Exercises 10.4 Programming Exercise
1.
Modify the assembly language program in Listing 10.3.1 so that it prints “Hello, yourName!” on the screen. Remember to change the documentation such that it accurately describes your program.
Solution
@ helloBob.s
@ Hello Bob program, in assembly language.
@ 2017-09-29: Bob Plantz
@ Define my Raspberry Pi
.cpu cortex-a53
.fpu neon-fp-armv8
.syntax unified @ modern syntax
@ Useful source code constant
.equ STDOUT,1
@ Constant program data
.section .rodata
.align 2
helloMsg:
.asciz "Hello, Bob!\n"
.equ helloLngth,.-helloMsg
@ Program code
.text
.align 2
.global main
.type main, %function
main:
sub sp, sp, 8 @ space for fp, lr
str fp, [sp, 0] @ save fp
str lr, [sp, 4] @ and lr
add fp, sp, 4 @ set our frame pointer
mov r0, STDOUT @ file number to write to
ldr r1, helloMsgAddr @ pointer to message
mov r2, helloLngth @ number of bytes to write
bl write @ write the message
mov r0, 0 @ return 0;
ldr fp, [sp, 0] @ restore caller fp
ldr lr, [sp, 4] @ lr
add sp, sp, 8 @ and sp
bx lr @ return
.align 2
helloMsgAddr:
.word helloMsg