dis.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <stdint.h>
   4 #include <string.h>
   5 #include <stdbool.h>
   6
   7 #include "dis.h"
   8 #include "dis_syn.h"
   9
  10 /*
  11  * Another World script disassembler
  12  *   Only DOS version are supported
  13  */
  14
  15 #define MSG_USAGE "usage: disasm [-a | -i | -u] [-p] OBJECT OUTFILE\n"
  16 #define MSG_OPENERR "can't open file %s.\n"
  17 #define MSG_WRITEERR "can't create file %s.\n"
  18 #define MSG_INVALIDOP "invalid opcode 0x%X\n"
  19 #define MSG_INVALIDJMP "invalid jump opcode %u\n"
  20
  21 char *input, *output;
  22
  23 FILE *fp;
  24
  25 uint8_t *code;
  26 uint16_t codesize;
  27 uint16_t pc, adr;
  28
  29 struct labelinfo label[MAX_LABEL];
  30 int labelnum;
  31 bool printcode;
  32 bool printadr;
  33
  34 void (*printlabel)(int);
  35 void (*printopcode)(uint16_t, uint16_t, uint16_t, uint16_t, uint16_t, int);
  36
  37 static uint8_t ubyte() {
  38         return code[pc++];
  39 }
  40
  41 static uint16_t uword() {
  42         return (ubyte() << 8) | ubyte();
  43 }
  44
  45 static int addlabel(uint16_t adr, int type) {
  46         for(int i = 0; i < labelnum; i++) {
  47                 if(label[i].adr == adr)
  48                         return i;
  49         }
  50
  51         label[labelnum].adr = adr;
  52         label[labelnum].type = type;
  53         ++labelnum;
  54         return labelnum - 1;
  55 }
  56
  57 static void fndlabel() {
  58         for(int i = 0; i < labelnum; i++) {
  59                 if(label[i].adr == pc) {
  60                         printlabel(i);
  61                         return;
  62                 }
  63         }
  64
  65         printlabel(-1);
  66 }
  67
  68 static void step() {
  69         adr = pc;
  70
  71         if(printcode)
  72                 fndlabel();
  73
  74         uint8_t op = ubyte();
  75         uint16_t x = -1, y = -1, z = -1, w = -1;
  76         int label = -666;
  77
  78         if(op & 0x80) { /* spr */
  79                 w = (((op << 8) | ubyte()) << 1) & 0x7FFF;
  80                 x = ubyte();
  81                 y = ubyte();
  82         } else if(op & 0x40) { /* spr */
  83                 w = (uword() << 1) & 0x7FFF;
  84
  85                 x = ubyte();
  86                 if((op & 48) == 0)
  87                         x = (x << 8) | ubyte();
  88                 else if((op & 48) == 48)
  89                         x = x + 256;
  90
  91                 y = ubyte();
  92                 if((op & 12) == 0)
  93                         y = (y << 8) | ubyte();
  94
  95                 if((op & 3) == 1 || (op & 3) == 2)
  96                         z = ubyte();
  97                 else
  98                         z = 64;
  99         } else {
 100                 switch(op) {
 101                 case 0x0: /* seti */
 102                         x = ubyte();
 103                         y = uword();
 104                         break;
 105                 case 0x1: /* set */
 106                         x = ubyte();
 107                         y = ubyte();
 108                         break;
 109                 case 0x2: /* add */
 110                         x = ubyte();
 111                         y = ubyte();
 112                         break;
 113                 case 0x3: /* addi */
 114                         x = ubyte();
 115                         y = uword();
 116                         break;
 117                 case 0x4: /* jsr */
 118                         x = uword();
 119                         label = addlabel(x, LT_CALL);
 120                         break;
 121                 case 0x5: /* return */
 122                         break;
 123                 case 0x6: /* break */
 124                         break;
 125                 case 0x7: /* jmp */
 126                         x = uword();
 127                         label = addlabel(x, LT_JUMP);
 128                         break;
 129                 case 0x8: /* setvec */
 130                         x = ubyte();
 131                         y = uword();
 132                         label = addlabel(y, LT_VEC);
 133                         break;
 134                 case 0x9: /* dbra */
 135                         x = ubyte();
 136                         y = uword();
 137                         label = addlabel(y, LT_JUMP);
 138                         break;
 139                 case 0xA: /* si */
 140                         w = ubyte();
 141                         x = ubyte();
 142
 143                         if(w & 0x80)
 144                                 y = ubyte();
 145                         else if(w & 0x40)
 146                                 y = uword();
 147                         else
 148                                 y = ubyte();
 149
 150                         if((w & 7) > 5) {
 151                                 printf(MSG_INVALIDJMP, w & 0x7);
 152                                 exit(1);
 153                         }
 154
 155                         z = uword();
 156                         label = addlabel(z, LT_JUMP);
 157                         break;
 158                 case 0xB: /* fade */
 159                         x = uword() >> 8;
 160                         break;
 161                 case 0xC: /* vec */
 162                         x = ubyte();
 163                         y = ubyte();
 164                         z = ubyte();
 165                         break;
 166                 case 0xD: /* setws */
 167                         x = ubyte();
 168                         break;
 169                 case 0xE: /* clr */
 170                         x = ubyte();
 171                         y = ubyte();
 172                         break;
 173                 case 0xF: /* copy */
 174                         x = ubyte();
 175                         y = ubyte();
 176                         break;
 177                 case 0x10: /* show */
 178                         x = ubyte();
 179                         break;
 180                 case 0x11: /* bigend */
 181                         break;
 182                 case 0x12: /* text */
 183                         z = uword();
 184                         x = ubyte();
 185                         y = ubyte();
 186                         w = ubyte();
 187                         break;
 188                 case 0x13: /* sub */
 189                         x = ubyte();
 190                         y = ubyte();
 191                         break;
 192                 case 0x14: /* andi */
 193                         x = ubyte();
 194                         y = uword();
 195                         break;
 196                 case 0x15: /* ori */
 197                         x = ubyte();
 198                         y = uword();
 199                         break;
 200                 case 0x16: /* lsl */
 201                         x = ubyte();
 202                         y = uword();
 203                         break;
 204                 case 0x17: /* lsr */
 205                         x = ubyte();
 206                         y = uword();
 207                         break;
 208                 case 0x18: /* play */
 209                         z = uword();
 210                         x = ubyte();
 211                         y = ubyte();
 212                         w = ubyte();
 213                         break;
 214                 case 0x19: /* load */
 215                         x = uword();
 216                         break;
 217                 case 0x1A: /* song */
 218                         x = uword();
 219                         y = uword();
 220                         z = ubyte();
 221                         break;
 222                 default:
 223                         printf(MSG_INVALIDOP, op);
 224                         exit(1);
 225                 }
 226         }
 227
 228         if(printcode)
 229                 printopcode(op, x, y, z, w, label);
 230 }
 231
 232 static void readarg(int argc, char **argv) {
 233         if(argc < 3)
 234                 goto error;
 235
 236         printadr = false;
 237         printlabel = aw_printlabel;
 238         printopcode = aw_printopcode;
 239
 240         int i = 1;
 241         while((i < argc) && (argv[i][0] == '-')) {
 242                 if(strcmp("-a", argv[i]) == 0) {
 243                         printlabel = aw_printlabel;
 244                         printopcode = aw_printopcode;
 245                 } else if(strcmp("-i", argv[i]) == 0) {
 246                         printlabel = intel_printlabel;
 247                         printopcode = intel_printopcode;
 248                 } else if(strcmp("-u", argv[i]) == 0) {
 249                         printlabel = att_printlabel;
 250                         printopcode = att_printopcode;
 251                 } else if(strcmp("-p", argv[i]) == 0) {
 252                         printadr = true;
 253                 } else {
 254                         goto error;
 255                 }
 256
 257                 ++i;
 258         }
 259
 260         if((argc - i) != 2)
 261                 goto error;
 262
 263         input = argv[i];
 264         output = argv[i + 1];
 265         return;
 266
 267 error:
 268         printf(MSG_USAGE);
 269         exit(1);
 270 }
 271
 272 int main(int argc, char **argv) {
 273         readarg(argc, argv);
 274
 275         if((fp = fopen(input, "r")) == NULL) {
 276                 printf(MSG_OPENERR, input);
 277                 exit(1);
 278         }
 279
 280         fseek(fp, 0, SEEK_END);
 281         codesize = ftell(fp);
 282         fseek(fp, 0, SEEK_SET);
 283
 284         code = malloc(codesize);
 285         fread(code, codesize, 1, fp);
 286         fclose(fp);
 287
 288         if((fp = fopen(output, "w")) == NULL) {
 289                 printf(MSG_WRITEERR, output);
 290                 exit(1);
 291         }
 292
 293         labelnum = 0;
 294
 295         pc = 0;
 296         printcode = false;
 297         while(pc < codesize)
 298                 step(); /* read labels */
 299
 300         pc = 0;
 301         printcode = true;
 302         while(pc < codesize)
 303                 step(); /* print code */
 304
 305         fclose(fp);
 306         free(code);
 307
 308         return 0;
 309 }