/* * interpre.c * * Main interpreter loop * */ #include "ztypes.h" static int halt = FALSE; /* * interpret * * Interpret Z code * */ #ifdef __STDC__ int interpret () #else int interpret () #endif { zbyte_t opcode; zword_t specifier, operand[8]; int maxoperands, count, extended, i; interpreter_status = 1; /* Loop until HALT instruction executed */ for (interpreter_state = RUN; interpreter_state == RUN && halt == FALSE; ) { /* Load opcode and set operand count */ opcode = read_code_byte (); if (h_type > V4 && opcode == 0xbe) { opcode = read_code_byte (); extended = TRUE; } else extended = FALSE; count = 0; /* Multiple operand instructions */ if ((opcode < 0x80 || opcode > 0xc0) || extended == TRUE) { /* Two operand class, load both operands */ if (opcode < 0x80 && extended == FALSE) { operand[count++] = load_operand ((opcode & 0x40) ? 2 : 1); operand[count++] = load_operand ((opcode & 0x20) ? 2 : 1); opcode &= 0x1f; } else { /* Variable operand class, load operand specifier */ opcode &= 0x3f; if (opcode == 0x2c || opcode == 0x3a) { /* Extended CALL instruction */ specifier = read_code_word (); maxoperands = 8; } else { specifier = read_code_byte (); maxoperands = 4; } /* Load operands */ for (i = (maxoperands - 1) * 2; i >= 0; i -= 2) if (((specifier >> i) & 0x03) != 3) operand[count++] = load_operand ((specifier >> i) & 0x03); else i = 0; } if (extended == TRUE) switch ((char) opcode) { /* Extended operand instructions */ case 0x00: save (); break; case 0x01: restore (); break; case 0x02: shift (operand[0], operand[1]); break; case 0x03: arith_shift (operand[0], operand[1]); break; case 0x04: set_font_attribute (operand[0]); break; case 0x09: undo_save (); break; case 0x0a: undo_restore (); break; default: fatal ("Illegal operation"); } else switch ((char) opcode) { /* Two or multiple operand instructions */ case 0x01: compare_je (count, operand); break; case 0x02: compare_jl (operand[0], operand[1]); break; case 0x03: compare_jg (operand[0], operand[1]); break; case 0x04: decrement_check (operand[0], operand[1]); break; case 0x05: increment_check (operand[0], operand[1]); break; case 0x06: compare_parent_object (operand[0], operand[1]); break; case 0x07: test (operand[0], operand[1]); break; case 0x08: or (operand[0], operand[1]); break; case 0x09: and (operand[0], operand[1]); break; case 0x0a: test_attr (operand[0], operand[1]); break; case 0x0b: set_attr (operand[0], operand[1]); break; case 0x0c: clear_attr (operand[0], operand[1]); break; case 0x0d: store_variable (operand[0], operand[1]); break; case 0x0e: insert_object (operand[0], operand[1]); break; case 0x0f: load_word (operand[0], operand[1]); break; case 0x10: load_byte (operand[0], operand[1]); break; case 0x11: load_property (operand[0], operand[1]); break; case 0x12: load_property_address (operand[0], operand[1]); break; case 0x13: load_next_property (operand[0], operand[1]); break; case 0x14: add (operand[0], operand[1]); break; case 0x15: subtract (operand[0], operand[1]); break; case 0x16: multiply (operand[0], operand[1]); break; case 0x17: divide (operand[0], operand[1]); break; case 0x18: remainder (operand[0], operand[1]); break; case 0x19: call (count, operand, FUNCTION); break; case 0x1a: call (count, operand, PROCEDURE); break; case 0x1b: set_colour_attribute (operand[0], operand[1]); break; case 0x1c: unwind (operand[0], operand[1]); break; /* Multiple operand instructions */ case 0x20: call (count, operand, FUNCTION); break; case 0x21: store_word (operand[0], operand[1], operand[2]); break; case 0x22: store_byte (operand[0], operand[1], operand[2]); break; case 0x23: store_property (operand[0], operand[1], operand[2]); break; case 0x24: read_line (count, operand); break; case 0x25: print_character (operand[0]); break; case 0x26: print_number (operand[0]); break; case 0x27: zip_random (operand[0]); break; case 0x28: push_var (operand[0]); break; case 0x29: pop_var (operand[0]); break; case 0x2a: set_status_size (operand[0]); break; case 0x2b: select_window (operand[0]); break; case 0x2c: call (count, operand, FUNCTION); break; case 0x2d: erase_window (operand[0]); break; case 0x2e: erase_line (operand[0]); break; case 0x2f: set_cursor_position (operand[0], operand[1]); break; case 0x31: set_video_attribute (operand[0]); break; case 0x32: set_format_mode (operand[0]); break; case 0x33: set_print_modes (operand[0], operand[1]); break; case 0x34: open_playback (operand[0]); break; case 0x35: sound (count, operand); break; case 0x36: read_character (count, operand); break; case 0x37: scan_data (count, operand); break; case 0x38: not (operand[0]); break; case 0x39: call (count, operand, PROCEDURE); break; case 0x3a: call (count, operand, PROCEDURE); break; case 0x3b: tokenise (count, operand); break; case 0x3c: encode (operand[0], operand[1], operand[2], operand[3]); break; case 0x3d: move_data (operand[0], operand[1], operand[2]); break; case 0x3e: print_window (count, operand); break; case 0x3f: check_argument (operand[0]); break; default: fatal ("Illegal operation"); } } else { /* Single operand class, load operand and execute instruction */ if (opcode < 0xb0) { operand[0] = load_operand ((opcode >> 4) & 0x03); switch ((char) opcode & 0x0f) { case 0x00: compare_zero (operand[0]); break; case 0x01: load_next_object (operand[0]); break; case 0x02: load_child_object (operand[0]); break; case 0x03: load_parent_object (operand[0]); break; case 0x04: load_property_length (operand[0]); break; case 0x05: increment (operand[0]); break; case 0x06: decrement (operand[0]); break; case 0x07: print_offset (operand[0]); break; case 0x08: call (1, operand, FUNCTION); break; case 0x09: remove_object (operand[0]); break; case 0x0a: print_object (operand[0]); break; case 0x0b: ret (operand[0]); break; case 0x0c: jump (operand[0]); break; case 0x0d: print_address (operand[0]); break; case 0x0e: load (operand[0]); break; case 0x0f: if (h_type > V4) call (1, operand, PROCEDURE); else not (operand[0]); break; } } else { /* Zero operand class, execute instruction */ switch ((char) opcode & 0x0f) { case 0x00: ret (TRUE); break; case 0x01: ret (FALSE); break; case 0x02: print_literal (); break; case 0x03: println_return (); break; case 0x05: save (); break; case 0x06: restore (); break; case 0x07: restart (); break; case 0x08: ret (stack[sp++]); break; case 0x09: get_fp (); break; case 0x0a: halt = TRUE; break; case 0x0b: new_line (); break; case 0x0c: display_status_line (); break; case 0x0d: verify (); break; case 0x0f: conditional_jump (TRUE); break; default: fatal ("Illegal operation"); } } } } return (interpreter_status); }/* interpret */