/arch/x86_64/lib/memcpy.S

  1/* Copyright 2002 Andi Kleen */
  2	
  3	#include <asm/cpufeature.h>		
  4/*
  5 * memcpy - Copy a memory block.
  6 *
  7 * Input:	
  8 * rdi destination
  9 * rsi source
 10 * rdx count
 11 * 
 12 * Output:
 13 * rax original destination
 14 */	
 15
 16 	.globl __memcpy
 17	.globl memcpy
 18	.p2align 4
 19__memcpy:
 20memcpy:		
 21	pushq %rbx
 22	movq %rdi,%rax
 23
 24	movl %edx,%ecx
 25	shrl $6,%ecx
 26	jz .Lhandle_tail
 27	
 28	.p2align 4
 29.Lloop_64:
 30	decl %ecx
 31	
 32	movq (%rsi),%r11
 33	movq 8(%rsi),%r8
 34
 35	movq %r11,(%rdi)
 36	movq %r8,1*8(%rdi)
 37
 38	movq 2*8(%rsi),%r9
 39	movq 3*8(%rsi),%r10
 40
 41	movq %r9,2*8(%rdi)
 42	movq %r10,3*8(%rdi)
 43		
 44	movq 4*8(%rsi),%r11
 45	movq 5*8(%rsi),%r8
 46
 47	movq %r11,4*8(%rdi)
 48	movq %r8,5*8(%rdi)
 49
 50	movq 6*8(%rsi),%r9
 51	movq 7*8(%rsi),%r10
 52
 53	movq %r9,6*8(%rdi)
 54	movq %r10,7*8(%rdi)
 55
 56	leaq 64(%rsi),%rsi
 57	leaq 64(%rdi),%rdi
 58	jnz  .Lloop_64
 59
 60.Lhandle_tail:
 61	movl %edx,%ecx
 62	andl $63,%ecx
 63	shrl $3,%ecx
 64	jz   .Lhandle_7
 65	.p2align 4
 66.Lloop_8: 
 67	decl %ecx
 68	movq (%rsi),%r8
 69	movq %r8,(%rdi) 
 70	leaq 8(%rdi),%rdi
 71	leaq 8(%rsi),%rsi
 72	jnz  .Lloop_8
 73
 74.Lhandle_7:
 75	movl %edx,%ecx
 76	andl $7,%ecx
 77	jz .Lende
 78	.p2align 4
 79.Lloop_1:
 80	movb (%rsi),%r8b
 81	movb %r8b,(%rdi) 
 82	incq %rdi
 83	incq %rsi
 84	decl %ecx
 85	jnz .Lloop_1
 86	
 87.Lende: 	
 88	popq %rbx
 89	ret
 90.Lfinal:
 91	
 92	/* C stepping K8 run faster using the string copy instructions.
 93	   It is also a lot simpler. Use this when possible */
 94	
 95	.section .altinstructions,"a"
 96	.align 8
 97	.quad  memcpy
 98	.quad  memcpy_c
 99	.byte  X86_FEATURE_K8_C
100	.byte  .Lfinal-memcpy
101	.byte  memcpy_c_end-memcpy_c	
102	.previous
103
104	.section .altinstr_replacement,"ax"
105 /* rdi	destination
106  * rsi source
107  * rdx count
108  */			
109memcpy_c:
110	movq %rdi,%rax
111	movl %edx,%ecx
112	shrl $3,%ecx
113	andl $7,%edx	
114	rep 
115	movsq 
116	movl %edx,%ecx
117	rep
118	movsb
119	ret
120memcpy_c_end:
121	.previous