Developer CD Series 1992 June: ROMin Holiday/ADC Developer CD (1992-06) (''ROMin Holiday'')_iso/Developer Connection - 06-1992.iso/Developer Essentials/MPW Interfaces & Libraries/PInterfaces/DisAsmLookup.p

Text File | 1992-01-29 | 22.6 KB | 481 lines | [TEXT/MPS ]

{
    Created: Wednesday, November 1, 1989
    DisAsmLookup.p
    Pascal Interface to the Macintosh Libraries

    Copyright Apple Computer, Inc.    1987-1991
    All rights reserved
}

{$IFC UNDEFINED UsingIncludes}
{$SETC UsingIncludes := 0}
{$ENDC}

{$IFC NOT UsingIncludes}
    UNIT DisAsmLookup;
    INTERFACE
{$ENDC}

{$IFC UNDEFINED UsingDisAsmLookup}
{$SETC UsingDisAsmLookup := 1}

{$I+}
{$SETC DisAsmLookupIncludes := UsingIncludes}
{$SETC UsingIncludes := 1}
{$IFC UNDEFINED UsingTypes}
{$I $$Shell(PInterfaces)Types.p}
{$ENDC}
{$SETC UsingIncludes := DisAsmLookupIncludes}


TYPE
    LookupRegs    = (_A0_, _A1_, _A2_, _A3_, _A4_, _A5_, _A6_, _A7_,
                                 _PC_, _ABS_, _TRAP_, _IMM_);

(*----------------------------------------------------------------------*)

PROCEDURE Disassembler(      DstAdjust:  LongInt;                  {addr correction}
                                             VAR BytesUsed:  Integer;                  {bytes used up  }
                                                     FirstByte:  UNIV Ptr;                 {starting byte  }
                                             VAR Opcode:         UNIV Str255;          {mnemonic             }
                                             VAR Operand:      UNIV Str255;        {operand        }
                                             VAR Comment:      UNIV Str255;          {comment        }
                                                     LookupProc: UNIV Ptr);              {search proc    }
    (*
     Disassembler is a Pascal routine to be called to disassemble a sequence
     of bytes.  All MC68xxx, MC68881, and MC68851 instructions are supported.
     The sequence of bytes to be disassembled are pointed to by FirstByte.
     BytesUsed bytes starting at FirstByte are consumed by the disassembly,
     and the Opcode, Operand, and Comment strings returned as NULL TERMINATED
     Pascal strings (for easier manipulation with C). The caller is then free
     to format or use the output strings any way appropriate to the
     application.

     Depending on the opcode and effective address(s) (EA's) to be
     disassembled, the Opcode, Operand, and Comment strings contain the
     following information:

     Case                     Opcode    Operand    Comment
     =======================================================================
     Non PC-relative EA's     op.sz     EA's             ; 'c…' (for immediates)
     PC-relative EA's         op.sz     EA's       ; address
     Toolbox traps            DC.W      $AXXX      ; TB XXXX
     OS traps                 DC.W      $AXXX      ; OS XXXX
     Invalid bytes            DC.W      $XXXX      ; ????
     =======================================================================

     For valid disassembly of processor instructions the appropriate MC68XXX
     opcode mnemonic is generated for the Opcode string along with a size
     attribute when required.  The source and destination EA's are generated
     as the Operand along with a possible comment. Comments start with a ';'.
     Traps use a DC.W assembler directive as the Opcode with the trap word
     as the Operand and a comment indicating whether the trap is a toolbox or
     OS trap and what the trap number is.  As described later the caller can
     generate symbolic substitutions into EA's and provide names for traps.

     Invalid instructions cause the string 'DC.W' to be returned in the
     Opcode string. Operand is '$XXXX' (the invalid word) with a comment of
     '; ????'.  BytesUsed is 2.  This is similar to the trap call case except
     for the comment.

     Note, the Operand EA's is syntatically similar to but NOT COMPATIBLE
     with the MPW assembler!    This is because the Disassembler generates
     byte hex constants as "$XX" and word hex constants as "$XXXX".  Negative
     values (e.g., $FF or $FFFF) produced by the Disassembler are treated as
     long word values by the MPW assembler.  Thus it is assumed that
     Disassembler output will NOT be used as MPW assembler input.  If that is
     the goal, then the caller must convert strings of the form $XX or $XXXX
     in the Operand string to their decimal equivalent.  The routine
     ModifyOperand is provided in this unit to aid with the conversion
     process.

     Since a PC-relative comment is an address, the only address that the
     Disassembler knows about is the address of the code pointed to by
     FirstByte.  Generally, that may be a buffer that has no relation to
     "reality", i.e., the actual code loaded into the buffer.  Therefore,
     to allow the address comment to be mapped back to some actual address
     the caller may specify an adjustment factor, specified by DstAdjust,
     that is ADDED to the value that normally would be placed in the
     comment.

     Operand effective address strings are generated as a function of the
     effective address mode and a special case is made for A-trap opcode
     strings. In places where a possible symbolic reference could be
     substituted for an address (or a portion of an address), the Disassembler
     can call a user specified routine to do the substitution (using the
     LookupProc parameter described later).  The following table summarizes
     the generated effective addresses and where symbolic substitutions (S)
     can be made:

     Mode    Generated Effective Address  Effective Address with Substitution
     ========================================================================
         0     Dn                           Dn
         1     An                           An
         2     (An)                         (An)
         3     (An)+                        (An)+
         4     -(An)                        -(An)
         5     ∂(An)                        S(An) or just S (if An=A5, ∂≥0)
        6n     ∂(An,Xn.Size*Scale)          S(An,Xn.Size*Scale)
        6n     (BD,An,Xn.Size*Scale)        (S,An,Xn.Size*Scale)
        6n     ([BD,An],Xm.Size*Scale,OD)   ([S,An],Xm.Size*Scale,OD)
        6n     ([BD,An,Xn.Size*Scale],OD)   ([S,An,Xn.Size*Scale],OD)
        70     ∂                            S
        71     ∂                            S
        72     *±∂                          S
        73     *±∂(Xn.Size*Scale)           S(Xn.Size*Scale)
        73     (*±∂,Xn.Size*Scale)          (S,Xn.Size*Scale)
        73     ([*±∂],Xm.Size*Scale,OD)     ([S],Xm.Size*Scale,OD)
        73     ([*±∂,Xn.Size*Scale],OD)     ([S,Xn.Size*Scale],OD)
        74     #data                        S (#data made comment)
     A-traps $AXXX                        S (as opcode, AXXX made comment)
     ========================================================================

     For A-traps, the substitution can be performed to substitute for the DC.W
     opcode string.  If the substitution is made then the Disassembler will
     generate ,Sys and/or ,Immed flags as operands for Toolbox traps and
     ,AutoPop for OS traps when the bits in the trap word indicates these
     settings.

                     |         Generated          |            Substituted
                     | Opcode  Operand  Comment   | Opcode  Operand        Comment
     ========================================================================
     Toolbox | DC.W    $AXXX    ; TB XXXX | S       [,Sys][,Immed] ; AXXX
     OS      | DC.W    $AXXX    ; OS XXXX | S       [,AutoPop]     ; AXXX
     ========================================================================

     All displacements (∂, BD, OD) are hexadecimal values shown as a byte
     ($XX), word ($XXXX), or long ($XXXXXXXX) as appropriate.  The *Scale is
     suppressed if 1. The Size is W or L.  Note that effective address
     substitutions can only be made for "∂(An)", "BD,An", and "*±∂" cases.

     For all the effective address modes 5, 6n, 7n, and for A-traps, a
     coroutine (a procedure) whose address is specified by the LookupProc
     parameter is called by the Disassembler (if LookupProc is not NIL) to
     do the substitution (or A-trap comment) with a string returned by the
     proc.  It is assumed that the proc pointed to by LookupProc is a level 1
     Pascal proc declared as follows:

     PROCEDURE Lookup(        PC:      UNIV Ptr;     {Addr of extension/trap word}
                                                BaseReg: LookupRegs;   {Base register/lookup mode  }
                                                Opnd:    UNIV LongInt; {Trap word, PC addr, disp.  }
                                        VAR S:       Str255);          {Returned substitution      }

     or in C,

     pascal void LookUp(Ptr         PC,      /* Addr of extension/trap word */
                                            LookupRegs  BaseReg, /* Base register/lookup mode   */
                                            long        Opnd,    /* Trap word, PC addr, disp.   */
                                            char              *S);     /* Returned substitution       */

     PC      = Pointer to instruction extension word or A-trap word in the
                         buffer pointed to by the Disassembler's FirstByte parameter.

     BaseReg = This determines the meaning of the Opnd value and supplies
                         the base register for the "∂(An)", "BD,An", and "*±∂" cases.
                         BaseReg may contain any one of the following values:

                         _A0_    =  0 ==> A0
                         _A1_    =  1 ==> A1
                         _A2_    =  2 ==> A2
                         _A3_    =  3 ==> A3
                         _A4_    =  4 ==> A4
                         _A5_    =  5 ==> A5
                         _A6_    =  6 ==> A6
                         _A7_    =  7 ==> A7
                         _PC_    =  8 ==> PC-relative (special case)
                         _ABS_   =  9 ==> Abs addr    (special case)
                         _TRAP_  = 10 ==> Trap word   (special case)
                         _IMM_     = 11 ==> Immediate   (special case)

                         For absolute addressing (modes 70 and 71), BaseReg contains
                         _ABS_.  For A-traps, BaseReg would contain _TRAP_.  For
                         immediate data (mode 74), BaseReg would contain _IMM_.

     Opnd    = The contents of this LongInt is determined by the BaseReg
                         parameter just described.

                         For BaseReg = _IMM_ (immediate data):
                                 Opnd contains the (extended) 32-bit immediate data specified
                                 by the instruction.

                         For BaseReg = _TRAP_ (A-traps):
                                 Opnd is the entire trap word. The high order 16 bits of
                                 Opnd are zero.

                         For BaseReg = _ABS_  (absolute effective address):
                                 Opnd contains the (extended) 32-bit address specifed by
                                 the instruction's effective address.  Such addresses would
                                 generally be used to reference low memory globals on a
                                 Macintosh.

                         For BaseReg = _PC_  (PC-relative effective address):
                                 Opnd contains the 32-bit address represented by "*±∂"
                                 adjusted by the Disassembler's DstAdjust parameter.

                         For BaseReg = _An_  (effective address with a base register):
                                 Opnd contains the (sign-extended) 32-bit (base)
                                 displacement from the instruction's effective address.

                                 In the Macintosh environment, a BaseReg specifying A5
                                 implies either global data references or Jump Table
                                 references. Positive Opnd values with an A5 BaseReg thus
                                 mean Jump Table references, while a negative offset would
                                 mean a global data reference.  Base registers of A6 or A7
                                 would usually mean local data.

     S       = Pascal string returned from Lookup containing the effective
                         address substitution string or a trap name for A-traps.  S is
                         set to null PRIOR to calling Lookup.  If it is still null on
                         return, the string is not used.  If not null, then for A-traps,
                         the returned string is used as the opcode string. In all other
                         cases the string is substituted as shown in the above table.

     Depending on the application, the caller has three choices on how to
     use the Disassembler and an associated Lookup proc:

     (1). The caller can call just the Disassembler and provide his own Lookup
                proc. In that case the calling conventions discussed above must be
                followed.

     (2). The caller can provide NIL for the LookupProc parameter, in which
                case, NO Lookup proc will be called.

     (3). The caller can call first InitLookup (described below, a proc
                provided with this unit) and pass the address of this unit's
                standard Lookup proc when Disassembler is called.    In this case all
                the control logic to determine the kind of substitution to be done
                is provided for the caller and all that need to be provided by the
                user are routines to look up any or all of the following:

                • PC-relative references
                • Jump Table references
                • Absolute address references
                • Trap names
                • Immediate data names
                • References with offsets from base registers                                            *)


PROCEDURE InitLookup(PCRelProc, JTOffProc, TrapProc, AbsAddrProc, IdProc, ImmDataProc: UNIV Ptr);
    {Prepare for use of this unit's Lookup proc.  When Disassembler is called
     and the address of this unit's Lookup proc is specified, then for immediate
     data, PC-relative, Jump Table references, A-traps, absolute addresses, and
     offsets from a base register, the associated level 1 Pascal proc
     specified here is called (if not NIL -- all six addresses are preset to
     NIL).  The calls assume the following declarations for these procs (see
     Lookup, below for further details):

     PROCEDURE PCRelProc(Address: UNIV LongInt;
                                             VAR S:      UNIV Str255);

     PROCEDURE JTOffProc(A5JTOffset: UNIV Integer;
                                             VAR S:         UNIV Str255);

     PROCEDURE TrapNameProc(TrapWord: UNIV Integer;
                                                    VAR S:      UNIV Str255);

     PROCEDURE AbsAddrProc(AbsAddr: UNIV LongInt;
                                                 VAR S:      UNIV Str255);

     PROCEDURE IdProc(BaseReg: LookupRegs;
                                        Offset:  UNIV LongInt;
                                        VAR S:     UNIV Str255);

     PROCEDURE ImmDataProc(ImmData: UNIV LongInt;
                                                 VAR S:      UNIV Str255);

     Note: InitLookup contains initialized data which requires initializing
                 at load time (this is of concern only to users with assembler
                 main programs.}


 PROCEDURE Lookup(        PC:      UNIV Ptr;     {Addr of extension/trap word}
                                            BaseReg: LookupRegs;   {Base register/lookup mode  }
                                            Opnd:    UNIV LongInt; {Trap word, PC addr, disp.  }
                                    VAR S:       Str255);          {Returned substitution      }
    {This is a standard Lookup proc available to the caller for calls to the
     Disassembler.    If the caller elects to use this proc, then InitLookup
     MUST be called prior to any calls to the Disassembler.  All the logic
     to determine the type of lookup is done by this proc.  For PC-relative,
     Jump Table references, A-traps, absolute addresses, and offsets from a
     base register, the associated level 1 Pascal proc specified in the
     InitLookup call (if not NIL) is called.

     This scheme simplifies the Lookup mechanism by allowing the caller
     to deal with just the problems related to the application.}


PROCEDURE LookupTrapName(TrapWord: UNIV Integer;
                                                 VAR S:       UNIV Str255);
    {This is a procedure provided to allow conversion of a trap instruction
     (in TrapWord) to its corresponding trap name (in S).  It is provided
     primarily for use with the Disassembler and its address may be passed to
     InitLookup above for use by this unit's Lookup routine.  Alternatively,
     there is nothing prohibiting the caller from using it directly for other
     purposes or by some other Lookup proc.

     Note: The tables in this proc make the size of this proc about 9500
                 bytes.  The trap names are fully spelled out in upper and lower
                 case.}

PROCEDURE ModifyOperand(VAR Operand: UNIV Str255);
    {Scan an operand string, i.e., the null terminated Pascal string returned
     by the Disassembler (null MUST be present here) and modify negative hex
     values to negated positive value.  For example, $FFFF(A5) would be
     modified to -$0001(A5).  The operand to be processed is    passed as the
     function's parameter which is edited "in place" and returned to the
     caller.

     This routine is essentially a pattern matcher and attempts to only
     modify 2, 4, and 8 digit hex strings in the operand that "might" be
     offsets from a base register.  If the matching tests are passed, the
     same number of original digits are output (because that indicates a
     value's size -- byte, word, or long).

     For a hex string to be modified, the following tests must be passed:

     • There must have been exactly 2, 4, or 8 digits.

         Only hex strings $XX, $XXXX, and $XXXXXXXX are possible candidates
         because that is the only way the Disassembler generates offsets.

     • Hex string must be delimited by a "(" or a ",".

         The "(" allows offsets for $XXXX(An,...) and $XX(An,Xn) addressing
         modes.  The comma allows for the MC68020 addressing forms.

     • The "$X..." must NOT be preceded by a "±".

         This eliminates the possibility of modifying the offset of a
         PC-relative addressing mode always generated in the form "*±$XXXX".

     • The "$X..." must NOT be preceded by a "#".

         This eliminates modifying immediate data.

     • Value must be negative.

         Negative values are the only values we modify.  A value $FFFF is
         modified to -$0001.}

FUNCTION validMacsBugSymbol(symStart, limit: UNIV Ptr;
                                                        symbol: StringPtr): StringPtr; C;
    {Check that the bytes pointed to by symStart represents a valid MacsBug
     symbol.  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.

     If a valid symbol is NOT found, then NIL is returned as the function's
     result.  However, if a valid symbol is found, it is copied to symbol (if
     it is not NIL) as a null terminated Pascal string, and return a pointer
     to where we think the FOLLOWING module begins. In the "old style" cases
     (see below) this will always be 8 or 16 bytes after the input symStart.
     For new style Apple Pascal and C cases this will depend on the symbol
     length, existence of a pad byte, and size of the constant (literal) area.
     In all cases, trailing blanks are removed from the symbol.

     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 follows:

        1st byte  | 2nd byte  |  Byte  |
            Range   |  Range    | Length | Comments
     =======================================================================
        $20 - $7F | $20 - $7F |    8   | "Old style" MacsBug symbol format
        $A0 - $7F | $20 - $7F |    8   | "Old style" MacsBug symbol format
     -----------------------------------------------------------------------
        $20 - $7F | $80 - $FF |   16   | "Old style" MacApp symbol ab==>b.a
        $A0 - $7F | $80 - $FF |   16   | "Old style" MacApp symbol ab==>b.a
     -----------------------------------------------------------------------
        $80       | $01 - $FF |    n   | n = 2nd byte           (Apple symbol)
        $81 - $9F | $00 - $FF |    m   | m = BAnd(1st byte,$7F) (Apple symbol)
     =======================================================================

     The formats are determined by whether bit 7 is set in the first and
     second bytes.  This bit will removed when we find it or'ed into the first
     and/or second valid symbol characters.

     The first two formats in the above table are the basic "old style" (pre-
     existing) MacsBug formats. The first byte may or may not have bit 7 set
     the second byte is a valid symbol character.  The first byte (with bit 7
     removed) and the next 7 bytes are assumed to comprise the symbol.

     The second pair of formats are also "old style" formats, but used for
     MacApp symbols.  Bit 7 set in the second character indicates these
     formats.  The symbol is assumed to be 16 bytes with the second 8 bytes
     preceding the first 8 bytes in the generated symbol.  For example,
     12345678abcdefgh represents the symbol abcdefgh.12345678.

     The last pair of formats are reserved by Apple and generated by the MPW
     Pascal and C compilers.  In these cases the value of the first byte is
     always between $80 and $9F, or with bit 7 removed, between $00 and $1F.
     For $00, the second byte is the length of the symbol with that many bytes
     following the second byte (thus a max length of 255). Values $01 to $1F
     represent the length itself.  A pad byte may follow these variable length
     cases if the symbol does not end on a word boundary.  Following the
     symbol and the possible pad byte is a word containing the size of the
     constants (literals) generated by the compiler.

     Note that if symStart actually does point to a valid MacsBug symbol,
     then you may use showMacsBugSymbol to convert the MacsBug symbol bytes to
     a string that could be used as a DC.B operand for disassembly purposes.
     This string explicitly shows the MacsBug symbol encodings.}

FUNCTION endOfModule(address, limit: UNIV Ptr; symbol: StringPtr;
                                         VAR nextModule: UNIV Ptr): StringPtr; C;
    {Check to see if the specified memory address, contains a RTS, JMP (A0) or
     RTD #n instruction immediately followed by a valid MacsBug symbol.  These
     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}