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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When executing this command, a byte, word, or double word is loaded into al, ax, or eax, respectively. Although the operations as such might be complex, their sequential order considerably simplifies code investigation.

Physically, these registers are used by the least significant bits of the FPU data registers ro-R7. To solve it at least, to begin solving it correctlyrecall that most window functions must be registered. This command adjusts two un packed BCDs the least significant digit in the al register and the most significant digit in the ah register so that a division operation disaasembling on the result will yield a correct unpacked BCD.

Disassembling Code: IDA Pro and SoftICE

In general, however, its features and behavior are the same as the ones of the program shown xode Listing 1. Using API functions, an application can communicate directly with the Windows operating system. Multiply the floating point number: The situation becomes clearer.

In the resulting number, separate the integer part this will be either zero or one. Converting a hex number to a binary number As already mentioned, the hex numeral system, out of all numeral systems, best maps to the computer memory’s architecture.

Introduction to IDA Pro. The calls to the ReadConsoieinput function in the loop allow you to detect events that cannot be traced by the handler function. In decimal system representation, this will equal Thus, C3 in binary representation is noooon.


Move the data into the 32 least significant bits peo an MMX register and fill the most significant bits with zeros. At this point, some difficulties might arise, which will be explained in the next section.

Numbers in hex numeral systems are easily converted into the binary system, and vice versa.


These are not trivial tasks. This means that every decimal system number can be represented as a sum of the powers of ten, where the number positions serve as coefficients. The disassembled listing of the executable code text: Load log 2 10 into st o. In the example from Listing 1. Note that this is the case only if you know for sure, from which address the command being studied starts.

The source operand can be a bit general-purpose register or a memory location. At that time, the problem of localizing code or reencoding printers was urgent. The choice of the counter depends on the contents of the ecx register. When carrying out this operation, the pfo is popped.

Four digits of a binary number, a quaternion, correspond to one digit of a hex number, and vice versa. Cod and Disassembling Assembly Programs. LTR src Load the task register tr.

Full text of “Disassembling Code IDA Pro And Soft ICE”

API functions are an additional interface layer between system procedures and application programs. Investigating the Memory Consider a simple program written in the C programming language Listing sofyice.

Such loops are more typical of windowing applications; however, for console applications this approach is also permitted. Finally, every professional programmer must be curious and willing to understand how his or her programs operate.


The control register or the clde word, cw contains the bits that influence the result of execution of the coprocessor commands. SIDT dest Store idtr in the memory. Looking deeper into the code of the puts function, for disasembling, 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. Basic Information about Working with Softlce. NET product, after which you needn’t worry about the contents of the resources file.

If the fractional part of the resulting number is not zero, return to step 1; otherwise, terminate computation.

Any console application can create graphical windows and work with them, and any GUI application, in turn, can work with console windows. A specific feature of this program is that it creates its own console, no matter whether it was started from a console or otherwise. This selects the bit in the bit string specified by src at the bit position specified by dest, stores the bit value in cf, and complements the bit value in the bit string.

If the coprocessor is busy, the processor is switched to the waiting state. When the bsf command is executed, the src operand is scanned starting from least disassemblint bits. Dump of the program code Jda, it is necessary to point out that the command length might range from 1 byte to 10 bytes or even more.

If the repne prefix is used, the command continues comparison until the end of the string is reached or clde elements are equal.