/**************************************************************************
 *                                                                        *
 *               Copyright (C) 1995, Silicon Graphics, Inc.               *
 *                                                                        *
 *  These coded instructions, statements, and computer programs  contain  *
 *  unpublished  proprietary  information of Silicon Graphics, Inc., and  *
 *  are protected by Federal copyright  law.  They  may not be disclosed  *
 *  to  third  parties  or copied or duplicated in any form, in whole or  *
 *  in part, without the prior written consent of Silicon Graphics, Inc.  *
 *                                                                        *
 *************************************************************************/

// $Id: tm_mux2.v,v 1.2 2002/11/22 00:34:20 rws Exp $

////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module:	tm_mux2
// description:	texel-type mux,	texel-size mux, 
//              hi-lo muxes, and texel-format muxes
//
// designer:	Tony DeLaurier
// date:	4/5/95
//
////////////////////////////////////////////////////////////////////////

module tm_mux2 (clk, start_gclk, tlut_type, tile_tex_type, tile_tex_size_2d, palette_1d, 
		tlut_en_2d, swap_a_low, swap_b_low, swap_c_low, swap_d_low, 
		swap_a_high, swap_b_high, swap_c_high, swap_d_high, 
		sort_tex_a_low, sort_tex_b_low, sort_tex_c_low, sort_tex_d_low, 
		sort_tex_a_high, sort_tex_b_high, sort_tex_c_high, 
		sort_tex_d_high, copy_bus, red_a, red_b, red_c, red_d, green_a, 
		green_b, green_c, green_d, blue_a, blue_b, blue_c, blue_d, 
		alpha_a, alpha_b, alpha_c, alpha_d);

  `include "tex.vh"

  input clk, start_gclk;                   // RDP gated clock

  input tlut_type;              // tlut type
  input [2:0] tile_tex_type;    // tile texel type

  // from tm_mux1
  input [1:0] tile_tex_size_2d; // tile texel size delayed 2
  input [3:0] palette_1d;       // palette delayed 1
  input tlut_en_2d;             // tlut_en delayed 2

  input [4:0] swap_a_low;      	// swapped address a (low half)
  input [4:0] swap_b_low;      	// swapped address b (low half)
  input [4:0] swap_c_low;      	// swapped address c (low half)
  input [4:0] swap_d_low;      	// swapped address d (low half)

  input [4:0] swap_a_high;     	// swapped address a (high half)
  input [4:0] swap_b_high;     	// swapped address b (high half)
  input [4:0] swap_c_high;     	// swapped address c (high half)
  input [4:0] swap_d_high;     	// swapped address d (high half)

  input [15:0] sort_tex_a_low; 	// sorted texel a (low half)
  input [15:0] sort_tex_b_low; 	// sorted texel b (low half)
  input [15:0] sort_tex_c_low; 	// sorted texel c (low half)
  input [15:0] sort_tex_d_low; 	// sorted texel d (low half)

  input [15:0] sort_tex_a_high;	// sorted texel a (high half)
  input [15:0] sort_tex_b_high;	// sorted texel b (high half)
  input [15:0] sort_tex_c_high;	// sorted texel c (high half)
  input [15:0] sort_tex_d_high;	// sorted texel d (high half)

  // outputs
  output [63:0] copy_bus;	// copy bus
  reg [63:0] copy_bus;		// copy bus

  output [8:0] red_a;		// texel a (red channel)
  output [8:0] red_b;		// texel b (red channel)
  output [8:0] red_c;		// texel c (red channel)
  output [8:0] red_d;		// texel d (red channel)

  output [8:0] green_a;		// texel a (green channel)
  output [8:0] green_b;		// texel b (green channel)
  output [8:0] green_c;		// texel c (green channel)
  output [8:0] green_d;		// texel d (green channel)

  output [8:0] blue_a;		// texel a (blue channel)
  output [8:0] blue_b;		// texel b (blue channel)
  output [8:0] blue_c;		// texel c (blue channel)
  output [8:0] blue_d;		// texel d (blue channel)

  output [8:0] alpha_a;		// texel a (alpha channel)
  output [8:0] alpha_b;		// texel b (alpha channel)
  output [8:0] alpha_c;		// texel c (alpha channel)
  output [8:0] alpha_d;		// texel d (alpha channel)

  reg [8:0] red_a;        	// texel a (red channel)
  reg [8:0] red_b;        	// texel b (red channel)
  reg [8:0] red_c;        	// texel c (red channel)
  reg [8:0] red_d;        	// texel d (red channel)

  reg [8:0] green_a;      	// texel a (green channel)
  reg [8:0] green_b;      	// texel b (green channel)
  reg [8:0] green_c;      	// texel c (green channel)
  reg [8:0] green_d;      	// texel d (green channel)

  reg [8:0] blue_a;       	// texel a (blue channel)
  reg [8:0] blue_b;       	// texel b (blue channel)
  reg [8:0] blue_c;       	// texel c (blue channel)
  reg [8:0] blue_d;       	// texel d (blue channel)

  reg [8:0] alpha_a;      	// texel a (alpha channel)
  reg [8:0] alpha_b;         	// texel b (alpha channel)
  reg [8:0] alpha_c;         	// texel c (alpha channel)
  reg [8:0] alpha_d;         	// texel d (alpha channel)

  reg [2:0] texel_type;		// tlut or tile texel type
  reg [1:0] texel_size;		// tlut or tile texel size

  reg long_texel;		// texel type is 32-RGBA or 16-YUV

  reg [15:0] tex_a_rg;		// texel a after hi-lo mux (low half)
  reg [15:0] tex_b_rg;		// texel b after hi-lo mux (low half)
  reg [15:0] tex_c_rg;		// texel c after hi-lo mux (low half)
  reg [15:0] tex_d_rg;		// texel d after hi-lo mux (low half)

  reg [15:0] tex_a_ba;		// texel a after hi-lo mux (high half)
  reg [15:0] tex_b_ba;		// texel b after hi-lo mux (high half)
  reg [15:0] tex_c_ba;		// texel c after hi-lo mux (high half)
  reg [15:0] tex_d_ba;		// texel d after hi-lo mux (high half)

  reg [7:0] repl_a;		// texel a replicate bus
  reg [7:0] repl_b;		// texel b replicate bus
  reg [7:0] repl_c;		// texel c replicate bus
  reg [7:0] repl_d;		// texel d replicate bus

  reg [2:0] tile_tex_type_1d;  	// tile texel type delayed 1
  reg [2:0] tile_tex_type_2d;  	// tile texel type delayed 2


  // nibble select mux

  function [3:0] nib_select;

    input [15:0] tex_rg;
    input [1:0] select;

    begin
  
      case (select[1:0])
        2'b00: nib_select[3:0] = tex_rg[3:0];
        2'b01: nib_select[3:0] = tex_rg[7:4];
        2'b10: nib_select[3:0] = tex_rg[11:8];
        2'b11: nib_select[3:0] = tex_rg[15:12];
        default: nib_select[3:0] = 4'hx;
      endcase
  
  end
  endfunction // nib_select


  // hi-lo mux (low half)

  function [15:0] hi_lo_rg;

    input tlut_en;
    input long_texel;
    input [15:0] sort_tex_high;
    input [15:0] sort_tex_low;
    input adrs_msb;

    begin

      if (tlut_en)
        hi_lo_rg = sort_tex_high;
      else if (long_texel)
        hi_lo_rg = sort_tex_low;
      else
        hi_lo_rg = adrs_msb ? sort_tex_high : sort_tex_low;

    end
  endfunction // hi_lo_rg


  // hi-lo mux (high half)

  function [15:0] hi_lo_ba;

    input tlut_en;
    input long_texel;
    input [15:0] sort_tex_high;
    input [15:0] sort_tex_low;
    input adrs_msb;

    begin

      if (tlut_en || long_texel)
        hi_lo_ba = sort_tex_high;
      else
        hi_lo_ba = adrs_msb ? sort_tex_high : sort_tex_low;

    end
  endfunction // hi_lo_ba


  // texel-format mux (replicate)

  function [7:0] tex_form_rep;

    input [15:0] tex_rg;
    input [1:0] swap_low;
    input [2:0] texel_type;
    input [1:0] texel_size;
    input [3:0] palette;

    reg [1:0] msb_sel;
    reg [1:0] lsb_sel;

    begin

      case (texel_size[1:0])

        SIZE_4BIT:
	begin
          msb_sel[1:0] = ~swap_low[1:0];
          lsb_sel[1:0] = ~swap_low[1:0];
	end

        SIZE_8BIT:
	begin
          msb_sel[1:0] = {~swap_low[1], 1'b1};
          if (texel_type[2:0] == TYPE_IA)
            lsb_sel[1:0] = {~swap_low[1], 1'b1};
          else
            lsb_sel[1:0] = {~swap_low[1], 1'b0};
	end

        default:
	begin
          msb_sel[1:0] = 2'b11;
          lsb_sel[1:0] = 2'b10;
	end

      endcase

      tex_form_rep[7:4] = nib_select(tex_rg[15:0], msb_sel[1:0]);
      tex_form_rep[3:0] = nib_select(tex_rg[15:0], lsb_sel[1:0]);

      // if 4-bit CI mux in palette

      tex_form_rep[7:4] = ((texel_size[1:0] == SIZE_4BIT) && 
			   (texel_type[2:0] == TYPE_CI)) ? palette[3:0] : 
							   tex_form_rep[7:4];

      // special case 4-bit IA 

      tex_form_rep[7:0] = ((texel_size[1:0] == SIZE_4BIT) && 
                           (texel_type[2:0] == TYPE_IA)) ? 
		    {tex_form_rep[7:5], tex_form_rep[7:5], tex_form_rep[7:6]} :
		     tex_form_rep[7:0];

    end
  endfunction // tex_form_rep


  // texel-format mux (red)

  function [8:0] tex_form_red;

    input [7:0] repl;
    input [15:11] tex;
    input [2:0] texel_type;
    input [1:0] texel_size;

    begin

      tex_form_red[7] = repl[7] ^ (texel_type == TYPE_YUV);

      tex_form_red[6:0] = repl[6:0];

      tex_form_red[8] = tex_form_red[7] & (texel_type == TYPE_YUV);

      tex_form_red[7:0] = ((texel_type == TYPE_RGBA) &&
                           (texel_size == SIZE_16BIT)) ?
                           {tex[15:11], tex[15:13]} : tex_form_red[7:0];

    end
  endfunction // tex_form_red


  // texel-format mux (green)

  function [8:0] tex_form_green;

    input [7:0] repl;
    input [10:0] tex;
    input [2:0] texel_type;
    input [1:0] texel_size;

    begin

      tex_form_green[7:0] = (((texel_type == TYPE_IA) &&
                             (texel_size == SIZE_16BIT)) ||
                             (texel_size == SIZE_4BIT) ||
                             (texel_size == SIZE_8BIT)) ?
                             repl[7:0] : tex[7:0];

      tex_form_green[7] = tex_form_green[7] ^ (texel_type == TYPE_YUV);

      tex_form_green[8] = tex_form_green[7] & (texel_type == TYPE_YUV);

      tex_form_green[7:0] = ((texel_type == TYPE_RGBA) &&
                             (texel_size == SIZE_16BIT)) ?
                             {tex[10:6], tex[10:8]} : tex_form_green[7:0];

    end
  endfunction // tex_form_green


  // texel-format mux (blue)

  function [8:0] tex_form_blue;

    input [7:0] repl;
    input [15:0] tex;
    input [1:1] swap_high;
    input [2:0] texel_type;
    input [1:0] texel_size;

    begin

      tex_form_blue[7:0] = ((!(texel_type == TYPE_YUV)) || (!swap_high[1])) ?
                             tex[15:8] : tex[7:0];

      tex_form_blue[7:0] = (((texel_type == TYPE_IA) &&
                             (texel_size == SIZE_16BIT)) ||
                             (texel_size == SIZE_4BIT) ||
                             (texel_size == SIZE_8BIT)) ?
                             repl[7:0] : tex_form_blue[7:0];

      tex_form_blue[7:0] = ((texel_type == TYPE_RGBA) &&
                            (texel_size == SIZE_16BIT)) ?
                            {tex[5:1], tex[5:3]} : tex_form_blue[7:0];

      tex_form_blue[8] = 1'b0;

    end
  endfunction // tex_form_blue


  // texel-format mux (alpha)

  function [8:0] tex_form_alpha;

    input [7:0] repl;
    input [15:0] tex;
    input [1:0] swap_high;
    input [2:0] texel_type;
    input [1:0] texel_size;

    reg [1:0] msb_sel;
    reg lsb_sel;

    begin

      case (texel_size[1:0])

        SIZE_4BIT:
          msb_sel[1:0] = {~swap_high[1], ~swap_high[0]};

        SIZE_8BIT:
          msb_sel[1:0] = {~swap_high[1], 1'b0};

        SIZE_16BIT:
          if (texel_type[2:0] == TYPE_YUV)
            msb_sel[1:0] = {~swap_high[1], 1'b1};
	  else
	    msb_sel[1:0] = 2'b01;

        default:
          msb_sel[1:0] = 2'b01;

      endcase

      tex_form_alpha[7:4] = nib_select(tex[15:0], msb_sel[1:0]);

      lsb_sel = (((texel_type[2:0] == TYPE_YUV) ||
                 ((texel_size[1:0] == SIZE_8BIT) &&
                  (texel_type[2:0] == TYPE_IA))) && (!swap_high[1]));

      tex_form_alpha[3:0] = lsb_sel ? tex[11:8] : tex[3:0];


      tex_form_alpha[7:0] = ((texel_size[1:0] == SIZE_4BIT) &&
                             (texel_type[2:0] == TYPE_IA)) ?
                             {8{tex_form_alpha[4]}} : tex_form_alpha[7:0];

      tex_form_alpha[7:0] = (((texel_size[1:0] == SIZE_4BIT) &&
                              (texel_type[2:0] != TYPE_IA)) ||
                             ((texel_size[1:0] == SIZE_8BIT) &&
                              (texel_type[2:0] != TYPE_IA))) ?
                               repl[7:0] : tex_form_alpha[7:0];

      tex_form_alpha[7:0] = ((texel_type == TYPE_RGBA) &&
                             (texel_size == SIZE_16BIT)) ?
                             {8{tex[0]}} : tex_form_alpha[7:0];

      tex_form_alpha[8] = 1'b0;

    end
  endfunction // tex_form_alpha


  always @(posedge clk)
   if (start_gclk) begin

    // delay signals into block

    tile_tex_type_1d <= tile_tex_type;
    tile_tex_type_2d <= tile_tex_type_1d;

    // texel-type and texel-size muxes

    if (tlut_en_2d)
    begin
      texel_size[1:0] = SIZE_16BIT;
      if (tlut_type == TLUT_RGBA)
	texel_type[2:0] = TYPE_RGBA;
      else
	texel_type[2:0] = TYPE_IA;
    end
    else
    begin
      texel_type[2:0] = tile_tex_type_2d[2:0];
      texel_size[1:0] = tile_tex_size_2d[1:0];
    end

    // hi-lo muxes (low half)

    long_texel = (((texel_type[2:0] == TYPE_RGBA) && 
		   (texel_size[1:0] == SIZE_32BIT)) || 
		   (texel_type[2:0] == TYPE_YUV));

    tex_a_rg = hi_lo_rg(tlut_en_2d, long_texel, sort_tex_a_high, 
		        sort_tex_a_low, swap_a_low[4]);

    tex_b_rg = hi_lo_rg(tlut_en_2d, long_texel, sort_tex_b_high, 
		        sort_tex_b_low, swap_b_low[4]);

    tex_c_rg = hi_lo_rg(tlut_en_2d, long_texel, sort_tex_c_high, 
		        sort_tex_c_low, swap_c_low[4]);

    tex_d_rg = hi_lo_rg(tlut_en_2d, long_texel, sort_tex_d_high, 
		        sort_tex_d_low, swap_d_low[4]);

    // hi-lo muxes (high half)

    tex_a_ba = hi_lo_ba(tlut_en_2d, long_texel, sort_tex_a_high, 
		        sort_tex_a_low, swap_a_high[4]);

    tex_b_ba = hi_lo_ba(tlut_en_2d, long_texel, sort_tex_b_high, 
		        sort_tex_b_low, swap_b_high[4]);

    tex_c_ba = hi_lo_ba(tlut_en_2d, long_texel, sort_tex_c_high, 
		        sort_tex_c_low, swap_c_high[4]);

    tex_d_ba = hi_lo_ba(tlut_en_2d, long_texel, sort_tex_d_high, 
		        sort_tex_d_low, swap_d_high[4]);

    // texel format muxes (replicate)

    repl_a = tex_form_rep(tex_a_rg, swap_a_low[1:0], texel_type, texel_size, 
		          palette_1d);

    repl_b = tex_form_rep(tex_b_rg, swap_b_low[1:0], texel_type, texel_size, 
		          palette_1d);

    repl_c = tex_form_rep(tex_c_rg, swap_c_low[1:0], texel_type, texel_size, 
		          palette_1d);

    repl_d = tex_form_rep(tex_d_rg, swap_d_low[1:0], texel_type, texel_size, 
		          palette_1d);

    // copy path

    copy_bus[31:0] <= {tex_c_rg, tex_d_rg};

    copy_bus[63:32] <= (texel_size[1:0] == SIZE_16BIT) ? {tex_a_rg, tex_b_rg} :
			{repl_a, repl_b, repl_c, repl_d};

    // texel-format muxes (red)

    red_a <= tex_form_red(repl_a, tex_a_rg[15:11], texel_type, texel_size); 
    
    red_b <= tex_form_red(repl_b, tex_b_rg[15:11], texel_type, texel_size); 
    
    red_c <= tex_form_red(repl_c, tex_c_rg[15:11], texel_type, texel_size); 
    
    red_d <= tex_form_red(repl_d, tex_d_rg[15:11], texel_type, texel_size); 
    
    // texel-format muxes (green)

    green_a <= tex_form_green(repl_a, tex_a_rg[10:0], texel_type, texel_size); 
    
    green_b <= tex_form_green(repl_b, tex_b_rg[10:0], texel_type, texel_size); 
    
    green_c <= tex_form_green(repl_c, tex_c_rg[10:0], texel_type, texel_size); 
    
    green_d <= tex_form_green(repl_d, tex_d_rg[10:0], texel_type, texel_size); 
    
    // texel-format muxes (blue)

    blue_a <= tex_form_blue(repl_a, tex_a_ba[15:0], swap_a_high[1], texel_type, 
			   texel_size); 

    blue_b <= tex_form_blue(repl_b, tex_b_ba[15:0], swap_b_high[1], texel_type, 
			   texel_size); 

    blue_c <= tex_form_blue(repl_c, tex_c_ba[15:0], swap_c_high[1], texel_type, 
			   texel_size); 

    blue_d <= tex_form_blue(repl_d, tex_d_ba[15:0], swap_d_high[1], texel_type, 
			   texel_size); 

    // texel-format muxes (alpha)

    alpha_a <= tex_form_alpha(repl_a, tex_a_ba[15:0], swap_a_high[1:0], 
			     texel_type, texel_size);

    alpha_b <= tex_form_alpha(repl_b, tex_b_ba[15:0], swap_b_high[1:0], 
			     texel_type, texel_size);

    alpha_c <= tex_form_alpha(repl_c, tex_c_ba[15:0], swap_c_high[1:0], 
			     texel_type, texel_size);

    alpha_d <= tex_form_alpha(repl_d, tex_d_ba[15:0], swap_d_high[1:0], 
			     texel_type, texel_size);

  end // always

endmodule // tm_mux2