Add regression tests for unary real minus special values

Check that unary real minus preserves the sign or bit pattern for zero,
NaN, and infinity. Each test starts with the positive value, negates it,
and then negates the result back to the positive value.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/ivltests/real_unary_minus_inf.v

@@ -0,0 +1,31 @@
+// Check that unary real minus preserves infinities.
+
+module test;
+
+  reg failed;
+  real inf;
+  real result;
+
+  `define check(val, exp) \
+    if (val !== exp) begin \
+      $display("FAILED(%0d). '%s' expected %h, got %h", `__LINE__, \
+               `"val`", exp, val); \
+      failed = 1'b1; \
+    end
+
+  initial begin
+    failed = 1'b0;
+    inf = $bitstoreal(64'h7ff0000000000000);
+
+    result = -inf;
+    `check($realtobits(result), 64'hfff0000000000000);
+
+    result = -result;
+    `check($realtobits(result), 64'h7ff0000000000000);
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/ivltests/real_unary_minus_nan.v

@@ -0,0 +1,31 @@
+// Check that unary real minus preserves NaN bits.
+
+module test;
+
+  reg failed;
+  real nan;
+  real result;
+
+  `define check(val, exp) \
+    if (val !== exp) begin \
+      $display("FAILED(%0d). '%s' expected %h, got %h", `__LINE__, \
+               `"val`", exp, val); \
+      failed = 1'b1; \
+    end
+
+  initial begin
+    failed = 1'b0;
+    nan = $bitstoreal(64'h7ff8000000000001);
+
+    result = -nan;
+    `check($realtobits(result), 64'hfff8000000000001);
+
+    result = -result;
+    `check($realtobits(result), 64'h7ff8000000000001);
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/ivltests/real_unary_minus_zero.v

@@ -0,0 +1,31 @@
+// Check that unary real minus preserves the sign of zero.
+
+module test;
+
+  reg failed;
+  real zero;
+  real result;
+
+  `define check(val, exp) \
+    if (val !== exp) begin \
+      $display("FAILED(%0d). '%s' expected %h, got %h", `__LINE__, \
+               `"val`", exp, val); \
+      failed = 1'b1; \
+    end
+
+  initial begin
+    failed = 1'b0;
+    zero = 0.0;
+
+    result = -zero;
+    `check($realtobits(result), 64'h8000000000000000);
+
+    result = -result;
+    `check($realtobits(result), 64'h0000000000000000);
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/regress-vvp.list

@@ -214,6 +214,9 @@ pv_wr_fn_vec4			vvp_tests/pv_wr_fn_vec4.json
 queue_fail			vvp_tests/queue_fail.json
 readmem-invalid			vvp_tests/readmem-invalid.json
 real_negative_zero		vvp_tests/real_negative_zero.json
+real_unary_minus_inf		vvp_tests/real_unary_minus_inf.json
+real_unary_minus_nan		vvp_tests/real_unary_minus_nan.json
+real_unary_minus_zero		vvp_tests/real_unary_minus_zero.json
 scaled_real			vvp_tests/scaled_real.json
 scan-invalid			vvp_tests/scan-invalid.json
 sdf_interconnect1		vvp_tests/sdf_interconnect1.json

ivtest/vvp_tests/real_unary_minus_inf.json

@@ -0,0 +1,4 @@
+{
+    "type"   : "normal",
+    "source" : "real_unary_minus_inf.v"
+}

ivtest/vvp_tests/real_unary_minus_nan.json

@@ -0,0 +1,4 @@
+{
+    "type"   : "normal",
+    "source" : "real_unary_minus_nan.v"
+}

ivtest/vvp_tests/real_unary_minus_zero.json

@@ -0,0 +1,4 @@
+{
+    "type"   : "normal",
+    "source" : "real_unary_minus_zero.v"
+}