| CompOrg Fall 2004 Lab |
| CompOrg Home | p1 | p2 | p3 | p4 | p5 |
This lab involves determining what command line input is necessary to get a various programs to print "You are a wizard". Each of the programs below will print this string if you enter the right thing(s) on the command line when you run the program.
For each of the programs, you are given the assembly code for the
entire program, including the function named "checkguess", this
function is passed values extracted from the command line args (argv).
You are also given the C code for main() so you can see
how checkguess is called (and what is expected on the command
line).
You can save the assembly code, compile to build an executable and run the executable using gdb to step through the code. Lab5 included some documentation on using gdb.
The files p1.s, p2.s, etc. are also available on monte.cs.rpi.edu
in ~hollingd/public/lab7:
> mkdir lab7 > cp ~hollingd/public/lab7/* lab7 > cd lab7
| p1.s | main() |
.file "p1.c" .section .rodata .LC0: .string "You are a wizard\n" .LC1: .string "You are wrong\n" .text .globl checkguess .type checkguess,@function checkguess: pushl %ebp movl %esp, %ebp subl $8, %esp cmpl $25, 8(%ebp) jne .L2 subl $12, %esp pushl $.LC0 call printf addl $16, %esp jmp .L1 .L2: subl $12, %esp pushl $.LC1 call printf addl $16, %esp .L1: leave ret .Lfe1: .size checkguess,.Lfe1-checkguess .section .rodata .align 32 .LC2: .string "You need to enter a number on the command line\n" .text .globl main .type main,@function main: pushl %ebp movl %esp, %ebp subl $8, %esp andl $-16, %esp movl $0, %eax subl %eax, %esp cmpl $1, 8(%ebp) jg .L5 subl $12, %esp pushl $.LC2 call printf addl $16, %esp movl $1, -8(%ebp) jmp .L4 .L5: subl $12, %esp movl 12(%ebp), %eax addl $4, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -4(%ebp) subl $12, %esp pushl -4(%ebp) call checkguess addl $16, %esp movl $0, -8(%ebp) .L4: movl -8(%ebp), %eax leave ret .Lfe2: .size main,.Lfe2-main |
int main(int argc, char **argv) {
int x;
if (argc < 2 ) {
printf("You need to enter a number on the command line\n");
return(1);
}
x = atoi(argv[1]);
checkguess(x);
return(0);
}
|
| p2.s | main() |
.file "p2.c" .section .rodata .LC0: .string "grOpmoC" .LC1: .string "You are a wizard\n" .LC2: .string "You are wrong\n" .text .globl checkguess .type checkguess,@function checkguess: pushl %ebp movl %esp, %ebp subl $8, %esp subl $8, %esp pushl $.LC0 pushl 8(%ebp) call strcmp addl $16, %esp testl %eax, %eax jne .L2 subl $12, %esp pushl $.LC1 call printf addl $16, %esp jmp .L1 .L2: subl $12, %esp pushl $.LC2 call printf addl $16, %esp .L1: leave ret .Lfe1: .size checkguess,.Lfe1-checkguess .section .rodata .align 32 .LC3: .string "You need to enter a string on the command line\n" .text .globl main .type main,@function main: pushl %ebp movl %esp, %ebp subl $8, %esp andl $-16, %esp movl $0, %eax subl %eax, %esp cmpl $1, 8(%ebp) jg .L5 subl $12, %esp pushl $.LC3 call printf addl $16, %esp movl $1, -4(%ebp) jmp .L4 .L5: subl $12, %esp movl 12(%ebp), %eax addl $4, %eax pushl (%eax) call checkguess addl $16, %esp movl $0, -4(%ebp) .L4: movl -4(%ebp), %eax leave ret .Lfe2: .size main,.Lfe2-main |
int main(int argc, char **argv) {
if (argc < 2 ) {
printf("You need to enter a string on the command line\n");
return(1);
}
checkguess(argv[1]);
return(0);
}
|
| p3.s | main() |
.file "p3.c" .section .rodata .LC0: .string "You are wrong\n" .LC1: .string "You are a wizard\n" .text .globl checkguess .type checkguess,@function checkguess: pushl %ebp movl %esp, %ebp subl $8, %esp cmpl $0, 8(%ebp) jg .L3 cmpl $9, 12(%ebp) jle .L3 movl 12(%ebp), %eax addl 8(%ebp), %eax cmpl $5, %eax jne .L3 jmp .L2 .L3: subl $12, %esp pushl $.LC0 call printf addl $16, %esp jmp .L1 .L2: subl $12, %esp pushl $.LC1 call printf addl $16, %esp .L1: leave ret .Lfe1: .size checkguess,.Lfe1-checkguess .section .rodata .align 32 .LC2: .string "You need to enter two numbers on the command line\n" .text .globl main .type main,@function main: pushl %ebp movl %esp, %ebp subl $24, %esp andl $-16, %esp movl $0, %eax subl %eax, %esp cmpl $2, 8(%ebp) jg .L6 subl $12, %esp pushl $.LC2 call printf addl $16, %esp movl $1, -12(%ebp) jmp .L5 .L6: subl $12, %esp movl 12(%ebp), %eax addl $4, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -4(%ebp) subl $12, %esp movl 12(%ebp), %eax addl $8, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -8(%ebp) subl $8, %esp pushl -8(%ebp) pushl -4(%ebp) call checkguess addl $16, %esp movl $0, -12(%ebp) .L5: movl -12(%ebp), %eax leave ret .Lfe2: .size main,.Lfe2-main |
int main(int argc, char **argv) {
int x,y;
if (argc < 3 ) {
printf("You need to enter two numbers on the command line\n");
return(1);
}
x = atoi(argv[1]);
y = atoi(argv[2]);
checkguess(x,y);
return(0);
}
|
| p4.s | main() |
.file "p4.c" .section .rodata .LC0: .string "You are wrong\n" .LC1: .string "You are a wizard\n" .text .globl checkguess .type checkguess,@function checkguess: pushl %ebp movl %esp, %ebp subl $8, %esp movl $3, -4(%ebp) movl $0, -8(%ebp) cmpl $7, 8(%ebp) ja .L2 movl 8(%ebp), %eax sall $2, %eax movl .L11(%eax), %eax jmp *%eax .section .rodata .align 4 .align 4 .L11: .long .L3 .long .L4 .long .L5 .long .L6 .long .L7 .long .L8 .long .L9 .long .L10 .text .L3: movl $12, -8(%ebp) jmp .L2 .L4: movl $4, -8(%ebp) jmp .L2 .L5: movl $7, -8(%ebp) jmp .L2 .L6: movl $1, -8(%ebp) jmp .L2 .L7: movl $23, -8(%ebp) jmp .L2 .L8: movl $14, -8(%ebp) jmp .L2 .L9: movl $102, -8(%ebp) jmp .L2 .L10: movl $-2, -8(%ebp) .L2: cmpl $0, -8(%ebp) jne .L13 subl $12, %esp pushl $.LC0 call printf addl $16, %esp jmp .L1 .L13: movl -8(%ebp), %eax leal -4(%ebp), %edx addl %eax, (%edx) movl -4(%ebp), %eax cmpl 12(%ebp), %eax jne .L14 subl $12, %esp pushl $.LC1 call printf addl $16, %esp jmp .L1 .L14: subl $12, %esp pushl $.LC0 call printf addl $16, %esp .L1: leave ret .Lfe1: .size checkguess,.Lfe1-checkguess .section .rodata .align 32 .LC2: .string "You need to enter two numbers on the command line\n" .text .globl main .type main,@function main: pushl %ebp movl %esp, %ebp subl $24, %esp andl $-16, %esp movl $0, %eax subl %eax, %esp cmpl $2, 8(%ebp) jg .L17 subl $12, %esp pushl $.LC2 call printf addl $16, %esp movl $1, -12(%ebp) jmp .L16 .L17: subl $12, %esp movl 12(%ebp), %eax addl $4, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -4(%ebp) subl $12, %esp movl 12(%ebp), %eax addl $8, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -8(%ebp) subl $8, %esp pushl -8(%ebp) pushl -4(%ebp) call checkguess addl $16, %esp movl $0, -12(%ebp) .L16: movl -12(%ebp), %eax leave ret .Lfe2: .size main,.Lfe2-main |
int main(int argc, char **argv) {
int x,y;
if (argc < 3 ) {
printf("You need to enter two numbers on the command line\n");
return(1);
}
x = atoi(argv[1]);
y = atoi(argv[2]);
checkguess(x,y);
return(0);
}
|
| p5.s | main() |
.file "p5.c" .globl x4 .data .align 4 .type x4,@object .size x4,12 x4: .long 3 .long 4 .long 0 .globl x3 .align 4 .type x3,@object .size x3,12 x3: .long 7 .long 2 .long x4 .globl x2 .align 4 .type x2,@object .size x2,12 x2: .long 1 .long 1 .long x3 .globl x1 .align 4 .type x1,@object .size x1,12 x1: .long 5 .long 6 .long x2 .section .rodata .LC0: .string "You are a wizard\n" .LC1: .string "You are wrong\n" .text .globl checkguess .type checkguess,@function checkguess: pushl %ebp movl %esp, %ebp subl $8, %esp movl $x1, -4(%ebp) movl $0, -8(%ebp) .L2: cmpl $0, -4(%ebp) jne .L4 jmp .L3 .L4: movl -4(%ebp), %eax movl (%eax), %edx leal -8(%ebp), %eax addl %edx, (%eax) movl -4(%ebp), %eax movl 8(%eax), %eax movl %eax, -4(%ebp) jmp .L2 .L3: movl 8(%ebp), %eax cmpl -8(%ebp), %eax jne .L5 subl $12, %esp pushl $.LC0 call printf addl $16, %esp jmp .L1 .L5: subl $12, %esp pushl $.LC1 call printf addl $16, %esp .L1: leave ret .Lfe1: .size checkguess,.Lfe1-checkguess .section .rodata .align 32 .LC2: .string "You need to enter a number on the command line\n" .text .globl main .type main,@function main: pushl %ebp movl %esp, %ebp subl $8, %esp andl $-16, %esp movl $0, %eax subl %eax, %esp cmpl $1, 8(%ebp) jg .L8 subl $12, %esp pushl $.LC2 call printf addl $16, %esp movl $1, -8(%ebp) jmp .L7 .L8: subl $12, %esp movl 12(%ebp), %eax addl $4, %eax pushl (%eax) call atoi addl $16, %esp movl %eax, -4(%ebp) subl $12, %esp pushl -4(%ebp) call checkguess addl $16, %esp movl $0, -8(%ebp) .L7: movl -8(%ebp), %eax leave ret .Lfe2: .size main,.Lfe2-main |
int main(int argc, char **argv) {
int x;
if (argc < 2 ) {
printf("You need to enter a number on the command line\n");
return(1);
}
x = atoi(argv[1]);
checkguess(x);
return(0);
}
|