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Text File | 1995-08-10 | 26.0 KB | 465 lines | [TEXT/MPS ]

(**---------------------------------------------------------------------------* | | | <<< Disassembler.p >>> | | | | Power[PC] Disassembler Interfaces | | | | Ira L. Ruben | | 5/9/93 | | | | Translated from C to Pascal by | | Greg Branche | | 7/20/94 | | | | Copyright Apple Computer, Inc. 1993-1995 | | All rights reserved. | | | *---------------------------------------------------------------------------**) (*$TAGS-*) (*$CALLING PASCAL*) MODULE Disassembler; IMPORT SYSTEM, Types; (* $PUSH*) CONST (** The following defines the "options" that can be passed to the disassembler. All **) (** except ONE of the target architecture options have preset defaults. **) (** Target architecture (one must be set): **) Disassemble_Power* = $00000001; (** Power **) Disassemble_PowerPC32* = $00000002; (** 32-bitPowerPC **) Disassemble_PowerPC64* = $00000004; (** 64-bit PowerPC **) Disassemble_PowerPC601* = $00000008; (** PowerPC 601 **) (** Error detection options*: **) Disassemble_RsvBitsErr* = $80000000; (** invalid reserved bits is error **) Disassemble_FieldErr* = $40000000; (** invalid field (regs, BO, etc.) error **) (** Formatting options (reverses presets): **) Disassemble_Extended* = $08000000; (** extended mnemonics (ppc only) **) Disassemble_BasicComm* = $04000000; (** basic form in comment if extended **) Disassemble_DecSI* = $02000000; (** SI fields formatted as decimal **) Disassemble_DecUI* = $01000000; (** UI fields formatted as decimal **) Disassemble_DecField* = $00800000; (** fields shown as decimal **) Disassemble_DecOffset* = $00400000; (** D of D(RA) shown in decimal **) Disassemble_DecPCRel* = $00200000; (** $+decimal offset instead of $+hex **) Disassemble_DollarHex* = $00100000; (** $XXX... instead of 0xXXX... **) Disassemble_Hex2sComp* = $00080000; (** negative hex shown in 2s compliment **) Disassemble_MinHex* = $00040000; (** min nbr of hex digits for values >= 0 **) Disassemble_CRBits* = $00020000; (** crN_LT, crN_GT, crN_EQ, crN_SO **) Disassemble_CRFltBits* = $00010000; (** crN_FX, crN_FEX, crN_VX, crN_OX **) Disassemble_BranchBO* = $00008000; (** branch BO meaning if not extended **) Disassemble_TrapTO* = $00004000; (** trap TO meaning if not extended **) Disassemble_IBM* = $00002000; (** IBM assembler conventions **) (** Except for the target architecture options, ONE of which must be set, here's an explanation of the other options and their preset default. Disassemble_RsvBitsErr - Reserved bits in PowerPC instructions are considered a "warning" and causes the return status to be set to indicate whether reserved bits were incorrectly coded (1's that should be 0's and vice versa). The option indicates incorrectly coded reserved bits cause the instruction to be treated as "invalid". Disassemble_FieldErr - Attempted use of a field value not valid for a target is considered a "warning" and causes the return status to be set to indicate that fact. The option indicates that use of a field whose value is not valid for the target is "invalid". An example of an invalid field would be the use of a SPR not supported for the target architecture like the "HIDx" SPRs which are only valid for the 601. Another example is non zero bits in the bc[l][a] BO field that are supposed to be zero. Note this is NOT the same as Disassemble_RsvBitsErr. But if a field has NO valid decoding value for ANY target, that is always considered as an invalid instruction. Disassemble_Extended - Extended mnemonics are NOT generated. The option allows the extended mnemonic generation (recommended). Only PowerPC32, PowerPC64, and PowerPC32 and PowerPC64 instructions used on the 601 are supported. Disassemble_BasicComm - The basic instruction form is NOT placed in the comment field. The option causes the basic form of the instruction to be placed in the comment if an extended mnemonic is generated for it. This option is not recommended since it is mainly for debugging and it tends to "clutter" up the comment field making it harder to see branch addresses. Disassemble_DecSI - SIs (signed immediate integers) are formatted as hex. The option causes SI operands to be generated as decimal integers. Disassemble_DecUI - UIs (unsigned immediate integers) are formatted as hex. The option causes UI operands to be generated as decimal integers. Disassemble_DecField - All fields (e.g., shift/rotate constants) are shown as hex. The option causes the offsets to be generated as decimal integers. Disassemble_DecOffset - The "D" offsets in operands of the form D(RA) are shown in hex. The option causes these to be generated as decimal. Disassemble_DecPCRel - PC-relative branch addresses are formatted as "$+n" or "$-n", with the offset ("n") generated in hex. The option causes the offset to be generated as decimal. Disassemble_DollarHex - Hex values are prefixed with "0x". The option causes hex values to be formatted as "$XXX...". Disassemble_Hex2sComp - Signed negative values that are shown in hex are negated and prefixed with a "-" (e.g. "-0x0001"). The option causes these values to be shown in their two's complement form (e.g., "0xFFFFFFFF"). Disassemble_MinHex - Positive hex values or negated negative values are always shown with the number of digits attempting to indicate the size of the instruction field which produced the value or the implied value size. Thus 32-bit target addresses are shown as 8 hex digits, 16-bit field values are shown with 4 hex digits, byte field values as 2 hex digits. 5 or six-bit values are also shown as 2 hex digits since the minimum is always at least 2. The option forces the generation to always use 2 as the minimum even if the value came from a bigger field (e.g., "0x1234" address, "0x01" or "-0x01" from a 16-bit field). Disassemble_CRBits - Condition register field bits are referenced as bit numbers 0:31 in the basic instruction operand forms. The option causes these bits to be referenced using the format “crN_X”, where N is a 4-bit CR field (0:7) and X is the bit “name” in the field (“LT”, “GT”, “EQ”, “SO” for bits 0, 1, 2, and 3 respectively). Note, this notation is always used with extended mnemonics. Disassemble_CRFltBits - Condition register field bits are referenced as bit numbers 0:31 in the basic instruction operand forms. The option is identical to Disassemble_CRBits to generate the references as “crN_X”, except that the bits (X) are referenced as “FX”, “FEX”, “VX” and “OX” for the four bits 0,1, 2, and 3 respectively. This option can be used if the context of floating-point operations, but it's up to the caller to determine that context. Disassemble_BranchBO - Branch test BO encodings are referenced as values 0:31 in the basic instruction operand forms. The option causes the BO value to be referenced as more meaningful names (e.g., "dCTR_NZERO_NOT", "ALWAYS", etc.). Disassemble_TrapTO - Trap TO operand encodings are referenced as values 0:31 in the basic instruction operand forms. The option causes the TO value to be an expression of the form "x|y|...", where the "x", "y", and so are the meaning of each of the five TO bits; "LT", "GT", "EQ", "LOW", "HI" for bits 0, 1, 2, 3, and 4 respectively. Disassemble_IBM - Apple assembler conventions are used for comments and invalid instructions. The option causes IBM assembler conventions to be used for these. A “#” is used instead of a “;” as the comment character, and “.long” is used instead of “dc.l” for the invalid instruction directive mnemonic. [Are we having fun yet?] **) (** The following defines a set of the above options which seem to give "acceptable" **) (** results*: **) DisStdOptions* = (Disassemble_Extended + (** permit extended mnemonics **) Disassemble_DecSI + (** decimal SIs but hex UIs **) Disassemble_DecField + (** decimal field numbers **) Disassemble_BranchBO + (** meaning of branch BO **) Disassemble_TrapTO + (** meaning of trap TO **) Disassemble_CRBits); (** CR bits references as crN_X **) (** Return status flags*: **) Disassembler_OK* = $0001; (** instruction successfully decoded **) Disassembler_InvRsvBits* = $0002; (** invalidly coded reserved bits **) Disassembler_InvField* = $0004; (** invalidly coded field(s) **) Disassembler_InvSprMaybe* = $0008; (** possibly invalid SPR **) Disassembler_601Power* = $0010; (** power instruction used with 601 **) Disassembler_Privileged* = $0020; (** privileged instruction **) Disassembler_Optional* = $0040; (** optional instruction **) Disassembler_Branch* = $0080; (** branch instruction **) Disassembler_601SPR* = $0100; (** SPR valid only for 601 has been used **) Disassembler_HasExtended* = $4000; (** possible extended mnemonic **) Disassembler_ExtendedUsed* = $8000; (** the extended mnemonic was generated **) DisInvalid* = $0000; (** invalid instruction **) (** Unless DisInvalid (0) is returned as the function result, Disassembler_OK will always be set. The other flags have the following meaning*: Disassembler_InvRsvBits - The instruction had some or all of its reserved bits incorrectly coded, and the Disassemble_RsvBitsErr option was NOT set. This is something like a "warning". With the option set, this condition is considered as an "error" and the "invalid instruction" is generated ("dc.l 0xXXXXXXXX"). Disassembler_InvField - The instruction had fields incorrectly coded for the target, but is is still valid for some target (e.g., not valid for the 601 but valid for the PowerPC64), and the Disassemble_FieldErr option was NOT set. Disassembler_InvSprMaybe - A mfspr or mtspr instruction references a POSSIBLY invalid SPR. This occurs when an SPR value is not for one of the predefined SPR names (see list above) and there is no lookup routine, or it does not supply a substitution name. In that case the SPR register number is generated. Since there is no way of the disassembler knowing whether the register is valid for the architecture of interest, this flag is set instead of Disassembler_InvField to indicate the possibility that the SPR may be invalid. Disassembler_601Power - The options specified that the target architecture is the 601 (Disassemble_PowerPC601), and a Power instruction was disassembled. The 601 is basically an ORing of the Power and PowerPC32 architectures. But this flag could be useful for "weeding" Power instructions out in preparation for use on a "pure" PowerPC32 or PowerPC64 architecture. Disassembler_601SPR - The options specified that the target architecture is the 601 (Disassemble_PowerPC601), and a mfspr or mtspr instruction references a SPR valid ONLY for the 601. Disassembler_Privileged - The instruction is privileged. Disassembler_Optional - The instruction is optional. Disassembler_Branch - Branch instruction; bc[l][a], b[l][a], bclr[l], bcctr[l] and Power bcr[l], bcc[l]. If any of these instructions are processed the flag is set. Branches are signaled because the caller might want to do some additional processing on these. For example, a debugger might want to dynamically show which way the branch is taken, or static analysis might want to know possible exit points from a function or show the branch in some graphical way. Although the caller could determine if the instruction is a branch, the disassembler always has to classify the instructions passed to it, so there is no sense having both do it if the information is already available. Note, the caller might still, however, need to extract the BO and BI fields to determine the condition of the branch, but at least it only needs to be done when the flag is set. Disassembler_HasExtended - The instruction POSSIBLY has an extended mnemonic, whether used or not used (as a function of the Disassemble_Extended option). Note, "possibly has an extended mnemonic"; the instruction could have extendeds, but not for all values of its operands. Disassembler_ExtendedUsed - The instruction has an extended mnemonic, and it was used because the option (Disassemble_Extended) permits it. The operand is formatted appropriate to the extended mnemonic. Whether the original basic form is placed in the comment or not is controlled by the Disassemble_BasicComm option. **) (** All assembler options are of type DisassemblerOptions*: **) TYPE DisassemblerOptions* = LONGINT; DisassemblerStatus* = INTEGER; (** disassembler return status (see above) **) (** The optional lookup function (NULL could be passed) is used to allow the caller to **) (** substitute name strings for various objects that can occur in an operand. It should **) (** return a pointer to a non-null string if substitution is desired. If NULL or a null **) (** string is returned, the disassembler uses its own default names. The following **) (** defines the possible substitable objects*: **) DisassemblerLookupType* = SHORTINT; (*ΔΔ ( *) (** Types of substitutable objects*: **) CONST Disassembler_Lookup_GPRegister* = 0; (*ΔΔ ,*) (** general purpose register **) Disassembler_Lookup_FPRegister* = 1; (*ΔΔ ,*) (** floating point register **) Disassembler_Lookup_UImmediate* = 2; (*ΔΔ ,*) (** unsigned immediate value **) Disassembler_Lookup_SImmediate* = 3; (*ΔΔ ,*) (** signed (32-bit) immediate value **) Disassembler_Lookup_AbsAddress* = 4; (*ΔΔ ,*) (** absolute addresse **) Disassembler_Lookup_RelAddress* = 5; (*ΔΔ ,*) (** relocatable addresse **) Disassembler_Lookup_RegOffset* = 6; (*ΔΔ ,*) (** offset from a base register **) Disassembler_Lookup_SPRegister* = 7; (*ΔΔ ,*) (** special purpose register **) (*ΔΔ );*) TYPE (** Here's a definition of an object (value) which is a function of each **) (** DisassemblerLookupType*: **) (* $ALIGN MAC68K*) DisLookupValue* = LONGINT; (*ΔΔ RECORD (** A "meaningful" name for each value type*: **) CASE INTEGER OF 0: (gpr: LONGINT;); (** Disassembler_Lookup_GPRegister **) 1: (fpr: LONGINT;); (** Disassembler_Lookup_FPRegister **) 2: (ui: LONGINT;); (** Disassembler_Lookup_UImmediate **) 3: (si: LONGINT;); (** Disassembler_Lookup_SImmediate **) 4: (absAddress: LONGINT;); (** Disassembler_Lookup_AbsAddress **) 5: (relAddress: LONGINT;); (** Disassembler_Lookup_RelAddress **) 6: (spr: LONGINT;); (** Disassembler_Lookup_SPRegister **) 7: ( (* regOffset*) offset*: INTEGER; baseReg*: INTEGER; ); (** Disassembler_Lookup_RegOffset **) END;*) (* $ALIGN RESET*) DisLookupValuePtr* = SYSTEM.PTR (*ΔΔ POINTER TO DisLookupValue*); (** Finally, at long last, here's the definition of the disassembler... **) PROCEDURE ppcDisassembler*( VAR instruction : LONGINT; dstAdjust : LONGINT; options : DisassemblerOptions; mnemonic : Types.CStringPtr; operand : Types.CStringPtr; comment : Types.CStringPtr; refCon : (*ΔΔUNIVΔΔ*) Types.Ptr; lookupRoutine : (*ΔΔUNIVΔΔ*) Types.Ptr) : DisassemblerStatus; (*ΔΔC;ΔΔ*) EXTERNAL (*•• C*); (** Takes the four bytes pointed to by instruction and disassembles it, placing the mnemonic, operand, and comment in the strings provided. The caller is then free to format or use the output strings any way appropriate to the application. Any of these strings may be a null pointer, in which case that portion of the disassembled instruction is not returned. If they are not null, it is ASSUMED that the associated buffers are large enough to hold the disassembled output. Comments are formatted starting with a "; " (or "#" if the appropriate "IBM" option is set). Invalid instructions generate a "dc.l" (".long" for IBM), an operand of the form 0xXXXXXXXX showing the actual instruction, and a comment with a message indicating what is wrong with the instruction. For PC-relative branches, the comment generated is the destination address, the only address that the disassembler "knows" about is the address of the code pointed to by the instruction. 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. Many operands usually consist of registers, absolute and relocatable addresses, and signed and unsigned values. In places where these occur, the disassembler can call a user specified routine to do the substitution using the lookupRoutine parameter if it is not NULL. A "refcon" is passed to the disassembler that is, in turn, passed on to the lookup routine to allow a communication path between the disassembler caller and its lookup routine. The refcon can be anything. The disassembler does not look at it. The caller also can control some aspects of the formatting with the DisassemblerOptions as described above. The options also specify the target architecture; Power, PowerPC32, PowerPC64, or PowerPC601. The disassembler returns as its function result the DisassemblerStatus. This may be tested for 0 ("false" or DisInvalid defined below) to find out if an invalid instruction was detected. For valid instructions, the DisassemblerStatus is non zero and indicates various attributes about the instruction as follows*: **) (** The "lookup" substitution routine for the objects is defined as follows*: PROCEDURE DisassemblerLookups*( refCon : (*ΔΔUNIVΔΔ*) Types.Ptr, VAR cia : LongInt, lookupType : DisassemblerLookupType, thingToReplace : DisLookupValue) : CStringPtr; (*ΔΔC;ΔΔ*) EXTERNAL (*•• C*); where, refCon* = A "reference constant" that can be used as a communication link between the lookup routine and the caller of the disassembler. It is the same refCon passed to the disassembler. cia* = The instruction address passed to the disassembler. lookupType and thingToReplace* = The kind of object and the associated value of that object to be replaced. As defined by DisLookupValue, the thingToReplace has the following value for each lookupType. lookupType value ============================================= Disassembler_Lookup_GPRegister 0:31 Disassembler_Lookup_FPRegister 0:31 Disassembler_Lookup_UImmediate integer Disassembler_Lookup_SImmediate integer Disassembler_Lookup_AbsAddress address [1] Disassembler_Lookup_RelAddress address [2] Disassembler_Lookup_RegOffset D + Ra [3] Disassembler_Lookup_SPRegister spr [4] ============================================= Notes*: [1] This is an absolute target branch address, i.e., the "a" bit in the branch instruction IS set. The passed absAddress is the address contained in the instruction. [2] This is a relocatable target branch address, i.e., the "a" bit in the branch instruction was NOT set. The relAddress is relative to the current instruction address adjusted by the dstAdjust. Thus, relAddress* = destinationAddress + dstAdjust + cia where cia is the current instruction address, i.e, the value of the instruction address passed to the disassembler. [3] Both the offset (D) and base register (Ra) are passed. The DisLookupValue.regOffset value defines how they are packed in the thingToReplace. The offset should be assigned to a long to get its true 32-bit value. It is valid to pass it as a signed short since the instruction field from which it came is never more than 16 bits wide. [4] The lookup for SPRs is slightly different in that it is only done as an ESCAPE mechanism, i.e., only when the SPR number is NOT one of the predefined Power, 601, PowerPC32, or PowerPC64 SPR names. This is done because a different PowerPC architectures can have additional SPRs specific to those architectures! The lookup routine is called only if the SPR is NOT one of the following predefined numbers*: 0 MQ 272 SPRG0 528 IBAT0U 536 DBAT0U 1008 HID0 1 XER 273 SPRG1 529 IBAT0L 537 DBAT0L 1009 HID1 4 RTCU 274 SPRG2 530 IBAT1U 538 DBAT1U 1010 IABR 5 RTCL 275 SPRG3 531 IBAT1L 539 DBAT1L 1013 DABR 6 DEC 280 ASR 532 IBAT2U 540 DBAT2U 1023 PIR 8 LR 282 EAR 533 IBAT2L 541 DBAT2L 9 CTR 284 TB 534 IBAT3U 542 DBAT3U 18 DSIAR 285 TBU 535 IBAT3L 543 DBAT3L 19 DAR 287 PVR 22 DEC 25 SDR1 26 SRR0 27 SRR1 Not all of these SPRs are valid for all targets. The disassembler will check to see if these SPRs are valid for the specified target architecture. If they are not, the SPR number is treated as an invalid field and processed according to the Disassemble_FieldErr option, i.e., it’s accepted but returns a status warning, or the instruction is treated as invalid (“DC.L 0xXXXXXXXX”). SPR numbers which are not on the list, and also do not have a lookup substitution name, are always accepted. But since there is no way for the disassembler to validate these against the target, the Disassembler_InvSprMaybe return status flag will be set. **) (** NOTES*: 1. The disassembler library uses the convention that, with the exception of **) (** the called routine name itself, i.e., "ppcDisassembler", all externally **) (** visible names (linker symbols and macro names) begin with the letters "dis"**) (** (in any case). The user should keep this in mind to avoid possible name **) (** conflicts. **) (** 2. Except for statically declared (read only) tables, the disassembler uses no**) (** other global data. **) (** 3. The disassembler is fully self contained in that it has no explicit **) (** references to any runtime library routines (e.g., strcpy). There may, **) (** however, be implicit references generated by the (C) compiler. **) (** 4. The disassembler is written in standard ANSI C making it possible to easily**) (** port to other platforms. **) (* $ALIGN RESET*) (* $POP*) END Disassembler.