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////////////////////////////////////////////////////////////////////////////////

//

// Filename:    softmpy.cpp

//

// Project:     A General Purpose Pipelined FFT Implementation

//

// Purpose:     If the chip doesn't have any hardware multiplies, you'll need

//              a soft-multiply implementation.  This provides that

//      implementation.

//

// Creator:     Dan Gisselquist, Ph.D.

//              Gisselquist Technology, LLC

//

////////////////////////////////////////////////////////////////////////////////

//

// Copyright (C) 2015-2018, Gisselquist Technology, LLC

//

// This program is free software (firmware): you can redistribute it and/or

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

// by the Free Software Foundation, either version 3 of the License, or (at

// your option) any later version.

//

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY 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 program.  (It's in the $(ROOT)/doc directory.  Run make with no

// target there if the PDF file isn't present.)  If not, see

// <http://www.gnu.org/licenses/> for a copy.

//

// License:     GPL, v3, as defined and found on www.gnu.org,

//              http://www.gnu.org/licenses/gpl.html

//

//

////////////////////////////////////////////////////////////////////////////////

//

//

#define _CRT_SECURE_NO_WARNINGS   //  ms vs 2012 doesn't like fopen

#include <stdio.h>

#include <stdlib.h>

#ifdef _MSC_VER //  added for ms vs compatibility

#include <io.h>

#include <direct.h>

#define _USE_MATH_DEFINES

#endif

#include <string.h>

#include <string>

#include <math.h>

#include <ctype.h>

#include <assert.h>

#include "defaults.h"

#include "legal.h"

#include "softmpy.h"

void    build_multiply(const char *fname) {

        FILE    *fp = fopen(fname, "w");

        if (NULL == fp) {

                fprintf(stderr, "Could not open \'%s\' for writing\n", fname);

                perror("O/S Err was:");

                return;

        }

        fprintf(fp,

SLASHLINE

"//\n"

"// Filename:\tshiftaddmpy.v\n"

"//\n"

"// Project:\t%s\n"

"//\n"

"// Purpose:\tA portable shift and add multiply.\n"

"//\n"

"//     While both Xilinx and Altera will offer single clock multiplies, this\n"

"//     simple approach will multiply two numbers on any architecture.  The\n"

"//     result maintains the full width of the multiply, there are no extra\n"

"//     stuff bits, no rounding, no shifted bits, etc.\n"

"//\n"

"//     Further, for those applications that can support it, this multiply\n"

"//     is pipelined and will produce one answer per clock.\n"

"//\n"

"//     For minimal processing delay, make the first parameter the one with\n"

"//     the least bits, so that AWIDTH <= BWIDTH.\n"

"//\n"

"//     The processing delay in this multiply is (AWIDTH+1) cycles.  That is,\n"

"//     if the data is present on the input at clock t=0, the result will be\n"

"//     present on the output at time t=AWIDTH+1;\n"

"//\n"

"//\n%s"

"//\n", prjname, creator);

        fprintf(fp, "%s", cpyleft);

        fprintf(fp, "//\n//\n`default_nettype\tnone\n//\n");

        fprintf(fp,

"module shiftaddmpy(i_clk, i_ce, i_a, i_b, o_r);\n"

        "\tparameter\tAWIDTH=%d,BWIDTH=", TST_SHIFTADDMPY_AW);

#ifdef  TST_SHIFTADDMPY_BW

        fprintf(fp, "%d;\n", TST_SHIFTADDMPY_BW);

#else

        fprintf(fp, "AWIDTH;\n");

#endif

        fprintf(fp,

        "\tinput\twire\t\t\t\ti_clk, i_ce;\n"

        "\tinput\twire\t[(AWIDTH-1):0]\t\ti_a;\n"

        "\tinput\twire\t[(BWIDTH-1):0]\t\ti_b;\n"

        "\toutput\treg\t[(AWIDTH+BWIDTH-1):0]\to_r;\n"

"\n"

        "\treg\t[(AWIDTH-1):0]\tu_a;\n"

        "\treg\t[(BWIDTH-1):0]\tu_b;\n"

        "\treg\t\t\tsgn;\n"

"\n"

        "\treg\t[(AWIDTH-2):0]\t\tr_a[0:(AWIDTH-1)];\n"

        "\treg\t[(AWIDTH+BWIDTH-2):0]\tr_b[0:(AWIDTH-1)];\n"

        "\treg\t\t\t\tr_s[0:(AWIDTH-1)];\n"

        "\treg\t[(AWIDTH+BWIDTH-1):0]\tacc[0:(AWIDTH-1)];\n"

        "\tgenvar k;\n"

"\n"

        "\t// If we were forced to stay within two\'s complement arithmetic,\n"

        "\t// taking the absolute value here would require an additional bit.\n"

        "\t// However, because our results are now unsigned, we can stay\n"

        "\t// within the number of bits given (for now).\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                        "\t\t\tu_a <= (i_a[AWIDTH-1])?(-i_a):(i_a);\n"

                        "\t\t\tu_b <= (i_b[BWIDTH-1])?(-i_b):(i_b);\n"

                        "\t\t\tsgn <= i_a[AWIDTH-1] ^ i_b[BWIDTH-1];\n"

                "\t\tend\n"

"\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                        "\t\t\tacc[0] <= (u_a[0]) ? { {(AWIDTH){1\'b0}}, u_b }\n"

                        "\t\t\t\t\t: {(AWIDTH+BWIDTH){1\'b0}};\n"

                        "\t\t\tr_a[0] <= { u_a[(AWIDTH-1):1] };\n"

                        "\t\t\tr_b[0] <= { {(AWIDTH-1){1\'b0}}, u_b };\n"

                        "\t\t\tr_s[0] <= sgn; // The final sign, needs to be preserved\n"

                "\t\tend\n"

"\n"

        "\tgenerate\n"

        "\tfor(k=0; k<AWIDTH-1; k=k+1)\n"

        "\tbegin : genstages\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                        "\t\t\tacc[k+1] <= acc[k] + ((r_a[k][0]) ? {r_b[k],1\'b0}:0);\n"

                        "\t\t\tr_a[k+1] <= { 1\'b0, r_a[k][(AWIDTH-2):1] };\n"

                        "\t\t\tr_b[k+1] <= { r_b[k][(AWIDTH+BWIDTH-3):0], 1\'b0};\n"

                        "\t\t\tr_s[k+1] <= r_s[k];\n"

                "\t\tend\n"

        "\tend\n"

        "\tendgenerate\n"

"\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                        "\t\t\to_r <= (r_s[AWIDTH-1]) ? (-acc[AWIDTH-1]) : acc[AWIDTH-1];\n"

"\n"

"endmodule\n");

        fclose(fp);

}

void    build_bimpy(const char *fname) {

        FILE    *fp = fopen(fname, "w");

        if (NULL == fp) {

                fprintf(stderr, "Could not open \'%s\' for writing\n", fname);

                perror("O/S Err was:");

                return;

        }

        fprintf(fp,

SLASHLINE

"//\n"

"// Filename:\t%s\n"

"//\n"

"// Project:\t%s\n"

"//\n"

"// Purpose:\tA simple 2-bit multiply based upon the fact that LUT's allow\n"

"//             6-bits of input.  In other words, I could build a 3-bit\n"

"//     multiply from 6 LUTs (5 actually, since the first could have two\n"

"//     outputs).  This would allow multiplication of three bit digits, save\n"

"//     only for the fact that you would need two bits of carry.  The bimpy\n"

"//     approach throttles back a bit and does a 2x2 bit multiply in a LUT,\n"

"//     guaranteeing that it will never carry more than one bit.  While this\n"

"//     multiply is hardware independent (and can still run under Verilator\n"

"//     therefore), it is really motivated by trying to optimize for a\n"

"//     specific piece of hardware (Xilinx-7 series ...) that has at least\n"

"//     4-input LUT's with carry chains.\n"

"//\n"

"//\n"

"//\n%s"

"//\n", fname, prjname, creator);

        fprintf(fp, "%s", cpyleft);

        fprintf(fp, "//\n//\n`default_nettype\tnone\n//\n");

        fprintf(fp,

"module bimpy(i_clk, i_ce, i_a, i_b, o_r);\n"

"\tparameter\tBW=18; // Number of bits in i_b\n"

"\tlocalparam\tLUTB=2; // Number of bits in i_a for our LUT multiply\n"

"\tinput\twire\t\t\ti_clk, i_ce;\n"

"\tinput\twire\t[(LUTB-1):0]\ti_a;\n"

"\tinput\twire\t[(BW-1):0]\ti_b;\n"

"\toutput\treg\t[(BW+LUTB-1):0] o_r;\n"

"\n"

"\twire [(BW+LUTB-2):0] w_r;\n"

"\twire [(BW+LUTB-3):1] c;\n"

"\n"

"\tassign\tw_r =  { ((i_a[1])?i_b:{(BW){1\'b0}}), 1\'b0 }\n"

"\t\t\t\t^ { 1\'b0, ((i_a[0])?i_b:{(BW){1\'b0}}) };\n"

"\tassign\tc = { ((i_a[1])?i_b[(BW-2):0]:{(BW-1){1\'b0}}) }\n"

"\t\t\t& ((i_a[0])?i_b[(BW-1):1]:{(BW-1){1\'b0}});\n"

"\n"

"\tinitial o_r = 0;\n"

"\talways @(posedge i_clk)\n"

"\tif (i_ce)\n"

"\t\to_r <= w_r + { c, 2'b0 };\n"

"\n");

        // Formal properties

        //

        // This module is formally verified as part of longbimpy.v

        // Hence, we'll use an ifdef LONGBIMPY to capture if it is being verified as part of

        // LONGBIMPY, or placed within another module.

        fprintf(fp,

"`ifdef FORMAL\n");

        if (formal_property_flag) {

                fprintf(fp,

"\treg\tf_past_valid;\n"

"\n"

"\tinitial\tf_past_valid = 1'b0;\n"

"\talways @(posedge i_clk)\n"

"\tf_past_valid <= 1'b1;\n"

"\n"

"`define\tASSERT\tassert\n"

"\n");

        // Now for our module specific assertions

        // These properties will be assumed if this proof is not part of LONGBIMPY's proof

        fprintf(fp,

        "\talways @(posedge i_clk)\n"

        "\tif ((f_past_valid)&&($past(i_ce)))\n"

        "\tbegin\n"

                "\t\tif ($past(i_a)==0)\n"

                        "\t\t\t`ASSERT(o_r == 0);\n"

                "\t\telse if ($past(i_a) == 1)\n"

                        "\t\t\t`ASSERT(o_r == $past(i_b));\n"

                "\n"

                "\t\tif ($past(i_b)==0)\n"

                        "\t\t\t`ASSERT(o_r == 0);\n"

                "\t\telse if ($past(i_b) == 1)\n"

                        "\t\t\t`ASSERT(o_r[(LUTB-1):0] == $past(i_a));\n"

        "\tend\n");

        } else {

                fprintf(fp, "// Enable the formal_property_flag to include formal properties\n");

        }

        fprintf(fp,

"`endif\n");

        // And then the end of the module

        fprintf(fp,

"endmodule\n");

        fclose(fp);

}

void    build_longbimpy(const char *fname) {

        FILE    *fp = fopen(fname, "w");

        if (NULL == fp) {

                fprintf(stderr, "Could not open \'%s\' for writing\n", fname);

                perror("O/S Err was:");

                return;

        }

        fprintf(fp,

SLASHLINE

"//\n"

"// Filename:   %s\n"

"//\n"

"// Project:    %s\n"

"//\n"

"// Purpose:    A portable shift and add multiply, built with the knowledge\n"

"//     of the existence of a six bit LUT and carry chain.  That knowledge\n"

"//     allows us to multiply two bits from one value at a time against all\n"

"//     of the bits of the other value.  This sub multiply is called the\n"

"//     bimpy.\n"

"//\n"

"//     For minimal processing delay, make the first parameter the one with\n"

"//     the least bits, so that AWIDTH <= BWIDTH.\n"

"//\n"

"//\n"

"//\n%s"

"//\n", fname, prjname, creator);

        fprintf(fp, "%s", cpyleft);

        fprintf(fp, "//\n//\n`default_nettype\tnone\n//\n");

        fprintf(fp,

"module longbimpy(i_clk, i_ce, i_a_unsorted, i_b_unsorted, o_r\n");

        if (formal_property_flag) fprintf(fp,

"`ifdef FORMAL\n"

        "\t, f_past_a_unsorted, f_past_b_unsorted\n"

"`endif\n\t\t");

        fprintf(fp, ");\n"

        "\tparameter    IAW=%d, // The width of i_a, min width is 5\n"

                        "\t\t\tIBW=", TST_LONGBIMPY_AW);

#ifdef  TST_LONGBIMPY_BW

        fprintf(fp, "%d", TST_LONGBIMPY_BW);

#else

        fprintf(fp, "IAW");

#endif

        fprintf(fp, ",  // The width of i_b, can be anything\n"

                        "\t\t\t// The following three parameters should not be changed\n"

                        "\t\t\t// by any implementation, but are based upon hardware\n"

                        "\t\t\t// and the above values:\n"

                        "\t\t\tOW=IAW+IBW;      // The output width\n");

        fprintf(fp,

        "\tlocalparam   AW = (IAW<IBW) ? IAW : IBW,\n"

                        "\t\t\tBW = (IAW<IBW) ? IBW : IAW,\n"

                        "\t\t\tIW=(AW+1)&(-2),  // Internal width of A\n"

                        "\t\t\tLUTB=2,  // How many bits we can multiply by at once\n"

                        "\t\t\tTLEN=(AW+(LUTB-1))/LUTB; // Nmbr of rows in our tableau\n"

        "\tinput\twire\t\t\ti_clk, i_ce;\n"

        "\tinput\twire\t[(IAW-1):0]\ti_a_unsorted;\n"

        "\tinput\twire\t[(IBW-1):0]\ti_b_unsorted;\n"

        "\toutput\treg\t[(AW+BW-1):0]\to_r;\n"

"\n");

        if (formal_property_flag) fprintf(fp,

"`ifdef FORMAL\n"

        "\toutput\twire\t[(IAW-1):0]\tf_past_a_unsorted;\n"

        "\toutput\twire\t[(IBW-1):0]\tf_past_b_unsorted;\n"

"`endif\n");

        fprintf(fp, "\n"

        "\t//\n"

        "\t// Swap parameter order, so that AW <= BW -- for performance\n"

        "\t// reasons\n"

        "\twire [AW-1:0]        i_a;\n"

        "\twire [BW-1:0]        i_b;\n"

        "\tgenerate if (IAW <= IBW)\n"

        "\tbegin : NO_PARAM_CHANGE\n"

        "\t\tassign i_a = i_a_unsorted;\n"

        "\t\tassign i_b = i_b_unsorted;\n"

        "\tend else begin : SWAP_PARAMETERS\n"

        "\t\tassign i_a = i_b_unsorted;\n"

        "\t\tassign i_b = i_a_unsorted;\n"

        "\tend endgenerate\n"

"\n"

        "\treg\t[(IW-1):0]\tu_a;\n"

        "\treg\t[(BW-1):0]\tu_b;\n"

        "\treg\t\t\tsgn;\n"

"\n"

        "\treg\t[(IW-1-2*(LUTB)):0]\tr_a[0:(TLEN-3)];\n"

        "\treg\t[(BW-1):0]\t\tr_b[0:(TLEN-3)];\n"

        "\treg\t[(TLEN-1):0]\t\tr_s;\n"

        "\treg\t[(IW+BW-1):0]\t\tacc[0:(TLEN-2)];\n"

        "\tgenvar k;\n"

"\n"

        "\t// First step:\n"

        "\t// Switch to unsigned arithmetic for our multiply, keeping track\n"

        "\t// of the along the way.  We'll then add the sign again later at\n"

        "\t// the end.\n"

        "\t//\n"

        "\t// If we were forced to stay within two's complement arithmetic,\n"

        "\t// taking the absolute value here would require an additional bit.\n"

        "\t// However, because our results are now unsigned, we can stay\n"

        "\t// within the number of bits given (for now).\n"

        "\tinitial u_a = 0;\n"

        "\tgenerate if (IW > AW)\n"

        "\tbegin : ABS_AND_ADD_BIT_TO_A\n"

                "\t\talways @(posedge i_clk)\n"

                        "\t\t\tif (i_ce)\n"

                        "\t\t\t\tu_a <= { 1\'b0, (i_a[AW-1])?(-i_a):(i_a) };\n"

        "\tend else begin : ABS_A\n"

                "\t\talways @(posedge i_clk)\n"

                        "\t\t\tif (i_ce)\n"

                        "\t\t\t\tu_a <= (i_a[AW-1])?(-i_a):(i_a);\n"

        "\tend endgenerate\n"

"\n"

        "\tinitial sgn = 0;\n"

        "\tinitial u_b = 0;\n"

        "\talways @(posedge i_clk)\n"

        "\tif (i_ce)\n"

        "\tbegin : ABS_B\n"

                "\t\tu_b <= (i_b[BW-1])?(-i_b):(i_b);\n"

                "\t\tsgn <= i_a[AW-1] ^ i_b[BW-1];\n"

        "\tend\n"

"\n"

        "\twire [(BW+LUTB-1):0] pr_a, pr_b;\n"

"\n"

        "\t//\n"

        "\t// Second step: First two 2xN products.\n"

        "\t//\n"

        "\t// Since we have no tableau of additions (yet), we can do both\n"

        "\t// of the first two rows at the same time and add them together.\n"

        "\t// For the next round, we'll then have a previous sum to accumulate\n"

        "\t// with new and subsequent product, and so only do one product at\n"

        "\t// a time can follow this--but the first clock can do two at a time.\n"

        "\tbimpy\t#(BW) lmpy_0(i_clk,i_ce,u_a[(  LUTB-1):   0], u_b, pr_a);\n"

        "\tbimpy\t#(BW) lmpy_1(i_clk,i_ce,u_a[(2*LUTB-1):LUTB], u_b, pr_b);\n"

        "\n"

        "\tinitial r_s    = 0;\n"

        "\tinitial r_a[0] = 0;\n"

        "\tinitial r_b[0] = 0;\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce) r_a[0] <= u_a[(IW-1):(2*LUTB)];\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce) r_b[0] <= u_b;\n"

        "\talways @(posedge i_clk)\n"

                "\t\tif (i_ce) r_s <= { r_s[(TLEN-2):0], sgn };\n"

        "\n"

        "\tinitial acc[0] = 0;\n"

        "\talways @(posedge i_clk) // One clk after p[0],p[1] become valid\n"

        "\tif (i_ce) acc[0] <= { {(IW-LUTB){1\'b0}}, pr_a}\n"

                "\t\t  +{ {(IW-(2*LUTB)){1\'b0}}, pr_b, {(LUTB){1\'b0}} };\n"

"\n"

        "\tgenerate // Keep track of intermediate values, before multiplying them\n"

        "\tif (TLEN > 3) for(k=0; k<TLEN-3; k=k+1)\n"

        "\tbegin : GENCOPIES\n"

                "\n"

                "\t\tinitial r_a[k+1] = 0;\n"

                "\t\tinitial r_b[k+1] = 0;\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                        "\t\t\tr_a[k+1] <= { {(LUTB){1\'b0}},\n"

                                "\t\t\t\tr_a[k][(IW-1-(2*LUTB)):LUTB] };\n"

                        "\t\t\tr_b[k+1] <= r_b[k];\n"

                        "\t\tend\n"

        "\tend endgenerate\n"

"\n"

        "\tgenerate // The actual multiply and accumulate stage\n"

        "\tif (TLEN > 2) for(k=0; k<TLEN-2; k=k+1)\n"

        "\tbegin : GENSTAGES\n"

                "\t\twire\t[(BW+LUTB-1):0] genp;\n"

                "\n"

                "\t\t// First, the multiply: 2-bits times BW bits\n"

                "\t\tbimpy #(BW) genmpy(i_clk,i_ce,r_a[k][(LUTB-1):0],r_b[k], genp);\n"

"\n"

                "\t\t// Then the accumulate step -- on the next clock\n"

                "\t\tinitial acc[k+1] = 0;\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                        "\t\t\tacc[k+1] <= acc[k] + {{(IW-LUTB*(k+3)){1\'b0}},\n"

                                "\t\t\t\tgenp, {(LUTB*(k+2)){1\'b0}} };\n"

        "\tend endgenerate\n"

"\n"

        "\twire [(IW+BW-1):0]   w_r;\n"

        "\tassign\tw_r = (r_s[TLEN-1]) ? (-acc[TLEN-2]) : acc[TLEN-2];\n"

        "\n"

        "\tinitial o_r = 0;\n"

        "\talways @(posedge i_clk)\n"

        "\tif (i_ce)\n"

                "\t\to_r <= w_r[(AW+BW-1):0];\n"

"\n");

        // Make Verilator happy

        fprintf(fp,

        "\tgenerate if (IW > AW)\n"

        "\tbegin : VUNUSED\n"

        "\t\t// verilator lint_off UNUSED\n"

        "\t\twire\t[(IW-AW)-1:0]\tunused;\n"

        "\t\tassign\tunused = w_r[(IW+BW-1):(AW+BW)];\n"

        "\t\t// verilator lint_on UNUSED\n"

        "\tend endgenerate\n"

"\n");

        // The formal property section

        // Starting with properties specific to this component's proof, and not

        // any parent modules

        fprintf(fp,

"`ifdef FORMAL\n");

        if (formal_property_flag) {

                fprintf(fp,

        "\treg  f_past_valid;\n"

        "\tinitial\tf_past_valid = 1'b0;\n"

        "\talways @(posedge i_clk)\n"

                "\t\tf_past_valid <= 1'b1;\n"

"\n"

"`define\tASSERT        assert\n"

"`ifdef LONGBIMPY\n"

"\n"

        "\talways @(posedge i_clk)\n"

        "\tif (!$past(i_ce))\n"

        "\t\tassume(i_ce);\n"

"\n"

"`endif\n"

"\n");

        // Now for properties specific to this core

                fprintf(fp,

        "\treg  [AW-1:0]        f_past_a        [0:TLEN];\n"

        "\treg  [BW-1:0]        f_past_b        [0:TLEN];\n"

        "\treg  [TLEN+1:0]      f_sgn_a, f_sgn_b;\n"

"\n");

                fprintf(fp,

        "\tinitial\tf_past_a[0] = 0;\n"

        "\tinitial\tf_past_b[0] = 0;\n"

        "\tinitial\tf_sgn_a = 0;\n"

        "\tinitial\tf_sgn_b = 0;\n"

        "\talways @(posedge i_clk)\n"

        "\tif (i_ce)\n"

        "\tbegin\n"

                "\t\tf_past_a[0] <= u_a;\n"

                "\t\tf_past_b[0] <= u_b;\n"

                "\t\tf_sgn_a[0] <= i_a[AW-1];\n"

                "\t\tf_sgn_b[0] <= i_b[BW-1];\n"

        "\tend\n"

"\n");

                fprintf(fp,

        "\tgenerate for(k=0; k<TLEN; k=k+1)\n"

        "\tbegin\n"

                "\t\tinitial\tf_past_a[k+1] = 0;\n"

                "\t\tinitial\tf_past_b[k+1] = 0;\n"

                "\t\tinitial\tf_sgn_a[k+1] = 0;\n"

                "\t\tinitial\tf_sgn_b[k+1] = 0;\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                                "\t\t\tf_past_a[k+1] <= f_past_a[k];\n"

                                "\t\t\tf_past_b[k+1] <= f_past_b[k];\n"

                "\n"

                                "\t\t\tf_sgn_a[k+1]  <= f_sgn_a[k];\n"

                                "\t\t\tf_sgn_b[k+1]  <= f_sgn_b[k];\n"

                        "\t\tend\n"

        "\tend endgenerate\n"

"\n");

                fprintf(fp,

        "\talways @(posedge i_clk)\n"

        "\tif (i_ce)\n"

        "\tbegin\n"

                "\t\tf_sgn_a[TLEN+1] <= f_sgn_a[TLEN];\n"

                "\t\tf_sgn_b[TLEN+1] <= f_sgn_b[TLEN];\n"

        "\tend\n"

"\n");

                fprintf(fp,

        "\talways @(posedge i_clk)\n"

        "\tbegin\n"

                "\t\tassert(sgn == (f_sgn_a[0] ^ f_sgn_b[0]));\n"

                "\t\tassert(r_s[TLEN-1:0] == (f_sgn_a[TLEN:1] ^ f_sgn_b[TLEN:1]));\n"

                "\t\tassert(r_s[TLEN-1:0] == (f_sgn_a[TLEN:1] ^ f_sgn_b[TLEN:1]));\n"

        "\tend\n"

"\n");

                fprintf(fp,

        "\talways @(posedge i_clk)\n"

        "\tif ((f_past_valid)&&($past(i_ce)))\n"

        "\tbegin\n"

                "\t\tif ($past(i_a)==0)\n"

                        "\t\t\t`ASSERT(u_a == 0);\n"

                "\t\telse if ($past(i_a[AW-1]) == 1'b0)\n"

                        "\t\t\t`ASSERT(u_a == $past(i_a));\n"

"\n"

                "\t\tif ($past(i_b)==0)\n"

                        "\t\t\t`ASSERT(u_b == 0);\n"

                "\t\telse if ($past(i_b[BW-1]) == 1'b0)\n"

                        "\t\t\t`ASSERT(u_b == $past(i_b));\n"

        "\tend\n"

"\n");

                fprintf(fp,

        "\tgenerate // Keep track of intermediate values, before multiplying them\n"

        "\tif (TLEN > 3) for(k=0; k<TLEN-3; k=k+1)\n"

        "\tbegin : ASSERT_GENCOPY\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif (i_ce)\n"

                "\t\tbegin\n"

                        "\t\t\tif (f_past_a[k]==0)\n"

                                "\t\t\t\t`ASSERT(r_a[k] == 0);\n"

                        "\t\t\telse if (f_past_a[k]==1)\n"

                                "\t\t\t\t`ASSERT(r_a[k] == 0);\n"

                        "\t\t\t`ASSERT(r_b[k] == f_past_b[k]);\n"

                "\t\tend\n"

        "\tend endgenerate\n"

"\n");

                fprintf(fp,

        "\tgenerate // The actual multiply and accumulate stage\n"

        "\tif (TLEN > 2) for(k=0; k<TLEN-2; k=k+1)\n"

        "\tbegin : ASSERT_GENSTAGE\n"

                "\t\talways @(posedge i_clk)\n"

                "\t\tif ((f_past_valid)&&($past(i_ce)))\n"

                "\t\tbegin\n"

                        "\t\t\tif (f_past_a[k+1]==0)\n"

                                "\t\t\t\t`ASSERT(acc[k] == 0);\n"

                        "\t\t\tif (f_past_a[k+1]==1)\n"

                                "\t\t\t\t`ASSERT(acc[k] == f_past_b[k+1]);\n"

                        "\t\t\tif (f_past_b[k+1]==0)\n"

                                "\t\t\t\t`ASSERT(acc[k] == 0);\n"

                        "\t\t\tif (f_past_b[k+1]==1)\n"

                        "\t\t\tbegin\n"

                                "\t\t\t\t`ASSERT(acc[k][(2*k)+3:0]\n"

                                "\t\t\t\t               == f_past_a[k+1][(2*k)+3:0]);\n"

                                "\t\t\t\t`ASSERT(acc[k][(IW+BW-1):(2*k)+4] == 0);\n"

                        "\t\t\tend\n"

                "\t\tend\n"

        "\tend endgenerate\n"

"\n");

                fprintf(fp,

        "\twire [AW-1:0]\tf_past_a_neg = - f_past_a[TLEN];\n"

        "\twire [BW-1:0]\tf_past_b_neg = - f_past_b[TLEN];\n"

"\n"

        "\twire [AW-1:0]\tf_past_a_pos = f_past_a[TLEN][AW-1]\n"

                                "\t\t\t\t\t? f_past_a_neg : f_past_a[TLEN];\n"

        "\twire [BW-1:0]\tf_past_b_pos = f_past_b[TLEN][BW-1]\n"

                                "\t\t\t\t\t? f_past_b_neg : f_past_b[TLEN];\n\n");

                fprintf(fp,

        "\talways @(posedge i_clk)\n"

        "\tif ((f_past_valid)&&($past(i_ce)))\n"

        "\tbegin\n"

                "\t\tif ((f_past_a[TLEN]==0)||(f_past_b[TLEN]==0))\n"

                        "\t\t\t`ASSERT(o_r == 0);\n"

                "\t\telse if (f_past_a[TLEN]==1)\n"

                "\t\tbegin\n"

                        "\t\t\tif ((f_sgn_a[TLEN+1]^f_sgn_b[TLEN+1])==0)\n"

                        "\t\t\tbegin\n"

                                "\t\t\t\t`ASSERT(o_r[BW-1:0] == f_past_b_pos[BW-1:0]);\n"

                                "\t\t\t\t`ASSERT(o_r[AW+BW-1:BW] == 0);\n"

                        "\t\t\tend else begin // if (f_sgn_b[TLEN+1]) begin\n"

                                "\t\t\t\t`ASSERT(o_r[BW-1:0] == f_past_b_neg);\n"

                                "\t\t\t\t`ASSERT(o_r[AW+BW-1:BW]\n"

                                        "\t\t\t\t\t== {(AW){f_past_b_neg[BW-1]}});\n"

                        "\t\t\tend\n"

                "\t\tend else if (f_past_b[TLEN]==1)\n"

                "\t\tbegin\n"