Write a NASM program that reads a set of integers from a fi le into an array. Th

Question

Write a NASM program that reads a set of integers from a file into an array. The data file name is to be read from the command line.

Format of the data file: Assume the file gives the number of data points on the first line.

Every line following the first line contains exactly one value. The maximum number of integers in the file will be 1000.

Add all the integers that you have read and print out the sum on the screen as well as the greatest and the smallest integer in your array.

You can construct your own data files for this in the format described above.

You may use the C library functions like fopen, fscanf and printf. You will need to use gcc to link your source code if you use the C library functions.

1.Your code must be modular i.e. you have subroutines for opening the file, reading integers and populating your array, doing your calculations, printing your output etc.

2.Any code that you use from our examples should be in (common_code.asm) and this file should be included in your main project file

Explanation / Answer

; this program demonstrates how to open files for reading

; It reads a text file line by line and displays it on the screen

extern fopen

extern fgets

extern fclose

extern printf

extern exit

global main

segment .data

readmode: db "r",0

filename: db "hw6_1.dat",0 ; filename to open

error1: db "Cannot open file",10,0

format_1: db "%d",0

segment .bss

buflen: equ 256 ; buffer length

buffer: resd buflen ; input buffer

segment .text

main: pusha

; OPENING FILE FOR READING

push readmode ; 1- push pointer to openmode   

push filename ; 2- push pointer to filename

call fopen ; fopen retuns a filehandle in eax

add esp, 8 ; or 0 if it cannot open the file

cmp eax, 0

jnz .L1   

push error1 ; report an error and exit

call printf

add esp, 4

jmp .L4

; READING FROM FILE   

.L1: mov ebx, eax ; save filepointer of opened file in ebx

; Get first line and pass to ecx

push ebx

push dword buflen

push buffer

call fgets

add esp, 12

cmp eax, 0

je .L3

;convert string -> numeric

push buffer

call parseInt

mov ecx, eax

.L2:

;debug

push ecx

push format_1

call printf

add esp, 8

push ebx ; 1- push filehandle for fgets

push dword buflen ; 2- push max number of read chars

push buffer ; 3- push pointer to text buffer

call fgets ; get a line of text

add esp, 12 ; clean up the stack

cmp eax, 0 ; eax=0 in case of error or EOF

je .L3

push buffer ; output the read string

call printf

add esp, 4 ; clean up the stack

dec ecx

cmp ecx, 0

jg .L2

;CLOSING FILE

.L3: push ebx ; push filehandle

call fclose ; close file

add esp, 4 ; clean up stack

.L4: popa

call exit

parseInt:   

push ebp

mov ebp, esp

push ebx

push esi

mov esi, [ebp+8] ; esi points to the string

xor eax, eax ; clear the accumulator

.I1 cmp byte [esi], 0 ; end of string?

je .I2

mov ebx, 10

mul ebx ; eax *= 10

xor ebx, ebx

mov bl, [esi] ; bl = character

sub bl, 48 ; ASCII conversion

add eax, ebx

inc esi

jmp .I1

.I2: pop esi

pop ebx

pop ebp

ret 4

If you're just printing data and not using any formatting features of printf, then use puts instead. (Note that puts automatically appends a newline. If you don't want that, use fputs but be aware of the extra FILE* parameter.)

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