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/**
* @file oric_e.c
* Oric tape encoding functions
* @author Marko Mkel (msmakela@nic.funet.fi)
*/
/* Copyright 2002 Marko Mkel.
This file is part of C2N, a program for processing data tapes in
Commodore C2N format and other formats.
C2N is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
C2N is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
The GNU General Public License is often shipped with GNU software, and
is generally kept in a file called COPYING or LICENSE. If you do not
have a copy of the license, write to the Free Software Foundation,
59 Temple Place, Suite 330, Boston, MA 02111 USA. */
#include <stdio.h>
#include <stdlib.h>
#include "c2n.h"
#include "oric_e.h"
/** The pulse writer */
static pulse_w_t enc_wr;
/**
* Encode a stream of synchronization pulses
* @param count number of pulses
*/
static void
encodeSync (unsigned count)
{
if (verbose)
fprintf (stderr, "encoding a sync mark (%u pulses)\n", count);
while (count--)
(*enc_wr) (Short);
}
/**
* Encode a bit
* @param b the bit to be encoded
*/
static void
encodeBit (unsigned b)
{
(*enc_wr) (b ? Short : Medium);
}
/**
* Encode a byte marker and a byte
* @param c the byte to be encoded
*/
static void
encodeByte (unsigned char c)
{
register unsigned i, parity;
/*
* Write 4 stop bits '1' followed by a '0'.
* The ROM routines write 3 stop bits, inverting the phase after each byte.
* However, the ROM is able to read data with 4 stop bits as well.
*/
for (i = 4; i--; )
encodeBit (1);
encodeBit (0);
/* Write the data, least significant bit first, odd parity */
for (parity = 1, i = 8; i--; c >>= 1) {
encodeBit (c & 1);
if (c & 1)
parity = !parity;
}
encodeBit (parity);
}
/**
* Encode a data block
* @param buf the data buffer
* @param size length of the data in bytes
*/
static void
encBlock (const char* buf, unsigned size)
{
register const char* bufe = buf + size;
while (buf < bufe)
encodeByte ((unsigned char) *buf++);
}
/** Oric pulse stream encoder
* @param in the data stream
* @param err the error reporter
* @param wr the pulse stream writer
* @param begin number of initial synchronization pulses
* @param intra number of intra-block synchronization pulses
* @return number of blocks written; 0 on failure
*/
unsigned
encode_oric (FILE* in, pulse_error_t err, pulse_w_t wr,
unsigned begin, unsigned intra)
{
/** current block */
unsigned block;
enc_wr = wr;
for (block = 0;; block++) {
/** program block header */
static char header[9];
int c;
/* read and skip synchronization bytes */
while ((c = fgetc (in)) == 0x16);
if (c == EOF)
break;
else if (c != 0x24) {
if (!err || !(*err) (Unexpected, block, c))
break;
continue;
}
if (1 != fread (header, sizeof header, 1, in))
break;
else {
/** program data buffer */
char* buf;
/** program length in bytes */
unsigned length;
/** received data length */
unsigned readlength;
/** null-terminated program name */
static char name[16];
/** length of the name */
unsigned namelength;
length = ((unsigned) (unsigned char) header[5]) |
((unsigned) (unsigned char) header[4]) << 8;
length -= ((unsigned) (unsigned char) header[7]) |
((unsigned) (unsigned char) header[6]) << 8;
length &= 0xffff;
length++;
/* read the file name */
for (namelength = 0; namelength < sizeof name; )
if ((c = fgetc (in)) == EOF || !(name[namelength++] = c))
break;
if (c == EOF)
break;
else if (c) {
if (err)
(*err) (LongBlock, block, sizeof header + sizeof name);
break;
}
if (!(buf = malloc (length))) {
fputs ("out of memory\n", stderr);
break;
}
block++;
readlength = fread (buf, 1, length, in);
if (readlength != length) {
if (!err || (*err) (ShortBlock, block, length - readlength)) {
free (buf);
return block;
}
}
if (block)
(*enc_wr) (Pause);
/* write the synchronization sequence followed by the header */
for (c = begin; c--; )
encodeByte (0x16);
encodeByte (0x24);
encBlock (header, sizeof header);
encBlock (name, namelength);
encodeSync (intra);
encBlock (buf, readlength);
free (buf);
encodeSync (4);
}
}
(*enc_wr) (Pause);
return block;
}
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