pi1541/src/prot.cpp

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2018-05-20 04:53:34 +00:00
/*
* Protection handlers for MNIB
* Copyright 2004-2005 Pete Rittwage <peter(at)rittwage(dot)com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "gcr.h"
#include "prot.h"
void
shift_buffer(BYTE * buffer, int length, int n)
{
int i;
BYTE tempbuf[NIB_TRACK_LENGTH];
BYTE carry;
int carryshift;
carryshift = 8 - n;
memcpy(tempbuf, buffer, length);
// shift buffer right by n bits
carry = tempbuf[length - 1];
for (i = 0; i < length; i++)
{
buffer[i] = (tempbuf[i] >> n) | (carry << carryshift);
carry = tempbuf[i];
}
}
BYTE *
align_vmax(BYTE * work_buffer, int tracklen)
{
BYTE *pos, *buffer_end, *start_pos;
int run;
run = 0;
pos = work_buffer;
start_pos = work_buffer;
buffer_end = work_buffer + tracklen;
/* Try to find V-MAX track marker bytes
0x4b (cinemaware track 20)
0xa5 (cinemaware other tracks)
0x5a (misc)
0x49 (misc)
*/
while (pos < buffer_end)
{
// duplicator's markers
if ((*pos == 0x4b) || (*pos == 0x5a) || (*pos == 0x49) || (*pos == 0xa5))
{
if(!run) start_pos = pos; // mark first byte
if (run > 5) return (start_pos); // assume this is it
run++;
}
else
run = 0;
pos++;
}
return (0);
}
// Line up the track cycle to the start of the longest gap mark
// this helps some custom protection tracks master properly
BYTE *
auto_gap(BYTE * work_buffer, int tracklen)
{
BYTE *pos, *buffer_end, *key_temp, *key;
int run, longest;
run = 0;
longest = 0;
pos = work_buffer;
buffer_end = work_buffer + tracklen;
key = key_temp = NULL;
/* try to find longest good gcr run */
while (pos < buffer_end - 2)
{
if (*pos == *(pos + 1)) // && (*pos != 0x00 ))
{
key_temp = pos + 2;
run++;
}
else
{
if (run > longest)
{
key = key_temp;
longest = run;
//gapbyte = *pos;
}
run = 0;
}
pos++;
}
/* last 5 bytes of gap */
// printf("gapbyte: %x, len: %d\n",gapbyte,longest);
if(key >= work_buffer + 5)
return(key - 5);
else
return(key);
}
// The idea behind this is that weak bits commonly occur
// at the ends of tracks when they were mastered.
// we can line up the track cycle to this
// in lieu of no other hints
BYTE *
find_weak_gap(BYTE * work_buffer, int tracklen)
{
BYTE *pos, *buffer_end, *key_temp, *key;
int run, longest;
run = 0;
longest = 0;
pos = work_buffer;
buffer_end = work_buffer + tracklen;
key = key_temp = NULL;
/* try to find longest bad gcr run */
while (pos < buffer_end)
{
if (is_bad_gcr(work_buffer, buffer_end - work_buffer,
pos - work_buffer))
{
// mark next GCR byte
key_temp = pos + 1;
run++;
}
else
{
if (run > longest)
{
key = key_temp;
longest = run;
}
run = 0;
}
pos++;
}
/* first byte after bad run */
return (key);
}
// Line up the track cycle to the start of the longest sync mark
// this helps some custom protection tracks master properly
BYTE *
find_long_sync(BYTE * work_buffer, int tracklen)
{
BYTE *pos, *buffer_end, *key_temp, *key;
int run, longest;
run = 0;
longest = 0;
pos = work_buffer;
buffer_end = work_buffer + tracklen;
key = key_temp = NULL;
/* try to find longest sync run */
while (pos < buffer_end)
{
if (*pos == 0xff)
{
if (run == 0)
key_temp = pos;
run++;
}
else
{
if (run > longest)
{
key = key_temp;
longest = run;
}
run = 0;
}
pos++;
}
/* first byte of longest sync run */
return (key);
}