mame/src/lib/formats/hti_tape.h
2017-08-23 19:33:27 +10:00

94 lines
2.9 KiB
C++

// license:BSD-3-Clause
// copyright-holders:F. Ulivi
/*********************************************************************
"HTI" format
Format of images of DC-100 tape cassettes as used in HP 9845
and HP 85 systems.
*********************************************************************/
#ifndef _HTI_TAPE_H_
#define _HTI_TAPE_H_
#pragma once
#include <map>
#include "ioprocs.h"
class hti_format_t {
public:
hti_format_t();
// Tape position, 1 unit = 1 inch / (968 * 1024)
typedef int32_t tape_pos_t;
// 1 inch in tape_pos_t
static constexpr tape_pos_t ONE_INCH_POS = 968 * 1024;
// Special value for invalid/unknown tape position
static constexpr tape_pos_t NULL_TAPE_POS = -1;
// Tape length: 140 ft of usable tape + 72" of punched tape at either end
static constexpr tape_pos_t TAPE_LENGTH = (140 * 12 + 72 * 2) * ONE_INCH_POS;
// Words stored on tape
typedef uint16_t tape_word_t;
// Storage of tracks: mapping from a tape position to word stored there
typedef std::map<tape_pos_t, tape_word_t> tape_track_t;
// Iterator to access words on tape
typedef tape_track_t::iterator track_iterator_t;
bool load_tape(io_generic *io);
void save_tape(io_generic *io);
void clear_tape();
// Return physical length of a 16-bit word on tape
static tape_pos_t word_length(tape_word_t w);
static tape_pos_t farthest_end(const track_iterator_t& it , bool forward);
static bool pos_offset(tape_pos_t& pos , bool forward , tape_pos_t offset);
// Position of next hole tape will reach in a given direction
static tape_pos_t next_hole(tape_pos_t pos , bool forward);
// Write a data word on tape
void write_word(unsigned track_no , tape_pos_t start , tape_word_t word , tape_pos_t& length , bool forward = true);
// Write a gap on tape
void write_gap(unsigned track_no , tape_pos_t a , tape_pos_t b);
// Check that a section of tape has no data (it's just gap)
bool just_gap(unsigned track_no , tape_pos_t a , tape_pos_t b);
// Return position of next data word in a given direction
bool next_data(unsigned track_no , tape_pos_t pos , bool forward , bool inclusive , track_iterator_t& it);
typedef enum {
ADV_NO_MORE_DATA,
ADV_CONT_DATA,
ADV_DISCONT_DATA
} adv_res_t;
// Advance an iterator to next word of data
adv_res_t adv_it(unsigned track_no , bool forward , track_iterator_t& it);
// Scan for beginning of next gap in a given direction
bool next_gap(unsigned track_no , tape_pos_t& pos , bool forward , tape_pos_t min_gap);
private:
// Content of tape tracks
tape_track_t m_tracks[ 2 ];
static bool load_track(io_generic *io , uint64_t& offset , tape_track_t& track);
static void dump_sequence(io_generic *io , uint64_t& offset , tape_track_t::const_iterator it_start , unsigned n_words);
static tape_pos_t word_end_pos(const track_iterator_t& it);
static void adjust_it(tape_track_t& track , track_iterator_t& it , tape_pos_t pos);
static void ensure_a_lt_b(tape_pos_t& a , tape_pos_t& b);
};
#endif /* _HTI_TAPE_H_ */