It is undesirable to disable these options because this reduces the information content of the disassembled code. Principally, disabling these options might be. General Information About Virtual Memory. If you load some executable module into IDA Pro, two files will be created into the directory, from which you have. Disassembling Code: IDA Pro and SoftICE,, (isbn , ean ), by Pirogov V.

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SUB dest, src Subtract one operand from another operand. For iva, H will take two memory cells, the least significant cell according to the convention will contain 4 5H, and the most significant cell will store 13H. This dump was created using the Oily Dbg debugger, which will be covered later in this chapter. Assume that it is necessary to convert The Intel processor command format Dissassembling begin with, consider prefixes. NET product, after which you needn’t worry about the contents of the resources file.

If you become interested in analysis of the command format, this will help you considerably when investigating executable code. This operation adjusts the sum of two packed BCDs to create a packed BCD result and is only useful when it follows an add instruction that adds binary addition a pair of two-digit, packed BCDs and stores a byte result in the al register. This saves msw into a register or ad location 16 bits. The following variants of the command are available: Looking deeper into the code of the puts function, for example, you can easily notice that execution of this function is finally reduced to execution of the writeFile API function, which in this case is equivalent to the WriteConsoie function.

The operand might be a bit or bit memory area or a register. This operation is used for checking coee there are nonzero bits. Initialize the coprocessor without waiting. Move the data into an MMX register. Move the data from the 32 least significant bits of an MMX register.


In this case, the system not only processes the message but also creates the window template and organizes the window message function. Note that the first 2 bits are matching. This command retrieves the return address and flags register from the stack and returns from the interrupt.

The W32Dasm Debugger and Disassembler. The pshuflw instruction copies words from the low quadword of the source operand second operand and inserts them in the low quadword erf the destination operand first por at word locations selected with the order operand third operand.

The operand might be a bit or bit number. Because contemporary Intel processors are oriented toward operations over bit numbers, djsassembling best approach for the moment is to orient them toward variables of the same dimensions. For the moment, consider the codes of bit working registers: Users, however, do not know this. For instance, consider conversion of the number to binary pfo Loop control; all commands of this group loop — Perform a loop operation if ecx decrement the contents of the ecx register content does not equal zero.

SIDT dest Store idtr in the memory. The computer memory is easily divided into cells containing 8 bits each.

Disassembling Code: IDA Pro and SoftICE – Vlad Pirogov – Google Books

Conditions are similar to the ones used in conditional jumps je, jc. This program stops instruction execution and switches the processor to the halt state.

The target address can be specified directly by a label or indirectly; in other words, this value can be stored in the memory cell or register jmp [eax]. However, this bit is not entirely isolated and participates with the other bits in forming the number value.

Furthermore, in addition to negative effects, attacks on protection systems, worms, and computer viruses have some positive effect, because their existence makes software developers pay more attention to security and develop protection mechanisms more carefully.


The algorithm of converting the integer part of the number has already been considered. Store the FPU environment sw, cw, tagw, fip, fdp in the memory without checking for error conditions. It would be logical to assume that all prefixes shown in Fig.

Extract the sign mask from two packed, double-precision, floating-point values.

Unpack the low-order double words of the source operand and interleave core with the low-order double words of the destination operand. The program will redirect all of its output to the existing console, despite the presence of the AiiocConsoie function. Therefore, combined use of MMX commands and coprocessor commands might cause certain difficulties. If this condition has the byte: Data exchange commands Command Description MOV dest, src Load data to lda from the register, memory, or immediate operand.

Read from the TRn test register. If the values in the destination operand and accumulator are equal, then the destination operand is replaced with the source operand, and initial value of the destination operand is loaded into the accumulator.


This writes all modified cache lines and invalidates the caches. Introduction to Disassembling 15 The Pentium microprocessor comprises general-purpose registers, the flags register, segment registers, control registers, system address registers, and debug registers. The disassembled listing of the executable code text: Bits are reserved for storing the mantissa.

Control flow commands Command Description JMP softcie There are five forms of sodtice command, differing by the distance of the destination and the current address and by the method of specifying the target address.