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gcr.c
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/*
gcr.c - Group Code Recording helper functions
(C) 2001-2005 Markus Brenner <markus(at)brenner(dot)de>
and Pete Rittwage <peter(at)rittwage(dot)com>
based on code by Andreas Boose
V 0.30 created file based on n2d
V 0.31 improved error handling of convert_GCR_sector()
V 0.32 removed some functions, added sector-2-GCR conversion
V 0.33 improved sector extraction, added find_track_cycle() function
V 0.34 added MAX_SYNC_OFFSET constant, for better error conversion
V 0.35 improved find_track_cycle() function
V 0.36 added bad GCR code detection
V 0.36b improved find_sync(), added find_sector_gap(), find_sector0()
V 0.36c convert_GCR_sector: search good header before using a damaged one
improved find_track_cycle(), return max len if no cycle found
V 0.36d most additions/fixes referenced in mnib.c (pjr)
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "gcr.h"
#include "prot.h"
#include "crc.h"
BYTE copyprot = 0;
BYTE sector_map[MAX_TRACKS_1541 + 1] = {
0,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, /* 1 - 10 */
21, 21, 21, 21, 21, 21, 21, 19, 19, 19, /* 11 - 20 */
19, 19, 19, 19, 18, 18, 18, 18, 18, 18, /* 21 - 30 */
17, 17, 17, 17, 17, /* 31 - 35 */
17, 17, 17, 17, 17, 17, 17 /* 36 - 42 (non-standard) */
};
BYTE speed_map[MAX_TRACKS_1541 + 1] = {
0,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, /* 1 - 10 */
3, 3, 3, 3, 3, 3, 3, 2, 2, 2, /* 11 - 20 */
2, 2, 2, 2, 1, 1, 1, 1, 1, 1, /* 21 - 30 */
0, 0, 0, 0, 0, /* 31 - 35 */
0, 0, 0, 0, 0, 0, 0 /* 36 - 42 (non-standard) */
};
BYTE align_map[MAX_TRACKS_1541 + 1] = {
0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 1 - 10 */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 11 - 20 */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 21 - 30 */
0, 0, 0, 0, 0, 0, /* 31 - 35 */
0, 0, 0, 0, 0, 0 /* 37 - 42 */
};
BYTE reduce_map[MAX_TRACKS_1541 + 1] = {
0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 1 - 10 */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 11 - 20 */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 21 - 30 */
0, 0, 0, 0, 0, 0, /* 31 - 35 */
0, 0, 0, 0, 0, 0 /* 37 - 42 */
};
char alignments[][20] = { "NONE", "GAP", "SEC0", "SYNC", "BADGCR", "VMAX", "AUTO", "VMAX-CW", "RAW", "PIRATESLAYER", "RAPIDLOK"};
/* Burst Nibbler defaults
size_t capacity_min[] = { 6183, 6598, 7073, 7616 };
size_t capacity[] = { 6231, 6646, 7121, 7664 };
size_t capacity_max[] = { 6311, 6726, 7201, 7824 };
*/
/* New calculated defaults */
size_t capacity_min[] = { (int) (DENSITY0 / 305), (int) (DENSITY1 / 305), (int) (DENSITY2 / 305), (int) (DENSITY3 / 305) };
size_t capacity[] = { (int) (DENSITY0 / 300), (int) (DENSITY1 / 300), (int) (DENSITY2 / 300), (int) (DENSITY3 / 300) };
size_t capacity_max[] = { (int) (DENSITY0 / 295), (int) (DENSITY1 / 295), (int) (DENSITY2 / 295), (int) (DENSITY3 / 295) };
/* Nibble-to-GCR conversion table */
static BYTE GCR_conv_data[16] = {
0x0a, 0x0b, 0x12, 0x13,
0x0e, 0x0f, 0x16, 0x17,
0x09, 0x19, 0x1a, 0x1b,
0x0d, 0x1d, 0x1e, 0x15
};
/* GCR-to-Nibble conversion tables */
static BYTE GCR_decode_high[32] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0x80, 0x00, 0x10, 0xff, 0xc0, 0x40, 0x50,
0xff, 0xff, 0x20, 0x30, 0xff, 0xf0, 0x60, 0x70,
0xff, 0x90, 0xa0, 0xb0, 0xff, 0xd0, 0xe0, 0xff
};
static BYTE GCR_decode_low[32] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0x08, 0x00, 0x01, 0xff, 0x0c, 0x04, 0x05,
0xff, 0xff, 0x02, 0x03, 0xff, 0x0f, 0x06, 0x07,
0xff, 0x09, 0x0a, 0x0b, 0xff, 0x0d, 0x0e, 0xff
};
int
find_sync(BYTE ** gcr_pptr, BYTE * gcr_end)
{
while (1)
{
if ((*gcr_pptr) + 1 >= gcr_end)
{
*gcr_pptr = gcr_end;
return 0; /* not found */
}
/* sync flag goes up after the 10th bit */
//if ( ((*gcr_pptr)[0] & 0x03) == 0x03 && (*gcr_pptr)[1] == 0xff)
/* but sometimes they are short a bit */
if ( ((*gcr_pptr)[0] & 0x01) == 0x01 && (*gcr_pptr)[1] == 0xff)
break;
(*gcr_pptr)++;
}
(*gcr_pptr)++;
while (*gcr_pptr < gcr_end && **gcr_pptr == 0xff)
(*gcr_pptr)++;
return (*gcr_pptr < gcr_end);
}
int
find_header(BYTE ** gcr_pptr, BYTE * gcr_end)
{
while (1)
{
if ((*gcr_pptr) + 2 >= gcr_end)
{
*gcr_pptr = gcr_end;
return 0; /* not found */
}
/* hardware sync flag goes up after the 10th bit */
//if ( (((*gcr_pptr)[0] & 0x03) == 0x03) && ((*gcr_pptr)[1] == 0xff) && ((*gcr_pptr)[2] == 0x52) )
/* but sometimes they are short a bit */
if ( (((*gcr_pptr)[0] & 0x01) == 0x01) && ((*gcr_pptr)[1] == 0xff) && ((*gcr_pptr)[2] == 0x52) )
break;
(*gcr_pptr)++;
}
(*gcr_pptr)++;
return (*gcr_pptr < gcr_end);
}
void
convert_4bytes_to_GCR(BYTE * buffer, BYTE * ptr)
{
*ptr = GCR_conv_data[(*buffer) >> 4] << 3;
*ptr |= GCR_conv_data[(*buffer) & 0x0f] >> 2;
ptr++;
*ptr = GCR_conv_data[(*buffer) & 0x0f] << 6;
buffer++;
*ptr |= GCR_conv_data[(*buffer) >> 4] << 1;
*ptr |= GCR_conv_data[(*buffer) & 0x0f] >> 4;
ptr++;
*ptr = GCR_conv_data[(*buffer) & 0x0f] << 4;
buffer++;
*ptr |= GCR_conv_data[(*buffer) >> 4] >> 1;
ptr++;
*ptr = GCR_conv_data[(*buffer) >> 4] << 7;
*ptr |= GCR_conv_data[(*buffer) & 0x0f] << 2;
buffer++;
*ptr |= GCR_conv_data[(*buffer) >> 4] >> 3;
ptr++;
*ptr = GCR_conv_data[(*buffer) >> 4] << 5;
*ptr |= GCR_conv_data[(*buffer) & 0x0f];
}
int
convert_4bytes_from_GCR(BYTE * gcr, BYTE * plain)
{
BYTE hnibble, lnibble;
int badGCR, nConverted;
badGCR = 0;
hnibble = GCR_decode_high[gcr[0] >> 3];
lnibble = GCR_decode_low[((gcr[0] << 2) | (gcr[1] >> 6)) & 0x1f];
if ((hnibble == 0xff || lnibble == 0xff) && !badGCR)
badGCR = 1;
*plain++ = hnibble | lnibble;
hnibble = GCR_decode_high[(gcr[1] >> 1) & 0x1f];
lnibble = GCR_decode_low[((gcr[1] << 4) | (gcr[2] >> 4)) & 0x1f];
if ((hnibble == 0xff || lnibble == 0xff) && !badGCR)
badGCR = 2;
*plain++ = hnibble | lnibble;
hnibble = GCR_decode_high[((gcr[2] << 1) | (gcr[3] >> 7)) & 0x1f];
lnibble = GCR_decode_low[(gcr[3] >> 2) & 0x1f];
if ((hnibble == 0xff || lnibble == 0xff) && !badGCR)
badGCR = 3;
*plain++ = hnibble | lnibble;
hnibble = GCR_decode_high[((gcr[3] << 3) | (gcr[4] >> 5)) & 0x1f];
lnibble = GCR_decode_low[gcr[4] & 0x1f];
if ((hnibble == 0xff || lnibble == 0xff) && !badGCR)
badGCR = 4;
*plain++ = hnibble | lnibble;
nConverted = (badGCR == 0) ? 4 : (badGCR - 1);
return (nConverted);
}
int
extract_id(BYTE * gcr_track, BYTE * id, int size)
{
BYTE header[10];
BYTE *gcr_ptr, *gcr_end;
int track, sector;
track = 18;
sector = 0;
gcr_ptr = gcr_track;
gcr_end = gcr_track + size;
do
{
if (!find_sync(&gcr_ptr, gcr_end))
return 0;
convert_4bytes_from_GCR(gcr_ptr, header);
convert_4bytes_from_GCR(gcr_ptr + 5, header + 4);
if (header[0] == 0x08 && header[2] == 0)
id[0] = header[3];
if (header[0] == 0x08 && header[2] == 0)
id[0] = header[3];
} while (header[0] != 0x08 || header[2] != sector || header[3] != track);
id[0] = header[5];
id[1] = header[4];
return 1;
}
int
extract_cosmetic_id(BYTE * gcr_track, BYTE * id)
{
BYTE secbuf[260];
BYTE error;
/* get sector into buffer- we don't care about id mismatch here */
error = convert_GCR_sector(gcr_track, gcr_track + NIB_TRACK_LENGTH, secbuf, 18, 0, id);
/* no valid 18,0 sector */
if((error != SECTOR_OK) && (error != ID_MISMATCH))
{
//printf("could not find directory sector!");
return 0;
}
id[0] = secbuf[0xa3];
id[1] = secbuf[0xa4];
return 1;
}
BYTE
convert_GCR_sector(BYTE *gcr_start, BYTE *gcr_cycle, BYTE *d64_sector, int track, int sector, BYTE *id)
{
// we should later try to repair some common GCR errors
// 1) tri-bit error, in which 01110 is misinterpreted as 01000
// 2) low frequency error, in which 10010 is misinterpreted as 11000
BYTE header[10]; /* block header */
BYTE hdr_chksum; /* header checksum */
BYTE blk_chksum; /* block checksum */
BYTE *gcr_ptr, *gcr_end;
BYTE *sectordata;
BYTE error_code;
size_t track_len;
int i, j;
if ((gcr_cycle == NULL) || (gcr_cycle <= gcr_start))
return SYNC_NOT_FOUND;
/* initialize sector data with Original Format Pattern */
memset(d64_sector, 0x01, 260);
d64_sector[0] = 0x07; /* Block header mark */
d64_sector[1] = 0x4b; /* Use Original Format Pattern */
for (blk_chksum = 0, i = 1; i < 257; i++)
blk_chksum ^= d64_sector[i + 1];
d64_sector[257] = blk_chksum;
/* setup pointers */
track_len = gcr_cycle - gcr_start;
gcr_ptr = gcr_start;
gcr_end = gcr_start + track_len;
error_code = SECTOR_OK;
/* Check for at least one Sync */
if (!find_sync(&gcr_ptr, gcr_end))
return SYNC_NOT_FOUND;
/* Try to find a good block header for Track/Sector */
error_code = HEADER_NOT_FOUND;
//for (gcr_ptr = gcr_start; gcr_ptr < gcr_end-1; gcr_ptr++)
for (gcr_ptr = gcr_start; gcr_ptr < gcr_end-10; gcr_ptr++)
{
if ((gcr_ptr[0] == 0xff) && (gcr_ptr[1] == 0x52))
{
gcr_ptr++;
memset(header, 0, 10);
convert_4bytes_from_GCR(gcr_ptr, header);
convert_4bytes_from_GCR(gcr_ptr+5, header+4);
if ((header[0] == 0x08) && (header[2] == sector) && (header[3] == track) )
{
/* this is the header we are searching for */
error_code = SECTOR_OK;
break;
}
if(verbose>2) printf("{1:%.2x, 2:%.2x, 3:%.2x, 4:%.2x, 5:%.2x}{I:%.2x, T:%.2d, S:%.2d}\n",
gcr_ptr[1], gcr_ptr[2], gcr_ptr[3], gcr_ptr[4], gcr_ptr[5], header[0],header[3],header[2]);
}
}
if(error_code != SECTOR_OK)
return error_code;
/* Header checksum calc */
hdr_chksum = 0;
for (i = 1; i <= 4; i++)
hdr_chksum = hdr_chksum ^ header[i];
if (hdr_chksum != header[5])
error_code = (error_code == SECTOR_OK) ? BAD_HEADER_CHECKSUM : error_code;
/* check for correct disk ID */
if (header[5] != id[0] || header[4] != id[1])
error_code = (error_code == SECTOR_OK) ? ID_MISMATCH : error_code;
/* verify that our header contains no bad GCR, since it can be false positive checksum match */
for(j = 0; j < 10; j++)
{
if (is_bad_gcr(gcr_ptr - 1, 10, j))
error_code = (error_code == SECTOR_OK) ? BAD_GCR_CODE : error_code;
}
/* done with header checks */
if((error_code != SECTOR_OK) && (error_code != ID_MISMATCH))
return error_code;
/* check for data sector, it will always be the data following header */
if (!find_sync(&gcr_ptr, gcr_end))
{
gcr_ptr = gcr_start;
if (!find_sync(&gcr_ptr, gcr_end))
return DATA_NOT_FOUND;
}
for (i = 0, sectordata = d64_sector; i < 65; i++)
{
convert_4bytes_from_GCR(gcr_ptr, sectordata);
if(verbose>3)
printf("%.4x: %.2x%.2x%.2x%.2x%.2x --- %.2x%.2x%.2x%.2x\n", (i*4),
gcr_ptr[0], gcr_ptr[1], gcr_ptr[2], gcr_ptr[3], gcr_ptr[4],
sectordata[0], sectordata[1], sectordata[2], sectordata[3]);
gcr_ptr += 5;
sectordata += 4;
}
/* check for Block header mark */
if (d64_sector[0] != 0x07)
error_code = (error_code == SECTOR_OK) ? DATA_NOT_FOUND : error_code;
/* Block checksum calc */
for (i = 1, blk_chksum = 0; i <= 256; i++)
blk_chksum ^= d64_sector[i];
if (blk_chksum != d64_sector[257])
error_code = (error_code == SECTOR_OK) ? BAD_DATA_CHECKSUM : error_code;
/* verify that our data contains no bad GCR, since it can be false positive checksum match */
for(j = 0; j < 320; j++)
{
if (is_bad_gcr(gcr_ptr - 325, 320, j))
error_code = (error_code == SECTOR_OK) ? BAD_GCR_CODE : error_code;
}
return error_code;
}
void
convert_sector_to_GCR(BYTE * buffer, BYTE * ptr, int track, int sector, BYTE * diskID, int error)
{
int i;
BYTE buf[4], databuf[0x104], chksum;
BYTE tempID[3];
memcpy(tempID, diskID, 3);
memset(ptr, 0x55, SECTOR_SIZE); /* 'unformat' GCR sector */
if (error == SYNC_NOT_FOUND)
return;
if (error == HEADER_NOT_FOUND)
{
ptr += 24;
}
else
{
memset(ptr, 0xff, SYNC_LENGTH); /* Sync */
ptr += SYNC_LENGTH;
if (error == ID_MISMATCH)
{
tempID[0] ^= 0xff;
tempID[1] ^= 0xff;
}
buf[0] = 0x08; /* Header identifier */
if (copyprot == 128)
buf[1] = (BYTE) (sector ^ track ^ 0x0f);
else
buf[1] = (BYTE) (sector ^ track ^ tempID[1] ^ tempID[0]);
buf[2] = (BYTE) sector;
buf[3] = (BYTE) track;
if (error == BAD_HEADER_CHECKSUM)
buf[1] ^= 0xff;
convert_4bytes_to_GCR(buf, ptr);
ptr += 5;
if (copyprot == 128)
{
buf[0] = 0x48;
buf[1] = 0x47;
buf[2] = buf[3] = 0x00;
}
else
{
buf[0] = tempID[1];
buf[1] = tempID[0];
buf[2] = buf[3] = 0x0f;
}
convert_4bytes_to_GCR(buf, ptr);
ptr += 5;
if (copyprot == 1)
{
memset(ptr, 0x55, HEADER_GAP_LENGTH-4); /* Header Gap */
ptr += HEADER_GAP_LENGTH - 4;
memset(ptr, 0x67, 1);
ptr++;
memset(ptr, 0x55, 2);
ptr += 2;
memset(ptr, 0x67, 1);
ptr++;
}
else if (copyprot == 128)
{
memcpy(ptr, "\x52\x94\xa5\x29\x4a\x52\x94\xa5\x2b", 9);
ptr += 9;
}
else
{
memset(ptr, 0x55, HEADER_GAP_LENGTH); /* Header Gap */
ptr += HEADER_GAP_LENGTH;
}
}
if (error == DATA_NOT_FOUND)
return;
memset(ptr, 0xff, SYNC_LENGTH); /* Sync */
ptr += SYNC_LENGTH;
chksum = 0;
databuf[0] = 0x07;
for (i = 0; i < 0x100; i++)
{
databuf[i + 1] = buffer[i];
chksum ^= buffer[i];
}
if (error == BAD_DATA_CHECKSUM)
chksum ^= 0xff;
databuf[0x101] = chksum;
databuf[0x102] = 0; /* 2 bytes filler */
databuf[0x103] = 0;
for (i = 0; i < 65; i++)
{
convert_4bytes_to_GCR(databuf + (4 * i), ptr);
ptr += 5;
}
if (copyprot == 1)
{
memset(ptr, 0x55, SECTOR_GAP_LENGTH-4); /* Header Gap */
ptr += SECTOR_GAP_LENGTH - 4;
memset(ptr, 0x67, 1);
ptr++;
memset(ptr, 0x55, 2);
ptr += 2;
memset(ptr, 0x67, 1);
ptr++;
}
else if (copyprot == 128 && track == 18)
{
memset(ptr, 0x11, 22); /* tail gap*/
ptr += 22;
}
else
{
memset(ptr, 0x55, SECTOR_GAP_LENGTH); /* tail gap*/
ptr += SECTOR_GAP_LENGTH;
}
}
size_t
find_track_cycle_headers(BYTE ** cycle_start, BYTE ** cycle_stop, size_t cap_min, size_t cap_max)
{
BYTE *nib_track; /* start of nibbled track data */
BYTE *start_pos; /* start of periodic area */
BYTE *cycle_pos; /* start of cycle repetition */
BYTE *stop_pos; /* maximum position allowed for cycle */
BYTE *data_pos; /* cycle search variable */
BYTE *p1, *p2; /* local pointers for comparisons */
nib_track = *cycle_start;
stop_pos = nib_track + NIB_TRACK_LENGTH - gap_match_length;
cycle_pos = NULL;
/* try to find a normal track cycle */
for (start_pos = nib_track;; find_header(&start_pos, stop_pos))
{
if ((data_pos = start_pos + cap_min) >= stop_pos)
break; /* no cycle found */
while (find_header(&data_pos, stop_pos))
{
p1 = start_pos;
cycle_pos = data_pos;
for (p2 = cycle_pos; p2 < stop_pos;)
{
/* try to match all remaining syncs, too */
if (memcmp(p1, p2, gap_match_length) != 0)
{
cycle_pos = NULL;
break;
}
if (!find_header(&p1, stop_pos))
break;
if (!find_header(&p2, stop_pos))
break;
}
if ((cycle_pos != NULL) && (check_valid_data(data_pos, gap_match_length)))
{
*cycle_start = start_pos;
*cycle_stop = cycle_pos;
return (cycle_pos - start_pos);
}
}
}
/* we got nothing useful, return it all */
*cycle_start = nib_track;
*cycle_stop = nib_track + NIB_TRACK_LENGTH;
return NIB_TRACK_LENGTH;
}
size_t
find_track_cycle_syncs(BYTE ** cycle_start, BYTE ** cycle_stop, size_t cap_min, size_t cap_max)
{
BYTE *nib_track; /* start of nibbled track data */
BYTE *start_pos; /* start of periodic area */
BYTE *cycle_pos; /* start of cycle repetition */
BYTE *stop_pos; /* maximum position allowed for cycle */
BYTE *data_pos; /* cycle search variable */
BYTE *p1, *p2; /* local pointers for comparisons */
nib_track = *cycle_start;
stop_pos = nib_track + NIB_TRACK_LENGTH - gap_match_length;
cycle_pos = NULL;
/* try to find a normal track cycle */
for (start_pos = nib_track;; find_sync(&start_pos, stop_pos))
{
if ((data_pos = start_pos + cap_min) >= stop_pos)
break; /* no cycle found */
while (find_sync(&data_pos, stop_pos))
{
p1 = start_pos;
cycle_pos = data_pos;
for (p2 = cycle_pos; p2 < stop_pos;)
{
/* try to match all remaining syncs, too */
if (memcmp(p1, p2, gap_match_length) != 0)
{
cycle_pos = NULL;
break;
}
if (!find_sync(&p1, stop_pos))
break;
if (!find_sync(&p2, stop_pos))
break;
}
if ((cycle_pos != NULL) && (check_valid_data(data_pos, gap_match_length)))
{
*cycle_start = start_pos;
*cycle_stop = cycle_pos;
return (cycle_pos - start_pos);
}
}
}
/* we got nothing useful, return it all */
*cycle_start = nib_track;
*cycle_stop = nib_track + NIB_TRACK_LENGTH;
return NIB_TRACK_LENGTH;
}
size_t
find_track_cycle_raw(BYTE ** cycle_start, BYTE ** cycle_stop, size_t cap_min, size_t cap_max)
{
BYTE *nib_track; /* start of nibbled track data */
BYTE *start_pos; /* start of periodic area */
BYTE *cycle_pos; /* start of cycle repetition */
BYTE *stop_pos; /* maximum position allowed for cycle */
BYTE *p1, *p2; /* local pointers for comparisons */
nib_track = *cycle_start;
start_pos = nib_track;
stop_pos = nib_track + NIB_TRACK_LENGTH - gap_match_length;
cycle_pos = NULL;
/* try to find a track cycle ignoring sync */
for (p1 = start_pos; p1 < stop_pos; p1++)
{
/* now try to match it */
for (p2 = p1 + (cap_min + CAP_ALLOWANCE); p2 < stop_pos; p2++)
//for (p2 = p1 + cap_max; p2 > p1 + cap_min; p2--)
{
/* try to match data */
if (memcmp(p1, p2, gap_match_length) != 0)
cycle_pos = NULL;
else
cycle_pos = p2;
/* we found one! */
if ((cycle_pos != NULL) && (check_valid_data(cycle_pos, gap_match_length)))
{
*cycle_start = p1;
*cycle_stop = cycle_pos;
return (cycle_pos - p1);
}
}
}
/* we got nothing useful */
*cycle_start = nib_track;
*cycle_stop = nib_track + NIB_TRACK_LENGTH;
return NIB_TRACK_LENGTH;
}
int
check_valid_data(BYTE * data, int matchlen)
{
/* makes a simple assumption whether this is good data to match track cycle overlap */
int i, redund=0;
for (i = 0; i < matchlen; i++)
{
if(data[i] == 0xff) return 0; /* sync marks */
if((data[i] == data[i+1]) && (data[i+1] == data[i+2])) redund++; /* repeating bytes */
if((data[i] == data[i+2]) && (data[i+1] == data[i+3])) redund++; /* alternating bytes (as seen on PirateSlayer tracks) */
if(redund>2)
{
//printf("{RB}");
return 0;
}
/* check we aren't matching gap data (GCR is 555555 or AAAAAA) */
if((data[i] == 0x55) && (data[i+1] == 0xaa) && (data[i+2] == 0x55)) return 0;
if((data[i] == 0xaa) && (data[i+1] == 0x55) && (data[i+2] == 0xaa)) return 0;
if((data[i] == 0x5a) && (data[i+1] == 0xa5) && (data[i+2] == 0x5a)) return 0;
/* check we aren't matching gap data (GCR encoded 555555 or AAAAAA) */
//if((data[i] == 0x52) && (data[i+1] == 0xd4) && (data[i+2] == 0xb5)) return 0;
//if((data[i] == 0x2d) && (data[i+1] == 0x4b) && (data[i+2] == 0x52)) return 0;
}
return 1;
}
BYTE *
find_sector0(BYTE * work_buffer, size_t tracklen, size_t * p_sectorlen)
{
BYTE *pos, *buffer_end, *sync_last;
pos = work_buffer;
buffer_end = work_buffer + 2 * tracklen - 10;
*p_sectorlen = 0;
if (!find_sync(&pos, buffer_end))
return NULL;
sync_last = pos;
/* try to find sector 0 */
while (pos < buffer_end)
{
if (!find_sync(&pos, buffer_end))
return NULL;
if (pos[0] == 0x52 && (pos[1] & 0xc0) == 0x40 &&
(pos[2] & 0x0f) == 0x05 && (pos[3] & 0xfc) == 0x28)
{
/* this is inaccurate if sector 0 is the first thing found */
/* *p_sectorlen = pos - sync_last; GCR_BLOCK_LEN; */
*p_sectorlen = GCR_BLOCK_LEN;
break;
}
sync_last = pos;
}
/* find last GCR byte before sync */
do
{
pos -= 1;
if (pos == work_buffer)
pos += tracklen;
} while (*pos == 0xff);
/* move to first sync byte */
pos += 1;
while (pos >= work_buffer + tracklen)
pos -= tracklen;
/*return pos - 1; // go to last byte that contains first few bits of sync */
return pos; // go to first full byte of sync
}
BYTE *
find_sector_gap(BYTE * work_buffer, size_t tracklen, size_t * p_sectorlen)
{
size_t gap, maxgap;
BYTE *pos;
BYTE *buffer_end;
BYTE *sync_last;
BYTE *sync_max;
pos = work_buffer;
buffer_end = work_buffer + 2 * tracklen - 10;
*p_sectorlen = 0;
if (!find_sync(&pos, buffer_end))
return NULL;
sync_last = pos;
sync_max = pos;
maxgap = 0;
/* try to find biggest (sector) gap */
while (pos < buffer_end)
{
if (!find_header(&pos, buffer_end))
break;
gap = pos - sync_last;
if (gap > maxgap)
{
maxgap = gap;
sync_max = pos;
}
sync_last = pos;
}
*p_sectorlen = maxgap;
if (maxgap == 0)
return NULL; /* no gap found */
/* find last GCR byte before header */
pos = sync_max;
do
{
pos -= 1;
if (pos == work_buffer)
pos += tracklen;
} while (*pos == 0xff);
/* move to first sync GCR byte */
pos += 1;
while (pos >= work_buffer + tracklen)
pos -= tracklen;
/*return pos - 1; // go to last byte that contains first few bits of sync*/
return pos; // return at first full byte of sync
}
/* checks if there is any reasonable section of formatted (GCR) data */
int check_formatted(BYTE *gcrdata, size_t length)
{
size_t i, run = 0;
/* try to find longest good gcr run */
for (i = 0; i < length; i++)
{
if (is_bad_gcr(gcrdata, length, i))
run = 0;
else
run++;
if (run >= GCR_MIN_FORMATTED)
return 1;
}
return 0;
}
/*
Try to extract one complete cycle of GCR data from an 8kB buffer.
Align track to sector gap if possible, else align to sector 0,
else copy cyclic loop from begin of source.
If buffer has no good GCR, return tracklen = 0;
[Input] destination buffer, source buffer
[Return] length of copied track fragment
*/
size_t
extract_GCR_track(BYTE *destination, BYTE *source, BYTE *align, int track, size_t cap_min, size_t cap_max)
{
BYTE work_buffer[NIB_TRACK_LENGTH*2]; /* working buffer */
BYTE *cycle_start; /* start position of cycle */
BYTE *cycle_stop; /* stop position of cycle */
BYTE *sector0_pos; /* position of sector 0 */
BYTE *sectorgap_pos;/* position of sector gap */
BYTE *longsync_pos; /* position of longest sync run */
BYTE *badgap_pos; /* position of bad gcr bit run */
BYTE *marker_pos; /* generic marker used by protection handlers */
size_t track_len;
size_t sector0_len; /* length of gap before sector 0 */
size_t sectorgap_len; /* length of longest gap */
BYTE fake_density = 0;
int i ,j;
sector0_pos = NULL;
sectorgap_pos = NULL;
longsync_pos = NULL;
badgap_pos = NULL;
marker_pos = NULL;
/* ignore minumum capacity by RPM/density */
if(!cap_min_ignore)
{
cap_min -= CAP_ALLOWANCE;
cap_max += CAP_ALLOWANCE;
}
/* if this track doesn't have enough formatted data, return blank */
if (!check_formatted(source, NIB_TRACK_LENGTH))
return 0;
/* if this track is all sync, return */
if(check_sync_flags(source, fake_density, NIB_TRACK_LENGTH) & BM_FF_TRACK)
{
if(verbose) printf("KILLER! ");
memcpy(destination, source, NIB_TRACK_LENGTH);
return NIB_TRACK_LENGTH;
}
cycle_start = source;
memset(work_buffer, 0, sizeof(work_buffer));
memcpy(work_buffer, cycle_start, NIB_TRACK_LENGTH);
/* find cycle */
if(verbose>1) printf("H");
find_track_cycle_headers(&cycle_start, &cycle_stop, cap_min, cap_max);
track_len = cycle_stop - cycle_start;
/* second pass to find a cycle in track w/non-standard headers */
if ((track_len > cap_max) || (track_len < cap_min))
{
if(verbose>1) printf("/S");
find_track_cycle_syncs(&cycle_start, &cycle_stop, cap_min, cap_max);
track_len = cycle_stop - cycle_start;
}
/* third pass to find a cycle in track w/non-standard headers */
if ((track_len > cap_max) || (track_len < cap_min))
{
if(verbose>1) printf("/R");
find_track_cycle_raw(&cycle_start, &cycle_stop, cap_min, cap_max);
track_len = cycle_stop - cycle_start;
}
if (track_len <= cap_min)
{
if(verbose>1) printf("/+");
track_len += (cap_max-cap_min)/2;
}
if(verbose>2)
{
if (track_len > cap_max)
printf("[LONG, max=%d<%d] ",cap_max, track_len);
if(track_len < cap_min)
printf("[SHORT, min=%d>%d] ", cap_min, track_len);
printf("{cycle:");
for(i=0;i<gap_match_length;i++)
printf("%.2x",cycle_start[i]);
printf("}");
}
/* copy twice the data to work buffer */
memcpy(work_buffer, cycle_start, track_len);
memcpy(work_buffer + track_len, cycle_start, track_len);
/* print sector0 offset from beginning of data (for index hole check) */
if(verbose>1)
{
sector0_pos = find_sector0(work_buffer, track_len, §or0_len);
printf("{sec0=%.4d;len=%d} ",(int)(sector0_pos - work_buffer), sector0_len);
}
/* forced track alignments */
if (align_map[track] != ALIGN_NONE)
{
if (align_map[track] == ALIGN_VMAX_CW)
{
*align = ALIGN_VMAX_CW;
marker_pos = align_vmax_cw(work_buffer, track_len);
if(!marker_pos)
align_map[track] = ALIGN_VMAX;
}
if (align_map[track] == ALIGN_VMAX)
{
*align = ALIGN_VMAX;
marker_pos = align_vmax_new(work_buffer, track_len);
}
if (align_map[track] == ALIGN_PSLAYER)
{
*align = ALIGN_PSLAYER;
marker_pos = align_pirateslayer(work_buffer, track_len);
}
if (align_map[track] == ALIGN_RAPIDLOK)
{
*align = ALIGN_RAPIDLOK;
marker_pos = align_rl_special(work_buffer, track_len);
}
if (align_map[track] == ALIGN_AUTOGAP)
{
*align = ALIGN_AUTOGAP;
marker_pos = auto_gap(work_buffer, track_len);
}
if (align_map[track] == ALIGN_LONGSYNC)
{
*align = ALIGN_LONGSYNC;
marker_pos = find_long_sync(work_buffer, track_len);
}
if (align_map[track] == ALIGN_BADGCR)
{
*align = ALIGN_BADGCR;
marker_pos = find_bad_gap(work_buffer, track_len);
}
if (align_map[track] == ALIGN_GAP)
{
*align = ALIGN_GAP;
marker_pos = find_sector_gap(work_buffer, track_len, §orgap_len);
}
if (align_map[track] == ALIGN_SEC0)