various I/O updates

c64/kernal/rs232/close_rs232.s

@@ -7,9 +7,33 @@
 #if HAS_RS232
 
 
+#if CONFIG_MEMORY_MODEL_60K
+	.error "CONFIG_MEMORY_MODEL_60K is not compatible with RS-232 memory allocation code"
+#endif
+
+
 close_rs232:
 
-	// XXX provide implementation for both UP2400 and UP960
+	// First check how many RS-232 channels are currently allocated.
+	// If more than one, skip deallocation (other channels still uses the buffer).
+
+	jsr rs232_count_channels
+	bcs close_rs232_end
+
+	// Deallocate buffer
+
+	inc MEMSIZK+1
+	inc MEMSIZK+1
+
+	// XXX is this needed? check with original ROM what it actually does
+
+	lda #$00
+	sta ROBUF+0
+	sta ROBUF+1
+	sta RIBUF+0
+	sta RIBUF+1
+
+close_rs232_end:
 
 	jmp close_remove_from_table