Initial revision

lib/i86/misc/alloca.s

@@ -0,0 +1,23 @@
+#
+!	alloca() - allocate space on the stack		Author: Kees J. Bot
+!								26 Jan 1994
+
+#if __ACK__	/* BCC can't do alloca(), register saving is wrong. */
+
+.text
+.define _alloca
+_alloca:
+	pop	cx		! Return address
+	pop	ax		! Bytes to allocate
+	add	ax, #2*2+1	! Add space for two saved register variables
+	andb	al, #0xFE	! Align
+	mov	bx, sp		! Keep current sp
+	sub	sp, ax		! Lower stack
+	mov	ax, sp		! Return value
+	push	2(bx)		! Push what is probably the saved si
+	push	(bx)		! Saved di
+				! Now ACK can still do:
+				!	pop di; pop si; mov sp, bp; pop bp; ret
+	push	ax		! Dummy argument
+	jmp	(cx)
+#endif