[libc] add memcpy

Author: mateoconlechuga

src/libc/memcpy.src

@@ -0,0 +1,28 @@
+	assume	adl=1
+
+	section	.text
+	public	_memcpy
+
+if PREFER_OS_LIBC
+
+_memcpy := $0000A4
+
+else
+
+_memcpy:
+	ld	iy,0
+	add	iy,sp
+	ld	bc,(iy + 6)
+	sbc	hl,hl
+	sbc	hl,bc
+	jr	z,.zero
+	ld	de,(iy + 0)
+	ld	hl,(iy + 3)
+	ldir
+.zero:
+	ld	hl,(iy + 0)
+	ret
+
+end if
+
+

src/libc/os.src

@@ -8,8 +8,6 @@ _longjmp    := 000098h
 _memchr     := 00009Ch
 	public	_memcmp
 _memcmp     := 0000A0h
-	public	_memcpy
-_memcpy     := 0000A4h
 	public	_memmove
 _memmove    := 0000A8h
 	public	_setjmp