4e, gap3);
    }
    bytes_mfm_add(fdi, 0x4e, 660 - gap3);
    fdi->track_src += fdi->track_len * 256;
}
static void
track_pc(struct fdi *fdi, int max_sector)
{
    int      gap3;
    uint8_t *p = fdi->track_src;

    switch (max_sector) {
        case 8:
            gap3 = 116;
            break;
        case 9:
            gap3 = 54;
            break;
        default:
            gap3 = 100; /* fixme */
            break;
    }
    s11(fdi);
    for (int i = 0; i < max_sector; i++) {
        byte_mfm_add(fdi, 0x4e);
        byte_mfm_add(fdi, 0x4e);
        ibm_sector_header(fdi, 0, 0, fdi->current_track, 1);
        ibm_data(fdi, p + i * 512, 0, 512);
        bytes_mfm_add(fdi, 0x4e, gap3);
    }
    bytes_mfm_add(fdi, 0x4e, 600 - gap3);
    fdi->track_src += fdi->track_len * 256;
}

/* amiga dd */
static void
track_amiga_dd(struct fdi *fdi)
{
    uint8_t *p = fdi->track_src;
    track_amiga(fdi, fdi->track_len >> 4, 11);
    fdi->track_src = p + (fdi->track_len & 15) * 512;
}
/* amiga hd */
static void
track_amiga_hd(struct fdi *fdi)
{
    uint8_t *p = fdi->track_src;
    track_amiga(fdi, 0, 22);
    fdi->track_src = p + fdi->track_len * 256;
}
/* atari st 9 sector */
static void
track_atari_st_9(struct fdi *fdi)
{
    track_atari_st(fdi, 9);
}
/* atari st 10 sector */
static void
track_atari_st_10(struct fdi *fdi)
{
    track_atari_st(fdi, 10);
}
/* pc 8 sector */
static void
track_pc_8(struct fdi *fdi)
{
    track_pc(fdi, 8);
}
/* pc 9 sector */
static void
track_pc_9(struct fdi *fdi)
{
    track_pc(fdi, 9);
}
/* pc 15 sector */
static void
track_pc_15(struct fdi *fdi)
{
    track_pc(fdi, 15);
}
/* pc 18 sector */
static void
track_pc_18(struct fdi *fdi)
{
    track_pc(fdi, 18);
}
/* pc 36 sector */
static void
track_pc_36(struct fdi *fdi)
{
    track_pc(fdi, 36);
}

typedef void (*decode_normal_track_func)(FDI *);

static decode_normal_track_func decode_normal_track[] = {
    track_empty,                                                   /* 0 */
    track_amiga_dd, track_amiga_hd,                                /* 1-2 */
    track_atari_st_9, track_atari_st_10,                           /* 3-4 */
    track_pc_8, track_pc_9, track_pc_15, track_pc_18, track_pc_36, /* 5-9 */
    zxx, zxx, zxx, zxx, zxx                                        /* A-F */
};

static void
fix_mfm_sync(FDI *fdi)
{
    int pos;
    int off1;
    int off2;
    int off3;
    int mask1;
    int mask2;
    int mask3;

    for (int i = 0; i < fdi->mfmsync_offset; i++) {
        pos   = fdi->mfmsync_buffer[i];
        off1  = (pos - 1) >> 3;
        off2  = (pos + 1) >> 3;
        off3  = pos >> 3;
        mask1 = 1 << (7 - ((pos - 1) & 7));
        mask2 = 1 << (7 - ((pos + 1) & 7));
        mask3 = 1 << (7 - (pos & 7));
        if (!(fdi->track_dst[off1] & mask1) && !(fdi->track_dst[off2] & mask2))
            fdi->track_dst[off3] |= mask3;
        else
            fdi->track_dst[off3] &= ~mask3;
    }
}

static int
handle_sectors_described_track(FDI *fdi)
{
#ifdef ENABLE_FDI2RAW_LOG
    int      oldout;
    uint8_t *start_src = fdi->track_src;
#endif
    fdi->encoding_type = *fdi->track_src++;
    fdi->index_offset  = get_u32(fdi->track_src);
    fdi->index_offset >>= 8;
    fdi->track_src += 3;
    fdi2raw_log("sectors_described, index offset: %d\n", fdi->index_offset);

    do {
        fdi->track_type = *fdi->track_src++;
        fdi2raw_log("%06.6X %06.6X %02.2X:", fdi->track_src - start_src + 0x200, fdi->out / 8, fdi->track_type);
#ifdef ENABLE_FDI2RAW_LOG
        oldout = fdi->out;
#endif
        decode_sectors_described_track[fdi->track_type](fdi);
        fdi2raw_log(" %d\n", fdi->out - oldout);
#ifdef ENABLE_FDI2RAW_LOG
        oldout = fdi->out;
#endif
        if (fdi->out < 0 || fdi->err) {
            fdi2raw_log("\nin %d bytes, out %d bits\n", fdi->track_src - fdi->track_src_buffer, fdi->out);
            return -1;
        }
        if (fdi->track_src - fdi->track_src_buffer >= fdi->track_src_len) {
            fdi2raw_log("source buffer overrun, previous type: %02.2X\n", fdi->track_type);
            return -1;
        }
    } while (fdi->track_type != 0xff);
    fdi2raw_log("\n");
    fix_mfm_sync(fdi);
    return fdi->out;
}

static uint8_t *
fdi_decompress(int pulses, uint8_t *sizep, uint8_t *src, int *dofree)
{
    uint32_t  size = get_u24(sizep);
    uint32_t *dst2;
    int       len = size & 0x3fffff;
    uint8_t  *dst;
    int       mode = size >> 22;

    *dofree = 0;
    if (mode == 0 && pulses * 2 > len)
        mode = 1;
    if (mode == 0) {
        dst2 = (uint32_t *) src;
        dst  = src;
        for (int i = 0; i < pulses; i++) {
            *dst2++ = get_u32(src);
            src += 4;
        }
    } else if (mode == 1) {
        dst     = fdi_malloc(pulses * 4);
        *dofree = 1;
        fdi_decode(src, pulses, dst);
    } else {
        dst = 0;
    }
    return dst;
}

static void
dumpstream(UNUSED(int track), UNUSED(uint8_t *stream), UNUSED(int len))
{
#if 0
    char name[100];
    FILE *fp;

    sprintf (name, "track_%d.raw", track);
    fp = fopen(name, "wb");
    fwrite (stream, 1, len * 4, fp);
    fclose (fp);
#endif
}

static int bitoffset;

static inline void
addbit(uint8_t *p, int bit)
{
    int off1 = bitoffset / 8;
    int off2 = bitoffset % 8;
    p[off1] |= bit << (7 - off2);
    bitoffset++;
}

struct pulse_sample {
    uint32_t size;
    int      number_of_bits;
};

#define FDI_MAX_ARRAY 10                        /* change this value as you want */
static int                 pulse_limitval = 15; /* tolerance of 15% */
static struct pulse_sample psarray[FDI_MAX_ARRAY];
static int                 array_index;
static uint32_t            total;
static int                 totaldiv;

static void
init_array(uint32_t standard_MFM_2_bit_cell_size, int nb_of_bits)
{
    for (uint8_t i = 0; i < FDI_MAX_ARRAY; i++) {
        psarray[i].size = standard_MFM_2_bit_cell_size; /* That is (total track length / 50000) for Amiga double density */
        total += psarray[i].size;
        psarray[i].number_of_bits = nb_of_bits;
        totaldiv += psarray[i].number_of_bits;
    }
    array_index = 0;
}

#if 0

static void fdi2_decode (FDI *fdi, uint32_t totalavg, uint32_t *avgp, uint32_t *minp, uint32_t *maxp, uint8_t *idx, int maxidx, int *indexoffsetp, int pulses, int mfm)
{
    uint32_t adjust;
    uint32_t adjusted_pulse;
    uint32_t standard_MFM_2_bit_cell_size = totalavg / 50000;
    uint32_t standard_MFM_8_bit_cell_size = totalavg / 12500;
    int real_size, i, j, eodat, outstep;
    int indexoffset = *indexoffsetp;
    uint8_t *d = fdi->track_dst_buffer;
    uint16_t *pt = fdi->track_dst_buffer_timing;
    uint32_t ref_pulse, pulse;

    /* detects a long-enough stable pulse coming just after another stable pulse */
    i = 1;
    while ( (i < pulses) && ( (idx[i] < maxidx)
        || (idx[i - 1] < maxidx)
        || (avgp[i] < (standard_MFM_2_bit_cell_size - (standard_MFM_2_bit_cell_size / 4))) ) )
            i++;
    if (i == pulses)  {
        fdi2raw_log("No stable and long-enough pulse in track.\n");
        return;
    }
    i--;
    eodat = i;
    adjust = 0;
    total = 0;
    totaldiv = 0;
    init_array(standard_MFM_2_bit_cell_size, 2);
    bitoffset = 0;
    ref_pulse = 0;
    outstep = 0;
    while (outstep < 2) {

        /* calculates the current average bitrate from previous decoded data */
        uint32_t avg_size = (total << 3) / totaldiv; /* this is the new average size for one MFM bit */
        /* uint32_t avg_size = (uint32_t)((((float)total)*8.0) / ((float)totaldiv)); */
        /* you can try tighter ranges than 25%, or wider ranges. I would probably go for tighter... */
        if ((avg_size < (standard_MFM_8_bit_cell_size - (pulse_limitval * standard_MFM_8_bit_cell_size / 100))) ||
            (avg_size > (standard_MFM_8_bit_cell_size + (pulse_limitval * standard_MFM_8_bit_cell_size / 100)))) {
                avg_size = standard_MFM_8_bit_cell_size;
        }
        /* this is to prevent the average value from going too far
        * from the theoretical value, otherwise it could progressively go to (2 *
        * real value), or (real value / 2), etc. */

        /* gets the next long-enough pulse (this may require more than one pulse) */
        pulse = 0;
        while (pulse < ((avg_size / 4) - (avg_size / 16))) {
            int indx;
            i++;
            if (i >= pulses)
                i = 0;
            indx = idx[i];
            if (rand() <= (indx * RAND_MAX) / maxidx) {
                pulse += avgp[i] - ref_pulse;
                if (indx >= maxidx)
                    ref_pulse = 0;
                else
                    ref_pulse = avgp[i];
            }
            if (i == eodat)
                outstep++;
            if (outstep == 1 && indexoffset == i)
                *indexoffsetp = bitoffset;
        }

        /* gets the size in bits from the pulse width, considering the current average bitrate */
        adjusted_pulse = pulse;
        real_size = 0;
        while (adjusted_pulse >= avg_size) {
            real_size += 4;
            adjusted_pulse -= avg_size / 2;
        }
        adjusted_pulse <<= 3;
        while (adjusted_pulse >= ((avg_size * 4) + (avg_size / 4))) {
            real_size += 2;
            adjusted_pulse -= avg_size * 2;
        }
        if (adjusted_pulse >= ((avg_size * 3) + (avg_size / 4))) {
            if (adjusted_pulse <= ((avg_size * 4) - (avg_size / 4))) {
                if ((2 * ((adjusted_pulse >> 2) - adjust)) <= ((2 * avg_size) - (avg_size / 4)))
                    real_size += 3;
                else
                    real_size += 4;
            } else
                real_size += 4;
        } else {
            if (adjusted_pulse > ((avg_size * 3) - (avg_size / 4))) {
                real_size += 3;
            } else {
                if (adjusted_pulse >= ((avg_size * 2) + (avg_size / 4))) {
                    if ((2 * ((adjusted_pulse >> 2) - adjust)) < (avg_size + (avg_size / 4)))
                        real_size += 2;
                    else
                        real_size += 3;
                } else
                    real_size += 2;
            }
        }

        if (outstep == 1) {
            for (j = real_size; j > 1; j--)
                addbit (d, 0);
            addbit (d, 1);
            for (j = 0; j < real_size; j++)
                *pt++ = (uint16_t)(pulse / real_size);
        }

        /* prepares for the next pulse */
        adjust = ((real_size * avg_size)/8) - pulse;
        total -= psarray[array_index].size;
        totaldiv -= psarray[array_index].number_of_bits;
        psarray[array_index].size = pulse;
        psarray[array_index].number_of_bits = real_size;
        total += pulse;
        totaldiv += real_size;
        array_index++;
        if (array_index >= FDI_MAX_ARRAY)
            array_index = 0;
    }

    fdi->out = bitoffset;
}

#else

static void
fdi2_decode(FDI *fdi, uint32_t totalavg, uint32_t *avgp, uint32_t *minp, uint32_t *maxp, uint8_t *idx, int maxidx, int *indexoffsetp, int pulses, int mfm)
{
    uint32_t  adjust;
    uint32_t  adjusted_pulse;
    uint32_t  standard_MFM_2_bit_cell_size = totalavg / 50000;
    uint32_t  standard_MFM_8_bit_cell_size = totalavg / 12500;
    int       real_size;
    int       i;
    int       j;
    int       nexti;
    int       eodat;
    int       outstep;
    int       randval;
    int       indexoffset = *indexoffsetp;
    uint8_t  *d           = fdi->track_dst_buffer;
    uint16_t *pt          = fdi->track_dst_buffer_timing;
    uint32_t  ref_pulse;
    uint32_t  pulse;
    int32_t   jitter;

    /* detects a long-enough stable pulse coming just after another stable pulse */
    i = 1;
    while ((i < pulses) && ((idx[i] < maxidx) || (idx[i - 1] < maxidx) || (minp[i] < (standard_MFM_2_bit_cell_size - (standard_MFM_2_bit_cell_size / 4)))))
        i++;
    if (i == pulses) {
        fdi2raw_log("FDI: No stable and long-enough pulse in track.\n");
        return;
    }
    nexti = i;
    eodat = i;
    i--;
    adjust   = 0;
    total    = 0;
    totaldiv = 0;
    init_array(standard_MFM_2_bit_cell_size, 1 + mfm);
    bitoffset = 0;
    ref_pulse = 0;
    jitter    = 0;
    outstep   = -1;
    while (outstep < 2) {

        /* calculates the current average bitrate from previous decoded data */
        uint32_t avg_size = (uint32_t) ((total << (2 + mfm)) / totaldiv); /* this is the new average size for one MFM bit */
#if 0
        uint32_t avg_size = (uint32_t)((((float)total)*((float)(mfm+1))*4.0) / ((float)totaldiv));
#endif
        /* you can try tighter ranges than 25%, or wider ranges. I would probably go for tighter... */
        if ((avg_size < (standard_MFM_8_bit_cell_size - (pulse_limitval * standard_MFM_8_bit_cell_size / 100))) || (avg_size > (standard_MFM_8_bit_cell_size + (pulse_limitval * standard_MFM_8_bit_cell_size / 100)))) {
            avg_size = standard_MFM_8_bit_cell_size;
        }
        /* this is to prevent the average value from going too far
         * from the theoretical value, otherwise it could progressively go to (2 *
         * real value), or (real value / 2), etc. */

        /* gets the next long-enough pulse (this may require more than one pulse) */
        pulse = 0;
        while (pulse < ((avg_size / 4) - (avg_size / 16))) {
            uint32_t avg_pulse;
            uint32_t min_pulse;
            uint32_t max_pulse;
            i++;
            if (i >= pulses)
                i = 0;
            if (i == nexti) {
                do {
                    nexti++;
                    if (nexti >= pulses)
                        nexti = 0;
                } while (idx[nexti] < maxidx);
            }
            if (idx[i] >= maxidx) { /* stable pulse */
                avg_pulse = avgp[i] - jitter;
                min_pulse = minp[i];
                max_pulse = maxp[i];
                if (jitter >= 0)
                    max_pulse -= jitter;
                else
                    min_pulse -= jitter;
                if ((maxp[nexti] - avgp[nexti]) < (avg_pulse - min_pulse))
                    min_pulse = avg_pulse - (maxp[nexti] - avgp[nexti]);
                if ((avgp[nexti] - minp[nexti]) < (max_pulse - avg_pulse))
                    max_pulse = avg_pulse + (avgp[nexti] - minp[nexti]);
                if (min_pulse < ref_pulse)
                    min_pulse = ref_pulse;
                randval = rand();
                if (randval < (RAND_MAX / 2)) {
                    if (randval > (RAND_MAX / 4)) {
                        if (randval <= ((3LL * (uint64_t) RAND_MAX) / 8))
                            randval = (2 * randval) - (RAND_MAX / 4);
                        else
                            randval = (4 * randval) - RAND_MAX;
                    }
                    jitter = 0 - (randval * (avg_pulse - min_pulse)) / RAND_MAX;
                } else {
                    randval -= RAND_MAX / 2;
                    if (randval > (RAND_MAX / 4)) {
                        if (randval <= ((3LL * (uint64_t) RAND_MAX) / 8))
                            randval = (2 * randval) - (RAND_MAX / 4);
                        else
                            randval = (4 * randval) - RAND_MAX;
                    }
                    jitter = (randval * (max_pulse - avg_pulse)) / RAND_MAX;
                }
                avg_pulse += jitter;
                if ((avg_pulse < min_pulse) || (avg_pulse > max_pulse)) {
                    fdi2raw_log("FDI: avg_pulse outside bounds! avg=%u min=%u max=%u\n", avg_pulse, min_pulse, max_pulse);
                    fdi2raw_log("FDI: avgp=%u (%u) minp=%u (%u) maxp=%u (%u) jitter=%d i=%d ni=%d\n",
                                avgp[i], avgp[nexti], minp[i], minp[nexti], maxp[i], maxp[nexti], jitter, i, nexti);
                }
                if (avg_pulse < ref_pulse)
                    fdi2raw_log("FDI: avg_pulse < ref_pulse! (%u < %u)\n", avg_pulse, ref_pulse);
                pulse += avg_pulse - ref_pulse;
                ref_pulse = 0;
                if (i == eodat)
                    outstep++;
            } else if (rand() <= ((idx[i] * RAND_MAX) / maxidx)) {
                avg_pulse = avgp[i];
                min_pulse = minp[i];
                max_pulse = maxp[i];
                randval   = rand();
                if (randval < (RAND_MAX / 2)) {
                    if (randval > (RAND_MAX / 4)) {
                        if (randval <= ((3LL * (uint64_t) RAND_MAX) / 8))
                            randval = (2 * randval) - (RAND_MAX / 4);
                        else
                            randval = (4 * randval) - RAND_MAX;
                    }
                    avg_pulse -= (randval * (avg_pulse - min_pulse)) / RAND_MAX;
                } else {
                    randval -= RAND_MAX / 2;
                    if (randval > (RAND_MAX / 4)) {
                        if (randval <= ((3LL * (uint64_t) RAND_MAX) / 8))
                            randval = (2 * randval) - (RAND_MAX / 4);
                        else
                            randval = (4 * randval) - RAND_MAX;
                    }
                    avg_pulse += (randval * (max_pulse - avg_pulse)) / RAND_MAX;
                }
                if ((avg_pulse > ref_pulse) && (avg_pulse < (avgp[nexti] - jitter))) {
                    pulse += avg_pulse - ref_pulse;
                    ref_pulse = avg_pulse;
                }
            }
            if (outstep == 1 && indexoffset == i)
                *indexoffsetp = bitoffset;
        }

        /* gets the size in bits from the pulse width, considering the current average bitrate */
        adjusted_pulse = pulse;
        real_size      = 0;
        if (mfm) {
            while (adjusted_pulse >= avg_size) {
                real_size += 4;
                adjusted_pulse -= avg_size / 2;
            }
            adjusted_pulse <<= 3;
            while (adjusted_pulse >= ((avg_size * 4) + (avg_size / 4))) {
                real_size += 2;
                adjusted_pulse -= avg_size * 2;
            }
            if (adjusted_pulse >= ((avg_size * 3) + (avg_size / 4))) {
                if (adjusted_pulse <= ((avg_size * 4) - (avg_size / 4))) {
                    if ((2 * ((adjusted_pulse >> 2) - adjust)) <= ((2 * avg_size) - (avg_size / 4)))
                        real_size += 3;
                    else
                        real_size += 4;
                } else
                    real_size += 4;
            } else {
                if (adjusted_pulse > ((avg_size * 3) - (avg_size / 4))) {
                    real_size += 3;
                } else {
                    if (adjusted_pulse >= ((avg_size * 2) + (avg_size / 4))) {
                        if ((2 * ((adjusted_pulse >> 2) - adjust)) < (avg_size + (avg_size / 4)))
                            real_size += 2;
                        else
                            real_size += 3;
                    } else
                        real_size += 2;
                }
            }
        } else {
            while (adjusted_pulse >= (2 * avg_size)) {
                real_size += 4;
                adjusted_pulse -= avg_size;
            }
            adjusted_pulse <<= 2;
            while (adjusted_pulse >= ((avg_size * 3) + (avg_size / 4))) {
                real_size += 2;
                adjusted_pulse -= avg_size * 2;
            }
            if (adjusted_pulse >= ((avg_size * 2) + (avg_size / 4))) {
                if (adjusted_pulse <= ((avg_size * 3) - (avg_size / 4))) {
                    if (((adjusted_pulse >> 1) - adjust) < (avg_size + (avg_size / 4)))
                        real_size += 2;
                    else
                        real_size += 3;
                } else
                    real_size += 3;
            } else {
                if (adjusted_pulse > ((avg_size * 2) - (avg_size / 4)))
                    real_size += 2;
                else {
                    if (adjusted_pulse >= (avg_size + (avg_size / 4))) {
                        if (((adjusted_pulse >> 1) - adjust) <= (avg_size - (avg_size / 4)))
                            real_size++;
                        else
                            real_size += 2;
                    } else
                        real_size++;
                }
            }
        }

        /* after one pass to correctly initialize the average bitrate, outputs the bits */
        if (outstep == 1) {
            for (j = real_size; j > 1; j--)
                addbit(d, 0);
            addbit(d, 1);
            for (j = 0; j < real_size; j++)
                *pt++ = (uint16_t) (pulse / real_size);
        }

        /* prepares for the next pulse */
        adjust = ((real_size * avg_size) / (4 << mfm)) - pulse;
        total -= psarray[array_index].size;
        totaldiv -= psarray[array_index].number_of_bits;
        psarray[array_index].size           = pulse;
        psarray[array_index].number_of_bits = real_size;
        total += pulse;
        totaldiv += real_size;
        array_index++;
        if (array_index >= FDI_MAX_ARRAY)
            array_index = 0;
    }

    fdi->out = bitoffset;
}

#endif

static void
fdi2_celltiming(FDI *fdi, uint32_t totalavg, int bitoffset, uint16_t *out)
{
    const uint16_t *pt2;
    uint16_t       *pt;
    double          avg_bit_len;

    avg_bit_len = (double) totalavg / (double) bitoffset;
    pt2         = fdi->track_dst_buffer_timing;
    pt          = out;
    for (int i = 0; i < bitoffset / 8; i++) {
        double v = (pt2[0] + pt2[1] + pt2[2] + pt2[3] + pt2[4] + pt2[5] + pt2[6] + pt2[7]) / 8.0;
        v        = 1000.0 * v / avg_bit_len;
        *pt++    = (uint16_t) v;
        pt2 += 8;
    }
    *pt++ = out[0];
    *pt   = out[0];
}

static int
decode_lowlevel_track(FDI *fdi, int track, struct fdi_cache *cache)
{
    uint8_t        *p1;
    const uint32_t *p2;
    uint32_t       *avgp;
    uint32_t       *minp = 0;
    uint32_t       *maxp = 0;
    uint8_t        *idxp = 0;
    uint32_t        maxidx;
    uint32_t        totalavg;
    uint32_t        weakbits;
    int             j;
    int             k;
    int             len;
    int             pulses;
    int             indexoffset;
    int             avg_free;
    int             min_free = 0;
    int             max_free = 0;
    int             idx_free;
    int             idx_off1 = 0;
    int             idx_off2 = 0;
    int             idx_off3 = 0;

    p1     = fdi->track_src;
    pulses = get_u32(p1);
    if (!pulses)
        return -1;
    p1 += 4;
    len  = 12;
    avgp = (uint32_t *) fdi_decompress(pulses, p1 + 0, p1 + len, &avg_free);
    dumpstream(track, (uint8_t *) avgp, pulses);
    len += get_u24(p1 + 0) & 0x3fffff;
    if (!avgp)
        return -1;
    if (get_u24(p1 + 3) && get_u24(p1 + 6)) {
        minp = (uint32_t *) fdi_decompress(pulses, p1 + 3, p1 + len, &min_free);
        len += get_u24(p1 + 3) & 0x3fffff;
        maxp = (uint32_t *) fdi_decompress(pulses, p1 + 6, p1 + len, &max_free);
        len += get_u24(p1 + 6) & 0x3fffff;
        /* Computes the real min and max values */
        for (int i = 0; i < pulses; i++) {
            maxp[i] = avgp[i] + minp[i] - maxp[i];
            minp[i] = avgp[i] - minp[i];
        }
    } else {
        minp = avgp;
        maxp = avgp;
    }
    if (get_u24(p1 + 9)) {
        idx_off1 = 0;
        idx_off2 = 1;
        idx_off3 = 2;
        idxp     = fdi_decompress(pulses, p1 + 9, p1 + len, &idx_free);
        if (idx_free) {
            if (idxp[0] == 0 && idxp[1] == 0) {
                idx_off1 = 2;
                idx_off2 = 3;
            } else {
                idx_off1 = 1;
                idx_off2 = 0;
            }
            idx_off3 = 4;
        }
    } else {
        idxp     = fdi_malloc(pulses * 2);
        idx_free = 1;
        for (int i = 0; i < pulses; i++) {
            idxp[i * 2 + 0] = 2;
            idxp[i * 2 + 1] = 0;
        }
        idxp[0] = 1;
        idxp[1] = 1;
    }

    maxidx      = 0;
    indexoffset = 0;
    p1          = idxp;
    for (int i = 0; i < pulses; i++) {
        if ((uint32_t) p1[idx_off1] + (uint32_t) p1[idx_off2] > maxidx)
            maxidx = p1[idx_off1] + p1[idx_off2];
        p1 += idx_off3;
    }
    p1 = idxp;
    for (k = 0; (k < pulses) && (p1[idx_off2] != 0); k++) /* falling edge, replace with idx_off1 for rising edge */
        p1 += idx_off3;
    if (k < pulses) {
        j = k;
        do {
            k++;
            p1 += idx_off3;
            if (k >= pulses) {
                k  = 0;
                p1 = idxp;
            }
        } while ((k != j) && (p1[idx_off2] == 0)); /* falling edge, replace with idx_off1 for rising edge */
        if (k != j)                                /* index pulse detected */
        {
            while ((k != j) && (p1[idx_off1] > p1[idx_off2])) { /* falling edge, replace with "<" for rising edge */
                k++;
                p1 += idx_off3;
                if (k >= pulses) {
                    k  = 0;
                    p1 = idxp;
                }
            }
            if (k != j)
                indexoffset = k; /* index position detected */
        }
    }
    p1       = idxp;
    p2       = avgp;
    totalavg = 0;
    weakbits = 0;
    for (int i = 0; i < pulses; i++) {
        uint32_t sum = p1[idx_off1] + p1[idx_off2];
        if (sum >= maxidx) {
            totalavg += *p2;
        } else {
            weakbits++;
        }
        p2++;
        p1 += idx_off3;
        idxp[i] = sum;
    }
    len = totalavg / 100000;
#if 0
    fdi2raw_log("totalavg=%u index=%d (%d) maxidx=%d weakbits=%d len=%d\n",
                totalavg, indexoffset, maxidx, weakbits, len);
#endif
    cache->avgp        = avgp;
    cache->idxp        = idxp;
    cache->minp        = minp;
    cache->maxp        = maxp;
    cache->avg_free    = avg_free;
    cache->idx_free    = idx_free;
    cache->min_free    = min_free;
    cache->max_free    = max_free;
    cache->totalavg    = totalavg;
    cache->pulses      = pulses;
    cache->maxidx      = maxidx;
    cache->indexoffset = indexoffset;
    cache->weakbits    = weakbits;
    cache->lowlevel    = 1;

    return 1;
}

static unsigned char fdiid[]            = { "Formatted Disk Image file" };
static int           bit_rate_table[16] = { 125, 150, 250, 300, 500, 1000 };

void
fdi2raw_header_free(FDI *fdi)
{
    fdi_free(fdi->mfmsync_buffer);
    fdi_free(fdi->track_src_buffer);
    fdi_free(fdi->track_dst_buffer);
    fdi_free(fdi->track_dst_buffer_timing);
    for (uint8_t i = 0; i < MAX_TRACKS; i++) {
        struct fdi_cache *c = &fdi->cache[i];
        if (c->idx_free)
            fdi_free(c->idxp);
        if (c->avg_free)
            fdi_free(c->avgp);
        if (c->min_free)
            fdi_free(c->minp);
        if (c->max_free)
            fdi_free(c->maxp);
    }
    fdi_free(fdi);
    fdi2raw_log("FREE: memory allocated %d\n", fdi_allocated);
}

int
fdi2raw_get_last_track(FDI *fdi)
{
    return fdi->last_track;
}

int
fdi2raw_get_num_sector(FDI *fdi)
{
    if (fdi->header[152] == 0x02)
        return 22;
    return 11;
}

int
fdi2raw_get_last_head(FDI *fdi)
{
    return fdi->last_head;
}

int
fdi2raw_get_rotation(FDI *fdi)
{
    return fdi->rotation_speed;
}

int
fdi2raw_get_bit_rate(FDI *fdi)
{
    return fdi->bit_rate;
}

FDI2RawDiskType
fdi2raw_get_type(FDI *fdi)
{
    return fdi->disk_type;
}

bool
fdi2raw_get_write_protect(FDI *fdi)
{
    return fdi->write_protect;
}

int
fdi2raw_get_tpi(FDI *fdi)
{
    return fdi->header[148];
}

FDI *
fdi2raw_header(FILE *fp)
{
    long    i;
    long    offset;
    long    oldseek;
    uint8_t type;
    uint8_t size;
    FDI    *fdi;

    fdi2raw_log("ALLOC: memory allocated %d\n", fdi_allocated);
    fdi = fdi_malloc(sizeof(FDI));
    memset(fdi, 0, sizeof(FDI));
    fdi->file = fp;
    oldseek   = ftell(fdi->file);
    if (oldseek == -1) {
        fdi_free(fdi);
        return NULL;
    }
    if (fseek(fdi->file, 0, SEEK_SET) == -1)
        fatal("fdi2raw_header(): Error seeking to the beginning of the file\n");
    if (fread(fdi->header, 1, 2048, fdi->file) != 2048)
        fatal("fdi2raw_header(): Error reading header\n");
    if (fseek(fdi->file, oldseek, SEEK_SET) == -1)
        fatal("fdi2raw_header(): Error seeking to offset oldseek\n");
    if (memcmp(fdiid, fdi->header, strlen((char *) fdiid))) {
        fdi_free(fdi);
        return NULL;
    }
    if ((fdi->header[140] != 1 && fdi->header[140] != 2) || (fdi->header[141] != 0 && !(fdi->header[140] == 2 && fdi->header[141] == 1))) {
        fdi_free(fdi);
        return NULL;
    }

    fdi->mfmsync_buffer          = fdi_malloc(MAX_MFM_SYNC_BUFFER * sizeof(int));
    fdi->track_src_buffer        = fdi_malloc(MAX_SRC_BUFFER);
    fdi->track_dst_buffer        = fdi_malloc(MAX_DST_BUFFER);
    fdi->track_dst_buffer_timing = fdi_malloc(MAX_TIMING_BUFFER);

    fdi->last_track = ((fdi->header[142] << 8) + fdi->header[143]) + 1;
    fdi->last_track *= fdi->header[144] + 1;
    if (fdi->last_track > MAX_TRACKS)
        fdi->last_track = MAX_TRACKS;
    fdi->last_head      = fdi->header[144];
    fdi->disk_type      = fdi->header[145];
    fdi->rotation_speed = fdi->header[146] + 128;
    fdi->write_protect  = !!(fdi->header[147] & 1);
    fdi2raw_log("FDI version %d.%d\n", fdi->header[140], fdi->header[141]);
    fdi2raw_log("last_track=%d rotation_speed=%d\n", fdi->last_track, fdi->rotation_speed);

    offset = 512;
    i      = fdi->last_track;
    if (i > 180) {
        offset += 512;
        i -= 180;
        while (i > 256) {
            offset += 512;
            i -= 256;
        }
    }
    for (i = 0; i < fdi->last_track; i++) {
        fdi->track_offsets[i] = offset;
        type                  = fdi->header[152 + i * 2];
        size                  = fdi->header[152 + i * 2 + 1];
        if (type == 1)
            offset += (size & 15) * 512;
        else if ((type & 0xc0) == 0x80)
            offset += (((type & 0x3f) << 8) | size) * 256;
        else
            offset += size * 256;
    }
    fdi->track_offsets[i] = offset;

    return fdi;
}

static int
fdi2raw_loadrevolution_2(FDI *fdi, uint16_t *mfmbuf, uint16_t *tracktiming, int track, int *tracklength, int *indexoffsetp, int *multirev, int mfm)
{
    struct fdi_cache *cache = &fdi->cache[track];
    int               len;
    int               idx;

    memset(fdi->track_dst_buffer, 0, MAX_DST_BUFFER);
    idx = cache->indexoffset;
    fdi2_decode(fdi, cache->totalavg,
                cache->avgp, cache->minp, cache->maxp, cache->idxp,
                cache->maxidx, &idx, cache->pulses, mfm);
#if 0
    fdi2raw_log("track %d: nbits=%d avg len=%.2f weakbits=%d idx=%d\n",
                track, bitoffset, (double)cache->totalavg / bitoffset, cache->weakbits, cache->indexoffset);
#endif
    len = fdi->out;
    if (cache->weakbits >= 10 && multirev)
        *multirev = 1;
    *tracklength = len;

    for (int i = 0; i < (len + 15) / (2 * 8); i++) {
        const uint8_t *data = fdi->track_dst_buffer + i * 2;
        *mfmbuf++     = 256 * *data + *(data + 1);
    }
    fdi2_celltiming(fdi, cache->totalavg, len, tracktiming);
    if (indexoffsetp)
        *indexoffsetp = idx;
    return 1;
}

int
fdi2raw_loadrevolution(FDI *fdi, uint16_t *mfmbuf, uint16_t *tracktiming, int track, int *tracklength, int mfm)
{
    track ^= fdi->reversed_side;
    return fdi2raw_loadrevolution_2(fdi, mfmbuf, tracktiming, track, tracklength, 0, 0, mfm);
}

int
fdi2raw_loadtrack(FDI *fdi, uint16_t *mfmbuf, uint16_t *tracktiming, int track, int *tracklength, int *indexoffsetp, int *multirev, int mfm)
{
    const uint8_t    *p;
    int               outlen;
    struct fdi_cache *cache = &fdi->cache[track];

    track ^= fdi->reversed_side;
    if (cache->lowlevel)
        return fdi2raw_loadrevolution_2(fdi, mfmbuf, tracktiming, track, tracklength, indexoffsetp, multirev, mfm);

    fdi->err           = 0;
    fdi->track_src_len = fdi->track_offsets[track + 1] - fdi->track_offsets[track];
    if (fseek(fdi->file, fdi->track_offsets[track], SEEK_SET) == -1)
        fatal("fdi2raw_loadtrack(): Error seeking to the beginning of the file\n");
    if (fread(fdi->track_src_buffer, 1, fdi->track_src_len, fdi->file) != fdi->track_src_len)
        fatal("fdi2raw_loadtrack(): Error reading data\n");
    memset(fdi->track_dst_buffer, 0, MAX_DST_BUFFER);
    fdi->track_dst_buffer_timing[0] = 0;

    fdi->current_track  = track;
    fdi->track_src      = fdi->track_src_buffer;
    fdi->track_dst      = fdi->track_dst_buffer;
    p                   = fdi->header + 152 + fdi->current_track * 2;
    fdi->track_type     = *p++;
    fdi->track_len      = *p++;
    fdi->bit_rate       = 0;
    fdi->out            = 0;
    fdi->mfmsync_offset = 0;

    if ((fdi->track_type & 0xf0) == 0xf0 || (fdi->track_type & 0xf0) == 0xe0)
        fdi->bit_rate = bit_rate_table[fdi->track_type & 0x0f];
    else
        fdi->bit_rate = 250;

#if 0
    fdi2raw_log("track %d: srclen: %d track_type: %02.2X, bitrate: %d\n",
                fdi->current_track, fdi->track_src_len, fdi->track_type, fdi->bit_rate);
#endif

    if ((fdi->track_type & 0xc0) == 0x80) {

        outlen = decode_lowlevel_track(fdi, track, cache);

    } else if ((fdi->track_type & 0xf0) == 0xf0) {

        outlen = decode_raw_track(fdi);

    } else if ((fdi->track_type & 0xf0) == 0xe0) {

        outlen = handle_sectors_described_track(fdi);

    } else if (fdi->track_type & 0xf0) {

        zxx(fdi);
        outlen = -1;

    } else if (fdi->track_type < 0x0f) {

        decode_normal_track[fdi->track_type](fdi);
        fix_mfm_sync(fdi);
        outlen = fdi->out;

    } else {

        zxx(fdi);
        outlen = -1;
    }

    if (fdi->err)
        return 0;

    if (outlen > 0) {
        if (cache->lowlevel)
            return fdi2raw_loadrevolution_2(fdi, mfmbuf, tracktiming, track, tracklength, indexoffsetp, multirev, mfm);
        *tracklength = fdi->out;
        for (int i = 0; i < ((*tracklength) + 15) / (2 * 8); i++) {
            const uint8_t *data = fdi->track_dst_buffer + i * 2;
            *mfmbuf++           = 256 * *data + *(data + 1);
        }
    }
    return outlen;
}
