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|
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cxmon, Version 3.0 |
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A command-line file manipulation tool and disassembler |
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|
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Copyright (C) 1997-2000 Christian Bauer, Marc Hellwig |
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GNU binutils disassemblers Copyright (C) 1988, 89, 91, 93, 94, 95, 96, 97, 1998 |
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Free Software Foundation, Inc. |
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|
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|
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License |
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------- |
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|
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cxmon is available under the terms of the GNU General Public License. See the |
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file "COPYING" that is included in the distribution for details. |
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|
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|
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Overview |
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-------- |
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|
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cxmon is an interactive command-driven file manipulation tool that is |
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inspired by the "Amiga Monitor" by Timo Rossi <trossi@jyu.fi>. It has |
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commands and features similar to a machine code monitor/debugger, but it |
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lacks any functions for running/tracing code. There are, however, built-in |
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PowerPC, 680x0, 80x86, 6502 and Z80 disassemblers. By default, cxmon operates |
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on a fixed-size (but adjustable) memory buffer with adresses starting at 0. |
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|
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|
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Installation |
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------------ |
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|
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Please consult the file "INSTALL" for installation instructions. |
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|
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|
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Usage |
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----- |
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|
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cxmon can be started from the Shell or from the Tracker (BeOS), but command |
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line history doesn't work when started from the Tracker. |
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|
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Options: |
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-m enables symbolic MacOS A-Trap and low memory globals display in the |
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680x0 disassembler |
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-r makes cxmon operate in real (virtual) memory space instead of an |
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allocated buffer |
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|
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If no additional command line arguments are given, cxmon enters interactive |
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mode. Otherwise, all remaining arguments are interpreted and executed as cxmon |
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commands. |
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|
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The default buffer size is 1MB. |
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|
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The cxmon command prompt looks like this: |
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|
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[00000000]-> |
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|
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The number in brackets is the value of "." (the "current address", see the |
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section on expressions). You can get a short command overview by entering |
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"h". |
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|
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Commands that create a longer output can be interrupted with Ctrl-C. |
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|
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To quit cxmon, enter the command "x". |
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|
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|
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Constants, variables and expressions |
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------------------------------------ |
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|
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The default number base is hexadecimal. Decimal numbers must be prefixed with |
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"_". Hexadecimal numbers may also be prefixed with "$" for clarity. Numbers |
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can also be entered as ASCII characters enclosed in single quotes (e.g. 'BAPP' |
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is the same as $42415050). All numbers are 32-bit values (one word). |
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|
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With the "set" command, variables can be defined that hold 32-bit integer |
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values. A variable is referred to by its name. Variable names may be arbitrary |
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combinations of digits and letters (they may also start with a digit) that |
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are not also valid hexadecimal numbers. Names are case-sensitive. |
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|
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cxmon accepts expressions in all places where you have to specify a number. |
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The following operators are available and have the same meaning and |
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precedence as in the C programming language: |
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|
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~ complement |
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+ unary plus |
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- unary minus |
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* multiplication |
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/ integer division |
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% modulo |
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+ addition |
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- subtraction |
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<< shift left |
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>> shift right |
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& bitwise AND |
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^ bitwise exclusive OR |
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| bitwise inclusive OR |
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|
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Parentheses may be used to change the evaluation order of sub-expressions. |
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|
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There are two special symbols that can be used in expressions: |
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|
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. represents the "current address" (the value of "." is also displayed in |
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the command prompt). What exactly the current address is, depends on the |
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command last executed. The display commands set "." to the address after |
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the last address displayed, the "hunt" commands sets "." to the address |
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of the first found occurence of the search string, etc. |
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: is used by the "apply" ("y") command and holds the value of the byte/ |
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half-word/word at the current address. |
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|
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The "modify" (":"), "fill" ("f") and "hunt" ("h") commands require you to |
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specify a byte string. Byte strings consist of an arbitrary number of byte |
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values and ASCII strings separated by commas. Examples: |
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|
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"string" |
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12,34,56,78,9a,bc,de,f0 |
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"this",0a,"is a string",0a,"with","newlines",_10 |
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|
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|
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The buffer |
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---------- |
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|
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Those cxmon commands that operate on "memory" operate on a buffer allocated |
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by cxmon whose size is adjustable with the "@" command. The default buffer |
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size is 1MB. The buffer is an array of bytes where each byte has a 32-bit |
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integer address. Addresses start at 0 and are taken modulo the buffer size |
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(i.e. for the default 1MB buffer, addresses 0 and 100000 refer to the same |
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byte). |
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|
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The buffer is the working area of cxmon where you load files into, manipulate |
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them, and write files back from. Arbitraty portions of the buffer may be used |
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as scratch space. |
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|
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|
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Commands |
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-------- |
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|
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The following commands are available in cxmon ('[]' marks a parameter than |
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can be left out): |
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|
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|
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x Quit cxmon |
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|
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quits cxmon and returns to the shell. |
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|
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|
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h Show help text |
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displays a short overview of commands. |
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|
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|
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?? Show list of commands |
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|
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displays a short list of available commands. |
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|
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|
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ver Show version |
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shows the version number of cxmon. |
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|
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|
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? expression Calculate expression |
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displays the value of the given expression in hex, decimal, and ASCII |
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characters. If the value is negative, it is displayed as a signed and unsigned |
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number. |
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|
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|
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@ [size] Reallocate buffer |
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|
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changes the size of the buffer to the given number of bytes while preserving |
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the contents of the buffer. If the "size" argument is omitted, the current |
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buffer size is displayed. |
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|
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|
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i [start [end]] ASCII memory dump |
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displays the buffer contents from address "start" to address "end" as ASCII |
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characters. Entering "i" without arguments is equivalent to "i .". The value |
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of "." is set to the address after the last address displayed. |
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|
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|
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b [start [end]] Binary memory dump |
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displays the buffer contents from address "start" to address "end" in a binary |
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format. Entering "b" without arguments is equivalent to "b .". The value of |
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"." is set to the address after the last address displayed. |
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|
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|
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m [start [end]] Hex/ASCII memory dump |
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|
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displays the buffer contents from address "start" to address "end" as hex |
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words and ASCII characters. Entering "m" without arguments is equivalent to |
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"m .". The value of "." is set to the address after the last address displayed. |
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|
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|
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d [start [end]] Disassemble PowerPC code |
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|
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d" without arguments is equivalent to "d .". The value of "." is |
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set to the address after the last address displayed. |
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|
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|
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d65 [start [end]] Disassemble 6502 code |
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d65" without arguments is equivalent to "d65 .". The value of |
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"." is set to the address after the last address displayed. |
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|
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|
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d68 [start [end]] Disassemble 680x0 code |
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d68" without arguments is equivalent to "d68 .". The value of |
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"." is set to the address after the last address displayed. |
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|
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d80 [start [end]] Disassemble Z80 code |
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d80" without arguments is equivalent to "d80 .". The value of |
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"." is set to the address after the last address displayed. |
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|
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|
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d86 [start [end]] Disassemble 80x86 (32-bit) code |
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d86" without arguments is equivalent to "d86 .". The value of |
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"." is set to the address after the last address displayed. |
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|
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|
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d8086 [start [end]] Disassemble 80x86 (16-bit) code |
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disassembles the buffer contents from address "start" to address "end". |
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Entering "d8086" without arguments is equivalent to "d8086 .". The value |
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of "." is set to the address after the last address displayed. |
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|
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|
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: start string Modify memory |
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|
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puts the specified byte string at the address "start" into the buffer. The |
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value of "." is set to the address after the last address modified. |
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|
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f start end string Fill memory |
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fill the buffer in the range from "start" to (and including) "end" with the |
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given byte string. |
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|
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|
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y[b|h|w] start end expr Apply expression to memory |
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works like the "fill" ("f") command, but it doesn't fill with a byte string |
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but with the value of an expression that is re-evaluated for each buffer |
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location to be filled. The command comes in three flavors: "y"/"yb" works on |
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bytes (8-bit), "yh" on half-words (16-bit) and "yw" on words (32-bit). The |
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value of "." is the current address to be modified, the value of ":" holds |
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the contents of this address before modification. |
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|
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Examples: |
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yw 0 fff :<<8 shifts all words in the address range 0..fff to the left |
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by 8 bits (you can use this to convert bitmap data from |
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ARGB to RGBA format, for example) |
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y 0 1234 ~: inverts all bytes in the address range 0..1234 |
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yh 2 ff 20000/. creates a table of the fractional parts of the reciprocals |
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of 1..7f |
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|
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|
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t start end dest Transfer memory |
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transfers the buffer contents from "start" to (and including) "end" to "dest". |
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Source and destination may overlap. |
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|
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|
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c start end dest Compare memory |
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compares the buffer contents in the range from "start" to (and including) |
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"end" with the contents at "dest". The addresses of all different bytes and |
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the total number of differences (decimal) are printed. |
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|
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|
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h start end string Search for byte string |
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searches for the given byte string in the buffer starting at "start" up to |
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(and including) "end". The addresses and the total number of occurrences are |
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displayed. The value of "." is set to the address of the first occurrence. |
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|
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\ "command" Execute shell command |
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executes the given shell command which must be enclosed in quotes. |
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ls [args] List directory contents |
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works as the shell command "ls". |
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rm [args] Remove file(s) |
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works as the shell command "rm". |
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cp [args] Copy file(s) |
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works as the shell command "cp". |
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mv [args] Move file(s) |
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works as the shell command "mv". |
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cd directory Change current directory |
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works as the shell command "cd". The name of the directory doesn't have to be |
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enclosed in quotes. |
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|
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|
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o ["file"] Redirect output |
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|
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When a file name is specified, all following output is redirected to this |
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file. The file name must be enclosed in quotation marks even if it contains |
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no spaces. Entering "o" without parameters closes the file and directs the |
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output into the terminal window again. |
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|
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|
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[ start "file" Load data from file |
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|
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loads the contents of the specified file into the buffer starting from address |
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"start". The file name must be enclosed in quotation marks even if it contains |
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no spaces. The value of "." is set to the address after the last address |
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affected by the load. |
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|
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|
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] start size "file" Save data to file |
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|
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writes "size" number of bytes of the buffer from "start" to the specified file. |
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The file name must be enclosed in quotation marks even if it contains no spaces. |
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|
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|
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set [var[=value]] Set/clear/show variables |
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|
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If no arguments are given, all currently defined variables are displayed. |
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Otherwise, the value of "var" is set to the specified value. If "=value" |
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is omitted, the variable "var" is cleared. |
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|
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|
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cv Clear all variables |
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clears all currently defined variables. |
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|
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|
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Examples |
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-------- |
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|
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Here are some simple examples for what is possible with cxmon. |
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|
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Join "file1" and "file2" to "file3": |
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|
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[ 0 "file1" |
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[ . "file2" |
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] 0 . "file3" |
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Remove the first 24 bytes (e.g. an unneeded header) of a file: |
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|
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[ 0 "file" |
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] 18 .-18 "file" |
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|
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Load the cxmon executable and search for PowerPC "nop" commands: |
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[ 0 "cxmon" |
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h 0 . 60,00,00,00 |
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|
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Create a modified version of cxmon so that the prompt has " $" instead of |
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"->": |
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[ 0 "cxmon" |
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set size=. |
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h 0 . "->" |
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: . " $" |
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] 0 size "cxmon1" |
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|
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Convert a binary file which contains 16-bit numbers in little-endian format |
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to big-endian format (or vice-versa): |
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|
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[ 0 "file" |
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yh 0 .-1 :>>8|:<<8 |
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] 0 . "file" |
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|
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Load a BeBox boot ROM image and start disassembling the system reset handler: |
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[ 0 "bootnub.image" |
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d 100 |
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|
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|
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Using cxmon in your own programs |
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-------------------------------- |
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|
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cxmon provides a simple interface for integration in other programs. It can, |
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for example, be used as a monitor/debugger for an emulator (it is used in |
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Basilisk II in this way). |
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|
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Here's how to do it (all functions are defined in the mon.h header file): |
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|
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1. Link all the cxmon object files, except main.o, to your program. |
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2. In your program, call mon_init() before using any other cxmon functions. |
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3. After calling mon_init(), set the mon_read_byte and mon_write_byte |
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function pointers to the routines used for accessing memory. |
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4. You can use mon_add_command() to add new commands to cxmon by specifying |
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the command name, function and help text. From within your command |
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function, you can use mon_get_token() and mon_expression() to parse the |
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arguments and the mon_read/write_*() functions to access memory. |
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5. To enter cxmon, call the mon() function like this: |
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|
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char *args[3] = {"mon", "-r", NULL}; |
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mon(2, args); |
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|
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6. If you're done with cxmon, call mon_exit(). |
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|
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|
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History |
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------- |
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|
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Please consult the file "ChangeLog" for the release history. |
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|
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|
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Christian Bauer |
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<Christian.Bauer@uni-mainz.de> |
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|
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Marc Hellwig |
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<Marc.Hellwig@uni-mainz.de> |