Using assembly writing algorithm programs

This's my first version.The logic is simple, just the selection sort.

I spent much time learning how to write AT&T assembly on 64-bit Linux.almost all books just talk about 32-bit assembly.

Such as registers, on 64-bit linux, rax, rbx, rcx..... are all 8 bytes. not like eax,ebx,ecx 4 bytes.

And the differences with the use of libraries such as printf.32-bit AT&T assembly push the parameters before calling printf.but 64-bit AT&T assembly saving the parameters in registers such as rsi or rdi before calling printf.

movq     .quad     8bytes 64-bit

movl      .long       4bytes 32-bit

movw     .word     2bytes 16-bit

movb     .byte       1bytes 8-bit

# func: selection sort algorithm # by whoami# Oct 1-4 2016# rdx --- i, rax --- min, rcx --- j, rbx --- tmp.section .datadata_item:        .quad 3,67,34,222,45,75,54,34,44,33,22,11,66,0before_sort:        .asciz "sorted nums:\n"sort_output_format:        .asciz "%d\n".section .text.globl _start_start:        movq $0, %rdx        out_loop:                                         # outer loop                movq %rdx, %rax                movq data_item(,%rdx,8), %rbx             # if arr[i] == 0 print all nums sorted and exit.                cmp $0, %rbx                je print_arr                movq %rdx, %rcx                incq %rcx                inner_loop:                               # inner loop, get the min-value                        cmp $0, data_item(,%rcx,8)                        je inner_loop_exit                        movq data_item(,%rax,8), %rbx                        cmp %ebx, data_item(,%rcx,8)                        jg not_change_min                        movq %rcx, %rax                        not_change_min:                                incq %rcx                                jmp inner_loop                inner_loop_exit:                        movq data_item(,%rdx,8), %rbx     # swap the value, of arr[i] and the min-value.                        movq data_item(,%rax,8), %rdi                        movq %rdi, data_item(,%rdx,8)                        movq %rbx, data_item(,%rax,8)                        incq %rdx                        jmp out_loop                      # inner loop exits.print_arr:        movq $0, %rbx                                      # print 'sorted nums:'        movq $before_sort, %rdi        call printf        print_loop:                                        # print all nums sorted in a loop                movq data_item(,%rbx,8),%rax                cmp $0, %rax                je end                movq $sort_output_format, %rdi                movq %rax, %rsi                call printf                incq %rbx                jmp print_loopend:                                                       # program ends.        movq $127, %rdi        movq $60, %rax        syscall