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//----------------------------------------------------------------------------

// Copyright (C) 2001 Authors

//

// 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 source file is free software; you can redistribute it and/or modify

// it under the terms of the GNU Lesser General Public License as published

// by the Free Software Foundation; either version 2.1 of the License, or

// (at your option) any later version.

//

// This source 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 Lesser General Public

// License for more details.

//

// You should have received a copy of the GNU Lesser General Public License

// along with this source; if not, write to the Free Software Foundation,

// Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

//

//----------------------------------------------------------------------------

//

// *File Name: omsp_dbg_hwbrk.v

// 

// *Module Description:

//                       Hardware Breakpoint / Watchpoint module

//

// *Author(s):

//              - Olivier Girard,    olgirard@gmail.com

//

//----------------------------------------------------------------------------

// $Rev: 37 $

// $LastChangedBy: olivier.girard $

// $LastChangedDate: 2009-12-29 21:58:14 +0100 (Tue, 29 Dec 2009) $

//----------------------------------------------------------------------------

`include "timescale.v"

`include "openMSP430_defines.v"

module  omsp_dbg_hwbrk (

// OUTPUTs

    brk_halt,                // Hardware breakpoint command

    brk_pnd,                 // Hardware break/watch-point pending

    brk_dout,                // Hardware break/watch-point register data input

// INPUTs

    brk_reg_rd,              // Hardware break/watch-point register read select

    brk_reg_wr,              // Hardware break/watch-point register write select

    dbg_din,                 // Debug register data input

    eu_mab,                  // Execution-Unit Memory address bus

    eu_mb_en,                // Execution-Unit Memory bus enable

    eu_mb_wr,                // Execution-Unit Memory bus write transfer

    eu_mdb_in,               // Memory data bus input

    eu_mdb_out,              // Memory data bus output

    exec_done,               // Execution completed

    fe_mb_en,                // Frontend Memory bus enable

    mclk,                    // Main system clock

    pc,                      // Program counter

    por                      // Power on reset

);

// OUTPUTs

//=========

output         brk_halt;     // Hardware breakpoint command

output         brk_pnd;      // Hardware break/watch-point pending

output  [15:0] brk_dout;     // Hardware break/watch-point register data input

// INPUTs

//=========

input    [3:0] brk_reg_rd;   // Hardware break/watch-point register read select

input    [3:0] brk_reg_wr;   // Hardware break/watch-point register write select

input   [15:0] dbg_din;      // Debug register data input

input   [15:0] eu_mab;       // Execution-Unit Memory address bus

input          eu_mb_en;     // Execution-Unit Memory bus enable

input    [1:0] eu_mb_wr;     // Execution-Unit Memory bus write transfer

input   [15:0] eu_mdb_in;    // Memory data bus input

input   [15:0] eu_mdb_out;   // Memory data bus output

input          exec_done;    // Execution completed

input          fe_mb_en;     // Frontend Memory bus enable

input          mclk;         // Main system clock

input   [15:0] pc;           // Program counter

input          por;          // Power on reset

//=============================================================================

// 1)  WIRE & PARAMETER DECLARATION

//=============================================================================

wire      range_wr_set;

wire      range_rd_set;

wire      addr1_wr_set;

wire      addr1_rd_set;

wire      addr0_wr_set;

wire      addr0_rd_set;

parameter BRK_CTL   = 0,

          BRK_STAT  = 1,

          BRK_ADDR0 = 2,

          BRK_ADDR1 = 3;

//=============================================================================

// 2)  CONFIGURATION REGISTERS

//=============================================================================

// BRK_CTL Register

//-----------------------------------------------------------------------------

//       7   6   5        4            3          2            1  0

//        Reserved    RANGE_MODE    INST_EN    BREAK_EN    ACCESS_MODE

//

// ACCESS_MODE: - 00 : Disabled

//              - 01 : Detect read access

//              - 10 : Detect write access

//              - 11 : Detect read/write access

//              NOTE: '10' & '11' modes are not supported on the instruction flow

//

// BREAK_EN:    -  0 : Watchmode enable

//              -  1 : Break enable

//

// INST_EN:     -  0 : Checks are done on the execution unit (data flow)

//              -  1 : Checks are done on the frontend (instruction flow)

//

// RANGE_MODE:  -  0 : Address match on BRK_ADDR0 or BRK_ADDR1

//              -  1 : Address match on BRK_ADDR0->BRK_ADDR1 range

//

//-----------------------------------------------------------------------------

reg   [4:0] brk_ctl;

wire        brk_ctl_wr = brk_reg_wr[BRK_CTL];

always @ (posedge mclk or posedge por)

  if (por)             brk_ctl <=  5'h00;

  else if (brk_ctl_wr) brk_ctl <=  dbg_din[4:0];

wire  [7:0] brk_ctl_full = {3'b000, brk_ctl};

// BRK_STAT Register

//-----------------------------------------------------------------------------

//     7    6       5         4         3         2         1         0

//    Reserved  RANGE_WR  RANGE_RD  ADDR1_WR  ADDR1_RD  ADDR0_WR  ADDR0_RD

//-----------------------------------------------------------------------------

reg   [5:0] brk_stat;

wire        brk_stat_wr  = brk_reg_wr[BRK_STAT];

wire  [5:0] brk_stat_set = {range_wr_set, range_rd_set,

                            addr1_wr_set, addr1_rd_set,

                            addr0_wr_set, addr0_rd_set};

wire  [5:0] brk_stat_clr = ~dbg_din[5:0];

always @ (posedge mclk or posedge por)

  if (por)              brk_stat <=  6'h00;

  else if (brk_stat_wr) brk_stat <= ((brk_stat & brk_stat_clr) | brk_stat_set);

  else                  brk_stat <=  (brk_stat                 | brk_stat_set);

wire  [7:0] brk_stat_full = {2'b00, brk_stat};

wire        brk_pnd       = |brk_stat;

// BRK_ADDR0 Register

//-----------------------------------------------------------------------------

reg  [15:0] brk_addr0;

wire        brk_addr0_wr = brk_reg_wr[BRK_ADDR0];

always @ (posedge mclk or posedge por)

  if (por)               brk_addr0 <=  16'h0000;

  else if (brk_addr0_wr) brk_addr0 <=  dbg_din;

// BRK_ADDR1/DATA0 Register

//-----------------------------------------------------------------------------

reg  [15:0] brk_addr1;

wire        brk_addr1_wr = brk_reg_wr[BRK_ADDR1];

always @ (posedge mclk or posedge por)

  if (por)               brk_addr1 <=  16'h0000;

  else if (brk_addr1_wr) brk_addr1 <=  dbg_din;

//============================================================================

// 3) DATA OUTPUT GENERATION

//============================================================================

wire [15:0] brk_ctl_rd   = {8'h00, brk_ctl_full}  & {16{brk_reg_rd[BRK_CTL]}};

wire [15:0] brk_stat_rd  = {8'h00, brk_stat_full} & {16{brk_reg_rd[BRK_STAT]}};

wire [15:0] brk_addr0_rd = brk_addr0              & {16{brk_reg_rd[BRK_ADDR0]}};

wire [15:0] brk_addr1_rd = brk_addr1              & {16{brk_reg_rd[BRK_ADDR1]}};

wire [15:0] brk_dout = brk_ctl_rd   |

                       brk_stat_rd  |

                       brk_addr0_rd |

                       brk_addr1_rd;

//============================================================================

// 4) BREAKPOINT / WATCHPOINT GENERATION

//============================================================================

// Comparators

//---------------------------

// Note: here the comparison logic is instanciated several times in order

//       to improve the timings, at the cost of a bit more area.

wire        equ_d_addr0 = eu_mb_en & (eu_mab==brk_addr0) & ~brk_ctl[`BRK_RANGE];

wire        equ_d_addr1 = eu_mb_en & (eu_mab==brk_addr1) & ~brk_ctl[`BRK_RANGE];

wire        equ_d_range = eu_mb_en & ((eu_mab>=brk_addr0) & (eu_mab<=brk_addr1)) &  brk_ctl[`BRK_RANGE];

reg         fe_mb_en_buf;

always @ (posedge mclk or posedge por)

  if (por)  fe_mb_en_buf <=  1'b0;

  else      fe_mb_en_buf <=  fe_mb_en;

wire        equ_i_addr0 = fe_mb_en_buf & (pc==brk_addr0) & ~brk_ctl[`BRK_RANGE];

wire        equ_i_addr1 = fe_mb_en_buf & (pc==brk_addr1) & ~brk_ctl[`BRK_RANGE];

wire        equ_i_range = fe_mb_en_buf & ((pc>=brk_addr0) & (pc<=brk_addr1))    &  brk_ctl[`BRK_RANGE];

// Detect accesses

//---------------------------

// Detect Instruction read access

wire i_addr0_rd =  equ_i_addr0 &  brk_ctl[`BRK_I_EN];

wire i_addr1_rd =  equ_i_addr1 &  brk_ctl[`BRK_I_EN];

wire i_range_rd =  equ_i_range &  brk_ctl[`BRK_I_EN];

// Detect Execution-Unit write access

wire d_addr0_wr =  equ_d_addr0 & ~brk_ctl[`BRK_I_EN] &  |eu_mb_wr;

wire d_addr1_wr =  equ_d_addr1 & ~brk_ctl[`BRK_I_EN] &  |eu_mb_wr;

wire d_range_wr =  equ_d_range & ~brk_ctl[`BRK_I_EN] &  |eu_mb_wr;

// Detect DATA read access

// Whenever an "ADD r9. &0x200" instruction is executed, &0x200 will be read

// before being written back. In that case, the read flag should not be set.

// In general, We should here make sure no write access occures during the

// same instruction cycle before setting the read flag.

reg [2:0] d_rd_trig;

always @ (posedge mclk or posedge por)

  if (por)            d_rd_trig <=  3'h0;

  else if (exec_done) d_rd_trig <=  3'h0;

  else                d_rd_trig <=  {equ_d_range & ~brk_ctl[`BRK_I_EN] & ~|eu_mb_wr,

                                     equ_d_addr1 & ~brk_ctl[`BRK_I_EN] & ~|eu_mb_wr,

                                     equ_d_addr0 & ~brk_ctl[`BRK_I_EN] & ~|eu_mb_wr};

wire d_addr0_rd =  d_rd_trig[0] & exec_done & ~d_addr0_wr;

wire d_addr1_rd =  d_rd_trig[1] & exec_done & ~d_addr1_wr;

wire d_range_rd =  d_rd_trig[2] & exec_done & ~d_range_wr;

// Set flags

assign addr0_rd_set = brk_ctl[`BRK_MODE_RD] & (d_addr0_rd  | i_addr0_rd);

assign addr0_wr_set = brk_ctl[`BRK_MODE_WR] &  d_addr0_wr;

assign addr1_rd_set = brk_ctl[`BRK_MODE_RD] & (d_addr1_rd  | i_addr1_rd);

assign addr1_wr_set = brk_ctl[`BRK_MODE_WR] &  d_addr1_wr;

assign range_rd_set = brk_ctl[`BRK_MODE_RD] & (d_range_rd  | i_range_rd);

assign range_wr_set = brk_ctl[`BRK_MODE_WR] &  d_range_wr;

// Break CPU

assign brk_halt     = brk_ctl[`BRK_EN] & |brk_stat_set;

endmodule // omsp_dbg_hwbrk

`include "openMSP430_undefines.v"