optimized atexit/on_exit

Author: ZERICO2005

src/libc/atexit.src

@@ -11,7 +11,7 @@ _on_exit:
 	ld	hl, 3 * 3
 	push	hl
 	call	_malloc
-	pop	bc
+	pop	de
 	ex	de, hl
 	scf
 	sbc	hl, hl
@@ -21,23 +21,19 @@ _on_exit:
 	ex	de, hl
 	ld	(__atexit_functions), hl
 	ld	(hl), de
-	pop	iy		; return address
-	inc	hl
-	inc	hl
-	inc	hl
-	pop	bc		; func pointer
-	ld	(hl), bc
-	inc	hl
-	inc	hl
-	inc	hl
-	pop	bc		; arg pointer (on_exit)
-	ld	(hl), bc
-	push	bc
-	push	bc
+	ld	de, 3
+	add	hl, de
+	ex	de, hl
+	add	hl, sp		; clears carry
+	ld	bc, 6
+	; (SP + 3) = func pointer
+	; (SP + 6) = arg pointer (on_exit)
+	; HL = SP + 3
+	; DE = (__atexit_functions) + 3
+	ldir
 	; return zero on success
-	or	a, a
 	sbc	hl, hl
-	jp	(iy)
+	ret
 
 	.section	.bss
 	.global	__atexit_functions