bitstream_buffer.v

a H.264/AVC Baseline Decoder

//--------------------------------------------------------------------------------------------------
// Design    : nova
// Author(s) : Ke Xu
// Email	   : [e-mail]
// File      : BitStream_buffer.v
// Generated : May 16,2005
// Copyright (C) 2008 Ke Xu                
//-------------------------------------------------------------------------------------------------
// Description 
// Circular buffer,interfacing between Beha_Bitstream_ram and the decoder
//-------------------------------------------------------------------------------------------------

// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
`include "nova_defines.v"

module BitStream_buffer (clk,reset_n,BitStream_buffer_input,pc,
	BitStream_ram_ren,BitStream_buffer_valid_n,BitStream_buffer_output,BitStream_ram_addr);
	input clk,reset_n;
	input [15:0] BitStream_buffer_input;
	input [6:0] pc;
	
	output BitStream_ram_ren;
	output BitStream_buffer_valid_n;
	output [15:0] BitStream_buffer_output;
	output [16:0]BitStream_ram_addr;
	
	reg BitStream_ram_ren;
	reg BitStream_buffer_valid_n;
	reg [15:0] BitStream_buffer_output;
	reg [16:0]BitStream_ram_addr;
	
	reg [0:127]BS_buffer;
	reg [6:0] pc_previous;
	reg [3:0] reset_counter;
	reg [2:0] half_fill_counter;
	reg [6:0] buffer_index; //for buffer write 
	
	/*
	// synopsys translate_off
	integer	pc_statistical;
	initial
		begin
			pc_statistical = $fopen("pc_statistical.txt");
		end
	always @ (posedge clk)
		$fdisplay (pc_statistical,"%d",pc);
	// synopsys translate_on
	*/
	always @ (posedge clk)
		if (reset_n == 1'b0)
			pc_previous <= 0;
		else
			pc_previous <= pc;
	
	always @ (posedge clk)
		if (reset_n == 1'b0)
			reset_counter <= 0;
		else if (reset_counter < 10)
			reset_counter <= reset_counter + 1;	
	
	always @ (posedge clk)
		if (reset_n == 1'b0)
			half_fill_counter <= 0;
		else if (reset_counter == 10) 
			begin
				if (((pc > 63 && pc_previous <= 63) || (pc <63 && pc_previous >=63)) && half_fill_counter == 0)
					half_fill_counter <= 1;
				else if (pc > 63 && half_fill_counter == 0 && buffer_index == 0)
					half_fill_counter <= 1;
				else if (pc < 63 && half_fill_counter == 0 && buffer_index == 64)
					half_fill_counter <= 1;
				else if (half_fill_counter > 0 && half_fill_counter < 5)
					half_fill_counter <= half_fill_counter + 1;
				else if (half_fill_counter == 5)
					half_fill_counter <= 0;
			end
				
	always @ (posedge clk)
		if (reset_n == 1'b0)
			buffer_index <= 0;
		else if (reset_counter > 1 && reset_counter < 10)
			buffer_index <= buffer_index + 16; 
		else if (half_fill_counter > 1 && half_fill_counter <= 5)
			buffer_index <= buffer_index + 16;
	
	always @ (posedge clk)
		if (reset_n == 1'b0)
			BitStream_buffer_valid_n <= 1'b1;
		else if (reset_counter == 10)
			BitStream_buffer_valid_n <= 1'b0;
				
	always @ (posedge clk)
		if (reset_n == 1'b0)
			BitStream_ram_ren <= 1'b0;
		else if (reset_counter < 9)
			BitStream_ram_ren <= 1'b0;
		else if (reset_counter == 9)
			BitStream_ram_ren <= 1'b1;
		else 						   
			begin
				if (((pc > 63 && pc_previous <= 63) || (pc <63 && pc_previous >=63)) && half_fill_counter == 0)
					BitStream_ram_ren <= 0;
				else if (half_fill_counter > 0 && half_fill_counter < 5)
					BitStream_ram_ren <= 0;
				else
					BitStream_ram_ren <= 1;
			end
	
	always @ (posedge clk)
		if (reset_n == 1'b0)
			BitStream_ram_addr <= 0;
		else if (reset_counter > 0 && reset_counter < 9)
			BitStream_ram_addr <= BitStream_ram_addr + 1;
		else if (half_fill_counter > 0 && half_fill_counter < 5 && BitStream_ram_addr != 17'd131071) //no wrap around
			BitStream_ram_addr <= BitStream_ram_addr + 1;
	
	integer	i;
	always @ (posedge clk)
		if (reset_n == 1'b0)
			BS_buffer <= 0;
		else if ((reset_counter > 1 && reset_counter < 10) || (half_fill_counter > 1 && half_fill_counter <= 5))  
			case (buffer_index[6:4])
				3'b000:
				for (i=0;i<16;i=i+1)
					BS_buffer[i] <= BitStream_buffer_input[15-i];
				3'b001:
				for (i=0;i<16;i=i+1)
					BS_buffer[16+i] <= BitStream_buffer_input[15-i];
				3'b010:
				for (i=0;i<16;i=i+1)
					BS_buffer[32+i] <= BitStream_buffer_input[15-i];
				3'b011:
				for (i=0;i<16;i=i+1)
					BS_buffer[48+i] <= BitStream_buffer_input[15-i];
				3'b100:
				for (i=0;i<16;i=i+1)
					BS_buffer[64+i] <= BitStream_buffer_input[15-i];
				3'b101:
				for (i=0;i<16;i=i+1)
					BS_buffer[80+i] <= BitStream_buffer_input[15-i];
				3'b110:
				for (i=0;i<16;i=i+1)
					BS_buffer[96+i] <= BitStream_buffer_input[15-i];
				3'b111:
				for (i=0;i<16;i=i+1)
					BS_buffer[112+i] <= BitStream_buffer_input[15-i];
			endcase
				
	always @ (posedge clk)
	//always @ (reset_n or BitStream_buffer_valid_n or pc)
		if (reset_n == 1'b0)
			BitStream_buffer_output <= 0;
		else if (BitStream_buffer_valid_n == 0)
			case (pc)
				0  :BitStream_buffer_output <= BS_buffer[0:15];
				1  :BitStream_buffer_output <= BS_buffer[1:16];
				2  :BitStream_buffer_output <= BS_buffer[2:17];
				3  :BitStream_buffer_output <= BS_buffer[3:18];
				4  :BitStream_buffer_output <= BS_buffer[4:19];
				5  :BitStream_buffer_output <= BS_buffer[5:20];
				6  :BitStream_buffer_output <= BS_buffer[6:21];
				7  :BitStream_buffer_output <= BS_buffer[7:22];
				8  :BitStream_buffer_output <= BS_buffer[8:23];
				9  :BitStream_buffer_output <= BS_buffer[9:24];
				10 :BitStream_buffer_output <= BS_buffer[10:25];
				11 :BitStream_buffer_output <= BS_buffer[11:26];
				12 :BitStream_buffer_output <= BS_buffer[12:27];
				13 :BitStream_buffer_output <= BS_buffer[13:28];
				14 :BitStream_buffer_output <= BS_buffer[14:29];
				15 :BitStream_buffer_output <= BS_buffer[15:30];
				16 :BitStream_buffer_output <= BS_buffer[16:31];
				17 :BitStream_buffer_output <= BS_buffer[17:32];
				18 :BitStream_buffer_output <= BS_buffer[18:33];
				19 :BitStream_buffer_output <= BS_buffer[19:34];
				20 :BitStream_buffer_output <= BS_buffer[20:35];
				21 :BitStream_buffer_output <= BS_buffer[21:36];
				22 :BitStream_buffer_output <= BS_buffer[22:37];
				23 :BitStream_buffer_output <= BS_buffer[23:38];
				24 :BitStream_buffer_output <= BS_buffer[24:39];
				25 :BitStream_buffer_output <= BS_buffer[25:40];
				26 :BitStream_buffer_output <= BS_buffer[26:41];
				27 :BitStream_buffer_output <= BS_buffer[27:42];
				28 :BitStream_buffer_output <= BS_buffer[28:43];
				29 :BitStream_buffer_output <= BS_buffer[29:44];
				30 :BitStream_buffer_output <= BS_buffer[30:45];
				31 :BitStream_buffer_output <= BS_buffer[31:46];
				32 :BitStream_buffer_output <= BS_buffer[32:47];
				33 :BitStream_buffer_output <= BS_buffer[33:48];
				34 :BitStream_buffer_output <= BS_buffer[34:49];
				35 :BitStream_buffer_output <= BS_buffer[35:50];
				36 :BitStream_buffer_output <= BS_buffer[36:51];
				37 :BitStream_buffer_output <= BS_buffer[37:52];
				38 :BitStream_buffer_output <= BS_buffer[38:53];
				39 :BitStream_buffer_output <= BS_buffer[39:54];
				40 :BitStream_buffer_output <= BS_buffer[40:55];
				41 :BitStream_buffer_output <= BS_buffer[41:56];
				42 :BitStream_buffer_output <= BS_buffer[42:57];
				43 :BitStream_buffer_output <= BS_buffer[43:58];
				44 :BitStream_buffer_output <= BS_buffer[44:59];
				45 :BitStream_buffer_output <= BS_buffer[45:60];
				46 :BitStream_buffer_output <= BS_buffer[46:61];
				47 :BitStream_buffer_output <= BS_buffer[47:62];
				48 :BitStream_buffer_output <= BS_buffer[48:63];
				49 :BitStream_buffer_output <= BS_buffer[49:64];
				50 :BitStream_buffer_output <= BS_buffer[50:65];
				51 :BitStream_buffer_output <= BS_buffer[51:66];
				52 :BitStream_buffer_output <= BS_buffer[52:67];
				53 :BitStream_buffer_output <= BS_buffer[53:68];
				54 :BitStream_buffer_output <= BS_buffer[54:69];
				55 :BitStream_buffer_output <= BS_buffer[55:70];
				56 :BitStream_buffer_output <= BS_buffer[56:71];
				57 :BitStream_buffer_output <= BS_buffer[57:72];
				58 :BitStream_buffer_output <= BS_buffer[58:73];
				59 :BitStream_buffer_output <= BS_buffer[59:74];
				60 :BitStream_buffer_output <= BS_buffer[60:75];
				61 :BitStream_buffer_output <= BS_buffer[61:76];
				62 :BitStream_buffer_output <= BS_buffer[62:77];
				63 :BitStream_buffer_output <= BS_buffer[63:78];
				64 :BitStream_buffer_output <= BS_buffer[64:79];
				65 :BitStream_buffer_output <= BS_buffer[65:80];
				66 :BitStream_buffer_output <= BS_buffer[66:81];
				67 :BitStream_buffer_output <= BS_buffer[67:82];
				68 :BitStream_buffer_output <= BS_buffer[68:83];
				69 :BitStream_buffer_output <= BS_buffer[69:84];
				70 :BitStream_buffer_output <= BS_buffer[70:85];
				71 :BitStream_buffer_output <= BS_buffer[71:86];
				72 :BitStream_buffer_output <= BS_buffer[72:87];
				73 :BitStream_buffer_output <= BS_buffer[73:88];
				74 :BitStream_buffer_output <= BS_buffer[74:89];
				75 :BitStream_buffer_output <= BS_buffer[75:90];
				76 :BitStream_buffer_output <= BS_buffer[76:91];
				77 :BitStream_buffer_output <= BS_buffer[77:92];
				78 :BitStream_buffer_output <= BS_buffer[78:93];
				79 :BitStream_buffer_output <= BS_buffer[79:94];
				80 :BitStream_buffer_output <= BS_buffer[80:95];
				81 :BitStream_buffer_output <= BS_buffer[81:96];
				82 :BitStream_buffer_output <= BS_buffer[82:97];
				83 :BitStream_buffer_output <= BS_buffer[83:98];
				84 :BitStream_buffer_output <= BS_buffer[84:99];
				85 :BitStream_buffer_output <= BS_buffer[85:100];
				86 :BitStream_buffer_output <= BS_buffer[86:101];
				87 :BitStream_buffer_output <= BS_buffer[87:102];
				88 :BitStream_buffer_output <= BS_buffer[88:103];
				89 :BitStream_buffer_output <= BS_buffer[89:104];
				90 :BitStream_buffer_output <= BS_buffer[90:105];
				91 :BitStream_buffer_output <= BS_buffer[91:106];
				92 :BitStream_buffer_output <= BS_buffer[92:107];
				93 :BitStream_buffer_output <= BS_buffer[93:108];
				94 :BitStream_buffer_output <= BS_buffer[94:109];
				95 :BitStream_buffer_output <= BS_buffer[95:110];
				96 :BitStream_buffer_output <= BS_buffer[96:111];
				97 :BitStream_buffer_output <= BS_buffer[97:112];
				98 :BitStream_buffer_output <= BS_buffer[98:113];
				99 :BitStream_buffer_output <= BS_buffer[99:114];
				100:BitStream_buffer_output <= BS_buffer[100:115];
				101:BitStream_buffer_output <= BS_buffer[101:116];
				102:BitStream_buffer_output <= BS_buffer[102:117];
				103:BitStream_buffer_output <= BS_buffer[103:118];
				104:BitStream_buffer_output <= BS_buffer[104:119]; 
				105:BitStream_buffer_output <= BS_buffer[105:120];
				106:BitStream_buffer_output <= BS_buffer[106:121];
				107:BitStream_buffer_output <= BS_buffer[107:122];
				108:BitStream_buffer_output <= BS_buffer[108:123];
				109:BitStream_buffer_output <= BS_buffer[109:124];
				110:BitStream_buffer_output <= BS_buffer[110:125];
				111:BitStream_buffer_output <= BS_buffer[111:126];
				112:BitStream_buffer_output <= BS_buffer[112:127];
				113:BitStream_buffer_output <= {BS_buffer[113:127],BS_buffer[0]};
				114:BitStream_buffer_output <= {BS_buffer[114:127],BS_buffer[0:1]};
				115:BitStream_buffer_output <= {BS_buffer[115:127],BS_buffer[0:2]}; 
				116:BitStream_buffer_output <= {BS_buffer[116:127],BS_buffer[0:3]};
				117:BitStream_buffer_output <= {BS_buffer[117:127],BS_buffer[0:4]};
				118:BitStream_buffer_output <= {BS_buffer[118:127],BS_buffer[0:5]};
				119:BitStream_buffer_output <= {BS_buffer[119:127],BS_buffer[0:6]};
				120:BitStream_buffer_output <= {BS_buffer[120:127],BS_buffer[0:7]};
				121:BitStream_buffer_output <= {BS_buffer[121:127],BS_buffer[0:8]};
				122:BitStream_buffer_output <= {BS_buffer[122:127],BS_buffer[0:9]};
				123:BitStream_buffer_output <= {BS_buffer[123:127],BS_buffer[0:10]};
				124:BitStream_buffer_output <= {BS_buffer[124:127],BS_buffer[0:11]};
				125:BitStream_buffer_output <= {BS_buffer[125:127],BS_buffer[0:12]}; 
				126:BitStream_buffer_output <= {BS_buffer[126:127],BS_buffer[0:13]};
				127:BitStream_buffer_output <= {BS_buffer[127],BS_buffer[0:14]};
			endcase
endmodule