From 97fd6a5a1327bec1af678494bde236b71af8128c Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sun, 22 Feb 2026 20:04:06 -0500
Subject: [PATCH] Support vpiScalarVal

---
 include/verilated_vpi.cpp    | 15 +++++++++++++++
 test_regress/t/t_vpi_var.cpp | 31 +++++++++++++++++++------------
 2 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/include/verilated_vpi.cpp b/include/verilated_vpi.cpp
index 6511d3c86..7bcee1bdc 100644
--- a/include/verilated_vpi.cpp
+++ b/include/verilated_vpi.cpp
@@ -2555,6 +2555,15 @@ bool vl_check_format(const VerilatedVpioVarBase* vop, const p_vpi_value valuep,
         case VLVT_REAL: return status;
         default: status = false;  // LCOV_EXCL_LINE
         }
+    } else if (valuep->format == vpiScalarVal) {
+        switch (varp->vltype()) {
+        case VLVT_UINT8:
+        case VLVT_UINT16:
+        case VLVT_UINT32:
+        case VLVT_UINT64:
+        case VLVT_WDATA: return status;
+        default: status = false;  // LCOV_EXCL_LINE
+        }
     } else if (valuep->format == vpiSuppressVal) {
         return status;
     } else {
@@ -2894,6 +2903,9 @@ void vl_vpi_get_value(const VerilatedVpioVarBase* vop, p_vpi_value valuep) {
         else
             valuep->value.real = *vop->varRealDatap();
 
+        return;
+    } else if (valuep->format == vpiScalarVal) {
+        valuep->value.scalar = get_word(vop, 32, 0) ? vpi1 : vpi0;
         return;
     } else if (valuep->format == vpiSuppressVal) {
         return;
@@ -3175,6 +3187,9 @@ vpiHandle vpi_put_value(vpiHandle object, p_vpi_value valuep, p_vpi_time /*time_
                 *(valueVop->varRealDatap()) = valuep->value.real;
                 return object;
             }
+        } else if (valuep->format == vpiScalarVal) {
+            vl_vpi_put_word(valueVop, (valuep->value.scalar == vpi1 ? 1 : 0), 1, 0);
+            return object;
         }
         VL_VPI_ERROR_(__FILE__, __LINE__, "%s: Unsupported format (%s) as requested for %s",
                       __func__, VerilatedVpiError::strFromVpiVal(valuep->format),
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 4aa8ca21f..caf9be138 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -420,18 +420,25 @@ int _mon_check_var() {
     }
 
     // other unsigned types
-    constexpr struct {
-        const char* name;
-        PLI_INT32 exp_type;
-    } uint_vars[] = {
-        // uvm_hdl_polling.v requires single bits return vpiBitVar
-        {"bit1", vpiBitVar},
-    };
-    for (const auto& s : uint_vars) {
-        TestVpiHandle vh101 = VPI_HANDLE(s.name);
-        CHECK_RESULT_NZ(vh101);
-        d = vpi_get(vpiType, vh101);
-        CHECK_RESULT(d, s.exp_type);
+    {
+        TestVpiHandle vh999 = VPI_HANDLE("bit1");
+        CHECK_RESULT_NZ(vh999);
+        d = vpi_get(vpiType, vh999);
+        CHECK_RESULT(d, vpiBitVar);  // Required by uvm_hdl_polling
+        for (PLI_INT32 i : {vpi0, vpi1, vpiX, vpiZ}) {
+            t_vpi_value value;
+            value.format = vpiScalarVal;
+            value.value.scalar = i;
+            vpi_put_value(vh999, &value, NULL, vpiNoDelay);
+            value.value.scalar = 9;
+            vpi_get_value(vh999, &value);
+#ifdef VERILATOR  // 2-state
+            const PLI_INT32 expv = (i == vpi1) ? vpi1 : vpi0;
+#else
+            const PLI_INT32 expv = i;
+#endif
+            TEST_CHECK_EQ(value.value.scalar, expv);
+        }
     }
 
     // other integer types