Assure that operands are the correct width.

tgt-vvp/eval_expr.c

@@ -17,12 +17,14 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #if !defined(WINNT)
-#ident "$Id: eval_expr.c,v 1.1 2001/03/22 05:06:21 steve Exp $"
+#ident "$Id: eval_expr.c,v 1.2 2001/03/23 01:10:24 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
 # include  <assert.h>
 
+struct vector_info draw_eval_expr_wid(ivl_expr_t exp, unsigned wid);
+
 static unsigned char allocation_map[0x10000/8];
 
 static inline int peek_bit(unsigned addr)
@@ -75,15 +77,21 @@ static unsigned short allocate_vector(unsigned short wid)
       return base;
 }
 
-/*
- * The draw_eval_expr() function draws code to evaluate the passed
- * expression, then returns the location and width of the result.
- */
 
-static struct vector_info draw_binary_expr(ivl_expr_t exp)
+static struct vector_info draw_binary_expr_eq(ivl_expr_t exp)
 {
-      struct vector_info lv = draw_eval_expr(ivl_expr_oper1(exp));
+      ivl_expr_t le = ivl_expr_oper1(exp);
-      struct vector_info rv = draw_eval_expr(ivl_expr_oper2(exp));
+      ivl_expr_t re = ivl_expr_oper2(exp);
+
+      struct vector_info lv;
+      struct vector_info rv;
+
+      unsigned wid = ivl_expr_width(le);
+      if (ivl_expr_width(re) > wid)
+	    wid = ivl_expr_width(re);
+
+      lv = draw_eval_expr_wid(le, wid);
+      rv = draw_eval_expr_wid(re, wid);
 
       switch (ivl_expr_opcode(exp)) {
 	  case 'e': /* == */
@@ -115,17 +123,73 @@ static struct vector_info draw_binary_expr(ivl_expr_t exp)
       return lv;
 }
 
-static struct vector_info draw_number_expr(ivl_expr_t exp)
+static struct vector_info draw_binary_expr(ivl_expr_t exp, unsigned wid)
+{
+      struct vector_info rv;
+
+      switch (ivl_expr_opcode(exp)) {
+	  case 'e': /* == */
+	  case 'n': /* != */
+	    assert(wid == 1);
+	    rv = draw_binary_expr_eq(exp);
+	    break;
+
+	  default:
+	    assert(0);
+      }
+
+      return rv;
+}
+
+/*
+ * A number in an expression is made up by copying constant bits into
+ * the allocated vector.
+ */
+static struct vector_info draw_number_expr(ivl_expr_t exp, unsigned wid)
 {
       unsigned idx;
-      unsigned wid = ivl_expr_width(exp);
+      struct vector_info res;
       const char*bits = ivl_expr_bits(exp);
 
-      struct vector_info res;
-      res.base = allocate_vector(wid);
       res.wid  = wid;
 
-      for (idx = 0 ;  idx < wid ;  idx += 1) {
+      assert(ivl_expr_width(exp) >= wid);
+
+	/* If all the bits of the number have the same value, then we
+	   can use a constant bit. There is no need to allocate wr
+	   bits, and there is no need to generate any code. */
+
+      for (idx = 1 ;  idx < res.wid ;  idx += 1) {
+	    if (bits[idx] != bits[0])
+		  break;
+      }
+
+      if (idx == res.wid) {
+	    switch (bits[0]) {
+		case '0':
+		  res.base = 0;
+		  break;
+		case '1':
+		  res.base = 1;
+		  break;
+		case 'x':
+		  res.base = 2;
+		  break;
+		case 'z':
+		  res.base = 3;
+		  break;
+	    }
+	    return res;
+      }
+
+	/* The number value needs to be represented as an allocated
+	   vector. Allocate the vector and use %mov instructions to
+	   load the constant bit values. */
+      res.base = allocate_vector(wid);
+
+      idx = 0;
+      while (idx < wid) {
+	    unsigned cnt;
 	    char src = '?';
 	    switch (bits[idx]) {
 		case '0':
@@ -142,30 +206,44 @@ static struct vector_info draw_number_expr(ivl_expr_t exp)
 		  break;
 	    }
 
-	    fprintf(vvp_out, "    %%mov %u, %c, 1;\n", res.base+idx, src);
+	    for (cnt = 1 ;  idx+cnt < wid ;  cnt += 1)
+		  if (bits[idx+cnt] != bits[idx])
+			break;
+
+	    fprintf(vvp_out, "    %%mov %u, %c, %u;\n",
+		    res.base+idx, src, cnt);
+
+	    idx += cnt;
       }
 
       return res;
 }
 
-static struct vector_info draw_signal_expr(ivl_expr_t exp)
+static struct vector_info draw_signal_expr(ivl_expr_t exp, unsigned wid)
 {
       unsigned idx;
-      unsigned wid = ivl_expr_width(exp);
+      unsigned swid = ivl_expr_width(exp);
       const char*name = ivl_expr_name(exp);
       struct vector_info res;
 
+      if (swid > wid)
+	    swid = wid;
+
       res.base = allocate_vector(wid);
       res.wid  = wid;
 
-      for (idx = 0 ;  idx < wid ;  idx += 1)
+      for (idx = 0 ;  idx < swid ;  idx += 1)
 	    fprintf(vvp_out, "    %%load  %u, V_%s[%u];\n",
 		    res.base+idx, name, idx);
 
+	/* Pad the signal value with zeros. */
+      if (swid < wid)
+	    fprintf(vvp_out, "    %%mov %u, 0, %u;\n",
+		    res.base+swid, wid-swid);
       return res;
 }
 
-struct vector_info draw_eval_expr(ivl_expr_t exp)
+struct vector_info draw_eval_expr_wid(ivl_expr_t exp, unsigned wid)
 {
       struct vector_info res;
 
@@ -178,23 +256,31 @@ struct vector_info draw_eval_expr(ivl_expr_t exp)
 	    break;
 
 	  case IVL_EX_BINARY:
-	    res = draw_binary_expr(exp);
+	    res = draw_binary_expr(exp, wid);
 	    break;
 
 	  case IVL_EX_NUMBER:
-	    res = draw_number_expr(exp);
+	    res = draw_number_expr(exp, wid);
 	    break;
 
 	  case IVL_EX_SIGNAL:
-	    res = draw_signal_expr(exp);
+	    res = draw_signal_expr(exp, wid);
 	    break;
       }
 
       return res;
 }
 
+struct vector_info draw_eval_expr(ivl_expr_t exp)
+{
+      return draw_eval_expr_wid(exp, ivl_expr_width(exp));
+}
+
 /*
  * $Log: eval_expr.c,v $
+ * Revision 1.2  2001/03/23 01:10:24  steve
+ *  Assure that operands are the correct width.
+ *
  * Revision 1.1  2001/03/22 05:06:21  steve
  *  Geneate code for conditional statements.
  *