What are the components of assembly language?

The composition of assembly language: 1. Transfer instructions, including general data transfer instructions, conditional transfer instructions, etc.; 2. Logical operations, this part of the instructions is used to perform arithmetic and logical operations; 3. Shift instructions, used To move the register or memory operand a specified number of times; 4. Bit operations, including test instructions BT, bit test and set instructions BTS, etc.; 5. Control transfer, including unconditional transfer instructions JMP, conditional transfer instructions "JCC/JCXZ" Etc.; 6. String operation, used to operate on data strings; 7. Input and output, used to exchange data with peripheral devices.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

What are the components of assembly language

Because the assembly instruction system is huge, it is necessary to build an instruction system system with a large number of instructions, complex formats, and poor memorability. The most difficult thing about the instruction is the addressing mode supported by the instruction. Its essence is how to obtain the operands in the instruction. For the processor, it's how to find the data it needs. However, for the underlying assembly language of the computer, this addressing method will involve a large number of calculation storage formats and is closely related to complex storage management methods, making it difficult to understand. Finally, assembly instructions are also related to how to affect flag bits, but processor flag bits are very complex, so it is difficult to master their mechanisms.

• Transfer instructions

##Including general data transfer instruction MOV, conditional transfer instruction CMOVcc, Stack operation instructions PUSH/PUSHA/PUSHAD/POP/POPA/POPAD, exchange instructions XCHG/XLAT/BSWAP, address or segment descriptor selection sub-transfer instructions LEA/LDS/LES/LFS/LGS/LSS, etc.

• Logical operations

This part of the instructions is used to perform arithmetic and logical operations, including Addition instructions ADD/ADC, subtraction instructions SUB/SBB, plus one instruction INC, minus one instruction DEC, comparison operation instruction CMP, multiplication instruction MUL/IMUL, division instruction DIV/IDIV, sign extension instruction CBW/CWDE/CDQE, decimal adjustment Instructions DAA/DAS/AAA/AAS, logical operation instructions NOT/AND/OR/XOR/TEST, etc.

• Shift instructions

This part of the instruction is used to shift register or memory operands Move the specified number of times. Including logical left shift instruction SHL, logical right shift instruction SHR, arithmetic left shift instruction SAL, arithmetic right shift instruction SAR, circular shift left instruction ROL, circular shift right instruction ROR, etc.

• Bit operations

This part of the instructions includes the bit test instruction BT, bit test and Set instruction BTS, bit test and reset instruction BTR, bit test and negate instruction BTC, bit forward scan instruction BSF, bit backward scan instruction BSR, etc.

• Control transfer

This part includes the unconditional transfer instruction JMP and the conditional transfer instruction JCC /JCXZ, loop instructions LOOP/LOOPE/LOOPNE, procedure call instruction CALL, sub-process return instruction RET, interrupt instructions INTn, INT3, INTO, IRET, etc.

• String operations

This part of the instructions is used to operate on data strings, including String transfer instructions MOVS, string comparison instructions CMPS, string scan instructions SCANS, string load instructions LODS, and string save instructions STOS. These instructions can selectively use the prefixes of REP/REPE/REPZ/REPNE and REPNZ to operate continuously.

• Input and output

This part of the instructions is used to exchange data with peripheral devices, including Port input instructions IN/INS, port output instructions OUT/OUTS.

Characteristics of assembly language

Assembly language is the fastest and most effective language that computers provide to users. It is also able to utilize all the hardware features of the computer and directly control the hardware. the only language. However, because writing and debugging assembly language programs is more complicated than high-level languages, its application is currently not as widespread as high-level languages.

Assembly language is more readable than machine language, but compared with high-level languages, its readability is still poor. However, programs written using it have the characteristics of small storage space usage and fast execution speed, which cannot be replaced by high-level languages. In actual applications, whether to use assembly language depends on specific application requirements, development time and quality.

Advantages

Assembly language is a second-generation programming language above machine language. It also has many advantages:

It can easily read memory Status and hardware I/O interface status

The code written can be executed accurately because it has fewer compilation links

As a low-level language, it has high scalability

shortcoming

Because the code is very monotonous and there are few special instruction characters, it makes the code lengthy and difficult to write.

Because the assembly still needs to call the memory to store the data, it is easy for BUG to occur, and it is difficult to debug. Not easy

Even if a program is completed, it will take a lot of time to maintain it later.

Because of the particularity of the machine, the defect of poor code compatibility is caused.

For more related knowledge, please visit the FAQ column!

The above is the detailed content of What are the components of assembly language?. For more information, please follow other related articles on the PHP Chinese website!