copy.ys

来自「深入理解计算机系统 的lab」· YS 代码 · 共 54 行

	.pos 0
init:	irmovl Stack, %esp
	irmovl Stack, %ebp
	jmp Main

# Source block
src:
        .long 0x00a
        .long 0x0b0
        .long 0xc00
# Destination block
dest:
        .long 0x111
        .long 0x222
        .long 0x333

Main:	irmovl $3, %eax
	pushl %eax
	irmovl dest, %edx
	pushl %edx
	irmovl src, %esi
	pushl %esi
	call copy_block
	halt

copy_block:
	pushl %ebp
	rrmovl %esp, %ebp
	mrmovl 16(%ebp), %ecx	#len
	mrmovl 12(%ebp), %edx	#dst
	mrmovl 8(%ebp), %ebx	#src
	xorl %eax, %eax		#result
	xorl %esi, %esi		#val
Loop:
	andl %ecx, %ecx
	jle DONE
	mrmovl (%ebx), %esi
	irmovl $4, %edi	
	addl %edi, %ebx		#*src++
	rmmovl %esi, (%edx)
	addl %edi, %edx
	xorl %esi, %eax 
	irmovl $1, %edi
	subl %edi, %ecx
	jmp Loop
DONE:
	rrmovl %ebp, %esp
	popl %ebp
	ret

	.pos 0x100
Stack: