nc_decoding.v

a H.264/AVC Baseline Decoder

	always @ (reset_n or cavlc_decoder_state or residual_state or mb_num_h or i8x8 or i4x4 or i4x4_CbCr or nA_availability_reg)
		if (reset_n == 1'b0)
			nA_availability <= 1'b0;
		else if (cavlc_decoder_state == `nAnB_decoding_s)
			case (residual_state)
				//luma
				`Intra16x16DCLevel_s:nA_availability <= (mb_num_h == 0)? 1'b0:1'b1;
				`Intra16x16ACLevel_s,`LumaLevel_s:
				if ((i8x8 == 0 || i8x8 == 2) && (i4x4 == 0 || i4x4 == 2))
					nA_availability <= (mb_num_h == 0)? 1'b0:1'b1;
				else 
					nA_availability <= 1'b1;
				//chroma
				`ChromaACLevel_Cb_s,`ChromaACLevel_Cr_s:
				nA_availability <= (mb_num_h == 0 && i4x4_CbCr[0] == 0)? 1'b0:1'b1;
				default:nA_availability <= 1'b0;
			endcase
		else
			nA_availability <= nA_availability_reg;
	//-------------------
	//nB_availability
	//-------------------
	always @ (posedge clk)
		if (reset_n == 0)
			nB_availability_reg <= 0;
		else if (cavlc_decoder_state == `nAnB_decoding_s)
			nB_availability_reg <= nB_availability;
	always @ (reset_n or cavlc_decoder_state or residual_state or mb_num_v or i8x8 or i4x4 or i4x4_CbCr
		or nB_availability_reg)
		if (reset_n == 1'b0)
			nB_availability <= 1'b0;
		else if (cavlc_decoder_state == `nAnB_decoding_s)
			case (residual_state)
				//luma
				`Intra16x16DCLevel_s:nB_availability <= (mb_num_v == 0)? 1'b0:1'b1;
				`Intra16x16ACLevel_s,`LumaLevel_s:
				if ((i8x8 == 0 || i8x8 == 1) && (i4x4 == 0 || i4x4 == 1))
					nB_availability <= (mb_num_v == 0)? 1'b0:1'b1;
				else 
					nB_availability <= 1'b1;
				//chroma
				`ChromaACLevel_Cb_s,`ChromaACLevel_Cr_s:
				nB_availability <= (mb_num_v == 0 && i4x4_CbCr[1] == 0)? 1'b0:1'b1;
				default:nB_availability <= 1'b0;
			endcase
		else 
			nB_availability <= nB_availability_reg;
	//------------
	//Derive nA
	//------------
	always @ (posedge clk)
		if (reset_n == 0)
			nA <= 0;
		else if (cavlc_decoder_state == `nAnB_decoding_s && nA_availability == 1)
			case (residual_state)
				//luma
				`Intra16x16DCLevel_s:nA <= (Luma_8x8_AllZeroCoeff_mbAddrA[0] == 0)? 0:LumaLevel_mbAddrA[4:0];
				`Intra16x16ACLevel_s,`LumaLevel_s:
				case (i8x8)
					0:
					case (i4x4)
						0:nA <= (Luma_8x8_AllZeroCoeff_mbAddrA[0] == 0)? 0:LumaLevel_mbAddrA[4:0];
						1:nA <= LumaLevel_CurrMb0[4:0];
						2:nA <= (Luma_8x8_AllZeroCoeff_mbAddrA[0] == 0)? 0:LumaLevel_mbAddrA[9:5];
						3:nA <= LumaLevel_CurrMb0[14:10];
					endcase
					1:
					case (i4x4)
						0:nA <= (CodedBlockPatternLuma[0] == 0)? 0:LumaLevel_CurrMb0[9:5];
						1:nA <= LumaLevel_CurrMb1[4:0];
						2:nA <= (CodedBlockPatternLuma[0] == 0)? 0:LumaLevel_CurrMb0[19:15];
						3:nA <= LumaLevel_CurrMb1[14:10];
					endcase
					2:
					case (i4x4)
						0:nA <= (Luma_8x8_AllZeroCoeff_mbAddrA[1] == 0)? 0:LumaLevel_mbAddrA[14:10];
						1:nA <= LumaLevel_CurrMb2[4:0];
						2:nA <= (Luma_8x8_AllZeroCoeff_mbAddrA[1] == 0)? 0:LumaLevel_mbAddrA[19:15];
						3:nA <= LumaLevel_CurrMb2[14:10];
					endcase
					3:
					case (i4x4)
						0:nA <= (CodedBlockPatternLuma[2] == 0)? 0:LumaLevel_CurrMb2[9:5];
						1:nA <= LumaLevel_CurrMb3[4:0];
						2:nA <= (CodedBlockPatternLuma[2] == 0)? 0:LumaLevel_CurrMb2[19:15];
						3:nA <= LumaLevel_CurrMb3[14:10];
					endcase
				endcase
				//chroma
				`ChromaACLevel_Cb_s:
				case (i4x4_CbCr)
					2'b00:nA <= (Chroma_8x8_AllZeroCoeff_mbAddrA == 0)? 0:ChromaLevel_Cb_mbAddrA[4:0];
					2'b10:nA <= (Chroma_8x8_AllZeroCoeff_mbAddrA == 0)? 0:ChromaLevel_Cb_mbAddrA[9:5];
					2'b01:nA <= (CodedBlockPatternChroma         != 2)? 0:ChromaLevel_Cb_CurrMb[4:0];
					2'b11:nA <= (CodedBlockPatternChroma         != 2)? 0:ChromaLevel_Cb_CurrMb[14:10];
				endcase
				`ChromaACLevel_Cr_s:
				case (i4x4_CbCr)
					2'b00:nA <= (Chroma_8x8_AllZeroCoeff_mbAddrA == 0)? 0:ChromaLevel_Cr_mbAddrA[4:0];
					2'b10:nA <= (Chroma_8x8_AllZeroCoeff_mbAddrA == 0)? 0:ChromaLevel_Cr_mbAddrA[9:5];
					2'b01:nA <= (CodedBlockPatternChroma         != 2)? 0:ChromaLevel_Cr_CurrMb[4:0];
					2'b11:nA <= (CodedBlockPatternChroma         != 2)? 0:ChromaLevel_Cr_CurrMb[14:10];
				endcase
			endcase
		else if (cavlc_decoder_state == `nAnB_decoding_s && nA_availability == 0)
			nA <= 0;
	//------------
	//Derive nB
	//------------
	always @ (posedge clk)
		if (reset_n == 0)
			nB <= 0;
		else if (cavlc_decoder_state == `nAnB_decoding_s && nB_availability == 1)
			case (residual_state)
				`Intra16x16DCLevel_s:
				nB <= (Luma_8x8_AllZeroCoeff_mbAddrB[0] == 0)? 0:LumaLevel_mbAddrB_dout[19:15];
				`Intra16x16ACLevel_s,`LumaLevel_s:
				case (i8x8)
					0:
					case (i4x4)
						0:nB <= (Luma_8x8_AllZeroCoeff_mbAddrB[0] == 0)? 0:LumaLevel_mbAddrB_dout[19:15];
						1:nB <= (Luma_8x8_AllZeroCoeff_mbAddrB[0] == 0)? 0:LumaLevel_mbAddrB_dout[14:10];
						2:nB <= LumaLevel_CurrMb0[4:0];
						3:nB <= LumaLevel_CurrMb0[9:5];
					endcase
					1:
					case (i4x4)
						0:nB <= (Luma_8x8_AllZeroCoeff_mbAddrB[1] == 0)? 0:LumaLevel_mbAddrB_dout[9:5];
						1:nB <= (Luma_8x8_AllZeroCoeff_mbAddrB[1] == 0)? 0:LumaLevel_mbAddrB_dout[4:0];
						2:nB <= LumaLevel_CurrMb1[4:0];
						3:nB <= LumaLevel_CurrMb1[9:5];
					endcase
					2:
					case (i4x4)
						0:nB <= (CodedBlockPatternLuma[0] == 0)? 0:LumaLevel_CurrMb0[14:10];
						1:nB <= (CodedBlockPatternLuma[0] == 0)? 0:LumaLevel_CurrMb0[19:15];
						2:nB <= LumaLevel_CurrMb2[4:0];
						3:nB <= LumaLevel_CurrMb2[9:5];
					endcase
					3:
					case (i4x4)
						0:nB <= (CodedBlockPatternLuma[1] == 0)? 0:LumaLevel_CurrMb1[14:10];
						1:nB <= (CodedBlockPatternLuma[1] == 0)? 0:LumaLevel_CurrMb1[19:15];
						2:nB <= LumaLevel_CurrMb3[4:0];
						3:nB <= LumaLevel_CurrMb3[9:5];
					endcase
				endcase
				`ChromaACLevel_Cb_s:
				case (i4x4_CbCr)
					0:nB <= (Chroma_8x8_AllZeroCoeff_mbAddrB == 0)? 0:ChromaLevel_Cb_mbAddrB_dout[9:5];
					1:nB <= (Chroma_8x8_AllZeroCoeff_mbAddrB == 0)? 0:ChromaLevel_Cb_mbAddrB_dout[4:0];
					2:nB <= ChromaLevel_Cb_CurrMb[4:0];
					3:nB <= ChromaLevel_Cb_CurrMb[9:5];
				endcase
				`ChromaACLevel_Cr_s:
				case (i4x4_CbCr)
					0:nB <= (Chroma_8x8_AllZeroCoeff_mbAddrB == 0)? 0:ChromaLevel_Cr_mbAddrB_dout[9:5];
					1:nB <= (Chroma_8x8_AllZeroCoeff_mbAddrB == 0)? 0:ChromaLevel_Cr_mbAddrB_dout[4:0];
					2:nB <= ChromaLevel_Cr_CurrMb[4:0];
					3:nB <= ChromaLevel_Cr_CurrMb[9:5];
				endcase
				default: nB <= 0;
			endcase
		else if (cavlc_decoder_state == `nAnB_decoding_s && nB_availability == 0)
			nB <= 0;
	//------------
	//Derive nC
	//------------
	always @ (posedge clk)
		if (reset_n == 0)
			nC <= 0;
		else if (cavlc_decoder_state == `nC_decoding_s)
			begin
				if (residual_state == `ChromaDCLevel_Cb_s || residual_state == `ChromaDCLevel_Cr_s)
					nC <= 5'b11111;
				else if (nA_availability == 1 && nB_availability == 1)
					nC <= (nA + nB + 1) >> 1;
				else
					nC <= nA + nB;
			end
	//-----------------------	
	//LumaLevel_CurrMb write 
	//-----------------------
	always @ (posedge clk)
		if (reset_n == 0)
			begin
				LumaLevel_CurrMb0 <= 0;	LumaLevel_CurrMb1 <= 0;	
				LumaLevel_CurrMb2 <= 0; LumaLevel_CurrMb3 <= 0;
			end
		else if (end_of_one_residual_block == 1 && (residual_state == `Intra16x16ACLevel_s || 
			residual_state == `LumaLevel_s))
			case (i8x8)
				0:
				case (i4x4)
					0:LumaLevel_CurrMb0[4:0]   <= TotalCoeff;
					1:LumaLevel_CurrMb0[9:5]   <= TotalCoeff;
					2:LumaLevel_CurrMb0[14:10] <= TotalCoeff;
					3:LumaLevel_CurrMb0[19:15] <= TotalCoeff;
				endcase
				1:
				case (i4x4)
					0:LumaLevel_CurrMb1[4:0]   <= TotalCoeff;
					1:LumaLevel_CurrMb1[9:5]   <= TotalCoeff;
					2:LumaLevel_CurrMb1[14:10] <= TotalCoeff;
					3:LumaLevel_CurrMb1[19:15] <= TotalCoeff;
				endcase
				2:
				case (i4x4)
					0:LumaLevel_CurrMb2[4:0]   <= TotalCoeff;
					1:LumaLevel_CurrMb2[9:5]   <= TotalCoeff;
					2:LumaLevel_CurrMb2[14:10] <= TotalCoeff;
					3:LumaLevel_CurrMb2[19:15] <= TotalCoeff;
				endcase
				3:
				case (i4x4)
					0:LumaLevel_CurrMb3[4:0]   <= TotalCoeff;
					1:LumaLevel_CurrMb3[9:5]   <= TotalCoeff;
					2:LumaLevel_CurrMb3[14:10] <= TotalCoeff;
					3:LumaLevel_CurrMb3[19:15] <= TotalCoeff;
				endcase
			endcase
	//---------------------------	
	//ChromaLevel_Cb_CurrMb write 
	//---------------------------
	always @ (posedge clk)
		if (reset_n == 0)
			ChromaLevel_Cb_CurrMb <= 0;
		else if (end_of_one_residual_block == 1 && residual_state == `ChromaACLevel_Cb_s)
			case (i4x4_CbCr)
				0:ChromaLevel_Cb_CurrMb[4:0]   <= TotalCoeff;
				1:ChromaLevel_Cb_CurrMb[9:5]   <= TotalCoeff;
				2:ChromaLevel_Cb_CurrMb[14:10] <= TotalCoeff;
				3:ChromaLevel_Cb_CurrMb[19:15] <= TotalCoeff;
			endcase
	//---------------------------	
	//ChromaLevel_Cr_CurrMb write 
	//---------------------------
	always @ (posedge clk)
		if (reset_n == 0)
			ChromaLevel_Cr_CurrMb <= 0;
		else if (end_of_one_residual_block == 1 && residual_state == `ChromaACLevel_Cr_s)
			case (i4x4_CbCr)
				0:ChromaLevel_Cr_CurrMb[4:0]   <= TotalCoeff;
				1:ChromaLevel_Cr_CurrMb[9:5]   <= TotalCoeff;
				2:ChromaLevel_Cr_CurrMb[14:10] <= TotalCoeff;
				3:ChromaLevel_Cr_CurrMb[19:15] <= TotalCoeff;
			endcase
	//-----------------------	
	//LumaLevel_mbAddrA write 
	//-----------------------
	always @ (posedge clk)
		if (reset_n == 0)
			LumaLevel_mbAddrA <= 0;
		else if (end_of_one_residual_block == 1 && (residual_state == `Intra16x16ACLevel_s || residual_state == `LumaLevel_s) && mb_num_h != 10)