/* Normally compiler builtins are used, but sometimes the compiler calls out
of line code. Based on asm-i386/string.h.
*/
#define _STRING_C
#include <linux/string.h>
#include <linux/module.h>
#undef memmove
void *memmove(void *dest, const void *src, size_t count)
{
unsigned long d0,d1,d2,d3,d4,d5,d6,d7;
char *ret;
__asm__ __volatile__(
/* Handle more 32bytes in loop */
"mov %2, %3\n\t"
"cmp $0x20, %0\n\t"
"jb 1f\n\t"
/* Decide forward/backward copy mode */
"cmp %2, %1\n\t"
"jb 2f\n\t"
/*
* movsq instruction have many startup latency
* so we handle small size by general register.
*/
"cmp $680, %0\n\t"
"jb 3f\n\t"
/*
* movsq instruction is only good for aligned case.
*/
"cmpb %%dil, %%sil\n\t"
"je 4f\n\t"
"3:\n\t"
"sub $0x20, %0\n\t"
/*
* We gobble 32byts forward in each loop.
*/
"5:\n\t"
"sub $0x20, %0\n\t"
"movq 0*8(%1), %4\n\t"
"movq 1*8(%1), %5\n\t"
"movq 2*8(%1), %6\n\t"
"movq 3*8(%1), %7\n\t"
"leaq 4*8(%1), %1\n\t"
"movq %4, 0*8(%2)\n\t"
"movq %5, 1*8(%2)\n\t"
"movq %6, 2*8(%2)\n\t"
"movq %7, 3*8(%2)\n\t"
"leaq 4*8(%2), %2\n\t"
"jae 5b\n\t"
"addq $0x20, %0\n\t"
"jmp 1f\n\t"
/*
* Handle data forward by movsq.
*/
".p2align 4\n\t"
"4:\n\t"
"movq %0, %8\n\t"
"movq -8(%1, %0), %4\n\t"
"lea -8(%2, %0), %5\n\t"
"shrq $3, %8\n\t"
"rep movsq\n\t"
"movq %4, (%5)\n\t"
"jmp 13f\n\t"
/*
* Handle data backward by movsq.
*/
".p2align 4\n\t"
"7:\n\t"
"movq %0, %8\n\t"
"movq (%1), %4\n\t"
"movq %2, %5\n\t"
"leaq -8(%1, %0), %1\n\t"
"leaq -8(%2, %0), %2\n\t"
"shrq $3, %8\n\t"
"std\n\t"
"rep movsq\n\t"
"cld\n\t"
"movq %4, (%5)\n\t"
"jmp 13f\n\t"
/*
* Start to prepare for backward copy.
*/
".p2align 4\n\t"
"2:\n\t"
"cmp $680, %0\n\t"
"jb 6f \n\t"
"cmp %%dil, %%sil\n\t"
"je 7b \n\t"
"6:\n\t"
/*
* Calculate copy position to tail.
*/
"addq %0, %1\n\t"
"addq %0, %2\n\t"
"subq $0x20, %0\n\t"
/*
* We gobble 32byts backward in each loop.
*/
"8:\n\t"
"subq $0x20, %0\n\t"
"movq -1*8(%1), %4\n\t"
"movq -2*8(%1), %5\n\t"
"movq -3*8(%1), %6\n\t"
"movq -4*8(%1), %7\n\t"
"leaq -4*8(%1), %1\n\t"
"movq %4, -1*8(%2)\n\t"
"movq %5, -2*8(%2)\n\t"
"movq %6, -3*8(%2)\n\t"
"movq %7, -4*8(%2)\n\t"
"leaq -4*8(%2), %2\n\t"
"jae 8b\n\t"
/*
* Calculate copy position to head.
*/
"addq $0x20, %0\n\t"
"subq %0, %1\n\t"
"subq %0, %2\n\t"
"1:\n\t"
"cmpq $16, %0\n\t"
"jb 9f\n\t"
/*
* Move data from 16 bytes to 31 bytes.
*/
"movq 0*8(%1), %4\n\t"
"movq 1*8(%1), %5\n\t"
"movq -2*8(%1, %0), %6\n\t"
"movq -1*8(%1, %0), %7\n\t"
"movq %4, 0*8(%2)\n\t"
"movq %5, 1*8(%2)\n\t"
"movq %6, -2*8(%2, %0)\n\t"
"movq %7, -1*8(%2, %0)\n\t"
"jmp 13f\n\t"
".p2align 4\n\t"
"9:\n\t"
"cmpq $8, %0\n\t"
"jb 10f\n\t"
/*
* Move data from 8 bytes to 15 bytes.
*/
"movq 0*8(%1), %4\n\t"
"movq -1*8(%1, %0), %5\n\t"
"movq %4, 0*8(%2)\n\t"
"movq %5, -1*8(%2, %0)\n\t"
"jmp 13f\n\t"
"10:\n\t"
"cmpq $4, %0\n\t"
"jb 11f\n\t"
/*
* Move data from 4 bytes to 7 bytes.
*/
"movl (%1), %4d\n\t"
"movl -4(%1, %0), %5d\n\t"
"movl %4d, (%2)\n\t"
"movl %5d, -4(%2, %0)\n\t"
"jmp 13f\n\t"
"11:\n\t"
"cmp $2, %0\n\t"
"jb 12f\n\t"
/*
* Move data from 2 bytes to 3 bytes.
*/
"movw (%1), %4w\n\t"
"movw -2(%1, %0), %5w\n\t"
"movw %4w, (%2)\n\t"
"movw %5w, -2(%2, %0)\n\t"
"jmp 13f\n\t"
"12:\n\t"
"cmp $1, %0\n\t"
"jb 13f\n\t"
/*
* Move data for 1 byte.
*/
"movb (%1), %4b\n\t"
"movb %4b, (%2)\n\t"
"13:\n\t"
: "=&d" (d0), "=&S" (d1), "=&D" (d2), "=&a" (ret) ,
"=r"(d3), "=r"(d4), "=r"(d5), "=r"(d6), "=&c" (d7)
:"0" (count),
"1" (src),
"2" (dest)
:"memory");
return ret;
}
EXPORT_SYMBOL(memmove);
