Add support for signed thread base index for &A<>

This patch adds support for getting a signed index for &A<> from
thread space. This mimics what was done for &PV<>.

tgt-vvp/draw_vpi.c

@@ -155,19 +155,9 @@ static int get_vpi_taskfunc_signal_arg(struct args_info *result,
 			/* Fallback case: evaluate expression. */
 			struct vector_info av;
 			av = draw_eval_expr(word_ex, STUFF_OK_XZ);
-			/* We need to enhance &A<> to support a signed index. */
-			if (ivl_expr_signed(word_ex) &&
-			    (ivl_expr_width(word_ex) < 8*sizeof(int))) {
-			      fprintf(stderr, "%s:%u: tgt-vvp warning: V0.9 "
-			                      "may give incorrect results for "
-			                      "an array select with a signed "
-			                      "index less than %zu bits.\n",
-			                      ivl_expr_file(expr),
-			                      ivl_expr_lineno(expr),
-			                      8*sizeof(int));
-			}
-			snprintf(buffer, sizeof buffer, "&A<v%p, %u %u>",
-			         sig, av.base, av.wid);
+			snprintf(buffer, sizeof buffer, "&A<v%p, %u %u \"%s\">",
+			         sig, av.base, av.wid,
+			         (ivl_expr_signed(word_ex) ? "s" : "u"));
 			result->vec = av;
 			result->vec_flag = 1;
 		  } else {

vvp/README.txt

@@ -813,11 +813,14 @@ The &A<> argument is a reference to the word of a variable array. The
 syntax is:
 
    &A '<' <symbol> , <number> '>'
-   &A '<' <symbol> , <base> <width> '>'
+   &A '<' <symbol> , <base_symbol> '>'
+   &A '<' <symbol> , <base> <width> <"s" or "u"> '>'
 
 The <symbol> is the label for a variable array, and the <number> is
 the canonical word index as an unsigned integer. The second form
-retrieves the index from thread space (<width> bits starting at <base>).
+retrieves the <base> from the given signal or &A<>/&PV<> select.
+The third form retrieves the index from thread space (<width> bits
+starting at <base>). The base value may be signed or unsigned.
 
 * The &PV<> argument
 

vvp/array.cc

@@ -128,6 +128,7 @@ struct __vpiArrayVthrA {
 	// If wid >0, then the address is the base and wid the vector
 	// width of the index to pull from the thread.
       unsigned wid;
+      bool is_signed;
 
       unsigned get_address() const
       {
@@ -150,14 +151,37 @@ struct __vpiArrayVthrA {
 	    if (wid == 0)
 		  return address;
 
-	    vvp_vector4_t tmp (wid);
-	    for (unsigned idx = 0 ; idx < wid ; idx += 1) {
-		  vvp_bit4_t bit = vthread_get_bit(vpip_current_vthread, address+idx);
-		  tmp.set_bit(idx, bit);
+	      /* Get the value from thread space. */
+	    int tval = 0;
+	    for (unsigned idx = 0 ; (idx < wid) && (idx < 8*sizeof(tval));
+	         idx += 1) {
+		  vvp_bit4_t bit = vthread_get_bit(vpip_current_vthread,
+		                                   address + idx);
+		  switch (bit) {
+		      case BIT4_X:
+		      case BIT4_Z:
+			  /* Return UINT_MAX to indicate an X base. */
+			return UINT_MAX;
+			break;
+
+		      case BIT4_1:
+			tval |= 1<<idx;
+			break;
+
+		      case BIT4_0:
+			break;  // Do nothing!
 		  }
-	    unsigned long val = ULONG_MAX;
-	    vector4_to_value(tmp, val);
-	    return val;
+	    }
+
+	    if (is_signed && (wid < 8*sizeof(tval))) {
+		  vvp_bit4_t msb = vthread_get_bit(vpip_current_vthread,
+		                                   address + wid - 1);
+		  if (msb == BIT4_1) {
+			tval |= ~((1 << wid) - 1);
+		  }
+	    }
+
+	    return tval;
       }
 };
 
@@ -1547,7 +1571,8 @@ vpiHandle vpip_make_vthr_A(char*label, unsigned addr)
       return &(obj->base);
 }
 
-vpiHandle vpip_make_vthr_A(char*label, unsigned tbase, unsigned twid)
+vpiHandle vpip_make_vthr_A(char*label, unsigned tbase, unsigned twid,
+                           char*is_signed)
 {
       struct __vpiArrayVthrA*obj = (struct __vpiArrayVthrA*)
 	    malloc(sizeof (struct __vpiArrayVthrA));
@@ -1563,6 +1588,9 @@ vpiHandle vpip_make_vthr_A(char*label, unsigned tbase, unsigned twid)
       obj->address_handle = 0;
       obj->address = tbase;
       obj->wid = twid;
+      obj->is_signed = strcmp(is_signed, "s") == 0;
+
+      delete [] is_signed;
 
       return &(obj->base);
 }

vvp/parse.y

@@ -873,8 +873,8 @@ argument
 symbol_access
   : K_A '<' T_SYMBOL ',' T_NUMBER '>'
       { $$ = vpip_make_vthr_A($3, $5); }
-  | K_A '<' T_SYMBOL ',' T_NUMBER T_NUMBER '>'
-      { $$ = vpip_make_vthr_A($3, $5, $6); }
+  | K_A '<' T_SYMBOL ',' T_NUMBER T_NUMBER T_STRING '>'
+      { $$ = vpip_make_vthr_A($3, $5, $6, $7); }
   | K_A '<' T_SYMBOL ',' T_SYMBOL '>'
       { $$ = vpip_make_vthr_A($3, $5); }
   | K_A '<' T_SYMBOL ',' symbol_access '>'

vvp/vpi_priv.h

@@ -496,7 +496,8 @@ vpiHandle vpip_make_vthr_word(unsigned base, const char*type);
 
 vpiHandle vpip_make_vthr_A(char*label, unsigned index);
 vpiHandle vpip_make_vthr_A(char*label, char*symbol);
-vpiHandle vpip_make_vthr_A(char*label, unsigned tbase, unsigned twid);
+vpiHandle vpip_make_vthr_A(char*label, unsigned tbase, unsigned twid,
+                           char*is_signed);
 vpiHandle vpip_make_vthr_A(char*label, vpiHandle handle);
 
 /*