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repo2/common/components/usbhostslave/trunk/RTL/serialInterfaceEngine/processRxBit.v
// File : ../RTL/serialInterfaceEngine/processRxBit.v
// Generated : 11/10/06 05:37:22
// From : ../RTL/serialInterfaceEngine/processRxBit.asf
// By : FSM2VHDL ver. 5.0.0.9

//////////////////////////////////////////////////////////////////////
//// ////
//// processrxbit
//// ////
//// This file is part of the usbhostslave opencores effort.
//// http://www.opencores.org/cores/usbhostslave/ ////
//// ////
//// Module Description: ////
////
//// ////
//// To Do: ////
////
//// ////
//// Author(s): ////
//// - Steve Fielding, sfielding@base2designs.com ////
//// ////
//////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2004 Steve Fielding and OPENCORES.ORG ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer. ////
//// ////
//// This source file is free software; you can redistribute it ////
//// and/or modify it under the terms of the GNU Lesser General ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any ////
//// later version. ////
//// ////
//// This source is distributed in the hope that it will be ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
//// PURPOSE. See the GNU Lesser General Public License for more ////
//// details. ////
//// ////
//// You should have received a copy of the GNU Lesser General ////
//// Public License along with this source; if not, download it ////
//// from http://www.opencores.org/lgpl.shtml ////
//// ////
//////////////////////////////////////////////////////////////////////
//
`include "timescale.v"
`include "usbSerialInterfaceEngine_h.v"


module processRxBit (JBit, KBit, RxBitsIn, RxCtrlOut, RxDataOut, RxWireActive, clk, processRxBitRdy, processRxBitsWEn, processRxByteRdy, processRxByteWEn, resumeDetected, rst, fullSpeedBitRate);
input [1:0] JBit;
input [1:0] KBit;
input [1:0] RxBitsIn;
input RxWireActive;
input clk;
input processRxBitsWEn;
input processRxByteRdy;
input rst;
output [7:0] RxCtrlOut;
output [7:0] RxDataOut;
output processRxBitRdy;
output processRxByteWEn;
output resumeDetected;
input fullSpeedBitRate;

wire [1:0] JBit;
wire [1:0] KBit;
wire [1:0] RxBitsIn;
reg [7:0] RxCtrlOut, next_RxCtrlOut;
reg [7:0] RxDataOut, next_RxDataOut;
wire RxWireActive;
wire clk;
reg processRxBitRdy, next_processRxBitRdy;
wire processRxBitsWEn;
wire processRxByteRdy;
reg processRxByteWEn, next_processRxByteWEn;
reg resumeDetected, next_resumeDetected;
wire rst;

// diagram signals declarations
reg [3:0]RXBitCount, next_RXBitCount;
reg [1:0]RXBitStMachCurrState, next_RXBitStMachCurrState;
reg [7:0]RXByte, next_RXByte;
reg [3:0]RXSameBitCount, next_RXSameBitCount;
reg [1:0]RxBits, next_RxBits;
reg bitStuffError, next_bitStuffError;
reg [1:0]oldRXBits, next_oldRXBits;
reg [4:0]resumeWaitCnt, next_resumeWaitCnt;
reg [7:0]delayCnt, next_delayCnt;

// BINARY ENCODED state machine: prRxBit
// State codes definitions:
`define START 4'b0000
`define IDLE_FIRST_BIT 4'b0001
`define WAIT_BITS 4'b0010
`define IDLE_CHK_KBIT 4'b0011
`define DATA_RX_LAST_BIT 4'b0100
`define DATA_RX_CHK_SE0 4'b0101
`define DATA_RX_DATA_DESTUFF 4'b0110
`define DATA_RX_BYTE_SEND2 4'b0111
`define DATA_RX_BYTE_WAIT_RDY 4'b1000
`define RES_RX_CHK 4'b1001
`define DATA_RX_ERROR_CHK_RES 4'b1010
`define RES_END_CHK1 4'b1011
`define IDLE_WAIT_PRB_RDY 4'b1100
`define DATA_RX_WAIT_PRB_RDY 4'b1101
`define DATA_RX_ERROR_WAIT_RDY 4'b1110
`define LOW_SPEED_EOP_DELAY 4'b1111

reg [3:0] CurrState_prRxBit;
reg [3:0] NextState_prRxBit;


//--------------------------------------------------------------------
// Machine: prRxBit
//--------------------------------------------------------------------
//----------------------------------
// Next State Logic (combinatorial)
//----------------------------------
always @ (*)
begin : prRxBit_NextState
NextState_prRxBit <= CurrState_prRxBit;
// Set default values for outputs and signals
next_processRxByteWEn <= processRxByteWEn;
next_RxCtrlOut <= RxCtrlOut;
next_RxDataOut <= RxDataOut;
next_resumeDetected <= resumeDetected;
next_RXBitStMachCurrState <= RXBitStMachCurrState;
next_RxBits <= RxBits;
next_RXSameBitCount <= RXSameBitCount;
next_RXBitCount <= RXBitCount;
next_oldRXBits <= oldRXBits;
next_RXByte <= RXByte;
next_bitStuffError <= bitStuffError;
next_resumeWaitCnt <= resumeWaitCnt;
next_delayCnt <= delayCnt;
next_processRxBitRdy <= processRxBitRdy;
case (CurrState_prRxBit)
`START:
begin
next_processRxByteWEn <= 1'b0;
next_RxCtrlOut <= 8'h00;
next_RxDataOut <= 8'h00;
next_resumeDetected <= 1'b0;
next_RXBitStMachCurrState <= `IDLE_BIT_ST;
next_RxBits <= 2'b00;
next_RXSameBitCount <= 4'h0;
next_RXBitCount <= 4'h0;
next_oldRXBits <= 2'b00;
next_RXByte <= 8'h00;
next_bitStuffError <= 1'b0;
next_resumeWaitCnt <= 5'h0;
next_processRxBitRdy <= 1'b1;
NextState_prRxBit <= `WAIT_BITS;
end
`WAIT_BITS:
if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `WAIT_RESUME_ST))
begin
NextState_prRxBit <= `RES_RX_CHK;
next_RxBits <= RxBitsIn;
next_processRxBitRdy <= 1'b0;
end
else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `DATA_RECEIVE_BIT_ST))
begin
NextState_prRxBit <= `DATA_RX_CHK_SE0;
next_RxBits <= RxBitsIn;
next_processRxBitRdy <= 1'b0;
end
else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `IDLE_BIT_ST))
begin
NextState_prRxBit <= `IDLE_CHK_KBIT;
next_RxBits <= RxBitsIn;
next_processRxBitRdy <= 1'b0;
end
else if ((processRxBitsWEn == 1'b1) && (RXBitStMachCurrState == `RESUME_END_WAIT_ST))
begin
NextState_prRxBit <= `RES_END_CHK1;
next_RxBits <= RxBitsIn;
next_processRxBitRdy <= 1'b0;
end
`IDLE_FIRST_BIT:
begin
next_processRxByteWEn <= 1'b0;
next_RXBitStMachCurrState <= `DATA_RECEIVE_BIT_ST;
next_RXSameBitCount <= 4'h0;
next_RXBitCount <= 4'h1;
next_oldRXBits <= RxBits;
//zero is always the first RZ data bit of a new packet
next_RXByte <= 8'h00;
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`IDLE_CHK_KBIT:
if ((RxBits == KBit) && (RxWireActive == 1'b1))
NextState_prRxBit <= `IDLE_WAIT_PRB_RDY;
else
begin
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`IDLE_WAIT_PRB_RDY:
if (processRxByteRdy == 1'b1)
begin
NextState_prRxBit <= `IDLE_FIRST_BIT;
next_RxDataOut <= 8'h00;
//redundant data
next_RxCtrlOut <= `DATA_START;
//start of packet
next_processRxByteWEn <= 1'b1;
end
`DATA_RX_LAST_BIT:
begin
next_processRxByteWEn <= 1'b0;
next_RXBitStMachCurrState <= `IDLE_BIT_ST;
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`DATA_RX_CHK_SE0:
begin
next_bitStuffError <= 1'b0;
if (RxBits == `SE0) begin
if (fullSpeedBitRate == 1'b0) begin
NextState_prRxBit <= `LOW_SPEED_EOP_DELAY;
next_delayCnt <= 8'h00;
end
else
NextState_prRxBit <= `DATA_RX_WAIT_PRB_RDY;
end
else
begin
NextState_prRxBit <= `DATA_RX_DATA_DESTUFF;
if (RxBits == oldRXBits) //if the current 'RxBits' are the same as the old 'RxBits', then
begin
next_RXSameBitCount <= RXSameBitCount + 1'b1;
//inc 'RXSameBitCount'
if (RXSameBitCount == `MAX_CONSEC_SAME_BITS) //if 'RXSameBitCount' == 6 there has been a bit stuff error
next_bitStuffError <= 1'b1;
//flag 'bitStuffError'
else //else no bit stuffing error
begin
next_RXBitCount <= RXBitCount + 1'b1;
if (RXBitCount != `MAX_CONSEC_SAME_BITS_PLUS1) begin
next_processRxBitRdy <= 1'b1;
//early indication of ready
end
next_RXByte <= { 1'b1, RXByte[7:1]};
//RZ bit = 1 (ie no change in 'RxBits')
end
end
else //else current 'RxBits' are different from old 'RxBits'
begin
if (RXSameBitCount != `MAX_CONSEC_SAME_BITS) //if this is not the RZ 0 bit after 6 consecutive RZ 1s, then
begin
next_RXBitCount <= RXBitCount + 1'b1;
if (RXBitCount != 4'h7) begin
next_processRxBitRdy <= 1'b1;
//early indication of ready
end
next_RXByte <= {1'b0, RXByte[7:1]};
//RZ bit = 0 (ie current'RxBits' is different than old 'RxBits')
end
next_RXSameBitCount <= 4'h0;
//reset 'RXSameBitCount'
end
next_oldRXBits <= RxBits;
end
end
`DATA_RX_WAIT_PRB_RDY:
if (processRxByteRdy == 1'b1)
begin
NextState_prRxBit <= `DATA_RX_LAST_BIT;
next_RxDataOut <= 8'h00;
//redundant data
next_RxCtrlOut <= `DATA_STOP;
//end of packet
next_processRxByteWEn <= 1'b1;
end
`DATA_RX_DATA_DESTUFF:
if (RXBitCount == 4'h8 & bitStuffError == 1'b0)
NextState_prRxBit <= `DATA_RX_BYTE_WAIT_RDY;
else if (bitStuffError == 1'b1)
NextState_prRxBit <= `DATA_RX_ERROR_WAIT_RDY;
else
begin
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`DATA_RX_BYTE_SEND2:
begin
next_processRxByteWEn <= 1'b0;
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`DATA_RX_BYTE_WAIT_RDY:
if (processRxByteRdy == 1'b1)
begin
NextState_prRxBit <= `DATA_RX_BYTE_SEND2;
next_RXBitCount <= 4'h0;
next_RxDataOut <= RXByte;
next_RxCtrlOut <= `DATA_STREAM;
next_processRxByteWEn <= 1'b1;
end
`DATA_RX_ERROR_CHK_RES:
begin
next_processRxByteWEn <= 1'b0;
if (RxBits == JBit) //if current bit is a JBit, then
next_RXBitStMachCurrState <= `IDLE_BIT_ST;
//next state is idle
else //else
begin
next_RXBitStMachCurrState <= `WAIT_RESUME_ST;
//check for resume
next_resumeWaitCnt <= 5'h0;
end
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`DATA_RX_ERROR_WAIT_RDY:
if (processRxByteRdy == 1'b1)
begin
NextState_prRxBit <= `DATA_RX_ERROR_CHK_RES;
next_RxDataOut <= 8'h00;
//redundant data
next_RxCtrlOut <= `DATA_BIT_STUFF_ERROR;
next_processRxByteWEn <= 1'b1;
end
`RES_RX_CHK:
begin
if (RxBits != KBit) //can only be a resume if line remains in Kbit state
next_RXBitStMachCurrState <= `IDLE_BIT_ST;
else
begin
next_resumeWaitCnt <= resumeWaitCnt + 1'b1;
//if we've waited long enough, then
if (resumeWaitCnt == `RESUME_RX_WAIT_TIME)
begin
next_RXBitStMachCurrState <= `RESUME_END_WAIT_ST;
next_resumeDetected <= 1'b1;
//report resume detected
end
end
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`RES_END_CHK1:
begin
if (RxBits != KBit) //line must leave KBit state for the end of resume
begin
next_RXBitStMachCurrState <= `IDLE_BIT_ST;
next_resumeDetected <= 1'b0;
//clear resume detected flag
end
NextState_prRxBit <= `WAIT_BITS;
next_processRxBitRdy <= 1'b1;
end
`LOW_SPEED_EOP_DELAY:
begin
//turn around time must be at least 2 low speed bit periods
next_delayCnt <= delayCnt + 1'b1;
if (delayCnt == `LS_OVER_SAMPLE_RATE * 2)
NextState_prRxBit <= `DATA_RX_WAIT_PRB_RDY;
end
endcase
end

//----------------------------------
// Current State Logic (sequential)
//----------------------------------
always @ (posedge clk)
begin : prRxBit_CurrentState
if (rst)
CurrState_prRxBit <= `START;
else
CurrState_prRxBit <= NextState_prRxBit;
end

//----------------------------------
// Registered outputs logic
//----------------------------------
always @ (posedge clk)
begin : prRxBit_RegOutput
if (rst)
begin
RXBitStMachCurrState <= `IDLE_BIT_ST;
RxBits <= 2'b00;
RXSameBitCount <= 4'h0;
RXBitCount <= 4'h0;
oldRXBits <= 2'b00;
RXByte <= 8'h00;
bitStuffError <= 1'b0;
resumeWaitCnt <= 5'h0;
delayCnt <= 8'h00;
processRxByteWEn <= 1'b0;
RxCtrlOut <= 8'h00;
RxDataOut <= 8'h00;
resumeDetected <= 1'b0;
processRxBitRdy <= 1'b1;
end
else
begin
RXBitStMachCurrState <= next_RXBitStMachCurrState;
RxBits <= next_RxBits;
RXSameBitCount <= next_RXSameBitCount;
RXBitCount <= next_RXBitCount;
oldRXBits <= next_oldRXBits;
RXByte <= next_RXByte;
bitStuffError <= next_bitStuffError;
resumeWaitCnt <= next_resumeWaitCnt;
delayCnt <= next_delayCnt;
processRxByteWEn <= next_processRxByteWEn;
RxCtrlOut <= next_RxCtrlOut;
RxDataOut <= next_RxDataOut;
resumeDetected <= next_resumeDetected;
processRxBitRdy <= next_processRxBitRdy;
end
end

endmodule
(5-5/18)