.file “Reverse2.s”
# Assembler directives to allocate storage for static array
.section .rodata
printf_line:
.string “Element %d in array1 and Element %d in array2 is %d\n”
.data
.align 4
array:
.long 1
.long 2
.long 3
.long 4
.long 5
.long 6
.long 7
.long 8
.long 9
.align 8
longarray:
.quad 0
.quad 0
.quad 0
.quad 0
.quad 0
.quad 0
.quad 0
.quad 0
.quad 0
.globl main
.type main, @function
.text
main:
push %rbp # save caller’s %rbp
movq %rsp, %rbp # copy %rsp to %rbp so our stack frame is ready to use
movq $array, %rdi #set rcx to point to array
movq $longarray, %rsi
movq $9, %rdx # count = 9
call Reverse
leave
ret
.size main, .-main
.globl Reverse
.type Reverse, @function
Reverse:
pushq %rbp #save caller’s rbp
movq %rsp, %rbp #set function’s frame pointer
# register rdi contains address of array
# register rsi contains address of long array
# register rdx contains size
movq $-1, %r12 #index for reverse (one less than I really want)
movq %rdi, %r13
movq %rsi, %r14
movq %rdx, %r15
loop: #loop to sum values in array
incq %r12 #increment index
decq %r15 #decrement number of remaining elements
jl exit #jump out of loop if no elements remaining
movslq (%r13,%r15,4), %rax #read integer value and sign extend to a long
movq %rax, (%r14, %r12,8) #write long value to Reverse array position
movq $printf_line, %rdi
movq %r15, %rsi
movq %r12, %rdx
movq %rax, %rcx
movq $0, %rax
call printf
jmp loop #jump to top of loop
exit:
leave
ret
.size Reverse, .-Reverse