modules/t64.c

   1 // This file is part of Deark.
   2 // Copyright (C) 2016 Jason Summers
   3 // See the file COPYING for terms of use.
   4
   5 // T64 (Commodore 64 "tape"-like format)
   6
   7 #include <deark-config.h>
   8 #include <deark-private.h>
   9 DE_DECLARE_MODULE(de_module_t64);
  10
  11 typedef struct localctx_struct {
  12         i64 version;
  13         i64 max_dir_entries;
  14         i64 used_dir_entries;
  15 } lctx;
  16
  17 static void do_extract_file(deark *c, lctx *d, i64 dir_pos,
  18         u8 filetype_c64s, u8 filetype)
  19 {
  20         i64 load_addr;
  21         i64 end_addr;
  22         i64 offset;
  23         dbuf *f = NULL;
  24         i64 payload_size; // = file_size-2
  25         de_ucstring *fname = NULL;
  26         i64 fname_len;
  27         i64 i;
  28         i64 fnpos;
  29         de_finfo *fi = NULL;
  30
  31         load_addr = de_getu16le(dir_pos+2);
  32         end_addr = de_getu16le(dir_pos+4);
  33         offset = de_getu32le(dir_pos+8);
  34         de_dbg(c, "load_addr=%d end_addr=%d offset=%d", (int)load_addr,
  35                 (int)end_addr, (int)offset);
  36
  37         // File name at pos+16
  38
  39         fnpos = dir_pos+16;
  40
  41         // Find the length of the (space-padded) filename.
  42         fname_len = 0;
  43         for(i=15; i>=0; i--) {
  44                 if(de_getbyte(fnpos+i)!=' ') {
  45                         fname_len = i+1;
  46                         break;
  47                 }
  48         }
  49         de_dbg2(c, "filename length: %d", (int)fname_len);
  50
  51         fname = ucstring_create(c);
  52         dbuf_read_to_ucstring(c->infile, fnpos, fname_len, fname, 0, DE_ENCODING_PETSCII);
  53         de_dbg(c, "filename: \"%s\"", ucstring_getpsz(fname));
  54
  55         ucstring_append_sz(fname, ".prg", DE_ENCODING_LATIN1);
  56
  57         fi = de_finfo_create(c);
  58         de_finfo_set_name_from_ucstring(c, fi, fname, 0);
  59         fi->original_filename_flag = 1;
  60
  61         payload_size = end_addr - load_addr;
  62         if(payload_size < 0) {
  63                 // TODO: Try to support files that don't have end_addr set properly.
  64                 de_err(c, "This type of T64 file is not supported.");
  65                 goto done;
  66         }
  67
  68         f = dbuf_create_output_file(c, NULL, fi, 0);
  69         dbuf_copy(c->infile, dir_pos+2, 2, f);
  70         dbuf_copy(c->infile, offset, payload_size, f);
  71
  72 done:
  73         dbuf_close(f);
  74         de_finfo_destroy(c, fi);
  75         ucstring_destroy(fname);
  76 }
  77
  78 static void do_dir_entry(deark *c, lctx *d, i64 entry_num, i64 pos)
  79 {
  80         u8 filetype_c64s;
  81         u8 filetype;
  82
  83         filetype_c64s = de_getbyte(pos);
  84         if(filetype_c64s==0) {
  85                 de_dbg2(c, "unused entry #%d at %d", (int)entry_num, (int)pos);
  86                 return;
  87         }
  88         de_dbg(c, "entry #%d at %d", (int)entry_num, (int)pos);
  89
  90         de_dbg_indent(c, 1);
  91
  92         filetype = de_getbyte(pos+1);
  93         de_dbg(c, "c64s filetype=%d, filetype=0x%02x", (int)filetype_c64s, (int)filetype);
  94
  95         if(filetype==0x00) {
  96                 de_err(c, "Unsupported file type (0x%02x)", (int)filetype);
  97         }
  98         else {
  99                 do_extract_file(c, d, pos, filetype_c64s, filetype);
 100         }
 101
 102         de_dbg_indent(c, -1);
 103 }
 104
 105 static void de_run_t64(deark *c, de_module_params *mparams)
 106 {
 107         lctx *d = NULL;
 108         i64 pos;
 109         i64 i;
 110
 111         d = de_malloc(c, sizeof(lctx));
 112
 113         pos = 32;
 114         d->version = de_getu16le(pos);
 115         de_dbg(c, "version: 0x%04x", (int)d->version);
 116         if(d->version!=0x100 && d->version!=0x101) {
 117                 de_warn(c, "Unexpected version number. This might not be a T64 file.");
 118         }
 119
 120         d->max_dir_entries = de_getu16le(pos+2);
 121         d->used_dir_entries = de_getu16le(pos+4);
 122         de_dbg(c, "max dir entries = %d, files = %d", (int)d->max_dir_entries, (int)d->used_dir_entries);
 123
 124         pos += 32;
 125         for(i=0; i<d->max_dir_entries; i++) {
 126                 do_dir_entry(c, d, i, pos+32*i);
 127         }
 128
 129         de_free(c, d);
 130 }
 131
 132 static int de_identify_t64(deark *c)
 133 {
 134         if(!dbuf_memcmp(c->infile, 0, "C64", 3)) return 80;
 135         return 0;
 136 }
 137
 138 void de_module_t64(deark *c, struct deark_module_info *mi)
 139 {
 140         mi->id = "t64";
 141         mi->desc = "T64 (C64 tape format)";
 142         mi->run_fn = de_run_t64;
 143         mi->identify_fn = de_identify_t64;
 144 }