iverilog/vvp/vpi_signal.cc

/*
 * Copyright (c) 2001-2008 Stephen Williams (steve@icarus.com)
 *
 *    This source code is free software; you can redistribute it
 *    and/or modify it in source code form under the terms of the GNU
 *    General Public License as published by the Free Software
 *    Foundation; either version 2 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
 *    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, write to the Free Software
 *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

/*
 * vpiReg handles are handled here. These objects represent vectors of
 * .var objects that can be manipulated by the VPI module.
 */

# include  "compile.h"
# include  "vpi_priv.h"
# include  "schedule.h"
# include  "statistics.h"
# include  <math.h>
# include  <iostream>
# include  <stdio.h>
#ifdef HAVE_MALLOC_H
# include  <malloc.h>
#endif
# include  <stdlib.h>
# include  <string.h>
# include  <assert.h>

/*
 * Hex digits that represent 4-value bits of Verilog are not as
 * trivially obvious to display as if the bits were the usual 2-value
 * bits. So, although it is possible to write a function that
 * generates a correct character for 4*4-value bits, it is easier to
 * just perform the lookup in a table. This only takes 256 bytes,
 * which is not many executable instructions:-)
 *
 * The table is calculated at compile time, therefore, by the
 * draw_tt.c program.
 */
extern const char hex_digits[256];
extern const char oct_digits[64];

/*
 * The string values need a result buf to hold the results. This
 * buffer can be reused for that purpose. Whenever I have a need, the
 * need_result_buf function makes sure that need can be met.
 */
char *need_result_buf(unsigned cnt, vpi_rbuf_t type)
{
      cnt = (cnt + 0x0fff) & ~0x0fff;

      static char*result_buf[2] = {0, 0};
      static size_t result_buf_size[2] = {0, 0};

      if (result_buf_size[type] == 0) {
	    result_buf[type] = (char*)malloc(cnt);
	    result_buf_size[type] = cnt;
      } else if (result_buf_size[type] < cnt) {
	    result_buf[type] = (char*)realloc(result_buf[type], cnt);
	    result_buf_size[type] = cnt;
      }

      return result_buf[type];
}

char *simple_set_rbuf_str(const char *s1)
{
	char *res = need_result_buf(strlen(s1)+1, RBUF_STR);
	if (res) strcpy(res,s1);
	return res;
}

char *generic_get_str(int code, vpiHandle ref, const char *name, const char *index)
{
	size_t len = strlen(name) + 1;  /* include space for null termination */
	char *bn = NULL;
	if (code == vpiFullName) {
		bn = strdup(vpi_get_str(code,ref));
		len += strlen(bn) + 1;  /* include space for "." separator */
	}
	if (index != NULL) len += strlen(index) + 2;  /* include space for brackets */

	char *res = need_result_buf(len, RBUF_STR);
	if (!res) return NULL;
	*res=0;  /* start with nothing */

	/* if this works, I can make it more efficient later */
	if (bn != NULL) {
		strcat(res, bn);
		strcat(res, ".");
		free(bn);
	}
	strcat(res, name);
	if (index != NULL) {
		strcat(res, "[");
		strcat(res, index);
		strcat(res, "]");
	}
	return res;
}

/*
 * The standard formating/conversion routines.
 * They work with full or partial signals.
 */

static void format_vpiBinStrVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                s_vpi_value*vp)
{
      char *rbuf = need_result_buf(wid+1, RBUF_VAL);
      long offset = wid - 1 + base;
      long end = base + (signed)wid;
      long ssize = (signed)sig->size();

      for (long idx = base ;  idx < end ;  idx += 1) {
	    if (idx < 0 || idx >= ssize) {
                  rbuf[offset-idx] = 'x';
	    } else {
                  rbuf[offset-idx] = vvp_bit4_to_ascii(sig->value(idx));
	    }
      }
      rbuf[wid] = 0;

      vp->value.str = rbuf;
}

static void format_vpiOctStrVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                s_vpi_value*vp)
{
      unsigned dwid = (wid + 2) / 3;
      char *rbuf = need_result_buf(dwid+1, RBUF_VAL);
      long end = base + (signed)wid;
      long ssize = (signed)sig->size();
      unsigned val = 0;

      rbuf[dwid] = 0;
      for (long idx = base ;  idx < end ;  idx += 1) {
	    unsigned bit = 0;
	    if (idx < 0 || idx >= ssize) {
                  bit = 2; // BIT4_X
	    } else {
                  switch (sig->value(idx)) {
		      case BIT4_0:
			bit = 0;
			break;
		      case BIT4_1:
			bit = 1;
			break;
		      case BIT4_X:
			bit = 2;
			break;
		      case BIT4_Z:
			bit = 3;
			break;
                  }
	    }
	    val |= bit << 2*((idx-base) % 3);

	    if ((idx-base) % 3 == 2) {
		dwid -= 1;
		rbuf[dwid] = oct_digits[val];
		val = 0;
	    }
      }

	/* Fill in X or Z if they are the only thing in the value. */
      switch (wid % 3) {
	  case 1:
	    if (val == 2) val = 42;
	    else if (val == 3) val = 63;
	    break;
	  case 2:
	    if (val == 10) val = 42;
	    else if (val == 15) val = 63;
	    break;
      }

      if (dwid > 0) rbuf[0] = oct_digits[val];

      vp->value.str = rbuf;
}

static void format_vpiHexStrVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                s_vpi_value*vp)
{
      unsigned dwid = (wid + 3) / 4;
      char *rbuf = need_result_buf(dwid+1, RBUF_VAL);
      long end = base + (signed)wid;
      long ssize = (signed)sig->size();
      unsigned val = 0;

      rbuf[dwid] = 0;
      for (long idx = base ;  idx < end ;  idx += 1) {
	    unsigned bit = 0;
	    if (idx < 0 || idx >= ssize) {
                  bit = 2; // BIT4_X
	    } else {
                  switch (sig->value(idx)) {
		      case BIT4_0:
			bit = 0;
			break;
		      case BIT4_1:
			bit = 1;
			break;
		      case BIT4_X:
			bit = 2;
			break;
		      case BIT4_Z:
			bit = 3;
			break;
                  }
	    }
	    val |= bit << 2*((idx-base) % 4);

	    if ((idx-base) % 4 == 3) {
		dwid -= 1;
		rbuf[dwid] = hex_digits[val];
		val = 0;
	    }
      }

	/* Fill in X or Z if they are the only thing in the value. */
      switch (wid % 4) {
	  case 1:
	    if (val == 2) val = 170;
	    else if (val == 3) val = 255;
	    break;
	  case 2:
	    if (val == 10) val = 170;
	    else if (val == 15) val = 255;
	    break;
	  case 3:
	    if (val == 42) val = 170;
	    else if (val == 63) val = 255;
	    break;
      }

      if (dwid > 0) rbuf[0] = hex_digits[val];

      vp->value.str = rbuf;
}

static void format_vpiDecStrVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                int signed_flag, s_vpi_value*vp)
{
      unsigned hwid = (sig->size()+2) / 3 + 1;
      char *rbuf = need_result_buf(hwid, RBUF_VAL);
      long ssize = (signed)sig->size();
      long end = base + (signed)wid;

	/* Do we have an end outside of the real signal vector. */
      if (base < 0 || end > ssize) {
	    bool all_x = true;
	    if (end > ssize) end = ssize;
	    if (base < 0) base = 0;
	    for (long idx = base ;  idx < end ;  idx += 1) {
		  if (sig->value(idx) != BIT4_X) {
			all_x = false;
			break;
		  }
	    }

	    if (all_x) {
		  rbuf[0] = 'x';
	    } else {
		  rbuf[0] = 'X';
	    }
	    rbuf[1] = 0;

	    vp->value.str = rbuf;
	    return;
      }

      vvp_vector4_t vec4;
      if (base == 0 && end == ssize) {
	    vec4 = sig->vec4_value();
      } else {
	    vec4 = sig->vec4_value().subvalue(base, wid);
      }

      vpip_vec4_to_dec_str(vec4, rbuf, hwid, signed_flag);

      vp->value.str = rbuf;
}

static void format_vpiIntVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                             int signed_flag, s_vpi_value*vp)
{
      vvp_vector4_t sub = sig->vec4_value().subvalue(base, wid);
      long val = 0;
      bool flag = vector4_to_value(sub, val, signed_flag);
      if (! flag) val = 0;
      vp->value.integer = val;
}

static void format_vpiRealVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                              int signed_flag, s_vpi_value*vp)
{
      vvp_vector4_t vec4(wid);
      long ssize = (signed)sig->size();
      long end = base + (signed)wid;
      if (end > ssize) end = ssize;

      for (long idx = (base < 0) ? 0 : base ;  idx < end ;  idx += 1) {
	    vec4.set_bit(idx-base, sig->value(idx));
      }

      vp->value.real = 0.0;
      vector4_to_value(vec4, vp->value.real, signed_flag);
}

static void format_vpiStringVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                s_vpi_value*vp)
{
      /* The result will use a character for each 8 bits of the
	 vector. Add one extra character for the highest bits that
	 don't form an 8 bit group. */
      char *rbuf = need_result_buf(wid/8 + ((wid&7)!=0) + 1, RBUF_VAL);
      char *cp = rbuf;

      char tmp = 0;
      for (long idx = base+(signed)wid-1; idx >= base; idx -= 1) {
	    tmp <<= 1;

	    if (idx >=0 && idx < (signed)sig->size() &&
	        sig->value(idx) == BIT4_1) {
		   tmp |= 1;
	    }

	    if (((idx-base)&7)==0){
		  /* Skip leading nulls. */
		  if (tmp == 0 && cp == rbuf)
			continue;

		  /* Nulls in the middle get turned into spaces. */
		  *cp++ = tmp ? tmp : ' ';
		  tmp = 0;
	    }
      }
      *cp++ = 0;

      vp->value.str = rbuf;
}

static void format_vpiScalarVal(vvp_fun_signal_vec*sig, int base, 
                                s_vpi_value*vp)
{
      if (base >= 0 && base < (signed)sig->size()) {
	    switch (sig->value(base)) {
		case BIT4_0:
		  vp->value.scalar = vpi0;
		  break;
		case BIT4_1:
		  vp->value.scalar = vpi1;
		  break;
		case BIT4_X: {
		  vvp_scalar_t strn = sig->scalar_value(base);
		  if (strn.strength0() == 1) vp->value.scalar = vpiH;
		  else if (strn.strength1() == 1) vp->value.scalar = vpiL;
		  else vp->value.scalar = vpiX;
		  break;
		}
		case BIT4_Z:
		  vp->value.scalar = vpiZ;
		  break;
	    }
      } else {
	    vp->value.scalar = vpiX;
      }
}

static void format_vpiStrengthVal(vvp_fun_signal_vec*sig, int base,
                                  unsigned wid, s_vpi_value*vp)
{
      long end = base + (signed)wid;
      s_vpi_strengthval*op;

      op = (s_vpi_strengthval*)
	    need_result_buf(wid * sizeof(s_vpi_strengthval), RBUF_VAL);

      for (long idx = base ;  idx < end ;  idx += 1) {
	    if (idx >=0 && idx < (signed)sig->size()) {
		  vvp_scalar_t val = sig->scalar_value(idx);

		  /* vvp_scalar_t strengths are 0-7, but the vpi strength
		     is bit0-bit7. This gets the vpi form of the strengths
		     from the vvp_scalar_t strengths. */
		  unsigned s0 = 1 << val.strength0();
		  unsigned s1 = 1 << val.strength1();

		  switch (val.value()) {
		      case BIT4_0:
			op[idx-base].logic = vpi0;
			op[idx-base].s0 = s0|s1;
			op[idx-base].s1 = 0;
			break;

		      case BIT4_1:
			op[idx-base].logic = vpi1;
			op[idx-base].s0 = 0;
			op[idx-base].s1 = s0|s1;
			break;

		      case BIT4_X:
			op[idx-base].logic = vpiX;
			op[idx-base].s0 = s0;
			op[idx-base].s1 = s1;
			break;

		      case BIT4_Z:
			op[idx-base].logic = vpiZ;
			op[idx-base].s0 = vpiHiZ;
			op[idx-base].s1 = vpiHiZ;
			break;
		  }
	    } else {
		  op[idx-base].logic = vpiX;
		  op[idx-base].s0 = vpiStrongDrive;
		  op[idx-base].s1 = vpiStrongDrive;
	    }
      }

      vp->value.strength = op;
}

static void format_vpiVectorVal(vvp_fun_signal_vec*sig, int base, unsigned wid,
                                s_vpi_value*vp)
{
      long end = base + (signed)wid;
      unsigned int obit = 0;
      unsigned hwid = (wid - 1)/32 + 1;

      s_vpi_vecval *op = (p_vpi_vecval)
                         need_result_buf(hwid * sizeof(s_vpi_vecval), RBUF_VAL);
      vp->value.vector = op;

      op->aval = op->bval = 0;
      for (long idx = base ;  idx < end ;  idx += 1) {
	    if (base >= 0 && base < (signed)sig->size()) {
		switch (sig->value(idx)) {
		case BIT4_0:
		  op->aval &= ~(1 << obit);
		  op->bval &= ~(1 << obit);
		  break;
		case BIT4_1:
		  op->aval |= (1 << obit);
		  op->bval &= ~(1 << obit);
		  break;
		case BIT4_X:
		  op->aval |= (1 << obit);
		  op->bval |= (1 << obit);
		  break;
		case BIT4_Z:
		  op->aval &= ~(1 << obit);
		  op->bval |= (1 << obit);
		  break;
		}
	    } else {  /* BIT4_X */
		  op->aval |= (1 << obit);
		  op->bval |= (1 << obit);
	    }

	    obit++;
	    if (!(obit % 32)) {
		  op += 1;
		  if ((op - vp->value.vector) < (ptrdiff_t)hwid)
			op->aval = op->bval = 0;
		  obit = 0;
	    }
      }
}

struct __vpiSignal* vpip_signal_from_handle(vpiHandle ref)
{
      if ((ref->vpi_type->type_code != vpiNet)
	  && (ref->vpi_type->type_code != vpiReg))
	    return 0;

      return (struct __vpiSignal*)ref;
}

/*
 * implement vpi_get for vpiReg objects.
 */
static int signal_get(int code, vpiHandle ref)
{
      struct __vpiSignal*rfp = vpip_signal_from_handle(ref);
      assert(rfp);

      switch (code) {
	  case vpiLineNo:
	    return 0;  // Not implemented for now!

	  case vpiSigned:
	    return rfp->signed_flag != 0;

	  case vpiArray:
	    return rfp->parent != 0;

	  case vpiIndex: // This only works while we have a single index.
	    if (rfp->parent) {
		  s_vpi_value vp;
		  vp.format = vpiIntVal;
		  vpi_get_value(rfp->id.index, &vp);
		  return vp.value.integer;
	    } else
		  return 0;

	  case vpiSize:
	    if (rfp->msb >= rfp->lsb)
		  return rfp->msb - rfp->lsb + 1;
	    else
		  return rfp->lsb - rfp->msb + 1;

	  case vpiNetType:
	    if (ref->vpi_type->type_code==vpiNet)
		  return vpiWire;
	    else
		  return 0;

	  case vpiLeftRange: return rfp->msb;
	  case vpiRightRange: return rfp->lsb;

	  case _vpiNexusId:
	    if (rfp->msb == rfp->lsb)
		  return (int) (unsigned long) rfp->node;
	    else
		  return 0;

	  default:
	    fprintf(stderr, "signal_get: property %d is unknown\n", code);
	    return 0;
      }
}

static char* signal_get_str(int code, vpiHandle ref)
{
      assert((ref->vpi_type->type_code==vpiNet)
	     || (ref->vpi_type->type_code==vpiReg));

      struct __vpiSignal*rfp = (struct __vpiSignal*)ref;

      if (code == vpiFile) {  // Not implemented for now!
	    return simple_set_rbuf_str(file_names[0]);
      }

      char *nm, *ixs;
      if (rfp->parent) {
	    nm = strdup(vpi_get_str(vpiName, rfp->parent));
	    s_vpi_value vp;
	    vp.format = vpiDecStrVal;
	    vpi_get_value(rfp->id.index, &vp);
            ixs = vp.value.str;  /* do I need to strdup() this? */
      } else {
	    nm = strdup(rfp->id.name);
	    ixs = NULL;
      }

      char *rbuf = generic_get_str(code, &rfp->scope->base, nm, ixs);
      free(nm);
      return rbuf;
}

static vpiHandle signal_get_handle(int code, vpiHandle ref)
{
      assert((ref->vpi_type->type_code==vpiNet)
	     || (ref->vpi_type->type_code==vpiReg));

      struct __vpiSignal*rfp = (struct __vpiSignal*)ref;

      switch (code) {

	  case vpiParent:
	    return rfp->parent;

	  case vpiIndex:
	    return rfp->parent ? rfp->id.index : 0;

	  case vpiScope:
	    return &rfp->scope->base;

	  case vpiModule:
	      { struct __vpiScope*scope = rfp->scope;
	        while (scope && scope->base.vpi_type->type_code != vpiModule)
		      scope = scope->scope;

		assert(scope);
		return &scope->base;
	      }
      }

      return 0;
}

static vpiHandle signal_iterate(int code, vpiHandle ref)
{
      assert((ref->vpi_type->type_code==vpiNet)
	     || (ref->vpi_type->type_code==vpiReg));

      struct __vpiSignal*rfp = (struct __vpiSignal*)ref;

      if (code == vpiIndex) {
	    return rfp->parent ? array_index_iterate(code, rfp->id.index) : 0;
      }

      return 0;
}

static unsigned signal_width(const struct __vpiSignal*rfp)
{
      unsigned wid = (rfp->msb >= rfp->lsb)
	    ? (rfp->msb - rfp->lsb + 1)
	    : (rfp->lsb - rfp->msb + 1);

      return wid;
}

/*
 * The get_value method reads the values of the functors and returns
 * the vector to the caller. This causes no side-effect, and reads the
 * variables like a %load would.
 */
static void signal_get_value(vpiHandle ref, s_vpi_value*vp)
{
      assert((ref->vpi_type->type_code==vpiNet)
	     || (ref->vpi_type->type_code==vpiReg));

      struct __vpiSignal*rfp = (struct __vpiSignal*)ref;

      unsigned wid = signal_width(rfp);

      vvp_fun_signal_vec*vsig = dynamic_cast<vvp_fun_signal_vec*>(rfp->node->fun);
      assert(vsig);

      switch (vp->format) {

	  case vpiIntVal:
	    format_vpiIntVal(vsig, 0, wid, rfp->signed_flag, vp);
	    break;

	  case vpiScalarVal:
	    format_vpiScalarVal(vsig, 0, vp);
	    break;

	  case vpiStrengthVal:
	    format_vpiStrengthVal(vsig, 0, wid, vp);
	    break;

	  case vpiBinStrVal:
	    format_vpiBinStrVal(vsig, 0, wid, vp);
	    break;

	  case vpiHexStrVal: {
	    format_vpiHexStrVal(vsig, 0, wid, vp);
	    break;
	  }

	  case vpiOctStrVal:
	    format_vpiOctStrVal(vsig, 0, wid, vp);
	    break;

	  case vpiDecStrVal:
	    format_vpiDecStrVal(vsig, 0, wid, rfp->signed_flag, vp);
	    break;

	  case vpiStringVal:
	    format_vpiStringVal(vsig, 0, wid, vp);
	    break;

	  case vpiVectorVal:
	    format_vpiVectorVal(vsig, 0, wid, vp);
	    break;

	  case vpiRealVal: {
	    format_vpiRealVal(vsig, 0, wid, rfp->signed_flag, vp);
	    break;
	  }

	  default:
	    fprintf(stderr, "vvp internal error: get_value: "
		    "value type %u not implemented."
		    " Signal is %s in scope %s\n",
		    vp->format, vpi_get_str(vpiName, ref), rfp->scope->name);
	    assert(0);
      }
}

/*
 * The put_value method writes the value into the vector, and returns
 * the affected ref. This operation works much like the %set or
 * %assign instructions and causes all the side-effects that the
 * equivalent instruction would cause.
 */

static vvp_vector4_t from_stringval(const char*str, unsigned wid)
{
      unsigned idx;
      const char*cp;

      cp = str + strlen(str);
      idx = 0;

      vvp_vector4_t val(wid, BIT4_0);

      while ((idx < wid) && (cp > str)) {
	    unsigned byte = *--cp;
	    int bit;

	    for (bit = 0 ;  bit < 8 ;  bit += 1) {
		  if (byte & 1)
			val.set_bit(idx, BIT4_1);

		  byte >>= 1;
		  idx += 1;
	    }
      }

      return val;
}

static vvp_bit4_t scalar_to_bit4(PLI_INT32 scalar)
{
      switch(scalar) {
	  case vpi0:
	    return BIT4_0;
	  case vpi1:
	    return BIT4_1;
	  case vpiX:
	    return BIT4_X;
	  case vpiZ:
	    return BIT4_Z;
	  default:
	    fprintf(stderr, "Unsupported scalar value %d.\n", scalar);
	    assert(0);
      }
}

static vpiHandle signal_put_value(vpiHandle ref, s_vpi_value*vp, int flags)
{
      unsigned wid;
      struct __vpiSignal*rfp = vpip_signal_from_handle(ref);
      assert(rfp);

	/* If this is a release, then we are not really putting a
	   value. Instead, issue a release "command" to the signal
	   node to cause it to release a forced value. */
      if (flags == vpiReleaseFlag) {
	    vvp_net_ptr_t dest_cmd(rfp->node, 3);
	      /* Assume this is a net. (XXXX Are we sure?) */
	    vvp_send_long(dest_cmd, 2 /* release/net */);
	    return ref;
      }

	/* Make a vvp_vector4_t vector to receive the translated value
	   that we are going to poke. This will get populated
	   differently depending on the format. */
      wid = (rfp->msb >= rfp->lsb)
	    ? (rfp->msb - rfp->lsb + 1)
	    : (rfp->lsb - rfp->msb + 1);


      vvp_vector4_t val = vec4_from_vpi_value(vp, wid);

	/* If this is a vpiForce, then instead of writing to the
	   signal input port, we write to the special "force" port. */
      int dest_port = 0;
      if (flags == vpiForceFlag)
	    dest_port = 2;

	/* This is the destination that I'm going to poke into. Make
	   it from the vvp_net_t pointer, and assume a write to
	   port-0. This is the port where signals receive input. */
      vvp_net_ptr_t destination (rfp->node, dest_port);

      vvp_send_vec4(destination, val);

      return ref;
}

vvp_vector4_t vec4_from_vpi_value(s_vpi_value*vp, unsigned wid)
{
      vvp_vector4_t val (wid, BIT4_0);

      switch (vp->format) {

	  case vpiIntVal: {
		long vpi_val = vp->value.integer;
		for (unsigned idx = 0 ;  idx < wid ;  idx += 1) {
		      vvp_bit4_t bit = vpi_val&1 ? BIT4_1 : BIT4_0;
		      val.set_bit(idx, bit);
		      vpi_val >>= 1;
		}
		break;
	  }

	  case vpiVectorVal:
	    for (unsigned idx = 0 ;  idx < wid ;  idx += 1) {
		  unsigned long aval = vp->value.vector[idx/32].aval;
		  unsigned long bval = vp->value.vector[idx/32].bval;
		  aval >>= idx%32;
		  bval >>= idx%32;
		  int bitmask = (aval&1) | ((bval<<1)&2);
		  vvp_bit4_t bit = scalar_to_bit4(bitmask);
		  val.set_bit(idx, bit);
	    }
	    break;
	  case vpiBinStrVal:
	    vpip_bin_str_to_vec4(val, vp->value.str, false);
	    break;
	  case vpiOctStrVal:
	    vpip_oct_str_to_vec4(val, vp->value.str);
	    break;
	  case vpiDecStrVal:
	    vpip_dec_str_to_vec4(val, vp->value.str, false);
	    break;
	  case vpiHexStrVal:
	    vpip_hex_str_to_vec4(val, vp->value.str);
	    break;
	  case vpiScalarVal:
	    val.set_bit(0, scalar_to_bit4(vp->value.scalar));
	    break;
	  case vpiStringVal:
	    val = from_stringval(vp->value.str, wid);
	    break;

	  default:
	    fprintf(stderr, "vvp internal error: put_value: "
		    "value type %u not implemented here.\n",
		    vp->format);
	    assert(0);

      }

      return val;
}

static const struct __vpirt vpip_reg_rt = {
      vpiReg,
      signal_get,
      signal_get_str,
      signal_get_value,
      signal_put_value,
      signal_get_handle,
      signal_iterate,
      0
};

static const struct __vpirt vpip_net_rt = {
      vpiNet,
      signal_get,
      signal_get_str,
      signal_get_value,
      signal_put_value,
      signal_get_handle,
      signal_iterate,
      0
};


/*
 * Construct a vpiIntegerVar object. Indicate the type using a flag
 * to minimize the code modifications. Icarus implements integers
 * as 'reg signed [31:0]'.
 */
vpiHandle vpip_make_int(const char*name, int msb, int lsb, vvp_net_t*vec)
{
      vpiHandle obj = vpip_make_net(name, msb,lsb, true, vec);
      struct __vpiSignal*rfp = (struct __vpiSignal*)obj;
      obj->vpi_type = &vpip_reg_rt;
      rfp->isint_ = true;
      return obj;
}

/*
 * Construct a vpiReg object. It's like a net, except for the type.
 */
vpiHandle vpip_make_reg(const char*name, int msb, int lsb,
			bool signed_flag, vvp_net_t*vec)
{
      vpiHandle obj = vpip_make_net(name, msb,lsb, signed_flag, vec);
      obj->vpi_type = &vpip_reg_rt;
      return obj;
}

static struct __vpiSignal* allocate_vpiSignal(void)
{
      static struct __vpiSignal*alloc_array = 0;
      static unsigned alloc_index = 0;
      const unsigned alloc_count = 512;

      if ((alloc_array == 0) || (alloc_index == alloc_count)) {
	    alloc_array = (struct __vpiSignal*)
		  calloc(alloc_count, sizeof(struct __vpiSignal));
	    alloc_index = 0;
      }

      struct __vpiSignal*cur = alloc_array + alloc_index;
      alloc_index += 1;
      return cur;
}

/*
 * Construct a vpiNet object. Give the object specified dimensions,
 * and point to the specified functor for the lsb.
 *
 * The name is the PLI name for the object. If it is an array it is
 * <name>[<index>].
 */
vpiHandle vpip_make_net(const char*name, int msb, int lsb,
			bool signed_flag, vvp_net_t*node)
{
      struct __vpiSignal*obj = allocate_vpiSignal();
      obj->base.vpi_type = &vpip_net_rt;
      obj->parent = 0;
      obj->id.name = name? vpip_name_string(name) : 0;
      obj->msb = msb;
      obj->lsb = lsb;
      obj->signed_flag = signed_flag? 1 : 0;
      obj->isint_ = false;
      obj->node = node;

      obj->scope = vpip_peek_current_scope();

      count_vpi_nets += 1;

      return &obj->base;
}

static int PV_get_base(struct __vpiPV*rfp)
{
	/* We return from the symbol base if it is defined. */
      if (rfp->sbase != 0) {
	    s_vpi_value val;
	    val.format = vpiIntVal;
	    vpi_get_value(rfp->sbase, &val);
	    return val.value.integer;
      }

	/* If the width is zero then tbase is the constant. */
      if (rfp->twid == 0) return rfp->tbase;

      int tval = 0;
      for (unsigned idx = 0 ;  idx < rfp->twid ;  idx += 1) {
	    vvp_bit4_t bit = vthread_get_bit(vpip_current_vthread,
                                             rfp->tbase + idx);
	    if (bit == BIT4_1) {
		  tval |= 1<<idx;
	    }
      }

      return tval;
}

static int PV_get(int code, vpiHandle ref)
{
      assert(ref->vpi_type->type_code == vpiPartSelect);
      struct __vpiPV*rfp = (struct __vpiPV*)ref;

      int rval = 0;
      switch (code) {
	case vpiLineNo:
	    return 0;  // Not implemented for now!

	case vpiSigned:
	    return 0;  // A part/bit select is always unsigned!

	case vpiSize:
	    return rfp->width;

	case vpiConstantSelect:
	    return rfp->twid == 0;

	case vpiLeftRange: rval += rfp->width;
	case vpiRightRange:
	    rval += vpi_get(vpiRightRange, rfp->parent) + PV_get_base(rfp);
	    return rval;

	default:
	    fprintf(stderr, "PV_get: property %d is unknown\n", code);
      }

      return 0;
}

static char* PV_get_str(int code, vpiHandle ref)
{
      assert(ref->vpi_type->type_code == vpiPartSelect);
      struct __vpiPV*rfp = (struct __vpiPV*)ref;

      switch (code) {
	case vpiFile:  // Not implemented for now!
	    return simple_set_rbuf_str(file_names[0]);

	case vpiName:
	case vpiFullName: {
	    const char*nm = vpi_get_str(code, rfp->parent);
	    char full[1024+strlen(nm)];
	    sprintf(full, "%s[%d:%d]", nm, vpi_get(vpiLeftRange, ref),
	                                   vpi_get(vpiRightRange, ref));
	    return simple_set_rbuf_str(full);
	}

	default:
	    fprintf(stderr, "PV_get_str: property %d is unknown\n", code);
      }

      return 0;
}

static void PV_get_value(vpiHandle ref, p_vpi_value vp)
{
      assert(ref->vpi_type->type_code == vpiPartSelect);
      struct __vpiPV*rfp = (struct __vpiPV*)ref;

      vvp_fun_signal_vec*sig = dynamic_cast<vvp_fun_signal_vec*>(rfp->net->fun);
      assert(sig);

      switch (vp->format) {

	  case vpiIntVal:
	    format_vpiIntVal(sig, PV_get_base(rfp), rfp->width, 0, vp);
	    break;

	  case vpiBinStrVal:
	    format_vpiBinStrVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiOctStrVal:
	    format_vpiOctStrVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiHexStrVal:
	    format_vpiHexStrVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiDecStrVal:
	    format_vpiDecStrVal(sig, PV_get_base(rfp), rfp->width, 0, vp);
	    break;

	  case vpiStringVal:
	    format_vpiStringVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiScalarVal:
	    format_vpiScalarVal(sig, PV_get_base(rfp), vp);
	    break;

	  case vpiStrengthVal:
	    format_vpiStrengthVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiVectorVal:
	    format_vpiVectorVal(sig, PV_get_base(rfp), rfp->width, vp);
	    break;

	  case vpiRealVal:
	    format_vpiRealVal(sig, PV_get_base(rfp), rfp->width, 0, vp);
	    break;

	  default:
	    fprintf(stderr, "vvp internal error: PV_get_value: "
		    "value type %u not implemented. Signal is %s.\n",
		    vp->format, vpi_get_str(vpiFullName, rfp->parent));
	    assert(0);
      }
}

static vpiHandle PV_put_value(vpiHandle ref, p_vpi_value vp, int)
{
      assert(ref->vpi_type->type_code == vpiPartSelect);
      struct __vpiPV*rfp = (struct __vpiPV*)ref;
      vvp_fun_signal_vec*sig = dynamic_cast<vvp_fun_signal_vec*>(rfp->net->fun);
      assert(sig);

      unsigned sig_size = sig->size();
      unsigned width = rfp->width;
      int base = PV_get_base(rfp);
      if (base >= (signed) sig_size) return 0;
      if (base + (signed) width < 0) return 0;

      vvp_vector4_t val = vec4_from_vpi_value(vp, width);

	/*
	 * If the base is less than zero then trim off any unneeded
	 * lower bits.
	 */
      if (base < 0) {
	    width += base;
	    val = val.subvalue(-base, width);
	    base = 0;
      }

	/*
	 * If the value is wider than the signal then trim off any
	 * unneeded upper bits.
	 */
      if (base+width > sig_size) {
	    width = sig_size - base;
	    val = val.subvalue(0, width);
      }

      bool full_sig = base == 0 && width == sig_size;

      vvp_net_ptr_t dest(rfp->net, 0);

      if (full_sig) {
	    vvp_send_vec4(dest, val);
      } else {
	    vvp_send_vec4_pv(dest, val, base, width, sig_size);
      }

      return 0;
}

static vpiHandle PV_get_handle(int code, vpiHandle ref)
{
      assert(ref->vpi_type->type_code==vpiPartSelect);
      struct __vpiPV*rfp = (struct __vpiPV*)ref;

      switch (code) {

	  case vpiParent:
	    return rfp->parent;
	    break;
      }

      return 0;
}

static const struct __vpirt vpip_PV_rt = {
      vpiPartSelect,
      PV_get,
      PV_get_str,
      PV_get_value,
      PV_put_value,
      PV_get_handle,
      0
};

struct __vpiPV* vpip_PV_from_handle(vpiHandle obj)
{
      if (obj->vpi_type->type_code == vpiPartSelect)
	    return (__vpiPV*) obj;
      else
	    return 0;
}

vpiHandle vpip_make_PV(char*var, int base, int width)
{
      struct __vpiPV*obj = (struct __vpiPV*) malloc(sizeof(struct __vpiPV));
      obj->base.vpi_type = &vpip_PV_rt;
      obj->parent = vvp_lookup_handle(var);
      obj->sbase = 0;
      obj->tbase = base;
      obj->twid = 0;
      obj->width = (unsigned) width;
      obj->net = (vvp_net_t*) malloc(sizeof(vvp_net_t));
      functor_ref_lookup(&obj->net, var);

      return &obj->base;
}

vpiHandle vpip_make_PV(char*var, char*symbol, int width)
{
      struct __vpiPV*obj = (struct __vpiPV*) malloc(sizeof(struct __vpiPV));
      obj->base.vpi_type = &vpip_PV_rt;
      obj->parent = vvp_lookup_handle(var);
      compile_vpi_lookup(&obj->sbase, symbol);
      obj->tbase = 0;
      obj->twid = 0;
      obj->width = (unsigned) width;
      obj->net = (vvp_net_t*) malloc(sizeof(vvp_net_t));
      functor_ref_lookup(&obj->net, var);

      return &obj->base;
}

vpiHandle vpip_make_PV(char*var, int tbase, int twid, int width)
{
      struct __vpiPV*obj = (struct __vpiPV*) malloc(sizeof(struct __vpiPV));
      obj->base.vpi_type = &vpip_PV_rt;
      obj->parent = vvp_lookup_handle(var);
      obj->sbase = 0;
      obj->tbase = tbase;
      obj->twid = (unsigned) twid;
      obj->width = (unsigned) width;
      obj->net = (vvp_net_t*) malloc(sizeof(vvp_net_t));
      functor_ref_lookup(&obj->net, var);

      return &obj->base;
}

void vpip_part_select_value_change(struct __vpiCallback*cbh, vpiHandle ref)
{
      struct __vpiPV*obj = vpip_PV_from_handle(ref);
      assert(obj);

      vvp_fun_signal_base*sig_fun;
      sig_fun = dynamic_cast<vvp_fun_signal_base*>(obj->net->fun);
      assert(sig_fun);

	/* Attach the __vpiCallback object to the signal. */
      sig_fun->add_vpi_callback(cbh);
}