csci2021/ArchLab/archlab-handout/sim/y86-code/asum.ys
Michael Zhang 1fa36db752
f
2018-01-29 17:45:27 -06:00

35 lines
874 B
Text

# Execution begins at address 0
.pos 0
irmovq stack, %rsp # Set up stack pointer
call main # Execute main program
halt # Terminate program
# Array of 4 elements
.align 8
array: .quad 0x000d000d000d
.quad 0x00c000c000c0
.quad 0x0b000b000b00
.quad 0xa000a000a000
main: irmovq array,%rdi
irmovq $4,%rsi
call sum # sum(array, 4)
ret
# long sum(long *start, long count)
# start in %rdi, count in %rsi
sum: irmovq $8,%r8 # Constant 8
irmovq $1,%r9 # Constant 1
xorq %rax,%rax # sum = 0
andq %rsi,%rsi # Set CC
jmp test # Goto test
loop: mrmovq (%rdi),%r10 # Get *start
addq %r10,%rax # Add to sum
addq %r8,%rdi # start++
subq %r9,%rsi # count--. Set CC
test: jne loop # Stop when 0
ret # Return
# Stack starts here and grows to lower addresses
.pos 0x200
stack: