void *memmove(void *dest, const void *src, size_t n)
{
- int d0, d1, d2;
-
- if (dest < src) {
- memcpy(dest, src, n);
- } else {
- __asm__ __volatile__(
- "std\n\t"
- "rep\n\t"
- "movsb\n\t"
- "cld"
- : "=&c" (d0), "=&S" (d1), "=&D" (d2)
- :"0" (n),
- "1" (n-1+src),
- "2" (n-1+dest)
- :"memory");
- }
- return dest;
+ int d0,d1,d2,d3,d4,d5;
+ char *ret = dest;
+
+ __asm__ __volatile__(
+ /* Handle more 16bytes in loop */
+ "cmp $0x10, %0\n\t"
+ "jb 1f\n\t"
+
+ /* Decide forward/backward copy mode */
+ "cmp %2, %1\n\t"
+ "jb 2f\n\t"
+
+ /*
+ * movs instruction have many startup latency
+ * so we handle small size by general register.
+ */
+ "cmp $680, %0\n\t"
+ "jb 3f\n\t"
+ /*
+ * movs instruction is only good for aligned case.
+ */
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 4f\n\t"
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts forward in each loop.
+ */
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov 2*4(%1), %3\n\t"
+ "mov 3*4(%1), %4\n\t"
+ "mov %3, 2*4(%2)\n\t"
+ "mov %4, 3*4(%2)\n\t"
+ "lea 0x10(%1), %1\n\t"
+ "lea 0x10(%2), %2\n\t"
+ "jae 3b\n\t"
+ "add $0x10, %0\n\t"
+ "jmp 1f\n\t"
+
+ /*
+ * Handle data forward by movs.
+ */
+ ".p2align 4\n\t"
+ "4:\n\t"
+ "mov -4(%1, %0), %3\n\t"
+ "lea -4(%2, %0), %4\n\t"
+ "shr $2, %0\n\t"
+ "rep movsl\n\t"
+ "mov %3, (%4)\n\t"
+ "jmp 11f\n\t"
+ /*
+ * Handle data backward by movs.
+ */
+ ".p2align 4\n\t"
+ "6:\n\t"
+ "mov (%1), %3\n\t"
+ "mov %2, %4\n\t"
+ "lea -4(%1, %0), %1\n\t"
+ "lea -4(%2, %0), %2\n\t"
+ "shr $2, %0\n\t"
+ "std\n\t"
+ "rep movsl\n\t"
+ "mov %3,(%4)\n\t"
+ "cld\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Start to prepare for backward copy.
+ */
+ ".p2align 4\n\t"
+ "2:\n\t"
+ "cmp $680, %0\n\t"
+ "jb 5f\n\t"
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 6b\n\t"
+
+ /*
+ * Calculate copy position to tail.
+ */
+ "5:\n\t"
+ "add %0, %1\n\t"
+ "add %0, %2\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts backward in each loop.
+ */
+ "7:\n\t"
+ "sub $0x10, %0\n\t"
+
+ "mov -1*4(%1), %3\n\t"
+ "mov -2*4(%1), %4\n\t"
+ "mov %3, -1*4(%2)\n\t"
+ "mov %4, -2*4(%2)\n\t"
+ "mov -3*4(%1), %3\n\t"
+ "mov -4*4(%1), %4\n\t"
+ "mov %3, -3*4(%2)\n\t"
+ "mov %4, -4*4(%2)\n\t"
+ "lea -0x10(%1), %1\n\t"
+ "lea -0x10(%2), %2\n\t"
+ "jae 7b\n\t"
+ /*
+ * Calculate copy position to head.
+ */
+ "add $0x10, %0\n\t"
+ "sub %0, %1\n\t"
+ "sub %0, %2\n\t"
+
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ ".p2align 4\n\t"
+ "1:\n\t"
+ "cmp $8, %0\n\t"
+ "jb 8f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov -2*4(%1, %0), %5\n\t"
+ "mov -1*4(%1, %0), %1\n\t"
+
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov %5, -2*4(%2, %0)\n\t"
+ "mov %1, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ ".p2align 4\n\t"
+ "8:\n\t"
+ "cmp $4, %0\n\t"
+ "jb 9f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov -1*4(%1, %0), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 2 bytes to 3 bytes.
+ */
+ ".p2align 4\n\t"
+ "9:\n\t"
+ "cmp $2, %0\n\t"
+ "jb 10f\n\t"
+ "movw 0*2(%1), %%dx\n\t"
+ "movw -1*2(%1, %0), %%bx\n\t"
+ "movw %%dx, 0*2(%2)\n\t"
+ "movw %%bx, -1*2(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data for 1 byte.
+ */
+ ".p2align 4\n\t"
+ "10:\n\t"
+ "cmp $1, %0\n\t"
+ "jb 11f\n\t"
+ "movb (%1), %%cl\n\t"
+ "movb %%cl, (%2)\n\t"
+ ".p2align 4\n\t"
+ "11:"
+ : "=&c" (d0), "=&S" (d1), "=&D" (d2),
+ "=r" (d3),"=r" (d4), "=r"(d5)
+ :"0" (n),
+ "1" (src),
+ "2" (dest)
+ :"memory");
+
+ return ret;
+
}
EXPORT_SYMBOL(memmove);
projects / mv-sheeva.git / blobdiff