tailieunhanh - Cracker Handbook 1.0 part 56

Tham khảo tài liệu 'cracker handbook part 56', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | therefore by subtracting 2 from the SP register what we do is to increase the size of the stack by two bytes which is the only quantity of information the stack can handle on each input and output of information. PUSHF INSTRUCTION Purpose It places the value of the flags on the stack. Syntax PUSHF This command decreases by 2 the value of the SP register and then the content of the flag register is transferred to the stack on the address indicated by SP. The flags are left stored in memory on the same bits indicated on the POPF command. Logic instructions They are used to perform logic operations on the operators. AND NEG NOT OR TEST XOR AND INSTRUCTION Purpose It performs the conjunction of the operators bit by bit. Syntax AND destiny source With this instruction the y logic operation for both operators is carried out Source Destiny Destiny 1 1 1 1 0 0 0 1 0 0 0 0 The result of this operation is stored on the destiny operator. NEG INSTRUCTION Purpose It generates the complement to 2. Syntax NEG destiny This instruction generates the complement to 2 of the destiny operator and stores it on the same operator. For example if AX stores the value of 1234H then NEG AX This would leave the EDCCH value stored on the AX register. NOT INSTRUCTION Purpose It carries out the negation of the destiny operator bit by bit. Syntax NOT destiny The result is stored on the same destiny operator. OR INSTRUCTION Purpose Logic inclusive OR Syntax OR destiny source The OR instruction carries out bit by bit the logic inclusive disjunction of the two operators Source Destiny Destiny 1 1 1 1 0 1 0 1 1 0 0 0 TEST .