Different String Manipulation Instructions
The string is a series of data bytes or words available in memory at consecutive locations. It is either referred as byte string or a word string. Their memory is always allocated in a sequential order. Instructions used to manipulate strings are called string manipulation instructions. Following is the table showing the list of string manipulation instructions:
| OPCODE | OPERAND | EXPLANATION | EXAMPLE |
|---|---|---|---|
| REP | instruction | repeat the given instruction till CX != 0 | REP MOVSB |
| REPE | instruction | repeat the given instruction while CX = 0 | REPE |
| REPZ | instruction | repeat the given instruction while ZF = 1 | REPZ |
| REPNE | instruction | repeat the given instruction while CX != 0 | REPNE |
| REPNZ | instruction | repeat the given instruction while ZF = 0 | REPNZ |
| MOVSB | none | moves contents of byte given by DS:SI into ES:DI | MOVSB |
| MOVSW | none | moves contents of word given by DS:SI into ES:DI | MOVSW |
| MOVD | none | moves contents of double word given by DS:SI into ES:DI | MOVD |
| LODSB | none | moves the byte at address DS:SI into AL; SI is incr/decr by 1 | LODSB |
| LODSW | none | moves the word at address DS: SI into AX; SI is incr/decr by 2 | LODSW |
| LODSD | none | moves the double word at address DS:SI into EAX; SI is incr/decr by 4 | LODSD |
| STOSB | none | moves contents of AL to byte address given by ES:DI; DI is incr/dec by 1 | STOSB |
| STOSW | none | moves the contents of AX to the word address given by ES:DI; DI is incr/decr by 2 | STOSW |
| STOSD | none | moves contents of EAX to the DOUBLE WORD address given by ES:DI; DI is incr/decr by 4 | STOSD |
| SCASB | none | compares byte at ES:DI with AL and sets flags according to result | SCASB |
| SCASW | none | compares word at ES:DI with AX and sets flags | SCASW |
| SCASD | none | compares double word at ES:DI with EAX and sets flags | SCASD |
| CMPSB | none | compares byte at ES:DI with byte at DS:SI and sets flags | CMPSB |
| CMPSW | none | compares word at ES:DI with word at DS:SI and sets flags | CMPSW |
| CMPSD | none | compares double word at ES:DI with double word at DS:SI and sets flags | CMPSD |
String manipulation instructions in 8086 microprocessor
In this Article, We will be going through the String Manipulation Instruction, We will start our Article with the Introduction of the String Manipulation Instruction in the 8086, Then We will go through the different String Manipulation Instructions with some Examples, and At last, we will conclude our Article with Some FAQs.