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module memdemo(clk, d, y);

input clk;
input [3:0] d;
output reg [3:0] y;

integer i;
reg [1:0] s1, s2;
reg [3:0] mem [0:3];

always @(posedge clk) begin
    for (i = 0; i < 4; i = i+1)
        mem[i] <= mem[(i+1) % 4] + mem[(i+2) % 4];
    { s2, s1 } = d ? { s1, s2 } ^ d : 4'b0;
    mem[s1] <= d;
    y <= mem[s2];
end

endmodule
ted */ .highlight .ge { font-style: italic } /* Generic.Emph */ .highlight .gr { color: #aa0000 } /* Generic.Error */ .highlight .gh { color: #333333 } /* Generic.Heading */ .highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */ .highlight .go { color: #888888 } /* Generic.Output */ .highlight .gp { color: #555555 } /* Generic.Prompt */ .highlight .gs { font-weight: bold } /* Generic.Strong */ .highlight .gu { color: #666666 } /* Generic.Subheading */ .highlight .gt { color: #aa0000 } /* Generic.Traceback */ .highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */ .highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */ .highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */ .highlight .kp { color: #008800 } /* Keyword.Pseudo */ .highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */ .highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */ .highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */ .highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */ .highlight .na { color: #336699 } /* Name.Attribute */ .highlight .nb { color: #003388 } /* Name.Builtin */ .highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */ .highlight .no { color: #003366; font-weight: bold } /* Name.Constant */ .highlight .nd { color: #555555 } /* Name.Decorator */ .highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */ .highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */ .highlight .nl { color: #336699; font-style: italic } /* Name.Label */ .highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */ .highlight .py { color: #336699; font-weight: bold } /* Name.Property */ .highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */ .highlight .nv { color: #336699 } /* Name.Variable */ .highlight .ow { color: #008800 } /* Operator.Word */ .highlight .w { color: #bbbbbb } /* Text.Whitespace */ .highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */ .highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */ .highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */ .highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */ .highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */ .highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */ .highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */ .highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */ .highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */ .highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */ .highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */ .highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */ .highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */ .highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */ .highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */ .highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */ .highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */ .highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */ .highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */ .highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */ .highlight .vc { color: #336699 } /* Name.Variable.Class */ .highlight .vg { color: #dd7700 } /* Name.Variable.Global */ .highlight .vi { color: #3333bb } /* Name.Variable.Instance */ .highlight .vm { color: #336699 } /* Name.Variable.Magic */ .highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
/*
    ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio.

    This file is part of ChibiOS.

    ChibiOS is free software; 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.

    ChibiOS 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 program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    chtrace.c
 * @brief   Tracer code.
 *
 * @addtogroup trace
 * @details System events tracing service.
 * @{
 */

#include "ch.h"

/*===========================================================================*/
/* Module local definitions.                                                 */
/*===========================================================================*/

/*===========================================================================*/
/* Module exported variables.                                                */
/*===========================================================================*/

/*===========================================================================*/
/* Module local types.                                                       */
/*===========================================================================*/

/*===========================================================================*/
/* Module local variables.                                                   */
/*===========================================================================*/

/*===========================================================================*/
/* Module local functions.                                                   */
/*===========================================================================*/

#if (CH_DBG_TRACE_MASK != CH_DBG_TRACE_MASK_DISABLED) || defined(__DOXYGEN__)
/**
 * @brief   Writes a time stamp and increases the trace buffer pointer.
 *
 * @notapi
 */
static NOINLINE void trace_next(void) {

  ch.dbg.trace_buffer.ptr->time    = chVTGetSystemTimeX();
#if PORT_SUPPORTS_RT == TRUE
  ch.dbg.trace_buffer.ptr->rtstamp = chSysGetRealtimeCounterX();
#else
  ch.dbg.trace_buffer.ptr->rtstamp = (rtcnt_t)0;
#endif

  /* Trace hook, useful in order to interface debug tools.*/
  CH_CFG_TRACE_HOOK(ch.dbg.trace_buffer.ptr);

  if (++ch.dbg.trace_buffer.ptr >=
      &ch.dbg.trace_buffer.buffer[CH_DBG_TRACE_BUFFER_SIZE]) {
    ch.dbg.trace_buffer.ptr = &ch.dbg.trace_buffer.buffer[0];
  }
}
#endif

/*===========================================================================*/
/* Module exported functions.                                                */
/*===========================================================================*/

#if (CH_DBG_TRACE_MASK != CH_DBG_TRACE_MASK_DISABLED) || defined(__DOXYGEN__)
/**
 * @brief   Trace circular buffer subsystem initialization.
 * @note    Internal use only.
 */
void _trace_init(void) {
  unsigned i;

  ch.dbg.trace_buffer.suspended = (uint16_t)~CH_DBG_TRACE_MASK;
  ch.dbg.trace_buffer.size      = CH_DBG_TRACE_BUFFER_SIZE;
  ch.dbg.trace_buffer.ptr       = &ch.dbg.trace_buffer.buffer[0];
  for (i = 0U; i < (unsigned)CH_DBG_TRACE_BUFFER_SIZE; i++) {
    ch.dbg.trace_buffer.buffer[i].type = CH_TRACE_TYPE_UNUSED;
  }
}

/**
 * @brief   Inserts in the circular debug trace buffer a context switch record.
 *
 * @param[in] ntp       the thread being switched in
 * @param[in] otp       the thread being switched out
 *
 * @notapi
 */
void _trace_switch(thread_t *ntp, thread_t *otp) {

  (void)ntp;

  if ((ch.dbg.trace_buffer.suspended & CH_DBG_TRACE_MASK_SWITCH) == 0U) {
    ch.dbg.trace_buffer.ptr->type        = CH_TRACE_TYPE_SWITCH;
    ch.dbg.trace_buffer.ptr->state       = (uint8_t)otp->state;
    ch.dbg.trace_buffer.ptr->u.sw.ntp    = currp;
    ch.dbg.trace_buffer.ptr->u.sw.wtobjp = otp->u.wtobjp;
    trace_next();
  }
}

/**
 * @brief   Inserts in the circular debug trace buffer an ISR-enter record.
 *
 * @param[in] isr       name of the isr
 *
 * @notapi
 */
void _trace_isr_enter(const char *isr) {

  if ((ch.dbg.trace_buffer.suspended & CH_DBG_TRACE_MASK_ISR) == 0U) {
    port_lock_from_isr();
    ch.dbg.trace_buffer.ptr->type        = CH_TRACE_TYPE_ISR_ENTER;
    ch.dbg.trace_buffer.ptr->state       = 0U;
    ch.dbg.trace_buffer.ptr->u.isr.name  = isr;
    trace_next();
    port_unlock_from_isr();
  }
}

/**
 * @brief   Inserts in the circular debug trace buffer an ISR-leave record.
 *
 * @param[in] isr       name of the isr
 *
 * @notapi
 */
void _trace_isr_leave(const char *isr) {

  if ((ch.dbg.trace_buffer.suspended & CH_DBG_TRACE_MASK_ISR) == 0U) {
    port_lock_from_isr();
    ch.dbg.trace_buffer.ptr->type        = CH_TRACE_TYPE_ISR_LEAVE;
    ch.dbg.trace_buffer.ptr->state       = 0U;
    ch.dbg.trace_buffer.ptr->u.isr.name  = isr;
    trace_next();
    port_unlock_from_isr();
  }
}

/**
 * @brief   Inserts in the circular debug trace buffer an halt record.
 *
 * @param[in] reason    the halt error string
 *
 * @notapi
 */
void _trace_halt(const char *reason) {

  if ((ch.dbg.trace_buffer.suspended & CH_DBG_TRACE_MASK_HALT) == 0U) {
    ch.dbg.trace_buffer.ptr->type          = CH_TRACE_TYPE_HALT;
    ch.dbg.trace_buffer.ptr->state         = 0;
    ch.dbg.trace_buffer.ptr->u.halt.reason = reason;
    trace_next();
  }
}

/**
 * @brief   Adds an user trace record to the trace buffer.
 *
 * @param[in] up1       user parameter 1
 * @param[in] up2       user parameter 2
 *
 * @iclass
 */
void chDbgWriteTraceI(void *up1, void *up2) {

  chDbgCheckClassI();

  if ((ch.dbg.trace_buffer.suspended & CH_DBG_TRACE_MASK_USER) == 0U) {
    ch.dbg.trace_buffer.ptr->type       = CH_TRACE_TYPE_USER;
    ch.dbg.trace_buffer.ptr->state      = 0;
    ch.dbg.trace_buffer.ptr->u.user.up1 = up1;
    ch.dbg.trace_buffer.ptr->u.user.up2 = up2;
    trace_next();
  }
}

/**
 * @brief   Adds an user trace record to the trace buffer.
 *
 * @param[in] up1       user parameter 1
 * @param[in] up2       user parameter 2
 *
 * @api
 */
void chDbgWriteTrace(void *up1, void *up2) {

  chSysLock();
  chDbgWriteTraceI(up1, up2);
  chSysUnlock();
}

/**
 * @brief   Suspends one or more trace events.
 *
 * @param[in] mask      mask of the trace events to be suspended
 *
 * @iclass
 */
void chDbgSuspendTraceI(uint16_t mask) {

  chDbgCheckClassI();

  ch.dbg.trace_buffer.suspended |= mask;
}

/**
 * @brief   Suspends one or more trace events.
 *
 * @param[in] mask      mask of the trace events to be suspended
 *
 * @api
 */
void chDbgSuspendTrace(uint16_t mask) {

  chSysLock();
  chDbgSuspendTraceI(mask);
  chSysUnlock();
}

/**
 * @brief   Resumes one or more trace events.
 *
 * @param[in] mask      mask of the trace events to be resumed
 *
 * @iclass
 */
void chDbgResumeTraceI(uint16_t mask) {

  chDbgCheckClassI();

  ch.dbg.trace_buffer.suspended &= ~mask;
}

/**
 * @brief   Resumes one or more trace events.
 *
 * @param[in] mask      mask of the trace events to be resumed
 *
 * @api
 */
void chDbgResumeTrace(uint16_t mask) {

  chSysLock();
  chDbgResumeTraceI(mask);
  chSysUnlock();
}
#endif /* CH_DBG_TRACE_MASK != CH_DBG_TRACE_MASK_DISABLED */

/** @} */