/arch/x86/lib/memset_64.S
Assembly | 127 lines | 113 code | 14 blank | 0 comment | 0 complexity | e3a1a9d1e6e6c42f1b2e4cfef7db0a39 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
- /* Copyright 2002 Andi Kleen, SuSE Labs */
- #include <linux/linkage.h>
- #include <asm/dwarf2.h>
- /*
- * ISO C memset - set a memory block to a byte value.
- *
- * rdi destination
- * rsi value (char)
- * rdx count (bytes)
- *
- * rax original destination
- */
- .section .altinstr_replacement, "ax", @progbits
- .Lmemset_c:
- movq %rdi,%r9
- movl %edx,%r8d
- andl $7,%r8d
- movl %edx,%ecx
- shrl $3,%ecx
- /* expand byte value */
- movzbl %sil,%esi
- movabs $0x0101010101010101,%rax
- mulq %rsi /* with rax, clobbers rdx */
- rep stosq
- movl %r8d,%ecx
- rep stosb
- movq %r9,%rax
- ret
- .Lmemset_e:
- .previous
- ENTRY(memset)
- ENTRY(__memset)
- CFI_STARTPROC
- movq %rdi,%r10
- movq %rdx,%r11
- /* expand byte value */
- movzbl %sil,%ecx
- movabs $0x0101010101010101,%rax
- mul %rcx /* with rax, clobbers rdx */
- /* align dst */
- movl %edi,%r9d
- andl $7,%r9d
- jnz .Lbad_alignment
- CFI_REMEMBER_STATE
- .Lafter_bad_alignment:
- movl %r11d,%ecx
- shrl $6,%ecx
- jz .Lhandle_tail
- .p2align 4
- .Lloop_64:
- decl %ecx
- movq %rax,(%rdi)
- movq %rax,8(%rdi)
- movq %rax,16(%rdi)
- movq %rax,24(%rdi)
- movq %rax,32(%rdi)
- movq %rax,40(%rdi)
- movq %rax,48(%rdi)
- movq %rax,56(%rdi)
- leaq 64(%rdi),%rdi
- jnz .Lloop_64
- /* Handle tail in loops. The loops should be faster than hard
- to predict jump tables. */
- .p2align 4
- .Lhandle_tail:
- movl %r11d,%ecx
- andl $63&(~7),%ecx
- jz .Lhandle_7
- shrl $3,%ecx
- .p2align 4
- .Lloop_8:
- decl %ecx
- movq %rax,(%rdi)
- leaq 8(%rdi),%rdi
- jnz .Lloop_8
- .Lhandle_7:
- movl %r11d,%ecx
- andl $7,%ecx
- jz .Lende
- .p2align 4
- .Lloop_1:
- decl %ecx
- movb %al,(%rdi)
- leaq 1(%rdi),%rdi
- jnz .Lloop_1
- .Lende:
- movq %r10,%rax
- ret
- CFI_RESTORE_STATE
- .Lbad_alignment:
- cmpq $7,%r11
- jbe .Lhandle_7
- movq %rax,(%rdi) /* unaligned store */
- movq $8,%r8
- subq %r9,%r8
- addq %r8,%rdi
- subq %r8,%r11
- jmp .Lafter_bad_alignment
- .Lfinal:
- CFI_ENDPROC
- ENDPROC(memset)
- ENDPROC(__memset)
- /* Some CPUs run faster using the string instructions.
- It is also a lot simpler. Use this when possible */
- #include <asm/cpufeature.h>
- .section .altinstructions,"a"
- .align 8
- .quad memset
- .quad .Lmemset_c
- .byte X86_FEATURE_REP_GOOD
- .byte .Lfinal - memset
- .byte .Lmemset_e - .Lmemset_c
- .previous