fix exc cause

openhwgroup · Aug 16, 2023 · 538f406 · 538f406
1 parent c4e9e51
commit 538f406
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/rtl/cve2_controller.sv b/rtl/cve2_controller.sv
@@ -502,9 +502,10 @@ module cve2_controller #(
           end else if (irqs_i.irq_fast != 16'b0) begin
             // generate exception cause ID from fast interrupt ID:
             // - first bit distinguishes interrupts from exceptions,
-            // - second bit adds 16 to fast interrupt ID
+            // - third bit adds 16 to fast interrupt ID so that the interrup 0 becomes 16 and the interrupt 15 becomes 31 (hence 5bits)
+            // - second bit is always 0 as the FAST interrupts are represented in the first 5bits, the 6th is always 0 cause is used by the NMI (in that case is 1 as represented by the number 32)
             // for example EXC_CAUSE_IRQ_FAST_0 = {1'b1, 6'd16}
-            exc_cause_o = exc_cause_e'({2'b11, mfip_id});
+            exc_cause_o = exc_cause_e'({3'b101, mfip_id});
           end else if (irqs_i.irq_external) begin
             exc_cause_o = EXC_CAUSE_IRQ_EXTERNAL_M;
           end else if (irqs_i.irq_software) begin