sdram读写

				// megafunction wizard: %FIFO%VBB%
				// GENERATION: STANDARD
				// VERSION: WM1.0
				// MODULE: dcfifo 
				
				// ============================================================
				// File Name: rdfifo.v
				// Megafunction Name(s):
				// 			dcfifo
				//
				// Simulation Library Files(s):
				// 			altera_mf
				// ============================================================
				// ************************************************************
				// THIS IS A WIZARD-GENERATED FILE. DO NOT EDIT THIS FILE!
				//
				// 8.1 Build 163 10/28/2008 SJ Full Version
				// ************************************************************
				
				//Copyright (C) 1991-2008 Altera Corporation
				//Your use of Altera Corporation's design tools, logic functions 
				//and other software and tools, and its AMPP partner logic 
				//functions, and any output files from any of the foregoing 
				//(including device programming or simulation files), and any 
				//associated documentation or information are expressly subject 
				//to the terms and conditions of the Altera Program License 
				//Subscription Agreement, Altera MegaCore Function License 
				//Agreement, or other applicable license agreement, including, 
				//without limitation, that your use is for the sole purpose of 
				//programming logic devices manufactured by Altera and sold by 
				//Altera or its authorized distributors.  Please refer to the 
				//applicable agreement for further details.
				
				module rdfifo (
					data,
					rdclk,
					rdreq,
					wrclk,
					wrreq,
					q,
					wrusedw);
				
					input	[15:0]  data;
					input	  rdclk;
					input	  rdreq;
					input	  wrclk;
					input	  wrreq;
					output	[15:0]  q;
					output	[8:0]  wrusedw;
				
				endmodule
				
				// ============================================================
				// CNX file retrieval info
				// ============================================================
				// Retrieval info: PRIVATE: AlmostEmpty NUMERIC "0"
				// Retrieval info: PRIVATE: AlmostEmptyThr NUMERIC "-1"
				// Retrieval info: PRIVATE: AlmostFull NUMERIC "0"
				// Retrieval info: PRIVATE: AlmostFullThr NUMERIC "-1"
				// Retrieval info: PRIVATE: CLOCKS_ARE_SYNCHRONIZED NUMERIC "1"
				// Retrieval info: PRIVATE: Clock NUMERIC "4"
				// Retrieval info: PRIVATE: Depth NUMERIC "512"
				// Retrieval info: PRIVATE: Empty NUMERIC "1"
				// Retrieval info: PRIVATE: Full NUMERIC "1"
				// Retrieval info: PRIVATE: INTENDED_DEVICE_FAMILY STRING "Cyclone"
				// Retrieval info: PRIVATE: LE_BasedFIFO NUMERIC "0"
				// Retrieval info: PRIVATE: LegacyRREQ NUMERIC "1"
				// Retrieval info: PRIVATE: MAX_DEPTH_BY_9 NUMERIC "0"
				// Retrieval info: PRIVATE: OVERFLOW_CHECKING NUMERIC "0"
				// Retrieval info: PRIVATE: Optimize NUMERIC "2"
				// Retrieval info: PRIVATE: RAM_BLOCK_TYPE NUMERIC "2"
				// Retrieval info: PRIVATE: SYNTH_WRAPPER_GEN_POSTFIX STRING "0"
				// Retrieval info: PRIVATE: UNDERFLOW_CHECKING NUMERIC "0"
				// Retrieval info: PRIVATE: UsedW NUMERIC "1"
				// Retrieval info: PRIVATE: Width NUMERIC "16"
				// Retrieval info: PRIVATE: dc_aclr NUMERIC "0"
				// Retrieval info: PRIVATE: diff_widths NUMERIC "0"
				// Retrieval info: PRIVATE: msb_usedw NUMERIC "0"
				// Retrieval info: PRIVATE: output_width NUMERIC "16"
				// Retrieval info: PRIVATE: rsEmpty NUMERIC "0"
				// Retrieval info: PRIVATE: rsFull NUMERIC "0"
				// Retrieval info: PRIVATE: rsUsedW NUMERIC "0"
				// Retrieval info: PRIVATE: sc_aclr NUMERIC "0"
				// Retrieval info: PRIVATE: sc_sclr NUMERIC "0"
				// Retrieval info: PRIVATE: wsEmpty NUMERIC "0"
				// Retrieval info: PRIVATE: wsFull NUMERIC "0"
				// Retrieval info: PRIVATE: wsUsedW NUMERIC "1"
				// Retrieval info: CONSTANT: ADD_RAM_OUTPUT_REGISTER STRING "OFF"
				// Retrieval info: CONSTANT: CLOCKS_ARE_SYNCHRONIZED STRING "TRUE"
				// Retrieval info: CONSTANT: INTENDED_DEVICE_FAMILY STRING "Cyclone"
				// Retrieval info: CONSTANT: LPM_HINT STRING "RAM_BLOCK_TYPE=M4K"
				// Retrieval info: CONSTANT: LPM_NUMWORDS NUMERIC "512"
				// Retrieval info: CONSTANT: LPM_SHOWAHEAD STRING "OFF"
				// Retrieval info: CONSTANT: LPM_TYPE STRING "dcfifo"
				// Retrieval info: CONSTANT: LPM_WIDTH NUMERIC "16"
				// Retrieval info: CONSTANT: LPM_WIDTHU NUMERIC "9"
				// Retrieval info: CONSTANT: OVERFLOW_CHECKING STRING "ON"
				// Retrieval info: CONSTANT: UNDERFLOW_CHECKING STRING "ON"
				// Retrieval info: CONSTANT: USE_EAB STRING "ON"
				// Retrieval info: USED_PORT: data 0 0 16 0 INPUT NODEFVAL data[15..0]
				// Retrieval info: USED_PORT: q 0 0 16 0 OUTPUT NODEFVAL q[15..0]
				// Retrieval info: USED_PORT: rdclk 0 0 0 0 INPUT NODEFVAL rdclk
				// Retrieval info: USED_PORT: rdreq 0 0 0 0 INPUT NODEFVAL rdreq
				// Retrieval info: USED_PORT: wrclk 0 0 0 0 INPUT NODEFVAL wrclk
				// Retrieval info: USED_PORT: wrreq 0 0 0 0 INPUT NODEFVAL wrreq
				// Retrieval info: USED_PORT: wrusedw 0 0 9 0 OUTPUT NODEFVAL wrusedw[8..0]
				// Retrieval info: CONNECT: @data 0 0 16 0 data 0 0 16 0
				// Retrieval info: CONNECT: q 0 0 16 0 @q 0 0 16 0
				// Retrieval info: CONNECT: @wrreq 0 0 0 0 wrreq 0 0 0 0
				// Retrieval info: CONNECT: @rdreq 0 0 0 0 rdreq 0 0 0 0
				// Retrieval info: CONNECT: @rdclk 0 0 0 0 rdclk 0 0 0 0
				// Retrieval info: CONNECT: @wrclk 0 0 0 0 wrclk 0 0 0 0
				// Retrieval info: CONNECT: wrusedw 0 0 9 0 @wrusedw 0 0 9 0
				// Retrieval info: LIBRARY: altera_mf altera_mf.altera_mf_components.all
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo.v TRUE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo.inc FALSE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo.cmp FALSE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo.bsf TRUE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo_inst.v TRUE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo_bb.v TRUE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo_waveforms.html TRUE
				// Retrieval info: GEN_FILE: TYPE_NORMAL rdfifo_wave*.jpg FALSE
				// Retrieval info: LIB_FILE: altera_mf