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Expressions are mathematical representations of 64-bit numerical values.
They can be displayed in different formats, be compared or used with all commands accepting numeric arguments. Expressions can use traditional arithmetic operations, as well as binary and boolean ones.
To evaluate mathematical expressions prepend them with command `?`: ``` [0xb7f9d810]> ?vi 0x8048000 134512640 [0xv7f9d810]> ?vi 0x8048000+34 134512674 [0xb7f9d810]> ?vi 0x8048000+0x34 134512692 [0xb7f9d810]> ? 1+2+3-4*3 hex 0xfffffffffffffffa octal 01777777777777777777772 unit 17179869184.0G segment fffff000:0ffa int64 -6 string "\xfa\xff\xff\xff\xff\xff\xff\xff" binary 0b1111111111111111111111111111111111111111111111111111111111111010 fvalue: -6.0 float: nanf double: nan trits 0t11112220022122120101211020120210210211201 ``` Supported arithmetic operations are:
- \+ : addition
- \- : subtraction
[0x00000000]> ?vi 1+2+3 6
To use of binary OR should quote the whole command to avoid executing the `|` pipe: ``` [0x00000000]> "? 1 | 2" hex 0x3 octal 03 unit 3 segment 0000:0003 int32 3 string "\x03" binary 0b00000011 fvalue: 2.0 float: 0.000000f double: 0.000000 trits 0t10 ```
Numbers can be displayed in several formats: ``` 0x033 : hexadecimal can be displayed 3334 : decimal sym.fo : resolve flag offset 10K : KBytes 10*1024 10M : MBytes 10*1024*1024 ```
You can also use variables and seek positions to build complex expressions.
Use the `?$?` command to list all the available commands or read the refcard chapter of this book.
$ here (the current virtual seek) $l opcode length $s file size $j jump address (e.g. jmp 0x10, jz 0x10 => 0x10) $f jump fail address (e.g. jz 0x10 => next instruction) $m opcode memory reference (e.g. mov eax,[0x10] => 0x10) $b block size
Some more examples: ``` [0x4A13B8C0]> ? $m + $l 140293837812900 0x7f98b45df4a4 03771426427372244 130658.0G 8b45d000:04a4 140293837812900 10100100 140293837812900.0 -0.000000 ``` ``` [0x4A13B8C0]> pd 1 @ +$l 0x4A13B8C2 call 0x4a13c000 ```