SPO600 64-bit Assembly Language Lab

This is a draft only!
It is still under construction and content may change. Do not rely on this information.

Purpose of this Lab
In this lab, you will experiment with assembler on the x86_64 and aarch64 platforms.

Ireland
Perform this lab on ireland.proximity.on.ca.)

Lab 3

Ireland - Configuration

The host Ireland (ireland.proximity.on.ca) has been set up so that you can use it normally as an x86_64 host, or use an emulation environment to build and run aarch64 binaries.

The directory ~/arm64/spo600/examples<code>, which is also accessible as <code>~/spo600-examples, contains these files:

── hello
   ├── assembler                 # 'hello world' example programs
   │   ├── aarch64               # aarch64 assembler version
   │   │   ├── hello.s
   │   │   └── Makefile
   │   └── x86_64                # x86_64 assembler versions
   │       ├── hello-gas.s       # 64-bit instructions for assembley with the gnu assembler (called 'gas', /usr/bin/as)
   │       ├── hello-nasm.s      # 32-bit instructions for assembley with the nasm assembler (/usr/bin/nasm)
   │       └── Makefile
   └── c
       ├── hello2.c              # C version using the write() syscall wrapper
       ├── hello.c               # C version using printf()
       └── Makefile

Throughout this lab, take advantage of make whenever possible.

Lab Tasks

1. Build and run the C versions of the program for x86_64. Use objdump to disassemble and review the machine code in the binaries - make sure you understand it. Save the binaries for later review.

2. Review, build, and run the x86_64 assembler code. Use objdump to disassemble and review the machine code in the binaries - make sure you understand it.

4. Build and run the C versions of the program for aarch64 (note: you may need to make clean).

5. Review, build, and run the aarch64 assembler code. Use objdump to disassemble and review the machine code in the binaries, and make sure you understand it.

6. Here is a basic loop in x86_64 assembler:

.text
.globl    _start

start = 0                       /* starting value for the loop index */
max = 10                        /* loop exits when the index hits this number (loop condition is i<max */

_start:
    mov     $0,%r15             /* loop index */

loop:
    /* ... do something useful here ... */

    inc     %r15                /* increment register 15 */
    cmpq    $10,%r15            /* see if we're done */
    jne     loop                /* loop if we're not */

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

Extend this code, combining it with code from the "Hello World" example, so that it prints each digit from 0 to 9 like this:

Loop: 0
Loop: 1
Loop: 2
Loop: 3
Loop: 4
Loop: 5
Loop: 6
Loop: 7
Loop: 8
Loop: 9

Character conversion
In order to print the loop index value, you will need to convert from an integer to digit character. In ASCII/ISO-9959-1/Unicode UTF-8, the digit characters are in the range 48-57 (0x30-0x39). You will also need to assemble the message that is output on each line - you can do this by writing the digit into the message buffer before writing it, or you can perform a sequence of writes for the various portions of the message.