source: XOpenSparcT1/trunk/T1-common/srams/bw_r_scm.v @ 27

// ========== Copyright Header Begin ==========================================
// 
// OpenSPARC T1 Processor File: bw_r_scm.v
// Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.
// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.
// 
// The above named program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public
// License version 2 as published by the Free Software Foundation.
// 
// The above named program 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
// General Public License for more details.
// 
// You should have received a copy of the GNU General Public
// License along with this work; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
// 
// ========== Copyright Header End ============================================
////////////////////////////////////////////////////////////////////////
/*
//      Description:    Store Buffer of Load/Store Unit (CAM Side)
//               - Physically divided into CAM and DATA RAMs.
//                              - CAM RAM has a single cam port and a single
//                              port for read/writes. The cam port is for loads,
//                              write for stores, read for test/diagnostic purposes.
//                              rd or write can be simultaneous with cam. can rd and cam
//                              a single entry simultaneously. cannot write and cam
//                              the same entry.
//                              - DATA RAM read occurs for a load raw match in the
//                              stb CAM RAM. DATA RAM write occurs a store. Both
//                              actions are architecturally guaranteed to be
//                              mutex.
//                              - Write occurs simultaneously to both arrays.
//                              - Reads are not necessarily simultaneous and are
//                              controlled by individual read signals.
//                              - Certain bits are maintained outside the array
//                              in the stb's control section, such as the valid
//                              bits.                   
//
*/

////////////////////////////////////////////////////////////////////////
// Local header file includes / local defines
////////////////////////////////////////////////////////////////////////

//FPGA_SYN enables all FPGA related modifications
`ifdef FPGA_SYN 
`define FPGA_SYN_SCM
`endif

module bw_r_scm (/*AUTOARG*/
   // Outputs
   stb_rdata_ramc, stb_ld_full_raw, stb_ld_partial_raw, 
   stb_cam_hit_ptr, stb_cam_hit, stb_cam_mhit, 
   // Inputs
   stb_cam_data, stb_alt_wr_data, stb_camwr_data, stb_alt_wsel, 
   stb_cam_vld, stb_cam_cm_tid, stb_cam_sqsh_msk, stb_cam_rw_ptr, 
   stb_cam_wptr_vld, stb_cam_rptr_vld, stb_cam_rw_tid, 
   stb_quad_ld_cam, rclk, rst_tri_en
   ) ;  

parameter NUMENTRIES = 32 ;                             // number of entries in stb

input   [44:15]         stb_cam_data ;    // data for compare; disjoint msb
input   [44:15]         stb_alt_wr_data ;         // data for compare; disjoint msb
input   [14:0]          stb_camwr_data ;  // data for compare/write; common lsb
input                   stb_alt_wsel ;
input                   stb_cam_vld ;     // cam is required.
input   [1:0]           stb_cam_cm_tid ;  // thread id for cam operation.
input   [7:0]           stb_cam_sqsh_msk; // mask for squashing cam results.

input   [2:0]           stb_cam_rw_ptr ;  // wr pointer for single port.
input                   stb_cam_wptr_vld ;// write pointer vld
input                   stb_cam_rptr_vld ;// write pointer vld
input   [1:0]           stb_cam_rw_tid ;  // thread id for rw.
input                   stb_quad_ld_cam ; // quad-ld cam.

input                   rclk ;            // clock

//input                 scan_ena ;        // no longer required !
//input [7:0]           adj ;

input                   rst_tri_en ;

output  [44:0]          stb_rdata_ramc ;  // rd data from CAM RAM.
// raw output is muxed on a thread basis.
output  [7:0]           stb_ld_full_raw ; // ld with full raw.
output  [7:0]           stb_ld_partial_raw ; // ld with partial raw.
output  [2:0]           stb_cam_hit_ptr ;
output                  stb_cam_hit ;     // any hit in stb
output                  stb_cam_mhit ;    // multiple hits in stb       


/*UTOREG*/
// Beginning of automatic regs (for this module's undeclared outputs)
// End of automatics
reg [44:0]              stb_rdata_ramc ;
reg [31:0]              rw_wdline ;
reg [44:0]              stb_ramc [NUMENTRIES-1:0] /* synthesis syn_ramstyle = block_ram  syn_ramstyle = no_rw_check */;
reg [44:0]              ramc_entry ;
reg [36:0]              cam_tag ;
reg [31:0]              ptag_hit ;
reg [7:0]               cam_bmask ;
reg [31:0]              byte_match ;
reg [31:0]              byte_overlap ;
reg [31:0]              ld_full_raw ;
reg [31:0]              ld_partial_raw ;
reg [44:15]             alt_wr_data ;
wire [44:15]            pipe_wr_data ;
reg [14:0]              camwr_data ;
reg                     wptr_vld ; 
reg                     rptr_vld_tmp ; 
reg [1:0]               cam_tid ;
reg [1:0]               cam_vld ;
reg                     alt_wsel ;

wire            rptr_vld ; 
wire            ldq ;
wire    [7:0]   sqsh_msk ;
wire    [7:0]   ld_full_raw_mx ;
wire    [7:0]   ld_partial_raw_mx ;
wire    [7:0]   ptag_hit_mx ;
wire    [7:0]   byte_overlap_mx ;
wire    [7:0]   byte_match_mx ;
wire    [7:0]   cam_hit ;
wire    [44:0]  wdata_ramc ;
wire    [44:0]  cam_data ;
wire    [44:15] wr_data ;
`ifdef FPGA_SYN_SCM
reg     [4:0]   stb_addr;
`endif

   
integer i,j,k,l ;


wire    scan_ena ;
assign  scan_ena = 1'b0 ;

//=========================================================================================
//      generate wordlines
//=========================================================================================

assign  sqsh_msk[7:0]   = stb_cam_sqsh_msk[7:0]; 

// cam_vld and cam_tid_tmp are set-up a phase earlier. 
// Comment out - Now setup to posedge.
/*always @(negedge clk)
        begin
                cam_tid_tmp[1:0]        <= stb_cam_cm_tid[1:0] ;
                cam_vld_tmp             <= stb_cam_vld ;
        end */

`ifdef FPGA_SYN_SCM
`else
// Wordlines need to be generated locally 
always @ (posedge rclk)
        begin
                for (i=0;i<32;i=i+1)
                        begin
                        if ({stb_cam_rw_tid[1:0],stb_cam_rw_ptr[2:0]} == i)
                                rw_wdline[i]  <= 1'b1;
                        else
                                rw_wdline[i]  <= 1'b0;
                        end
        end
`endif

assign pipe_wr_data[44:15] = stb_cam_data[44:15];

always @(posedge rclk)
        begin
                alt_wr_data[44:15] <= stb_alt_wr_data[44:15];
                camwr_data[14:0] <= stb_camwr_data[14:0];
                wptr_vld        <= stb_cam_wptr_vld ;
                rptr_vld_tmp    <= stb_cam_rptr_vld ;
                cam_tid[1:0]    <= stb_cam_cm_tid[1:0] ;
                //cam_tid[1:0]  <= cam_tid_tmp[1:0] ;
                //ldq           <=  stb_quad_ld_cam ; Bug 2870
                alt_wsel        <= stb_alt_wsel ;
`ifdef FPGA_SYN_SCM
                stb_addr        <= {stb_cam_rw_tid[1:0],stb_cam_rw_ptr[2:0]};
`endif
        end

assign  ldq =  stb_quad_ld_cam ;
assign  rptr_vld = rptr_vld_tmp | rst_tri_en ;

//=========================================================================================
//      write or read to/from memory
//=========================================================================================

// For blk-st, select out-of-pipe.
assign  wr_data[44:15] = alt_wsel ? 
                alt_wr_data[44:15] : pipe_wr_data[44:15] ;      

assign  wdata_ramc[44:0] = {wr_data[44:15],camwr_data[14:0]};

// Write
always @ (negedge rclk)
        begin
`ifdef FPGA_SYN_SCM
        if(wptr_vld) begin
                if(~rst_tri_en) begin
                        stb_ramc[stb_addr] <= wdata_ramc[44:0];
                        stb_rdata_ramc[44:0] <=  wdata_ramc[44:0];
                end else begin
                        stb_rdata_ramc[44:0] <=  stb_ramc[stb_addr];
                end
        end
`else
                for (j=0;j<NUMENTRIES;j=j+1)
                        begin
                        if (rw_wdline[j] & wptr_vld)
                                begin
                                if (~rst_tri_en)
                                        begin
                                        stb_ramc[j] <=  wdata_ramc[44:0];
                                        // write data is write-thru
                                        stb_rdata_ramc[44:0] <=  wdata_ramc[44:0];
                                        end
                                else
                                        begin
                                        // INNO - default rd if wr squashed by scan_ena.
                                        stb_rdata_ramc[44:0] <=  stb_ramc[j];
                                        end
                                end
                        end
`endif
// Read
`ifdef FPGA_SYN_SCM
                if(rptr_vld & ~scan_ena) begin
                        if (rptr_vld & wptr_vld & ~rst_tri_en) begin
                                stb_rdata_ramc[44:0] <=  wdata_ramc[44:0];
                        end
                        else begin
                                stb_rdata_ramc[44:0] <=  stb_ramc[stb_addr];
                        end
                end
`else
                for (k=0;k<NUMENTRIES;k=k+1)
                        begin
                        if (rw_wdline[k] & rptr_vld & ~scan_ena)
                                begin
                                if (rptr_vld & wptr_vld & ~rst_tri_en) // INNO - write-thru
                                        stb_rdata_ramc[44:0] <=  wdata_ramc[44:0];
                                else
                                        stb_rdata_ramc[44:0] <=  stb_ramc[k];
                                end
                        end
`endif
        end

//=========================================================================================
//      CAM contents of CAM RAM
//=========================================================================================

// - Generate full/partial raw for incoming load.
// - Output signals need to be qualified with per entry
// vlds before causing any subsequent event, the read of
// the DATA RAM specifically.
// - full_raw & vld will cause rd of DATA RAM.
// - partial_raw & vld will cause ld to follow corresponding
// st on way out to xbar.
// - logic to generate partial and full raws may be done outside
// but that would require an additional signal per entry to
// be output.

// Mapping of cam/write data
// 
//      |       40-3=37b(pa)    | 1b(stquad)    |       8b(bytemask)    | <- use
//      |       45:9            | 8             |       7:0             | <- input port
//                              **^ stquad rm'ed

reg [14:0] stb_camwr_data_d;
reg        ldq_d;
reg        stb_cam_vld_d;
reg        scan_ena_d;
reg [44:0]              stb_ramc_d [NUMENTRIES-1:0] /* synthesis syn_ramstyle = block_ram  syn_ramstyle = no_rw_check */;

always @(posedge rclk)
   begin
      stb_camwr_data_d[14:0]<=stb_camwr_data[14:0];
      ldq_d<=ldq;
      stb_cam_vld_d<=stb_cam_vld;
      scan_ena_d<=scan_ena;
                for (l=0;l<NUMENTRIES;l=l+1)
         stb_ramc_d[l]<=stb_ramc[l];
   end

assign  cam_data[44:0] = {stb_cam_data[44:15],stb_camwr_data_d[14:0]}; 

// tolgo stb_ramc_d dalla sensitivity list...
always @( byte_overlap or ramc_entry,cam_tag or cam_bmask or ptag_hit or byte_match or stb_ramc_d)
  begin
        for (l=0;l<NUMENTRIES;l=l+1)
    begin
                ramc_entry[44:0] = stb_ramc_d[l] ;
                cam_tag[36:0] = ramc_entry[44:8] ;
                cam_bmask[7:0] = ramc_entry[7:0] ;
      ptag_hit[l] = (cam_tag[36:1] == cam_data[44:9]) & 
                  (((cam_tag[0] == cam_data[8]) & ~ldq_d) | ldq_d) & stb_cam_vld_d & ~scan_ena_d ;
                byte_match[l] = |(cam_bmask[7:0] & cam_data[7:0]) & stb_cam_vld_d & ~scan_ena_d ;
                // Simplification :
                byte_overlap[l] = |(~cam_bmask[7:0] & cam_data[7:0]) & stb_cam_vld_d & ~scan_ena_d ;
    end
  end
// Mux the raw signals down to 8b quantities. Squash mask comes mid-way thru cycle.

assign  byte_overlap_mx[7:0] =
        (cam_tid[1:0] == 2'b00) ? byte_overlap[7:0] :
                (cam_tid[1:0] == 2'b01) ? byte_overlap[15:8] :
                        (cam_tid[1:0] == 2'b10) ? byte_overlap[23:16] :
                                (cam_tid[1:0] == 2'b11) ? byte_overlap[31:24] : 8'bxxxx_xxxx ;

assign  byte_match_mx[7:0] =
        (cam_tid[1:0] == 2'b00) ? byte_match[7:0] :
                (cam_tid[1:0] == 2'b01) ? byte_match[15:8] :
                        (cam_tid[1:0] == 2'b10) ? byte_match[23:16] :
                                (cam_tid[1:0] == 2'b11) ? byte_match[31:24] : 8'bxxxx_xxxx ;

assign  ptag_hit_mx[7:0] =
        (cam_tid[1:0] == 2'b00) ? ptag_hit[7:0] :
                (cam_tid[1:0] == 2'b01) ? ptag_hit[15:8] :
                        (cam_tid[1:0] == 2'b10) ? ptag_hit[23:16] :
                                (cam_tid[1:0] == 2'b11) ? ptag_hit[31:24] : 8'bxxxx_xxxx ;

assign  stb_ld_full_raw[7:0] =  
        ptag_hit_mx[7:0] & byte_match_mx[7:0] & ~byte_overlap_mx[7:0] & ~sqsh_msk[7:0] ;
assign  stb_ld_partial_raw[7:0] =  
        ptag_hit_mx[7:0] & byte_match_mx[7:0] &  byte_overlap_mx[7:0] & ~sqsh_msk[7:0] ;

assign  cam_hit[7:0] = 
        ptag_hit_mx[7:0] & byte_match_mx[7:0] & ~sqsh_msk[7:0] ;
assign  stb_cam_hit = |(cam_hit[7:0]);

// The stb data is meant to be read for single hit full raw case. It may actually be read
// for full raw, partial raw or multiple hit case but the read output will be ignored for
// partial and multiple hit case. Multiple hits will not cause a hazard as the ptr is first
// encoded and then decoded to form the wdline for the stb-data
// Use cam_hit result to void false hits.
assign  stb_cam_hit_ptr[0]      =  cam_hit[1] | cam_hit[3] | cam_hit[5] | cam_hit[7] ;
assign  stb_cam_hit_ptr[1]      =  cam_hit[2] | cam_hit[3] | cam_hit[6] | cam_hit[7] ;
assign  stb_cam_hit_ptr[2]      =  cam_hit[4] | cam_hit[5] | cam_hit[6] | cam_hit[7] ;

//Generating multiple hits
assign  stb_cam_mhit            =  (cam_hit[0]  & cam_hit[1]) | (cam_hit[2] & cam_hit[3])  |
                                   (cam_hit[4]  & cam_hit[5]) | (cam_hit[6] & cam_hit[7])  |
                                   ((cam_hit[0] | cam_hit[1]) & (cam_hit[2] | cam_hit[3])) |
                                   ((cam_hit[4] | cam_hit[5]) & (cam_hit[6] | cam_hit[7])) |
                                   ((|cam_hit[3:0]) & (|cam_hit[7:4]));

//--------------------------------------------------------------
// Error Checking.
//--------------------------------------------------------------

// 1. simultaneous rd/wr on single port - terminate 
// 2. simultaneous cam and wr - terminate
// * PUT OUTSIDE OF SRAM RTL, AS RST NOT AVAILABLE. *

endmodule