/* SPDX-License-Identifier: MPL-2.0 */
// Sets `size` bytes of memory at `dst` to the byte value given by `value`.
// This function works with exception handling and can recover from a page fault.
//
// Returns number of bytes that failed to set.
//
// Ref: [https://github.com/torvalds/linux/blob/2ab79514109578fc4b6df90633d500cf281eb689/arch/x86/lib/memset_64.S]
.text
.global __memset_fallible
.code64
__memset_fallible: # (dst: *mut u8, value: u8, size: usize) -> usize
mov rcx, rdx # Move the size to rcx for counting
mov al, sil # Move the value to al
.set:
rep stosb # Store the value byte repeatedly
.memset_exit:
mov rax, rcx # Return the size remaining
ret
.pushsection .ex_table, "a"
.align 8
.quad [.set]
.quad [.memset_exit]
.popsection