Subversion Repositories HelenOS-historic

.global memcpy

.global memcpy_from_uspace

.global memcpy_from_uspace_failover_address

.global memcpy_to_uspace

.global memcpy_to_uspace_failover_address

#define MEMCPY_DST	4

#define MEMCPY_SRC	8

#define MEMCPY_SIZE	12

/** Copy memory to/from userspace.

 *

 * This is almost conventional memcpy().

 * The difference is that there is a failover part

 * to where control is returned from a page fault

 * if the page fault occurs during copy_from_uspace()

 * or copy_to_uspace().

 *

 * @param MEMCPY_DST(%esp)	Destination address.

 * @param MEMCPY_SRC(%esp)	Source address.

 * @param MEMCPY_SIZE(%esp)	Size.

 *

 * @return MEMCPY_SRC(%esp) on success and 0 on failure.

 */

memcpy:

memcpy_from_uspace:

memcpy_to_uspace:

	movl %edi, %edx				/* save %edi */

	movl %esi, %eax				/* save %esi */

	movl MEMCPY_SIZE(%esp), %ecx

	shrl $2, %ecx				/* size / 4 */

	movl MEMCPY_DST(%esp), %edi

	movl MEMCPY_SRC(%esp), %esi

	rep movsl				/* copy as much as possible word by word */

	movl MEMCPY_SIZE(%esp), %ecx

	andl $3, %ecx				/* size % 4 */

	jz 0f

	rep movsb				/* copy the rest byte by byte */

0:

	movl %edx, %edi

	movl %eax, %esi

	movl MEMCPY_SRC(%esp), %eax		/* MEMCPY_SRC(%esp), success */

	ret

/*

 * We got here from as_page_fault() after the memory operations

 * above had caused a page fault.

 */

memcpy_from_uspace_failover_address:

memcpy_to_uspace_failover_address:

	movl %edx, %edi

	movl %eax, %esi

	xorl %eax, %eax				/* return 0, failure */

	ret