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[/] [zipcpu/] [trunk/] [sim/] [verilator/] [div_tb.cpp] - Blame information for rev 204

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1 204 dgisselq
///////////////////////////////////////////////////////////////////////////////
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//
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// Filename:    div_tb.cpp
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//
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// Project:     Zip CPU -- a small, lightweight, RISC CPU soft core
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//
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// Purpose:     Bench testing for the divide unit found within the Zip CPU.
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//
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//
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// Creator:     Dan Gisselquist, Ph.D.
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//              Gisselquist Technology, LLC
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//
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///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 2015, Gisselquist Technology, LLC
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//
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// This program is free software (firmware): you can redistribute it and/or
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// modify it under the terms of  the GNU General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or (at
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// your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
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// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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// for more details.
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//
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// License:     GPL, v3, as defined and found on www.gnu.org,
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//              http://www.gnu.org/licenses/gpl.html
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//
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//
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///////////////////////////////////////////////////////////////////////////////
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//
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//
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#include <signal.h>
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#include <stdint.h>
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#include <time.h>
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#include <unistd.h>
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#include <assert.h>
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#include <ctype.h>
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#include "verilated.h"
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#include "Vdiv.h"
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#include "testb.h"
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// #include "twoc.h"
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class   DIV_TB : public TESTB<Vdiv> {
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public:
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        DIV_TB(void) {
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        }
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        ~DIV_TB(void) {}
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        void    reset(void) {
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                // m_flash.debug(false);
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                TESTB<Vdiv>::reset();
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        }
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        bool    on_tick(void) {
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                tick();
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                return true;
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        }
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        void    bprint(char *str, int nbits, unsigned long v) {
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                while(*str)
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                        str++;
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                for(int i=0; i<nbits; i++) {
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                        if ((1l<<(nbits-1-i))&v)
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                                *str++ = '1';
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                        else
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                                *str++ = '0';
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                        if (((nbits-1-i)&3)==0)
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                                *str++ = ' ';
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                } *str = '\0';
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        }
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        void    dbgdump(void) {
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                char    outstr[2048], *s;
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                sprintf(outstr, "Tick %4ld %s%s%s%s%s%s%s %2d(%s= 0)",
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                        m_tickcount,
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                        (m_core->o_busy)?"B":" ",
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                        (m_core->v__DOT__r_busy)?"R":" ",
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                        (m_core->o_valid)?"V":" ",
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                        (m_core->i_wr)?"W":" ",
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                        (m_core->v__DOT__pre_sign)?"+":" ",
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                        (m_core->v__DOT__r_sign)?"-":" ",
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                        (m_core->v__DOT__r_z)?"Z":" ",
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                        m_core->v__DOT__r_bit,
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                        (m_core->v__DOT__last_bit)?"=":"!");
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                s = &outstr[strlen(outstr)];
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                sprintf(s, "%s\n%10s %40s",s, "Div","");
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                        s = &s[strlen(s)];
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                bprint( s, 32, m_core->v__DOT__r_dividend);
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                        s=&s[strlen(s)];
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                sprintf(s, "%s\n%10s ",s, "Div"); s = &s[strlen(s)];
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                bprint( s, 64, m_core->v__DOT__r_divisor);
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                        s=&s[strlen(s)];
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                sprintf(s, "%s\n%10s %40s",s, "Q",""); s=&s[strlen(s)];
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                bprint( s, 32, m_core->o_quotient); s = &s[strlen(s)];
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                sprintf(s, "%s\n%10s %38s",s, "Diff","");
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                        s=&s[strlen(s)];
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                bprint( s, 33, m_core->v__DOT__diff); s = &s[strlen(s)];
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                strcat(s, "\n");
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                puts(outstr);
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        }
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        void    tick(void) {
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                bool    debug = false;
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                if (debug)
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                        dbgdump();
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                TESTB<Vdiv>::tick();
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        }
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        void    divtest(uint32_t n, uint32_t d, uint32_t ans, bool issigned) {
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                const bool      dbg = false;
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                // The test bench is supposed to assert that we are idle when
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                // we come in here.
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                assert(m_core->o_busy == 0);
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                // Request a divide
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                m_core->i_rst = 0;
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                m_core->i_wr = 1;
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                m_core->i_signed = (issigned)?1:0;
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                m_core->i_numerator = n;
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                m_core->i_denominator = d;
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                // Tick once for the request to be registered
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                tick();
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                // Clear the input lines.
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                m_core->i_wr = 0;
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                m_core->i_signed = 0;
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                m_core->i_numerator = 0;
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                m_core->i_denominator = 0;
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                // Make certain busy is immediately true upon the first clock
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                // after we issue the divide, and that our result is not also
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                // listed as a valid result.
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                if (!m_core->o_busy) {
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                        closetrace();
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                        assert(m_core->o_busy);
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                } if (m_core->o_valid != 0) {
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                        closetrace();
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                        assert(m_core->o_valid == 0);
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                }
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                // while((!m_core->o_valid)&&(!m_core->o_err))
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                while(!m_core->o_valid) {
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                        // If we aren't yet valid, we'd better at least
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                        // be busy--the CPU requires this.
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                        if (!m_core->o_busy) {
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                                // We aren't valid, and we aren't busy.  This
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                                // is a test failure.
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                                dbgdump();
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                                closetrace();
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                                assert(m_core->o_busy);
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                        }
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                        // Let the algorithm work for another clock tick.
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                        tick();
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                } if (dbg) dbgdump();
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                // Insist that the core not be busy any more, now that a valid
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                // result has been produced.
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                if (m_core->o_busy) {
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                        closetrace();
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                        assert(!m_core->o_busy);
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                }
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                if (dbg) {
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                        printf("%s%s: %d / %d =? %d\n",
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                                (m_core->o_valid)?"V":" ",
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                                (m_core->o_err)?"E":" ",
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                                n, d, m_core->o_quotient);
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                }
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                // Now that we're done, we need to check the result.
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                //
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                // First case to check: was there an error condition or, if not,
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                // should there have been one?
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                if (d == 0) {
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                        // We attempted to divide by zero, the result should've
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                        // been an error condition.  Let's check:
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                        // Then insist on a division by zero error
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                        if (!m_core->o_err) {
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                                // Don't forget to close the trace before the
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                                // assert, lest the file not get the final
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                                // values into it.
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                                closetrace();
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                                assert(m_core->o_err);
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                        }
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                } else if (m_core->o_err) {
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                        // Otherwise, there should not have been any divide
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                        // errors.  The only errors allowed should be the
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                        // divide by zero.  So, this is an error.  Let's
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                        // stop and report it.
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                        closetrace();
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                        assert(!m_core->o_err);
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                } else if (ans != (uint32_t)m_core->o_quotient) {
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                        // The other problem we might encounter would be if the
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                        // result doesn't match the one we are expecting.
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                        //
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                        // Stop on this bug as well.
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                        //
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                        closetrace();
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                        assert(ans == (uint32_t)m_core->o_quotient);
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                }
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        }
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        // Test a signed divide
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        void    divs(int n, int d) {
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                int     ans;
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                // Calculate the answer we *should* get from the divide
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                ans = (d==0)?0:   (n / d);
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                divtest((uint32_t)n, (uint32_t)d, (uint32_t)ans, true);
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        }
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        // Test an unsigned divide
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        void    divu(unsigned n, unsigned d) {
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                unsigned        ans;
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                // Pre-Calculate the answer we *should* get from the divide
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                ans = (d==0)?0:   (n / d);
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                divtest((uint32_t)n, (uint32_t)d, (uint32_t)ans, false);
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        }
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        // divide() is just another name for a signed divide--just switch to
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        // that function call instead.
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        void    divide(int n, int d) {
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                divs(n,d);
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        }
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};
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//
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// Standard usage functions.
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//
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// Notice that the test bench provides no options.  Everything is
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// self-contained.
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void    usage(void) {
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        printf("USAGE: div_tb\n");
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        printf("\n");
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        printf("\t\n");
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}
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//
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int     main(int argc, char **argv) {
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        // Setup
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        Verilated::commandArgs(argc, argv);
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        DIV_TB  *tb = new DIV_TB();
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        // tb->opentrace("divtrace.vcd");
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        tb->reset();
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        // tb->opentrace("div_tb.vcd");
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        // Now we're ready.  All we need to do to test the divide of two
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        // numbers is to call the respective divide(), divs(), or divu()
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        // functions.  The program will crash on an assert error if anything
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        // goes wrong.
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        tb->divu((unsigned)-1,10);
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        tb->divide(125,7);
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        // And give us an extra clock tick in-between each test for good
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        // measure.
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        tb->tick();
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        // Some other gentle tests
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        tb->divide(125,-7);
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        tb->tick();
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        tb->divu((1u<<31),7);
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        // Now some boundary conditions
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        tb->divu((7u<<29),(1u<<31));
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        tb->tick();
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        tb->divs(32768,0);
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        tb->tick();
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        tb->divu((1u<<31),0);
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        tb->tick();
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        tb->divs((1u<<30),0);
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        tb->tick();
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        //
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        // Now we switch to a more thorough test set.  It's not complete, just
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        // ... more thorough.
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        for(int i=32767; i>=0; i--) {
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                tb->divs((1u<<30),i);
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                tb->tick();
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        } for(int i=32767; i>=0; i--) {
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                // tb->divu(-1, i);
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                tb->divu((1u<<31), i);
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                tb->tick();
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        } for(int i=32767; i>=0; i--) {
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                tb->divide(32768, i);
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                tb->tick();
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        }
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        /*
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         * While random data is a nice test idea, the following just never
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         * really tested the divide unit thoroughly enough.
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         *
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        tb->divide(rand(),rand()/2);
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        tb->tick();
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        tb->divide(rand(),rand()/2);
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        tb->tick();
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        tb->divide(rand(),rand()/2);
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        tb->tick();
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        tb->divide(rand(),rand()/2);
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        */
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        // Any failures above will be captured with a failed assert.  If we
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        // get here, it means things worked.  Close up shop ...
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        //
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        // This closes any potential trace file
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        delete  tb;
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        // And declare success
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        printf("SUCCESS!\n");
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        exit(EXIT_SUCCESS);
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}
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