- Problem 1 : Table Lookup Functions
<![CDATA[
; -- External Functions (Use these freely) --
extrn dspmsg near ; Input : DX = message pointer
extrn random near ; Output : AX = Random Integer between 0 .. 2^15-1
; -- Variable Section --
Title1 db 'Twister','$'
Title2 db 'Field of Debris','$'
Title3 db 'Four Weddings and a Funnel','$'
Title4 db 'Roofless in Seattle','$'
Title5 db 'Splintered Bridges of Madison County','$'
Titletable dw offset Title1, offset Title2, offset Title3, offset Title4,
offset Title5
; -- Code Section --
ChooseTitle PROC Near
; Preserve registers AX,BX,DX
call random ; Returns AX=0..2^16-1 in AX
mov DX, 0
mov BX, 5
div BX ; Mod by 5 to get Random value between 0..4
mov BX, DX
shl BX, 1 ; Multiply by 2 to index word table
mov DX, TitleTable[BX] ; Fetch pointer using Table Lookup
call DspMsg ; Print the message
ret
; Restore registers AX,BX,DX
ChooseTitle ENDP
]]>
- Problem 2 : Text-Mode Video Graphics
<![CDATA[
ColorPrint PROC NEAR
; DI=Pointer to String
; DH=Row
; DL=Column
mov AX, 0B800h
mov ES, AX ; Set Video Text Segment (Assume already in text mode)
mov SI, DI ; Store string pointer in SI (not DI)
mov AL, 80
mul DH ; Calculate Postion = Row * 80 + Column
mov DH, 0
add AX, DX ; Add column
mov DI, AX
shl DI, 1 ; Screen offset = 2 (80*row + col)
CLoop1:
mov AL, 4 ; Start with attribute = Red
cmp [SI], '$' ; Test for completion
je CDone
CLoop2:
and ES:[DI], 11110000b ; Write color Attribute byte to screen
or ES:[DI], AL
mov AH, [SI]
mov ES:[DI+1], AH ; Write Data byte to screen
add SI, 1
add DI, 2 ; Prepare for next data
shr al, 1 ; Alternate colors (4,2,1)
cmp al, 0
je CLoop1
jmp CLoop2
CDone:
ret
ColorPrint ENDP
]]>
- Problem 3: ISRs
- Table Values
- Task A: Period=5ms, CPU load=40% (Period=inverse Freq)
- Task B: Run Time=4ms, Period=10ms
- Task C: Freq=10Hz, CPU load=1%
- Total CPU Load=81% (Sum of process load)
- Preemptive Case
- Task A: 2ms (interrupts any other process): AA
- Task B: 8ms (interrupted by A twice): AABBBAAB
- Task C: 9ms (interrupted by A twice and B once): AABBBAABC
- Non-Preemptive Case
- Task A: 6ms (task B runs first): BBBBAA
- Task B: 7ms (task C runs first, then A): CAABBBB
- Task C: 9ms (task A twice, B once): AABBBBAAC or BBBBAAAAC
- Problem 4 : String Operations
<![CDATA[
StrOld db 'ECE291 Is The Greatest Class In This Universe.','$'
StrNew db 50 dup (?)
CreateMessage PROC NEAR
; preserve registers (PUSH AX,SI,DI,ES)
mov AX, DS
mov ES, AX ; set ES=DS
mov SI, offset StrOld+32 ; SI points to "This" in StrOld
mov DI, offset StrNew ; DI points to start of StrNew
CLD ; Auto-increment
mov CX, 5
rep movsb ; copy "This" and following space
mov SI, offset StrOld+7 ; SI points to "Is" in StrOld
mov CX, 22
rep movsb ; copy "Is The Greatest Class"
mov AL, '!'
mov CX, 6
rep stosb ; append "!!!!!!"
mov AL, '$' ; End string marker
stosb
; restore registers
CreateMessage ENDP
]]>
- Problem 5: Algorithms / Data Structure
- (9 Entries) * (2 Bytes for X + 1 Byte for Counter) = 27 Bytes
- (Relevant to Spring 97): Hanoi: N=1:1, N=2:3, N=3:7, N=5,15
- (Relevant to Spring 97): Lander: A=T-G, V=Vo+A*t, Y=Yo+V*t
Thus Y=(T-G)+Vo+Yo
- Macros expand to code. Unless base case value is known at
compile time, recursion cannot be expanded.
- Problem 6: Hardware Devices
- Horizontal Line
<![CDATA[
MOV AX,0A000h
MOV ES,AX
MOV DI,320
MOV CX,160
MOV AX,0202h
CLD
REP STOSW]]>
- Video Card
- Colors=2^15
- Simultaneous colors=16 (palette)
- VRAM=500kByte
- 16 colors (limited by palette)
- Number of IN operations is proportional to
polling time, T. T=RC is a capacitive-resistive time constant.
T=RC is a linear function because C is constant.
R varies linearly with position. Thus number of INs is
linearly proportional to position.