In this blog post, you can read about my experiment with assembler on the x86_64 and aarch64 servers.
If you didn't ever see assembler language instructions, here is the ready source code for the Aarch64 system for this lab.
Aarch64
.text
.globl _start
min = 0 /* starting value for the loop index; note that this is a symbol (constant), not a variable */
max = 31 /* loop exits when the index hits this number (loop condition is i<max) */
_start:
mov x19, min
mov x17, 10
loop:
mov x0, 1 /* file descriptor: 1 is stdout */
adr x1, msg /* message location (memory address) */
mov x2, len /* message length (bytes) */
mov x18, x19 /*mov x19 into x18 */
udiv x9, x18, x17
add x13, x9, 0x30
msub x10, x9, x17, x18 /*get remainder*/
add x14, x10, 0x30
adr x15, msg
strb w13, [x15, 13]
strb w14, [x15, 14]
mov x8, 64 /* write is syscall #64 */
svc 0 /* invoke syscall */
add x19, x19, 1
cmp x19, max
b.ne loop
.data
msg: .ascii "Hello, World #\n"
len= . - msg
This is how we build this code on a specific server
This is the output of our source code:
For those interested in how my tree looks right now on the Israel server.
X84_64
Here is almost the same code, but for a different system.
/*
This is a 'hello world' program in x86_64 assembler using the
GNU assembler (gas) syntax. Note that this program runs in 64-bit
mode.
CTyler, Seneca College, 2014-01-20
Licensed under GNU GPL v2+
*/
.text
.globl _start
_start:
movq $0, %r15 /* Loop counter */
movq $0x30, %r12 /* value of 0 in Ascii */
loop:
movq $0, %rdx /* clearing reminder for division */
movq %r15, %rax /* set rax to be divide */
movq $10, %r10 /* set divisor */
div %r10 /* divide */
movq %rax, %r14 /* store quotient */
movq %rdx, %r13 /* store remainder */
add $0x30, %r14 /* quotient to ascii */
add $0x30, %r13 /* remainder to ascii */
mov %r13b, msg+14 /* Modify 1 byte inmsg with remainder */
cmp %r12, %r14
mov %r14b, msg+13 /* Modify 1 byte in msg with quotient */
movq $len, %rdx /* message length */
movq $msg, %rsi /* message location */
movq $1, %rdi /* file descriptor stdout */
movq $1, %rax /* syscall sys_write */
syscall
inc %r15 /* increment counter */
cmp $31, %r15 /* see if we're done */
jne loop /* if not, loop */
movq $0, %rdi /* exit status */
movq $60, %rax /* syscall sys_exit */
syscall
.section .data
msg: .ascii "Hello World: \n"
len = . - msg
~
On a different server.
Conclusion
⚠️ Computer Architecture Blog Post: Link
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_p.s This post was made for my Software Portability and Optimization class.
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