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490 lines
23 KiB
OpenEdge ABL
490 lines
23 KiB
OpenEdge ABL
{
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Created: Wednesday, November 1, 1989
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DisAsmLookup.p
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Pascal Interface to the Macintosh Libraries
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Copyright Apple Computer, Inc. 1987-1991
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All rights reserved
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This file is used in these builds: ROM System
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Change History (most recent first):
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<3> 8/8/91 JL Updated Copyright.
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<2> 3/13/91 JL Checked in MPW version.
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To Do:
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}
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{$IFC UNDEFINED UsingIncludes}
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{$SETC UsingIncludes := 0}
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{$ENDC}
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{$IFC NOT UsingIncludes}
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UNIT DisAsmLookup;
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INTERFACE
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{$ENDC}
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{$IFC UNDEFINED UsingDisAsmLookup}
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{$SETC UsingDisAsmLookup := 1}
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{$I+}
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{$SETC DisAsmLookupIncludes := UsingIncludes}
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{$SETC UsingIncludes := 1}
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{$IFC UNDEFINED UsingTypes}
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{$I $$Shell(PInterfaces)Types.p}
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{$ENDC}
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{$SETC UsingIncludes := DisAsmLookupIncludes}
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TYPE
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LookupRegs = (_A0_, _A1_, _A2_, _A3_, _A4_, _A5_, _A6_, _A7_,
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_PC_, _ABS_, _TRAP_, _IMM_);
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(*----------------------------------------------------------------------*)
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PROCEDURE Disassembler( DstAdjust: LongInt; {addr correction}
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VAR BytesUsed: Integer; {bytes used up }
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FirstByte: UNIV Ptr; {starting byte }
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VAR Opcode: UNIV Str255; {mnemonic }
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VAR Operand: UNIV Str255; {operand }
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VAR Comment: UNIV Str255; {comment }
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LookupProc: UNIV Ptr); {search proc }
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(*
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Disassembler is a Pascal routine to be called to disassemble a sequence
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of bytes. All MC68xxx, MC68881, and MC68851 instructions are supported.
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The sequence of bytes to be disassembled are pointed to by FirstByte.
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BytesUsed bytes starting at FirstByte are consumed by the disassembly,
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and the Opcode, Operand, and Comment strings returned as NULL TERMINATED
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Pascal strings (for easier manipulation with C). The caller is then free
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to format or use the output strings any way appropriate to the
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application.
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Depending on the opcode and effective address(s) (EA's) to be
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disassembled, the Opcode, Operand, and Comment strings contain the
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following information:
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Case Opcode Operand Comment
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=======================================================================
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Non PC-relative EA's op.sz EA's ; 'c<>' (for immediates)
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PC-relative EA's op.sz EA's ; address
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Toolbox traps DC.W $AXXX ; TB XXXX
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OS traps DC.W $AXXX ; OS XXXX
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Invalid bytes DC.W $XXXX ; ????
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=======================================================================
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For valid disassembly of processor instructions the appropriate MC68XXX
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opcode mnemonic is generated for the Opcode string along with a size
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attribute when required. The source and destination EA's are generated
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as the Operand along with a possible comment. Comments start with a ';'.
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Traps use a DC.W assembler directive as the Opcode with the trap word
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as the Operand and a comment indicating whether the trap is a toolbox or
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OS trap and what the trap number is. As described later the caller can
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generate symbolic substitutions into EA's and provide names for traps.
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Invalid instructions cause the string 'DC.W' to be returned in the
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Opcode string. Operand is '$XXXX' (the invalid word) with a comment of
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'; ????'. BytesUsed is 2. This is similar to the trap call case except
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for the comment.
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Note, the Operand EA's is syntatically similar to but NOT COMPATIBLE
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with the MPW assembler! This is because the Disassembler generates
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byte hex constants as "$XX" and word hex constants as "$XXXX". Negative
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values (e.g., $FF or $FFFF) produced by the Disassembler are treated as
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long word values by the MPW assembler. Thus it is assumed that
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Disassembler output will NOT be used as MPW assembler input. If that is
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the goal, then the caller must convert strings of the form $XX or $XXXX
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in the Operand string to their decimal equivalent. The routine
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ModifyOperand is provided in this unit to aid with the conversion
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process.
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Since a PC-relative comment is an address, the only address that the
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Disassembler knows about is the address of the code pointed to by
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FirstByte. Generally, that may be a buffer that has no relation to
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"reality", i.e., the actual code loaded into the buffer. Therefore,
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to allow the address comment to be mapped back to some actual address
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the caller may specify an adjustment factor, specified by DstAdjust,
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that is ADDED to the value that normally would be placed in the
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comment.
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Operand effective address strings are generated as a function of the
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effective address mode and a special case is made for A-trap opcode
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strings. In places where a possible symbolic reference could be
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substituted for an address (or a portion of an address), the Disassembler
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can call a user specified routine to do the substitution (using the
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LookupProc parameter described later). The following table summarizes
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the generated effective addresses and where symbolic substitutions (S)
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can be made:
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Mode Generated Effective Address Effective Address with Substitution
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========================================================================
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0 Dn Dn
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1 An An
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2 (An) (An)
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3 (An)+ (An)+
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4 -(An) -(An)
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5 <EFBFBD>(An) S(An) or just S (if An=A5, <EFBFBD><EFBFBD>0)
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6n <EFBFBD>(An,Xn.Size*Scale) S(An,Xn.Size*Scale)
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6n (BD,An,Xn.Size*Scale) (S,An,Xn.Size*Scale)
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6n ([BD,An],Xm.Size*Scale,OD) ([S,An],Xm.Size*Scale,OD)
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6n ([BD,An,Xn.Size*Scale],OD) ([S,An,Xn.Size*Scale],OD)
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70 <EFBFBD> S
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71 <EFBFBD> S
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72 *<EFBFBD><EFBFBD> S
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73 *<EFBFBD><EFBFBD>(Xn.Size*Scale) S(Xn.Size*Scale)
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73 (*<EFBFBD><EFBFBD>,Xn.Size*Scale) (S,Xn.Size*Scale)
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73 ([*<EFBFBD><EFBFBD>],Xm.Size*Scale,OD) ([S],Xm.Size*Scale,OD)
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73 ([*<EFBFBD><EFBFBD>,Xn.Size*Scale],OD) ([S,Xn.Size*Scale],OD)
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74 #data S (#data made comment)
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A-traps $AXXX S (as opcode, AXXX made comment)
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========================================================================
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For A-traps, the substitution can be performed to substitute for the DC.W
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opcode string. If the substitution is made then the Disassembler will
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generate ,Sys and/or ,Immed flags as operands for Toolbox traps and
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,AutoPop for OS traps when the bits in the trap word indicates these
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settings.
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| Generated | Substituted
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| Opcode Operand Comment | Opcode Operand Comment
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========================================================================
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Toolbox | DC.W $AXXX ; TB XXXX | S [,Sys][,Immed] ; AXXX
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OS | DC.W $AXXX ; OS XXXX | S [,AutoPop] ; AXXX
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========================================================================
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All displacements (<EFBFBD>, BD, OD) are hexadecimal values shown as a byte
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($XX), word ($XXXX), or long ($XXXXXXXX) as appropriate. The *Scale is
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suppressed if 1. The Size is W or L. Note that effective address
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substitutions can only be made for "<22>(An)", "BD,An", and "*<2A><>" cases.
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For all the effective address modes 5, 6n, 7n, and for A-traps, a
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coroutine (a procedure) whose address is specified by the LookupProc
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parameter is called by the Disassembler (if LookupProc is not NIL) to
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do the substitution (or A-trap comment) with a string returned by the
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proc. It is assumed that the proc pointed to by LookupProc is a level 1
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Pascal proc declared as follows:
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PROCEDURE Lookup( PC: UNIV Ptr; {Addr of extension/trap word}
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BaseReg: LookupRegs; {Base register/lookup mode }
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Opnd: UNIV LongInt; {Trap word, PC addr, disp. }
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VAR S: Str255); {Returned substitution }
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or in C,
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pascal void LookUp(Ptr PC, /* Addr of extension/trap word */
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LookupRegs BaseReg, /* Base register/lookup mode */
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long Opnd, /* Trap word, PC addr, disp. */
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char *S); /* Returned substitution */
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PC = Pointer to instruction extension word or A-trap word in the
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buffer pointed to by the Disassembler's FirstByte parameter.
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BaseReg = This determines the meaning of the Opnd value and supplies
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the base register for the "<22>(An)", "BD,An", and "*<2A><>" cases.
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BaseReg may contain any one of the following values:
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_A0_ = 0 ==> A0
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_A1_ = 1 ==> A1
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_A2_ = 2 ==> A2
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_A3_ = 3 ==> A3
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_A4_ = 4 ==> A4
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_A5_ = 5 ==> A5
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_A6_ = 6 ==> A6
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_A7_ = 7 ==> A7
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_PC_ = 8 ==> PC-relative (special case)
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_ABS_ = 9 ==> Abs addr (special case)
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_TRAP_ = 10 ==> Trap word (special case)
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_IMM_ = 11 ==> Immediate (special case)
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For absolute addressing (modes 70 and 71), BaseReg contains
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_ABS_. For A-traps, BaseReg would contain _TRAP_. For
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immediate data (mode 74), BaseReg would contain _IMM_.
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Opnd = The contents of this LongInt is determined by the BaseReg
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parameter just described.
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For BaseReg = _IMM_ (immediate data):
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Opnd contains the (extended) 32-bit immediate data specified
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by the instruction.
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For BaseReg = _TRAP_ (A-traps):
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Opnd is the entire trap word. The high order 16 bits of
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Opnd are zero.
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For BaseReg = _ABS_ (absolute effective address):
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Opnd contains the (extended) 32-bit address specifed by
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the instruction's effective address. Such addresses would
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generally be used to reference low memory globals on a
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Macintosh.
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For BaseReg = _PC_ (PC-relative effective address):
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Opnd contains the 32-bit address represented by "*<2A><>"
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adjusted by the Disassembler's DstAdjust parameter.
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For BaseReg = _An_ (effective address with a base register):
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Opnd contains the (sign-extended) 32-bit (base)
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displacement from the instruction's effective address.
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In the Macintosh environment, a BaseReg specifying A5
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implies either global data references or Jump Table
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references. Positive Opnd values with an A5 BaseReg thus
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mean Jump Table references, while a negative offset would
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mean a global data reference. Base registers of A6 or A7
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would usually mean local data.
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S = Pascal string returned from Lookup containing the effective
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address substitution string or a trap name for A-traps. S is
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set to null PRIOR to calling Lookup. If it is still null on
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return, the string is not used. If not null, then for A-traps,
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the returned string is used as the opcode string. In all other
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cases the string is substituted as shown in the above table.
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Depending on the application, the caller has three choices on how to
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use the Disassembler and an associated Lookup proc:
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(1). The caller can call just the Disassembler and provide his own Lookup
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proc. In that case the calling conventions discussed above must be
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followed.
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(2). The caller can provide NIL for the LookupProc parameter, in which
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case, NO Lookup proc will be called.
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(3). The caller can call first InitLookup (described below, a proc
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provided with this unit) and pass the address of this unit's
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standard Lookup proc when Disassembler is called. In this case all
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the control logic to determine the kind of substitution to be done
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is provided for the caller and all that need to be provided by the
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user are routines to look up any or all of the following:
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<09> PC-relative references
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<09> Jump Table references
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<09> Absolute address references
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<09> Trap names
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<09> Immediate data names
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<09> References with offsets from base registers *)
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PROCEDURE InitLookup(PCRelProc, JTOffProc, TrapProc, AbsAddrProc, IdProc, ImmDataProc: UNIV Ptr);
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{Prepare for use of this unit's Lookup proc. When Disassembler is called
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and the address of this unit's Lookup proc is specified, then for immediate
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data, PC-relative, Jump Table references, A-traps, absolute addresses, and
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offsets from a base register, the associated level 1 Pascal proc
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specified here is called (if not NIL -- all six addresses are preset to
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NIL). The calls assume the following declarations for these procs (see
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Lookup, below for further details):
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PROCEDURE PCRelProc(Address: UNIV LongInt;
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VAR S: UNIV Str255);
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PROCEDURE JTOffProc(A5JTOffset: UNIV Integer;
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VAR S: UNIV Str255);
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PROCEDURE TrapNameProc(TrapWord: UNIV Integer;
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VAR S: UNIV Str255);
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PROCEDURE AbsAddrProc(AbsAddr: UNIV LongInt;
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VAR S: UNIV Str255);
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PROCEDURE IdProc(BaseReg: LookupRegs;
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Offset: UNIV LongInt;
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VAR S: UNIV Str255);
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PROCEDURE ImmDataProc(ImmData: UNIV LongInt;
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VAR S: UNIV Str255);
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Note: InitLookup contains initialized data which requires initializing
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at load time (this is of concern only to users with assembler
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main programs.}
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PROCEDURE Lookup( PC: UNIV Ptr; {Addr of extension/trap word}
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BaseReg: LookupRegs; {Base register/lookup mode }
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Opnd: UNIV LongInt; {Trap word, PC addr, disp. }
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VAR S: Str255); {Returned substitution }
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{This is a standard Lookup proc available to the caller for calls to the
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Disassembler. If the caller elects to use this proc, then InitLookup
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MUST be called prior to any calls to the Disassembler. All the logic
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to determine the type of lookup is done by this proc. For PC-relative,
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Jump Table references, A-traps, absolute addresses, and offsets from a
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base register, the associated level 1 Pascal proc specified in the
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InitLookup call (if not NIL) is called.
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This scheme simplifies the Lookup mechanism by allowing the caller
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to deal with just the problems related to the application.}
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PROCEDURE LookupTrapName(TrapWord: UNIV Integer;
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VAR S: UNIV Str255);
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{This is a procedure provided to allow conversion of a trap instruction
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(in TrapWord) to its corresponding trap name (in S). It is provided
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primarily for use with the Disassembler and its address may be passed to
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InitLookup above for use by this unit's Lookup routine. Alternatively,
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there is nothing prohibiting the caller from using it directly for other
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purposes or by some other Lookup proc.
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Note: The tables in this proc make the size of this proc about 9500
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bytes. The trap names are fully spelled out in upper and lower
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case.}
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PROCEDURE ModifyOperand(VAR Operand: UNIV Str255);
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{Scan an operand string, i.e., the null terminated Pascal string returned
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by the Disassembler (null MUST be present here) and modify negative hex
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values to negated positive value. For example, $FFFF(A5) would be
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modified to -$0001(A5). The operand to be processed is passed as the
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function's parameter which is edited "in place" and returned to the
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caller.
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This routine is essentially a pattern matcher and attempts to only
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modify 2, 4, and 8 digit hex strings in the operand that "might" be
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offsets from a base register. If the matching tests are passed, the
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same number of original digits are output (because that indicates a
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value's size -- byte, word, or long).
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For a hex string to be modified, the following tests must be passed:
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<EFBFBD> There must have been exactly 2, 4, or 8 digits.
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Only hex strings $XX, $XXXX, and $XXXXXXXX are possible candidates
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because that is the only way the Disassembler generates offsets.
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<EFBFBD> Hex string must be delimited by a "(" or a ",".
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The "(" allows offsets for $XXXX(An,...) and $XX(An,Xn) addressing
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modes. The comma allows for the MC68020 addressing forms.
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<EFBFBD> The "$X..." must NOT be preceded by a "<22>".
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This eliminates the possibility of modifying the offset of a
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PC-relative addressing mode always generated in the form "*<2A>$XXXX".
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<EFBFBD> The "$X..." must NOT be preceded by a "#".
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This eliminates modifying immediate data.
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<EFBFBD> Value must be negative.
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Negative values are the only values we modify. A value $FFFF is
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modified to -$0001.}
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FUNCTION validMacsBugSymbol(symStart, limit: UNIV Ptr;
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symbol: StringPtr): StringPtr; C;
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{Check that the bytes pointed to by symStart represents a valid MacsBug
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symbol. The symbol must be fully contained in the bytes starting at
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symStart, up to, but not including, the byte pointed to by the limit
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parameter.
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If a valid symbol is NOT found, then NIL is returned as the function's
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result. However, if a valid symbol is found, it is copied to symbol (if
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it is not NIL) as a null terminated Pascal string, and return a pointer
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to where we think the FOLLOWING module begins. In the "old style" cases
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(see below) this will always be 8 or 16 bytes after the input symStart.
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For new style Apple Pascal and C cases this will depend on the symbol
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length, existence of a pad byte, and size of the constant (literal) area.
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In all cases, trailing blanks are removed from the symbol.
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A valid MacsBug symbol consists of the characters '_', '%', spaces,
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digits, and upper/lower case letters in a format determined by the first
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two bytes of the symbol as follows:
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1st byte | 2nd byte | Byte |
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Range | Range | Length | Comments
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=======================================================================
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$20 - $7F | $20 - $7F | 8 | "Old style" MacsBug symbol format
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$A0 - $7F | $20 - $7F | 8 | "Old style" MacsBug symbol format
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-----------------------------------------------------------------------
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$20 - $7F | $80 - $FF | 16 | "Old style" MacApp symbol ab==>b.a
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$A0 - $7F | $80 - $FF | 16 | "Old style" MacApp symbol ab==>b.a
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-----------------------------------------------------------------------
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$80 | $01 - $FF | n | n = 2nd byte (Apple symbol)
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$81 - $9F | $00 - $FF | m | m = BAnd(1st byte,$7F) (Apple symbol)
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=======================================================================
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The formats are determined by whether bit 7 is set in the first and
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second bytes. This bit will removed when we find it or'ed into the first
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and/or second valid symbol characters.
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The first two formats in the above table are the basic "old style" (pre-
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existing) MacsBug formats. The first byte may or may not have bit 7 set
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the second byte is a valid symbol character. The first byte (with bit 7
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removed) and the next 7 bytes are assumed to comprise the symbol.
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The second pair of formats are also "old style" formats, but used for
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MacApp symbols. Bit 7 set in the second character indicates these
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formats. The symbol is assumed to be 16 bytes with the second 8 bytes
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preceding the first 8 bytes in the generated symbol. For example,
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12345678abcdefgh represents the symbol abcdefgh.12345678.
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The last pair of formats are reserved by Apple and generated by the MPW
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Pascal and C compilers. In these cases the value of the first byte is
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always between $80 and $9F, or with bit 7 removed, between $00 and $1F.
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For $00, the second byte is the length of the symbol with that many bytes
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following the second byte (thus a max length of 255). Values $01 to $1F
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represent the length itself. A pad byte may follow these variable length
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cases if the symbol does not end on a word boundary. Following the
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symbol and the possible pad byte is a word containing the size of the
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constants (literals) generated by the compiler.
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Note that if symStart actually does point to a valid MacsBug symbol,
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then you may use showMacsBugSymbol to convert the MacsBug symbol bytes to
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a string that could be used as a DC.B operand for disassembly purposes.
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This string explicitly shows the MacsBug symbol encodings.}
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FUNCTION endOfModule(address, limit: UNIV Ptr; symbol: StringPtr;
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VAR nextModule: UNIV Ptr): StringPtr; C;
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{Check to see if the specified memory address, contains a RTS, JMP (A0) or
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RTD #n instruction immediately followed by a valid MacsBug symbol. These
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||
sequences are the only ones which can determine an end of module when
|
||
MacsBug symbols are present. During the check, the instruction and its
|
||
following MacsBug symbol must be fully contained in the bytes starting at
|
||
the specified address parameter, up to, but not including, the byte
|
||
pointed to by the limit parameter.
|
||
|
||
If the end of module is NOT found, then NIL is returned as the
|
||
function's result. However, if a end of module is found, the MacsBug
|
||
symbol is returned in symbol (if it is not NIL) as a null terminated
|
||
Pascal string (with trailing blanks removed), and the functions returns
|
||
the pointer to the start of the MacsBug symbol (i.e., address+2 for RTS
|
||
or JMP (A0) and address+4 for RTD #n). This address may then be used as
|
||
in input parameter to showMacsBugSymbol to convert the MacsBug symbol to
|
||
a Disassembler operand string.
|
||
|
||
Also returned in nextModule is where we think the FOLLOWING module
|
||
begins. In the "old style" cases (see validMacsBugSymbol) this will
|
||
always be 8 or 16 bytes after the input address. For new style the
|
||
Apple Pascal and C cases this will depend on the symbol length, existence
|
||
of a pad byte, and size of the constant (literal) area. See
|
||
validMacsBugSymbol for a description of valid MacsBug symbol formats.}
|
||
|
||
FUNCTION showMacsBugSymbol(symStart, limit: UNIV Ptr; operand: StringPtr;
|
||
VAR bytesUsed: Integer): StringPtr; C;
|
||
{Format a MacsBug symbol as a operand of a DC.B directive. The first one
|
||
or two bytes of the symbol are generated as $80+'c' if they have there
|
||
high high bits set. All other characters are shown as characters in a
|
||
string constant. The pad byte, if present, is one is also shown as $00.
|
||
|
||
When called, showMacsBugSymbol assumes that symStart is pointing at a
|
||
valid MacsBug symbol as validated by the validMacsBugSymbol or
|
||
endOfModule routines. As with validMacsBugSymbol, the symbol must be
|
||
fully contained in the bytes starting at symStart up to, but not
|
||
including, the byte pointed to by the limit parameter.
|
||
|
||
The string is returned in the 'operand' parameter as a null terminated
|
||
Pascal string. The function also returns a pointer to this string as its
|
||
return value (NIL is returned only if the byte pointed to by the limit
|
||
parameter is reached prior to processing the entire symbol -- which
|
||
should not happen if properly validated). The number of bytes used for
|
||
the symbol is returned in bytesUsed. Due to the way MacsBug symbols are
|
||
encoded, bytesUsed may not necessarily be the same as the length of the
|
||
operand string.
|
||
|
||
A valid MacsBug symbol consists of the characters '_', '%', spaces,
|
||
digits, and upper/lower case letters in a format determined by the first
|
||
two bytes of the symbol as described in the validMacsBugSymbol routine.}
|
||
|
||
{$ENDC} { UsingDisAsmLookup }
|
||
|
||
{$IFC NOT UsingIncludes}
|
||
END.
|
||
{$ENDC}
|
||
|