/* * Change history * $Log: decode_ea.c,v $ * Revision 3.0 93/09/24 17:53:50 Martin_Apel * New feature: Added extra 68040 FPU opcodes * * Revision 2.5 93/07/18 22:55:43 Martin_Apel * *** empty log message *** * * Revision 2.4 93/07/11 21:38:04 Martin_Apel * Major mod.: Jump table support tested and changed * * Revision 2.3 93/07/10 13:01:56 Martin_Apel * Major mod.: Added full jump table support. Seems to work quite well * * Revision 2.2 93/07/08 22:27:46 Martin_Apel * * Minor mod.: Displacements below 4 used with pc indirect indexed are * not entered into the symbol table anymore * * Revision 2.1 93/07/08 20:47:04 Martin_Apel * Bug fix: Extended precision reals were printed wrong * * Revision 2.0 93/07/01 11:53:45 Martin_Apel * *** empty log message *** * * Revision 1.12 93/07/01 11:38:28 Martin_Apel * Minor mod.: PC relative addressing is now marked as such * * Revision 1.11 93/06/16 20:26:17 Martin_Apel * Minor mod.: Added jump table support. UNTESTED !!! * * Revision 1.10 93/06/06 13:45:34 Martin_Apel * Minor mod.: Replaced first_pass and read_symbols by pass1, pass2, pass3 * * Revision 1.9 93/06/03 18:22:12 Martin_Apel * Minor mod.: Addressing relative to hunk end changed * */ #include #include #include #include "defs.h" static char rcsid [] = "$Id: decode_ea.c,v 3.0 93/09/24 17:53:50 Martin_Apel Exp $"; int decode_ea (short mode, short reg, char *where_to, short access, short first_ext) /* returns the number of extension words used for ea */ { ULONG ref; register UWORD first_word; /* Used for jump table disassembly */ static ULONG last_code_reference = UNSET; if (pass2 && mode <= 4) return (0); first_word = *(code + first_ext); switch (mode) { /********************** data register direct ************************/ case 0: strcpy (where_to, reg_names [reg]); return (0); /********************* address register direct **********************/ case 1: if (access & ACC_BYTE) { detected_illegal = TRUE; return (0); } strcpy (where_to, reg_names [reg + 8]); return (0); /********************** address register indirect *******************/ case 2: indirect (where_to, (short)(reg + 8)); return (0); /************ address register indirect post-increment **************/ case 3: post_inc (where_to, (short)(reg + 8)); return (0); /************* address register indirect pre-decrement **************/ case 4: pre_dec (where_to, (short)(reg + 8)); return (0); /************* address register indirect with displacement **********/ case 5: if (try_small && reg == 4) { ref = (short)first_word + a4_offset; if (pass3) gen_label (where_to, ref, TRUE); else enter_ref (ref, 0L, access); } else if (pass3) disp_an (where_to, (short)(reg + 8), (short)first_word); return (1); /****************** address register indirect indexed ***************/ case 6: if (first_word & 0x100) { if (mc68020 && ext_68020_modes) return (full_extension (where_to, code + first_ext, mode, reg)); else { detected_illegal = TRUE; return (0); } } else { short size = (first_word >> 9) & 0x3; if (!mc68020 && size != 0) /* Only size of 1 allowed for 68000 */ { detected_illegal = TRUE; return (0); } if (pass3) { /* To get the sign right */ disp_an_indexed (where_to, (short)(reg + 8), (char)first_word, (short)(first_word >> 12), (short)(1 << size), (first_word & 0x0800) ? ACC_LONG : ACC_WORD); } return (1); } /************************* Mode 7 with submodes *********************/ case 7: switch (reg) { /*********************** absolute short *********************/ case 0: if (pass3) format_d (where_to, first_word, FALSE); return (1); /*********************** absolute long **********************/ case 1: ref = (first_word << 16) + *(code + first_ext + 1); if (IS_RELOCATED (current_address + first_ext * 2)) { if (pass2) { enter_ref (ref, NULL, access); if (ref >= first_address && ref < last_address && EVEN (ref)) last_code_reference = ref; } else /* This reference is relocated and thus needs a label */ gen_label (where_to, ref, TRUE); } else if (pass3) format_ld (where_to, ref, FALSE); return (2); /************************** d16(PC) *************************/ case 2: /* It's possible, that a program accesses its hunk structure PC relative, thus it generates a reference to a location outside valid code addresses */ ref = current_address + 2 + (short)first_word; if (pass3) { if ((long)ref < (long)first_address) { gen_label (where_to, first_address, TRUE); strcat (where_to, "-"); format_ld (where_to + strlen (where_to), *(hunk_start + current_hunk) - ref, TRUE); } else if (ref >= last_address) { gen_label (where_to, last_address, TRUE); strcat (where_to, "+"); format_ld (where_to + strlen (where_to), ref - *(hunk_end + current_hunk), TRUE); } else gen_label (where_to, ref, TRUE); strcat (where_to, "("); strcat (where_to, reg_names [PC]); strcat (where_to, ")"); } else if (ref >= first_address && ref < last_address) { enter_ref (ref, NULL, access); if (EVEN (ref)) last_code_reference = ref; } return (1); /***************** PC memory indirect with index ************/ case 3: if (first_word & 0x0100) { /* long extension word */ if (mc68020 && ext_68020_modes) return (full_extension (where_to, code + first_ext, mode, reg)); else { detected_illegal = TRUE; return (0); } } else { /* short extension word */ short size = (first_word >> 9) & 0x3; if (!mc68020 && size != 0) /* Only size of 1 allowed for 68000 */ { detected_illegal = TRUE; return (0); } if (pass3) disp_an_indexed (where_to, PC, (char)first_word, (short)(first_word >> 12), (short)(1 << size), (first_word & 0x0800) ? ACC_LONG : ACC_WORD); else { ref = current_address + (char)first_word + 2; /* Check for JMP (PC,Dx) opcode */ if (*code == 0x4efb) { enter_jmptab (last_code_reference, (ULONG)((char)first_word)); enter_ref (current_address, NULL, ACC_CODE); } else { if (ref >= first_address && ref < last_address) { enter_ref (ref, NULL, access); last_code_reference = ref; } } } return (1); } /************************ immediate *************************/ case 4: if (access & ACC_BYTE) { if (pass3) { *where_to = '#'; format_d (where_to + 1, (short)(first_word & 0xff), TRUE); } return (1); } else if (access & ACC_WORD) { if (pass3) { *where_to = '#'; format_d (where_to + 1, (short)first_word, TRUE); } return (1); } else if (access & ACC_LONG) { ref = (first_word << 16) + *(code + first_ext + 1); if (IS_RELOCATED (current_address + first_ext * 2)) { if (pass2) { enter_ref (ref, NULL, access); if (ref >= first_address && ref < last_address && EVEN (ref)) last_code_reference = ref; } else { /* This reference is relocated and thus needs a label */ *where_to++ = '#'; *where_to++ = '('; gen_label (where_to, ref, TRUE); strcat (where_to, ")"); } } else if (pass3) { *where_to = '#'; format_ld (where_to + 1, ref, TRUE); } return (2); } else if (access & ACC_DOUBLE) { if (pass3) { sprintf (where_to, "#$%lx%08lx", *(ULONG*)(code + first_ext), *(ULONG*)(code + first_ext + 2)); } return (4); } else if (access & ACC_EXTEND) { if (pass3) { sprintf (where_to, "#$%lx%08lx%08lx", *(ULONG*)(code + first_ext), *(ULONG*)(code + first_ext + 2), *(ULONG*)(code + first_ext + 4)); } return (6); } else { fprintf (stderr, "INTERNAL ERROR: decode_ea: immediate addressing with unknown size\n"); fprintf (stderr, " Current address is: %lx\n", current_address); } break; default: /* Should not occur, as it should be caught by the submode test in disasm.c */ detected_illegal = TRUE; fprintf (stderr, "INTERNAL ERROR: decode_ea: illegal submode\n"); fprintf (stderr, " Current address is: %lx\n", current_address); } break; } return (0); }