guard CSR[misa] checks

Author: jevinjojo

spec/std/isa/csr/cycle.yaml

@@ -45,7 +45,7 @@ sw_read(): |
       raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
     }
   } else if (mode() == PrivilegeMode::U) {
-    if (CSR[misa].S == 1'b1) {
+    if ((!MISA_CSR_IMPLEMENTED) || ((!MISA_CSR_IMPLEMENTED) || (CSR[misa].S == 1'b1))) {
       # S-mode is present ->
       #   mcounteren and scounteren together determine access in U-mode
       if ((CSR[mcounteren].CY & CSR[scounteren].CY) == 1'b0) {

spec/std/isa/csr/mip.yaml

@@ -411,6 +411,6 @@ sw_read(): |
   # OR in the hidden smode external interrupt
   return
     $bits(CSR[mip])
-    | ((CSR[misa].S == 1'b1 && pending_smode_external_interrupt)
+    | (((!MISA_CSR_IMPLEMENTED) || ((!MISA_CSR_IMPLEMENTED) || (CSR[misa].S == 1'b1 ))&& pending_smode_external_interrupt)
          ? 10'h200
          : 0);