.file “lab5.s”
.globl main
.typemain, @function
.text
main:
pushq %rbp#stack housekeeping
movq %rsp, %rbp
Label1:
#as you go through this program note the changes to %rip
movq$0x8877665544332211, %rax# the value of %rax is:
# Recall that -1 is represented as 0xff, 0xffff, etc. depending upon the size of the value
movb$-1, %al# the value of %rax is:
movw$-1, %ax# the value of %rax is:
movl$-1, %eax# the value of %rax is:
movq$-1, %rax# the value of %rax is:
movl$-1, %eax# the value of %rax is:
cltq# the value of %rax is:
movl$0x7fffffff, %eax# the value of %rax is:
cltq# the value of %rax is:
movl$0x8fffffff, %eax# the value of %rax is:
cltq# the value of %rax is:
# what do you think the cltq instruction does?
movq$0x8877665544332211, %rax# the value of %rax is:
# the value of %rdx *before* movb $0xAA, %dl executes is:
# Note the value of the 8-byte register values vs the 1, 2, or 4-byte register values
# How does each size instruction suffix affect the 8-byte register?Don’t write answers here; you’ll need this info later.
movb$0xAA, %dl# the value of %rdx is:
movb%dl, %al# the value of %rax is:
movsbw%dl, %ax# the value of %rax is:
movzbw%dl, %ax# the value of %rax is:
movq$0x8877665544332211, %rax# the value of %rax is:
movb %dl, %al# the value of %rax is:
movsbl%dl, %eax# the value of %rax is:
movzbl%dl, %eax# the value of %rax is:
movq$0x8877665544332211, %rax# the value of %rax is:
movb %dl, %al# the value of %rax is:
movsbq%dl, %rax# the value of %rax is:
movzbq%dl, %rax# the value of %rax is:
movq$0x8877665544332211, %rax# the value of %rax is:
# the value of %rdx *before* movb $0x55, %dl executes is:
movb$0x55, %dl# the value of %rdx is:
movb%dl, %al# the value of %rax is:
movsbw%dl, %ax# the value of %rax is:
movzbw%dl, %ax# the value of %rax is:
movq$0x8877665544332211, %rax# the value of %rax is:
movb %dl, %al# the value of %rax is:
movsbl%dl, %eax# the value of %rax is:
movzbl%dl, %eax# the value of %rax is:
movq$0x8877665544332211, %rax# the value of %rax is:
movb %dl, %al# the value of %rax is:
movsbq%dl, %rax# the value of %rax is:
movzbq%dl, %rax# the value of %rax is:
#movq$0x8877665544332211, %rax
#pushb%al
#movq$0, %rax
#popb%al
movq$0x8877665544332211, %rax# the value of %rax is:the value of %rsp is:
pushw%ax# the value of %rsp is:
# the difference between the two values of %rsp is:
movq$0, %rax# the value of %rax is:
popw%ax# the value of %rax is:How did the value of %rsp change?
movq$0x8877665544332211, %rax# the value of %rax is:the value of %rsp is:
pushw%ax# the value of %rsp is:
# the difference between the two values of %rsp is:
movq$-1, %rax# the value of %rax is:
popw%ax# the value of %rax is:How did the value of %rsp change?
#movq$0x8877665544332211, %rax
#pushl%eax
#movq$0, %rax
#popl%eax
movq$0x8877665544332211, %rax# the value of %rax is:the value of %rsp is:
pushq%rax# the value of %rsp is:
# the difference between the two values of %rsp is:
movq$0, %rax# the value of %rax is:
popq%rax# the value of %rax is:How did the value of %rsp change?
# what rflags are set?
movq$0x500, %rax# the value of %rax is:
movq$0x123, %rcx# the value of %rcx is:
# 0x123 – 0x500
subq%rax, %rcx# the value of %rax is:
# the value of %rcx is:
# what rflags are set?
movq $0x500, %rax# the value of %rax is:
movq$0x123, %rcx# the value of %rcx is:
# 0x500 – 0x123
subq%rcx, %rax# the value of %rax is:
# what rflags are set?
movq$0x500, %rax# the value of %rax is:
movq$0x500, %rcx# the value of %rcx is:
# 0x500 – 0x500
subq%rcx, %rax# the value of %rax is:
# what rflags are set?
movb$0xff, %al# the value of %rax is:
# 0xff +=1 (1 byte)
incb%al# the value of %rax is:what rflags are set?
movb$0xff, %al# the value of %rax is:
# 0xff +=1 (4 bytes)
incl%eax# the value of %rax is:what rflags are set?
movq$-1, %rax# the value of %rax is:
# 0xff +=1 (8 bytes)
incq%rax# the value of %rax is:what rflags are set?
movq$0x8877665544332211, %rax# the value of %rax is:
movq$0x8877665544332211, %rcx# the value of %rax is:what rflags are set?
addq%rcx, %rax# the value of %rax is:what rflags are set?
movq $0x8877665544332211, %rax# the value of %rax is:
andq$0x1, %rax# the value of %rax is:
movq $0x8877665544332211, %rax# the value of %rax is:explain why the values for AND/OR/XOR are
andq%rax, %rax# the value of %rax is:what they are
orq%rax, %rax# the value of %rax is:
xorq%rax, %rax# the value of %rax is:
movq $0x8877665544332211, %rax# the value of %rax is:
andw$0x3300, %ax# the value of %rax is:explain the value in the 8 byte register vs
#the value in the 2 byte register
salq$4, %rax# the value of %rax is:Why?
movq$0xff0000001f000000, %rax# the value of %rax is:to help you understand what’s happening in this part of the code, write the value in %rax in binary
# on a piece of scratch paper for the remaining instructions in this file
#and watch the bits move as each shift instruction occurs.
#You should notice how each of the 1-, 2-, 4-, and 8-byte shift instructions works
#within the 8-byte register.
sall$1, %eax# the value of %rax is:do these shift instructions do what you expected?
sall$1, %eax# the value of %rax is:
sall$1, %eax# the value of %rax is:
sall$1, %eax# the value of %rax is:
sall$1, %eax# the value of %rax is:
movq$0xff000000ff000000, %rax# the value of %rax is:
salq$1, %rax# the value of %rax is:
salq$1, %rax# the value of %rax is:
salq$1, %rax# the value of %rax is:
salq$1, %rax# the value of %rax is:
salq$1, %rax# the value of %rax is:
movq$0xff000000000000ff, %rax# the value of %rax is:
sarq$1, %rax# the value of %rax is:
sarq$1, %rax# the value of %rax is:
sarq$1, %rax# the value of %rax is:
sarq$1, %rax# the value of %rax is:
sarq$1, %rax# the value of %rax is:
movq$0xff000000000000ff, %rax# the value of %rax is:
shrq$1, %rax# the value of %rax is:
shrq$1, %rax# the value of %rax is:
shrq$1, %rax# the value of %rax is:
shrq$1, %rax# the value of %rax is:
shrq$1, %rax# the value of %rax is:
movq$0xff000000000000ff, %rax# the value of %rax is:
sarw$1, %ax# the value of %rax is:
sarw$1, %ax# the value of %rax is:
sarw$1, %ax# the value of %rax is:
sarw$1, %ax# the value of %rax is:
sarw$1, %ax# the value of %rax is:
movq$0xff000000000000ff, %rax# the value of %rax is:
shrw$1, %ax# the value of %rax is:
shrw$1, %ax# the value of %rax is:
shrw$1, %ax# the value of %rax is:
shrw$1, %ax# the value of %rax is:
shrw$1, %ax# the value of %rax is:
leave#post function stack cleanup
ret
.sizemain, .-main
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