Addressing Mode Wannachai Wannasawade Department of Computer Education Faculty of Technical Education, KMITNB.

Addressing Mode ในการพัฒนาโปรแกรมต่าง ๆ มีการอ้างถึงตำแหน่งของข้อมูล ตามที่มีในคำสั่งของไมโครโพรเซสเซอร์ ซึ่งมีหลายวิธีในการติดต่อ ดังนั้นสิ่งที่จะต้องเรียนรู้คือ Addressing Mode หรือวิธีการอ้างตำแหน่ง วิธีการอ้างตำแหน่งแบ่งได้ 3 แบบคือ Data Addressing Mode Program Memory Addressing Mode Stack Memory Addressing Mode

Data Addressing Mode Register addressing Immediate addressing Direct addressing Register indirect address Base-plus-index addressing Register relative addressing Base relative-plus-index addressing Scaled-index address

Data Addressing Mode Register Addressing Transfer byte or word from source register or memory location to destination register or memory location

Data Addressing Mode MOV BX,CX

Data Addressing Mode Immediate Addressing Transfer source immediate byte or word of data into the destination register or memory location

Data Addressing Mode MOV EAX,13456H

Data Addressing Mode Direct Addressing Moves byte or word between a memory location and register Direct Addressing move between memory location and AL,AX or EAX Displacement Addressing applies to almost any instruction in the instruction set

Data Addressing Mode

Data Addressing Mode MOV AL,[1234H]

Data Addressing Mode Register Indirect Addressing Transfer byte or word between register and memory location address by index or base register

Data Addressing Mode MOV AX,[BX]

Data Addressing Mode Base-Plus-Index Addressing Transfer byte or word between register and memory location address by base register (BX or BP) plus index register (DI or SI)

Data Addressing Mode MOV DX,[BX+DI]

Data Addressing Mode Register-Relative Addressing Moves byte or word between register and memory location address by index or base register plus displacement

Data Addressing Mode MOV AX,[BX+1000H]

Data Addressing Mode Base Relative-Plus-Index Addressing Transfer byte or word between register and memory location address by base register and index register plus displacement

Data Addressing Mode MOV AX,[BX+SI+1000H]

Data Addressing Mode Scale-Index Addressing Available 80386-Pentium used second register of pair of register is modified by the scale factor of 2X, 4X or 8X to generate the operand memory address

Program Memory Addressing Mode Used with the JMP and CALL instruction มีใช้งาน 3 แบบคือ Direct Program Memory Addressing Relative Program Memory Addressing Indirect Program Memory Addressing

Direct Program Memory Addressing What many early microprocessors used for all jumps and calls and also used in high-level languages. For example, JMP [10000H] Opcode Offset(low) Offset(High) Segment(high) Segment(low) E A 0 0 1 0 Used in intersegment jumps or often called far jump

Relative Program Memory Addressing Not available in all early microprocessors, but available to some family of microprocessors. Relative means relative to instruction Pointer (IP) used in short jump or call (+127 and -128 byte from next instruction) and near jump or call (64K bytes)

Indirect Program Memory Addressing Allows several forms of program indirect memory addressing for JMP and CALL. This type of jump is sometimes called indirect-indirect or double-indirect jump Examples of indirect program memory addressing JMP AX JMP CX JMP NEAR PTR [BX] JMP TABLE [BX] JMP ECX

Stack Memory Addressing Mode The stack plays an importance role in all microprocessor. It holds data temporarily and stores return address of procedures. Used by PUSH and POP that maintained by two register Stack Pointer register (SP or ESP) Stack Segment register (SS)

Stack Memory Addressing Mode PUSH and POP a) PUSH BX b) POP CX

Instruction Set เป็นกลุ่มคำสั่งที่ไมโครโพรเซสเซอร์รู้จักและเข้าใจ ซึ่งสามารถแบ่งเป็นกลุ่มต่าง ๆ ได้ดังนี้ Data Movement Instructions Arithmetic and Logic Instructions Program Control Instructions

Data Movement Instructions MOV Instruction Opcode 1-2 bytes MOD-REG-R/M 0-1 bytes Displacement 0-1 bytes Immediate 0-2 bytes 16 bits Instruction mode Address size 0-1 bytes Operand size 0-1 bytes Opcode 1-2 bytes MOD-REG-R/M 0-1 bytes Scaled-index 0-1 bytes Displacement 0-4 bytes Immediate 0-4 bytes 32 bits Instruction mode (80386,80486 and Pentium)

Data Movement Instructions PUSH and POP Load-Effective Address LEA LDS LES LFS LGS LSS String Data Transfer LODS STOS MOVS INS OUTS XCHG LAHF and SAHF XLAT IN and OUT

Data Movement Instructions MOVSX and MOVZX BSWAP CMOV Segment Override Prefix

Arithmetic and Logic Instructions Addition Register Addition Immediate Addition Memory to Register Addition Array Addition Increment Addition Addition with Carry

Arithmetic and Logic Instructions Subtraction Register Subtraction Immediate Subtraction Decrement Subtraction Subtract with Borrow

Arithmetic and Logic Instructions Comparison CMP (Compare) CMPXCHG (Compare and Exchange) used in 80486 - Pentium

Arithmetic and Logic Instructions Multiplication 8 bit Multiplication 16 bit Multiplication Special Immediate 16 bit Multiplication 32 bit Multiplication

Arithmetic and Logic Instructions Division 8 bit Division 16 bit Division 32 bit Division

Arithmetic and Logic Instructions BCD and ASCII BCD Arithmetic DAA DAS ASCII Arithmetic AAA AAD AAM AAS

Arithmetic and Logic Instructions Basic Logic AND OR XOR TEST and Bit Test NOT and NEG

Arithmetic and Logic Instructions Shift SHL SHR SAR SAL SHLD SHRD

Arithmetic and Logic Instructions Rotate ROL ROR RCL RCR

Arithmetic and Logic Instructions Bit Scan Instruction BSF BSR String Comparisons SCAS CMPS

Program Comtrol Instructions Jump Group Unconditional Jump (JMP) Short Jump Near Jump Far Jump Jumps with Register Operands Indirect Jumps Using Index

Program Comtrol Instructions Jump Group Conditional Jump and Condition Sets JA JAE JB JBE JC JE or JZ JG JGE JL JLE JNC JNE or JNZ JNO JNS JNP or JPO JO JP or JPE JS JCXZ JECXZ LOOP Condition LOOPs

Program Comtrol Instructions Procedures CALL Near CALL Far CALL CALL with Register Operands CALL with Indirect Memory Address RET

Program Comtrol Instructions Other Instructions Interrupt Instructions INT X IRET/IRETD WAIT HLT NOP

Program Comtrol Instructions Other Instructions LOCK Prefix ESC BOUND ENTER and LEAVE