mith College Computer Science CSC231 - Assembly Week #9 Dominique Thiébaut

Transcription

1 mith College Computer Science CSC231 - Assembly Week #9 Dominique Thiébaut dthiebaut@smith.edu

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3 1,000,000 DNA Bases: How fast? section.data DNA db "AGCTANATTTTAGC " db "GGTC " db "GCCCTTTTAAAA" N equ mov ebx, DNA ; ebx points to DNA mov ecx, N ; ready to loop N times for: add byte[ebx], -'A'+'a' ; transform char to lowercase inc ebx ; ebx points to next byte loop for ; loop N times

4 1,000,000 DNA Bases: How fast? N equ section.bss DNA resb N Better! section.text ; some code goes here to fill DNA with actual letters mov ebx, DNA ; ebx points to DNA mov ecx, N ; ready to loop N times for: add byte[ebx], -'A'+'a' ; transform char to lowercase inc ebx ; ebx points to next byte loop for ; loop N times

5 1,000,000 DNA Bases: How fast? DNA db "AGCTANATTTTAGC " db "GGTC " db "GCCCTTTTAAAA" N equ mov ebx, DNA ; ebx points to DNA mov ecx, N ; ready to loop N times for: add byte[ebx], -'A'+'a' ; transform char to lowercase inc ebx ; ebx points to next byte loop for ; loop N times Total # cycles = 2 + 3*1,000,000 = 3,000,002 cycles Assuming frequency of 1GHz, 1 cycle = 1ns 3,000,0002 ns = sec

6 Addressing Modes

7 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

8 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

9 Immediate mov ax, 0x1122 eax XXXXXXXX Before

10 Immediate mov ax, 0x1122 eax XXXXXXXX eax XXXX1122 Before After

11 Immediate a db "Hello" mov eax, a eax XXXXXXXX eax 0x Before After

12 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

13 Direct Memory 0x1104B 33 0x1104A 78 0x mov eax, dword[a] 0x E < a 0x11047 F0 0x x eax Before

14 Direct Memory 0x1104B 33 0x1104A 78 0x mov eax, dword[a] 0x E < a 0x11047 F0 0x x eax eax E Before After

15 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

16 Memory Indirect 0x1104B 33 0x1104A 78 0x mov ebx, a mov eax, dword[ebx] 0x x E F0 < a 0x x eax XXXXXXXX ebx a Before

17 Memory Indirect 0x1104B 33 0x1104A 78 0x mov ebx, a mov eax, dword[ebx] 0x x E F0 < a 0x x eax XXXXXXXX eax E ebx a Before After

18 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

19 Indirect plus Dispt. mov ebx, a mov eax, dword[ebx+3] 0x1104B 0x1104A 0x x x x x11045 Memory E F0 3 1 < a eax ebx a Before

20 Indirect plus Dispt. Memory 0x1104B 33 mov ebx, a mov eax, dword[ebx+3] + 0x1104A 0x x E 0x11047 F0 0x x < a eax ebx a eax E Before After

21 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

22 2 New Registers! eax ebx ecx edx

23 2 New Registers! eax eip ebx ecx edx

24 2 New Registers! eax ebx ecx eip esi edi edx "i" in esi, edi for index "s" for source, "d" for destination

25 2 New Registers! eax ebx ecx eip esi edi edx Index Registers Data Registers

26 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

27 Indirect Indexed Memory mov ebx, a mov esi, 2 mov ax, word[ebx+esi] 0x1104B 0x1104A 0x x x E F0 0x x < a eax ebx esi XXXXXXXX a 2 Before

28 Indirect Indexed Memory mov ebx, a mov esi, 2 mov ax, word[ebx+esi] 0x1104B 0x1104A 0x x x E F0 0x x < a eax ebx XXXXXXXX a + esi 2 eax XXXX3EF0 Before After

29 Immediate Direct Indirect Indirect plus Displacement Indirect Indexed Indirect Indexed plus Displacement

30 Indirect Indexed plus Displacement mov ebx, a mov esi, 2 mov ax, word[ebx+esi+1] 0x1104B 0x1104A 0x x x x x11045 Memory E F0 3 1 < a eax ebx esi XXXXXXXX a 2 Before

31 Indirect Indexed plus Displacement mov ebx, a mov esi, 2 mov ax, word[ebx+esi+1] 0x1104B 0x1104A 0x x x x x11045 Memory E F0 3 1 < a eax XXXXXXXX + ebx a esi 2 eax XXXX563E Before After

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33 We Stopped Here Last Time (and finished first exercise on next slide)

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35 Hw7 Pb 5

36 short x, y; x = ; y = ; x + y = x + y + y =

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38 java MysteryShortsPrintNegativeNumbers x0000BDDB

39 java MysteryShorts

40 msg1 db "A man, a plan, a canal, Panama" msg2 db " " MSGLEN equ $-msg2 mov mov mov esi, msg1 edi, msg2+msglen-1 ecx, MSGLEN for mov al, byte[esi] mov byte[edi], al inc esi dec edi loop for

41 Solution 2 (upper to lower) msg db "HELLOTHEREHOWAREYOU" MSGLEN equ $-msg mov ebx, msg ; ebx points to 1st char of msg mov ecx, MSGLEN ; # of chars in string for: sub byte[ebx],32 ; lower to upper case, in memory inc ebx ; ebx points to next char loop for

42 Solution 3 (powers of 2) Table db 0,0,0,0,0,0,0,0 N equ 8 mov ebx, Table ; ebx points to Table[0] mov esi, 0 ; esi is index 0 mov al, 1 ; first power of 2 mov ecx, N ; number of items in Table for: mov byte[ebx+esi], al ; Table[i] <- al inc esi ; point to next uncomputed fib add al, al ; al <- 2*al loop for ; go back

43 Solution 4 (array of 16 fib terms) fib dw 0, 0, 0, 0, 0, 0, 0, 0 dw 0, 0, 0, 0, 0, 0, 0, 0 NOFIB equ 16 mov word[fib], 1 ; init fib[0] mov word[fib+2], 1 ; init fib[1] mov ebx, fib ; ebx points to fib mov esi, 2*2 ; esi is index 2 mov ecx, NOFIB-2 ; compute 14 fib in loop mov ax, word[ebx+esi-1*2] ; ax <- fib[0] for: add ax, word[ebx+esi-2*2] ; ax <- fib[0]+fib[1] mov word[ebx+esi], ax ; fib[i] <- ax add esi,2 ; esi now index of next fib loop for

44 Solution 5 (10 powers of 2 as ints) Powers dd 0,0,0,0,0,0,0,0,0,0 NOPOW equ 10 mov ebx, Powers ; ebx points to powers mov eax, 1 mov ecx, NOPOW ; ready to loop 9 times for: mov dword[ebx], eax ; cell of array add ebx, 4 ; point to next empty cell add eax, eax ; eax <- eax * 2 loop for ; go 10 times

45 Solution 6 msg1 db "A man, a plan, a canal, Panama" msg2 db " " MSGLEN equ $-msg2 mov ebx, msg1 mov esi, 0 mov edi, msg2+msglen-1 mov ecx, MSGLEN for mov al, byte[ebx+esi] mov byte[edi], al inc esi dec edi loop for

46 The IF-Statement

47 2 Videos to Watch at a Later Time

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49 time A 1-D Version # # # # # # #

50 time A 1-D Version # # # # # # # # # #

51 time A 1-D Version # # # # # # # # # #

52 time Rules of Life Rule 1: 0 neighbors #

53 time Rules of Life Rule 1: 0 neighbors # Underpopulation

54 time Rules of Life Rule 2: 1 neighbor # # #

55 time Rules of Life Rule 2: 1 neighbor # # # # # # # Right Environment

56 time Rules of Life Rule 3: 2 neighbors # # # # #

57 time Rules of Life Rule 3: 2 neighbors # # # # # # # # # Overpopulation

58 Problem of the Day(s): Implement 1D Game of Life in Assembly!

59 How to Approach This?