Split memcpy and memmove, since the former is used a lot more often than

the latter.
Optimized the code for smaller size and greater speed.


git-svn-id: svn://svn.cc65.org/cc65/trunk@2382 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/common/memmove.s

@@ -0,0 +1,67 @@
+;
+; Ullrich von Bassewitz, 2003-08-20
+;
+; void* __fastcall__ memmove (void* dest, const void* src, size_t size);
+;
+; NOTE: This function uses entry points from memcpy!
+;
+
+       	.export	    	_memmove
+        .import         memcpy_getparams, memcpy_upwards
+       	.importzp      	ptr1, ptr2, ptr3, ptr4, tmp1
+
+        .macpack        generic
+        .macpack        longbranch
+
+; ----------------------------------------------------------------------
+_memmove:
+        sta     ptr4
+        stx     ptr4+1          ; Size -> ptr4
+
+        jsr     memcpy_getparams
+
+; Check for the copy direction. If dest < src, we must copy upwards (start at
+; low addresses and increase pointers), otherwise we must copy downwards
+; (start at high addresses and decrease pointers).
+
+        sec
+        sbc     ptr1
+        txa
+        sbc     ptr1+1
+        jcc     memcpy_upwards  ; Branch if dest < src (upwards copy)
+
+; Copy downwards. Adjust the pointers to the end of the memory regions.
+
+        lda	ptr1+1
+       	add	ptr4+1
+	sta	ptr1+1
+
+	lda	ptr2+1
+	add	ptr4+1
+	sta	ptr2+1
+
+; Load the low offset into Y, and the counter low byte into X.
+
+        ldy     ptr4
+        ldx     ptr3
+        jmp     @L2
+
+; Copy loop
+
+@L1:    dey
+        lda     (ptr1),y
+        sta     (ptr2),y
+
+@L2:    inx                     ; Bump counter low byte
+        bne     @L1
+        dec     ptr1+1
+        dec     ptr2+1
+        inc     ptr3+1          ; Bump counter high byte
+        bne     @L1
+
+; Done, return dest
+
+done:  	lda	ptr2
+       	ldx    	tmp1            ; get function result (dest)
+       	rts
+