For the following block-move program, is it repeat-until or while-do loop structure? Can you change it into While-do loop structure?
For the following block-move program, is it repeat-until or while-do loop structure? Can you change it into While-do loop structure?
Computer Networking: A Top-Down Approach (7th Edition)
7th Edition
ISBN:9780133594140
Author:James Kurose, Keith Ross
Publisher:James Kurose, Keith Ross
Chapter1: Computer Networks And The Internet
Section: Chapter Questions
Problem R1RQ: What is the difference between a host and an end system? List several different types of end...
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Question
For the following block-move
![### Block-Move Program Analysis
**3) For the following block-move program, is it repeat-until or while-do loop structure? Can you change it into While-do loop structure?**
```assembly
MOV AX, DATASEGADDR
MOV DS, AX
MOV SI, BLK1ADDR
MOV DI, BLK2ADDR
MOV CX, N
NXTPT:
MOV AH, [SI]
MOV [DI], AH
INC SI
INC DI
DEC CX
JNZ NXTPT
HLT
```
### Explanation
This assembly language program is designed to move a block of data from one memory location to another.
#### Key Instructions:
- **MOV AX, DATASEGADDR**: Loads the data segment address into the AX register.
- **MOV DS, AX**: Sets the Data Segment (DS) register.
- **MOV SI, BLK1ADDR**: Sets the Source Index (SI) to the address of the source block.
- **MOV DI, BLK2ADDR**: Sets the Destination Index (DI) to the address of the destination block.
- **MOV CX, N**: Initializes the CX register with the number of elements to move (N).
#### Loop Structure:
- **NXTPT**: Label for the loop.
- **MOV AH, [SI]**: Moves data from the source index to the AH register.
- **MOV [DI], AH**: Copies data from AH to the destination index.
- **INC SI / INC DI**: Increments both the Source and Destination Indexes.
- **DEC CX**: Decreases the counter (CX) with each iteration.
- **JNZ NXTPT**: Jumps to NXTPT if CX is not zero, continuing the loop.
- **HLT**: Halts the program once the loop is complete.
### Loop Type
This is a "repeat-until" loop because it will execute at least once and continue until CX equals zero.
#### Conversion to While-Do Loop
To adapt this to a while-do structure, the loop should check the condition at the beginning. However, in assembly language, this involves setting up a conditional check before entering the block movement, ensuring it does not proceed if CX is zero initially.
An additional preliminary check on CX would need to be implemented before entering the loop.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9762c577-116a-4e42-b98e-d0fc2ccf3980%2F9a2f365a-f99b-4d4b-99b4-bfa7eed6f41e%2Faeeq8k2_processed.png&w=3840&q=75)
Transcribed Image Text:### Block-Move Program Analysis
**3) For the following block-move program, is it repeat-until or while-do loop structure? Can you change it into While-do loop structure?**
```assembly
MOV AX, DATASEGADDR
MOV DS, AX
MOV SI, BLK1ADDR
MOV DI, BLK2ADDR
MOV CX, N
NXTPT:
MOV AH, [SI]
MOV [DI], AH
INC SI
INC DI
DEC CX
JNZ NXTPT
HLT
```
### Explanation
This assembly language program is designed to move a block of data from one memory location to another.
#### Key Instructions:
- **MOV AX, DATASEGADDR**: Loads the data segment address into the AX register.
- **MOV DS, AX**: Sets the Data Segment (DS) register.
- **MOV SI, BLK1ADDR**: Sets the Source Index (SI) to the address of the source block.
- **MOV DI, BLK2ADDR**: Sets the Destination Index (DI) to the address of the destination block.
- **MOV CX, N**: Initializes the CX register with the number of elements to move (N).
#### Loop Structure:
- **NXTPT**: Label for the loop.
- **MOV AH, [SI]**: Moves data from the source index to the AH register.
- **MOV [DI], AH**: Copies data from AH to the destination index.
- **INC SI / INC DI**: Increments both the Source and Destination Indexes.
- **DEC CX**: Decreases the counter (CX) with each iteration.
- **JNZ NXTPT**: Jumps to NXTPT if CX is not zero, continuing the loop.
- **HLT**: Halts the program once the loop is complete.
### Loop Type
This is a "repeat-until" loop because it will execute at least once and continue until CX equals zero.
#### Conversion to While-Do Loop
To adapt this to a while-do structure, the loop should check the condition at the beginning. However, in assembly language, this involves setting up a conditional check before entering the block movement, ensuring it does not proceed if CX is zero initially.
An additional preliminary check on CX would need to be implemented before entering the loop.
Expert Solution
Step 1
Two differences between repeat-until and while-do loop program structures. and change it into the other loop program structure instead.
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