64-Bit Assembly Language Lab

The very first thing to do is setup the the servers:

Go to the folder: cd spo600/examples/hello/assembler/
Then using make building the c files:

Open the files using cat command and By objdump -d objectfile we can look at the code:

The code to include loop index values, showing each digit from 0 to 30 in AArch64 assembly language:

.text
.global _start

start = 0                               /* loop index starting value */
max = 31                                /* loop exits when the index hits this number */

_start:
        mov     x3,start                /* set loop index */

loop:
        mov     x9,10           /* store divisor in register */
        udiv    x10,x3,x9       /* divide and store quotient in register */
        msub    x11,x9,x10,x3       /* store remainder in register */
    adr     x1,msg                  /* message location */
    cmp     x10,0           /* check if quotient is 0 */ 
    b.eq    next            /* jump if quotient is 0 */
    add     x12,x10,0x30            /* convert to ascii and store in register */
    strb    w12,[x1,6]              /* place quotient in msg */


next:
    add     x13,x11,0x30            /* convert to ascii and store in register */
    strb    w13,[x1,7]              /* place remainder in msg */
        mov     x2,len                  /* message length */
        mov     x0,1                    /* file descriptor stdout */
        mov     x8,64                   /* syscall sys_write */
        svc     0                       /* syscall */

        add     x3,x3,1                 /* increment index */
        cmp     x3,max                  /* check if index is at max */
        b.ne    loop                    /* loop if index not at max */

        mov     x0,0                    /* exit status */
        mov     x8,93                   /* syscall sys_exit */
        svc     0                       /* syscall */

.data

msg:    .ascii  "Loop:   \n"
.set len, . - msg

In x86_64 assembly language program:

.text
.global  _start

start = 0               /* loop index starting value */
max = 31                /* loop exits when the index hits this number */

_start:
    mov     $start,%r15     /* set loop index */

loop:
    mov $0,%rdx         /* clear register */
    mov %r15,%rax       /* store dividend in register */
    mov $10,%r10        /* store divisor in register */
    div %r10            /* divide */
    mov %rax,%r11       /* store quotient in register */
    mov %rdx,%r12       /* store remainder in register */
    cmp $0,%r11         /* check if quotient is 0 */
    je  next            /* jump if quotient is 0 */
    add $0x30,%r11      /* convert to ascii */
    mov %r11b,msg+6     /* place quotient in msg */

next:
    add $0x30,%r12      /* convert to ascii */
    mov %r12b,msg+7     /* place remainder in msg */
        mov $len,%rdx       /* message length */
        mov $msg,%rsi       /* message location */
        mov $1,%rdi         /* file descriptor stdout */
        mov $1,%rax         /* syscall sys_write */
        syscall             /* syscall */

    inc     %r15            /* increment index */
    cmp     $max,%r15       /* check if index is at max */
    jne     loop            /* loop if index not at max */

        mov $0,%rdi         /* exit status */
        mov $60,%rax        /* syscall sys_exit */
        syscall             /* syscall */

.data

msg:    .ascii      "Loop:   \n"
.set len , . - msg

In conclusion, exploring assembly programming across diverse architectures provided invaluable insights into low-level computing. From the nostalgic simplicity of 6502 to the complex optimizations of x86_64 and AArch64, each architecture challenged and expanded my understanding, enriching my programming journey with hands-on experience and newfound

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64-Bit Assembly Language Lab

Heavendeep Kaur Munjal

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