| ///////////////////////////////////////////////////////////////////// | |
| //// //// | |
| //// Forward Discrete Cosine Transform and ZigZag unit //// | |
| //// //// | |
| //// Author: Richard Herveille //// | |
| //// richard@asics.ws //// | |
| //// www.asics.ws //// | |
| //// //// | |
| ///////////////////////////////////////////////////////////////////// | |
| //// //// | |
| //// Copyright (C) 2002 Richard Herveille //// | |
| //// richard@asics.ws //// | |
| //// //// | |
| //// 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 SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY //// | |
| //// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED //// | |
| //// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS //// | |
| //// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR //// | |
| //// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, //// | |
| //// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES //// | |
| //// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE //// | |
| //// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR //// | |
| //// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF //// | |
| //// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT //// | |
| //// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT //// | |
| //// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE //// | |
| //// POSSIBILITY OF SUCH DAMAGE. //// | |
| //// //// | |
| ///////////////////////////////////////////////////////////////////// | |
| // CVS Log | |
| // | |
| // $Id: fdct.v,v 1.3 2002-10-31 12:50:03 rherveille Exp $ | |
| // | |
| // $Date: 2002-10-31 12:50:03 $ | |
| // $Revision: 1.3 $ | |
| // $Author: rherveille $ | |
| // $Locker: $ | |
| // $State: Exp $ | |
| // | |
| // Change History: | |
| // $Log: not supported by cvs2svn $ | |
| // Revision 1.2 2002/10/23 09:06:59 rherveille | |
| // Improved many files. | |
| // Fixed some bugs in Run-Length-Encoder. | |
| // Removed dependency on ud_cnt and ro_cnt. | |
| // Started (Motion)JPEG hardware encoder project. | |
| // | |
| module fdct(clk, ena, rst, dstrb, din, dout, douten); | |
| // | |
| // parameters | |
| // | |
| //////////////////////////////////////////////////////////////////// | |
| // // | |
| // ITU-T.81, ITU-T.83 & Coefficient resolution notes // | |
| // // | |
| //////////////////////////////////////////////////////////////////// | |
| // // | |
| // Worst case error (all input values -128) is // | |
| // zero (i.e. no errors) when using 15bit coefficients // | |
| // // | |
| // Using less bits for the coefficients produces a biterror // | |
| // approx. equal to (15 - used_coefficient-bits). // | |
| // i.e. 14bit coefficients, errors in dout-bit[0] only // | |
| // 13bit coefficients, errors in dout-bits[1:0] // | |
| // 12bit coefficients, errors in dout-bits[2:0] etc. // | |
| // Tests with real non-continous tone image data have shown that // | |
| // even when using 13bit coefficients errors remain in the lsb // | |
| // only (i.e. dout-bit[0] // | |
| // // | |
| // The amount of coefficient-bits needed is dependent on the // | |
| // desired quality. // | |
| // The JPEG-standard compliance specs.(ITU-T.83) prescribe // | |
| // that the output of the combined DCT AND Quantization unit // | |
| // shall not exceed 1 for the desired quality. // | |
| // // | |
| // This means for high quantization levels, lesser bits // | |
| // for the DCT unit can be used. // | |
| // // | |
| // Looking at the recommended "quantization tables for generic // | |
| // compliance testing of DCT-based processes" (ITU-T.83 annex B) // | |
| // it can be noticed that relatively large quantization values // | |
| // are being used. Errors in the lower-order bits should // | |
| // therefore not be visible. // | |
| // For certain applications some of the lower-order bits could // | |
| // actually be discarded. When looking at the luminance and // | |
| // chrominance example quantization tables (ITU-T.81 annex K) // | |
| // it can be seen that the smallest quantization value is ten // | |
| // (qnt_val_min = 10). This means that the lowest 2bits can be // | |
| // discarded (set to zero '0') without having any effect on the // | |
| // final result. In this example 11 bit or 12 bit coefficients // | |
| // would be sufficient. // | |
| // // | |
| //////////////////////////////////////////////////////////////////// | |
| parameter coef_width = 11; | |
| parameter di_width = 8; | |
| parameter do_width = 12; | |
| // | |
| // inputs & outputs | |
| // | |
| input clk; // system clock | |
| input ena; // clock enable | |
| input rst; // active low asynchronous reset | |
| input dstrb; // data-strobe. Present dstrb 1clk-cycle before data block | |
| input [di_width-1:0] din; | |
| output [do_width-1:0] dout; | |
| output douten; // data-out enable | |
| // | |
| // variables | |
| // | |
| wire doe; | |
| wire [do_width -1:0] // results from DCT module | |
| res00, res01, res02, res03, res04, res05, res06, res07, | |
| res10, res11, res12, res13, res14, res15, res16, res17, | |
| res20, res21, res22, res23, res24, res25, res26, res27, | |
| res30, res31, res32, res33, res34, res35, res36, res37, | |
| res40, res41, res42, res43, res44, res45, res46, res47, | |
| res50, res51, res52, res53, res54, res55, res56, res57, | |
| res60, res61, res62, res63, res64, res65, res66, res67, | |
| res70, res71, res72, res73, res74, res75, res76, res77; | |
| // | |
| // module body | |
| // | |
| // Hookup DCT module | |
| dct #(coef_width, di_width, do_width) | |
| dct_mod( | |
| .clk(clk), | |
| .ena(ena), | |
| .rst(rst), | |
| .dstrb(dstrb), | |
| .din(din), | |
| .dout_00(res00), | |
| .dout_01(res01), | |
| .dout_02(res02), | |
| .dout_03(res03), | |
| .dout_04(res04), | |
| .dout_05(res05), | |
| .dout_06(res06), | |
| .dout_07(res07), | |
| .dout_10(res10), | |
| .dout_11(res11), | |
| .dout_12(res12), | |
| .dout_13(res13), | |
| .dout_14(res14), | |
| .dout_15(res15), | |
| .dout_16(res16), | |
| .dout_17(res17), | |
| .dout_20(res20), | |
| .dout_21(res21), | |
| .dout_22(res22), | |
| .dout_23(res23), | |
| .dout_24(res24), | |
| .dout_25(res25), | |
| .dout_26(res26), | |
| .dout_27(res27), | |
| .dout_30(res30), | |
| .dout_31(res31), | |
| .dout_32(res32), | |
| .dout_33(res33), | |
| .dout_34(res34), | |
| .dout_35(res35), | |
| .dout_36(res36), | |
| .dout_37(res37), | |
| .dout_40(res40), | |
| .dout_41(res41), | |
| .dout_42(res42), | |
| .dout_43(res43), | |
| .dout_44(res44), | |
| .dout_45(res45), | |
| .dout_46(res46), | |
| .dout_47(res47), | |
| .dout_50(res50), | |
| .dout_51(res51), | |
| .dout_52(res52), | |
| .dout_53(res53), | |
| .dout_54(res54), | |
| .dout_55(res55), | |
| .dout_56(res56), | |
| .dout_57(res57), | |
| .dout_60(res60), | |
| .dout_61(res61), | |
| .dout_62(res62), | |
| .dout_63(res63), | |
| .dout_64(res64), | |
| .dout_65(res65), | |
| .dout_66(res66), | |
| .dout_67(res67), | |
| .dout_70(res70), | |
| .dout_71(res71), | |
| .dout_72(res72), | |
| .dout_73(res73), | |
| .dout_74(res74), | |
| .dout_75(res75), | |
| .dout_76(res76), | |
| .dout_77(res77), | |
| .douten(doe) | |
| ); | |
| // Hookup ZigZag unit | |
| zigzag zigzag_mod( | |
| .clk(clk), | |
| .ena(ena), | |
| .dstrb(doe), | |
| .din_00(res00), | |
| .din_01(res01), | |
| .din_02(res02), | |
| .din_03(res03), | |
| .din_04(res04), | |
| .din_05(res05), | |
| .din_06(res06), | |
| .din_07(res07), | |
| .din_10(res10), | |
| .din_11(res11), | |
| .din_12(res12), | |
| .din_13(res13), | |
| .din_14(res14), | |
| .din_15(res15), | |
| .din_16(res16), | |
| .din_17(res17), | |
| .din_20(res20), | |
| .din_21(res21), | |
| .din_22(res22), | |
| .din_23(res23), | |
| .din_24(res24), | |
| .din_25(res25), | |
| .din_26(res26), | |
| .din_27(res27), | |
| .din_30(res30), | |
| .din_31(res31), | |
| .din_32(res32), | |
| .din_33(res33), | |
| .din_34(res34), | |
| .din_35(res35), | |
| .din_36(res36), | |
| .din_37(res37), | |
| .din_40(res40), | |
| .din_41(res41), | |
| .din_42(res42), | |
| .din_43(res43), | |
| .din_44(res44), | |
| .din_45(res45), | |
| .din_46(res46), | |
| .din_47(res47), | |
| .din_50(res50), | |
| .din_51(res51), | |
| .din_52(res52), | |
| .din_53(res53), | |
| .din_54(res54), | |
| .din_55(res55), | |
| .din_56(res56), | |
| .din_57(res57), | |
| .din_60(res60), | |
| .din_61(res61), | |
| .din_62(res62), | |
| .din_63(res63), | |
| .din_64(res64), | |
| .din_65(res65), | |
| .din_66(res66), | |
| .din_67(res67), | |
| .din_70(res70), | |
| .din_71(res71), | |
| .din_72(res72), | |
| .din_73(res73), | |
| .din_74(res74), | |
| .din_75(res75), | |
| .din_76(res76), | |
| .din_77(res77), | |
| .dout(dout), | |
| .douten(douten) | |
| ); | |
| endmodule | |