Chapter 1 answers to all exercises in Chapter 13th of Wang Shuang's Assembly Language

Note that there are programs and test programs. For example, exp1303.asm refers to Chapter 13's third question. exp1303. ASM refers to the test of exp1303 program...

 

; Exp1301.asm

 

Install the 7ch Interrupt Routine
Function: calculates the square of a word number.
;
;
Assume Cs: Code

Code segment
Start:
; Copy the code to a non-system management area
MoV ax, CS
MoV ds, ax
MoV Si, offset sqr; copy from sqr of CS segment to 0: 200

MoV ax, 0
MoV es, ax
MoV Di, 200 h

MoV CX, offset sqrend-offset sqr; CX is the number of Code bytes to be copied
ClD
Rep movsb; call movsb to copy ES: [di] bytes to DS: [Si]

; Set the interrupt vector
MoV ax, 0
MoV es, ax
MoV word ptr es: [7ch * 4], 200 h; Use Word PTR to indicate that a word is to be copied
MoV word ptr es: [7ch * 4 + 2], 0

MoV ax, 3
Int 7ch

MoV ax, 4c00h
Int 21 h

Sqr:
Mul ax
Iret
Sqrend:
NOP

Code ends

End start

 

 

; Exp1302.asm

 

 

Install the 7ch Interrupt Routine
Function: Display strings starting with DS: [Si ].

Assume Cs: Code

Data Segment
DB "Welcome to MASM! ", 0
Data ends

Code segment
Start:
; Copy the code to a non-system management area
MoV ax, CS
MoV ds, ax
MoV Si, offset int7c; copy from int7c of CS segment to 0: 200

MoV ax, 0
MoV es, ax
MoV Di, 200 h

MoV CX, offset int7cend-offset int7c
ClD
Rep movsb

; Set the interrupt vector
MoV ax, 0
MoV es, ax
MoV word ptr es: [7ch * 4], 200 h
MoV word ptr es: [7ch * 4 + 2], 0

; DH = number of rows, DL = strong, CL = color, DS: Si points to the first address
MoV DH, 10
MoV DL, 10
MoV Cl, 2

MoV ax, Data
MoV ds, ax

MoV Si, 0
Int 7ch

MoV ah, 01 H
Int 21 h

MoV ax, 4c00h
Int 21 h

Int7c:
PUSH AX
Push BX
Push CX
Push DX
Push es

The address y = 160 * (number of rows-1) + number of columns * 2-2, b800: Y
; Cyclically write the strings in the parameters into the memory of the video card, and return the results if 0 is detected.

; BX = 160 * (number of rows-1)
Sub DH, 1 h
MoV Al 160
Mul DH
MoV BX, ax; BX is the offset value calculated based on the number of rows

; AX = number of columns * 2-2
MoV Al, 2
Mul DL
Sub ax, 2; offset value calculated based on the number of Columns
Add Bx, ax; The sum of the number of rows and columns exists in BX.

MoV ax, 0b800h
MoV es, ax

MoV DL, Cl; Save the font color attribute
MoV CH, 0

S_show_str:
MoV Cl, DS: [Si]
MoV ES: [BX], Cl
Jcxz OK _show_str

MoV ES: [bx + 1], DL

INC Si
Add Bx, 2
JMP short s_show_str

OK _show_str:
Pop es
Pop DX
Pop CX
Pop BX
Pop ax
Iret
Int7cend:
NOP

Code ends

End start

 

; Exp1302t. ASM

; Test procedure of the previous program

 

; Test 7ch interrupt, display string

Assume Cs: Code

Data Segment
DB "Welcome to MASM 6.11! ", 0
Data ends

Code segment
Start:
MoV ax, Data
MoV ds, ax

MoV DH, 10
MoV DL, 10
MoV Cl, 2
MoV Si, 0

Int 7ch

MoV ax, 4c00h
Int 21 h
Code ends

End start

 

; Exp1303.asm

 

Install the 7ch Interrupt Routine
Function: converts all strings starting with DS: Si and ending with 0 to uppercase.

Assume Cs: Code

Data Segment
DB "Welcome to MASM! ", 0
Data ends

Code segment
Start:
; Copy the code to a non-system management area
MoV ax, CS
MoV ds, ax
MoV Si, offset int7c; copy the interrupt code from int7c of CS segment

MoV ax, 0
MoV es, ax
MoV Di, 200 h

MoV CX, offset int7cend-offset int7c
ClD
Rep movsb

; Set the interrupt vector
MoV ax, 0
MoV es, ax
MoV word ptr es: [7ch * 4], 200 h
MoV word ptr es: [7ch * 4 + 2], 0

MoV ax, Data
MoV ds, ax
MoV Si, 0
Int 7ch

MoV ah, 01 H
Int 21 h

MoV ax, 4c00h
Int 21 h

Int7c:
 
; Compares the characters starting with DS: [Si]. If it is a lowercase letter, converts it to uppercase.
Because it ends with 0, jcxz can be used here
The lower-case letters are in the range of 61h ~ 7ah, 20 h less capital letters than it
And can be judged by JB 61 H and Ja 7ah, and cyclically
Push CX
Push Si
 
MoV CH, 0
Loop1:
MoV Cl, DS: [Si]
Jcxz loop1end
 
CMP Cl, 61 H
JB notcase
CMP Cl, 7ah
Ja notcase

Sub Cl, 20 h
MoV DS: [Si], Cl
INC Si
JMP short loop1

Notcase:
INC Si
JMP short loop1

Loop1end:
Pop Si
Pop CX
Iret

Int7cend:
NOP

Code ends

End start

 

; Exp1303t. ASM

Test exp1303. Use the 7ch interrupt to convert all lowercase letters of DS: [Si] To uppercase letters.
; Show_str is shown below

Note: Using and bytr PTR [Si] And 110111b to uppercase can simplify the process.

Assume Cs: Code

Data Segment
DB "Welcome to MASM! ", 0
Data ends

Stack segment

Stack ends

Code segment
Start:
 
MoV ax, Data
MoV ds, ax
MoV Si, 0
 
Int 7ch

MoV ax, Data
MoV ds, ax
MoV Si, 0
MoV DH, 2
MoV DL, 3
MoV Cl, 2
Call show_str

MoV ah, 01 H
Int 21 h

MoV ax, 4c00h
Int 21 h
 

; Name: show_str
Function: Specify the position and color to display a string ending with 0
; Parameter: (DH) = row number (0--24), (DL) = column number (0--79)
; (CL) = color, DS: Si points to the first address of the string
; Return: None
Show_str:
PUSH AX
Push BX
Push CX
Push DX
Push es

The address y = 160 * (number of rows-1) + number of columns * 2-2, b800: Y
; Cyclically write the strings in the parameters into the memory of the video card, and return the results if 0 is detected.

; BX = 160 * (number of rows-1)
Sub DH, 1 h
MoV Al 160
Mul DH
MoV BX, ax; BX is the offset value calculated based on the number of rows

; AX = number of columns * 2-2
MoV Al, 2
Mul DL
Sub ax, 2; offset value calculated based on the number of Columns
Add Bx, ax; The sum of the number of rows and columns exists in BX.

MoV ax, 0b800h
MoV es, ax

MoV DL, Cl; Save the font color attribute
MoV CH, 0

S_show_str:
MoV Cl, DS: [Si]
MoV ES: [BX], Cl
Jcxz OK _show_str

MoV ES: [bx + 1], DL

INC Si
Add Bx, 2
JMP short s_show_str

OK _show_str:
Pop es
Pop DX
Pop CX
Pop BX
Pop ax

RET

Code ends

End start

 

; Exp1304.asm

 

; Use BIOS interrupt and DOS interrupt

Assume Cs: code, DS: Data

Data Segment
DB 'Welcome to ASM! ',' $'
Data ends

Stack segment

Stack ends

Code segment
Start:
; Call BIOS Interrupt Routine
MoV ah, 2
MoV BH, 0
MoV DH, 5
MoV DL, 12
Int 10 h

MoV ah, 9
MoV Al, 'A'
MoV BL, 11001010b
MoV BH, 0
MoV CX, 3
Int 10 h

; Call dos Interrupt Routine
MoV ax, 4c00h
Int 21 h

Code ends

End start

 

; Exp1305.asm

 

Assume Cs: code, DS: Data

Data Segment
DB 'Welcome to ASM! ',' $'
Data ends

Stack segment

Stack ends

Code segment
Start:
MoV ah, 2; BIOS light indicator routine
MoV BH, 0; Page 0th
MoV DH, 5; DH row number
MoV DL, 12; dl column number
Int 10 h

MoV ax, data;
MoV ds, ax
MoV dx, 0; DS: DX points to the first address of the string data: 0
MoV ah, 9; Child Program of Interrupt Routine No. 21
Int 21 h

MoV ax, 4c00h
Int 21 h

Code ends

End start

 

; Exp1306.asm

 

; Use int 7ch instead of loop function, BX is the offset address, CX is the number of cycles
; 7ch installation interrupted
The key is to convert the Cs: IP address to be jumped to by the current program after int7ch.

When the call is interrupted, several important registers will press the stack. The sequence is: Mark register, Cs, IP
The principle here is to change the IP value in the stack to the starting address of the loop when calling the interrupt 7 CH, and then return the interrupt
; Understand the above two points, this question is OK, otherwise the access will go wrong, encountering the operating system's restricted area

Assume Cs: Code

Code segment
Start:
; Copy the code to the 0: 200 memory Zone
MoV ax, CS
MoV ds, ax
MoV Si, offset int7c

MoV ax, 0
MoV es, ax
MoV Di, 200 h
 
MoV CX, offset int7cend-offset int7c
ClD
Rep movsb

; Installation interrupt variable
MoV ax, 0
MoV es, ax
MoV word ptr es: [7ch * 4], 200 h
MoV word ptr es: [7ch * 4 + 2], 0

MoV ax, 4c00h
Int 21 h

Int7c:
Push BP

MoV bp, SP
Dec CX
Jcxz offset int7cok

Sub [bp + 2], BX; IP

Int7cok:
Pop BP
Iret
Int7cend:
NOP

Code ends

End start

 

; Exp1306t

 

; Use int 7ch instead of loop function, BX is the offset address, CX is the number of cycles
; Display 80' in the middle of the screen '! '

Assume Cs: Code

Code segment
Start:
MoV ax, 0b800h
MoV es, ax
MoV Di, 160*12; 12 rows, right in the middle of the 80*24 Screen

MoV BX, offset se-offset s
MoV CX, 80
S:
MoV byte ptr es: [di], '! '
MoV byte ptr es: [di + 1], 2
Add Di, 2
Int 7ch
SE:
NOP

MoV ax, 4c00h
Int 21 h

Code ends

End start

 

; Exp1307.asm

 

Directly address the table and call the bios, DOS interrupt display string

Assume Cs: Code

Code segment
S1 dB 'good, better, best! ',' $'
S2 dB 'Never let it rest! ',' $'
S3 dB 'till good is better ',' $'
S4 dB 'and better, best.', '$'
S DW offset S1, offset S2, offset S3, offset S4
Row dB

Start:
MoV ax, CS
MoV ds, ax
MoV BX, offset s
MoV Si, offset row
MoV CX, 4
OK:
BiOS cursor placement
MoV BH, 0
MoV DH, [Si]
MoV DL, 0
MoV ah, 2
Int 10 h

; Dos display string routine
MoV dx, [BX]
MoV ah, 9
Int 21 h

INC Si; row is dB, one byte
Add Bx, 2; Because DW occupies two bytes, add 2

Loop OK

MoV ax, 4c00h
Int 21 h
Code ends

End start

 

In this chapter, I have learned more about interrupt. Through debugging and observation, I can better understand the changes in the stack and various registers when I call the int and iret commands...