From 4b6b34e131363d8eca9bb0114b76db9f2350236c Mon Sep 17 00:00:00 2001
From: David Anderson <dave@natulte.net>
Date: Mon, 9 Sep 2024 11:15:43 -0700
Subject: [PATCH] vram/VRAMCore: add tests, fix bug found by same

---
 vram/VRAMCore.bsv      |   4 +-
 vram/VRAMCore_Test.bsv | 196 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 198 insertions(+), 2 deletions(-)
 create mode 100644 vram/VRAMCore_Test.bsv

diff --git a/vram/VRAMCore.bsv b/vram/VRAMCore.bsv
index bc120d6..b704c95 100644
--- a/vram/VRAMCore.bsv
+++ b/vram/VRAMCore.bsv
@@ -120,7 +120,7 @@ module mkByteRAMArray(Integer num_chips, ByteRAM ifc);
       method Action put(ChipAddr chip_select, Bool write, ByteAddr addr, VRAMData data_in);
          for (Integer i=0; i<num_chips; i=i+1)
             blocks[i].portA.put(chip_select, write, addr, data_in);
-         if (write)
+         if (!write)
             read_chip_A <= chip_select;
       endmethod
       method VRAMData read();
@@ -138,7 +138,7 @@ module mkByteRAMArray(Integer num_chips, ByteRAM ifc);
       method Action put(ChipAddr chip_select, Bool write, ByteAddr addr, VRAMData data_in);
          for (Integer i=0; i<num_chips; i=i+1)
             blocks[i].portB.put(chip_select, write, addr, data_in);
-         if (write)
+         if (!write)
             read_chip_B <= chip_select;
       endmethod
       method VRAMData read();
diff --git a/vram/VRAMCore_Test.bsv b/vram/VRAMCore_Test.bsv
new file mode 100644
index 0000000..6f0c1df
--- /dev/null
+++ b/vram/VRAMCore_Test.bsv
@@ -0,0 +1,196 @@
+package VRAMCore_Test;
+
+import Assert::*;
+import GetPut::*;
+import ClientServer::*;
+import Testing::*;
+import StmtFSM::*;
+
+import VRAMCore::*;
+import Testing::*;
+
+interface Machine;
+   method Action start(VRAMAddr start, VRAMAddr count);
+   method Bool done();
+endinterface
+
+function ActionValue#(Bool) verbose();
+   return (actionvalue
+              let ret <- $test$plusargs("v");
+              return ret;
+           endactionvalue);
+endfunction
+
+typedef (function ActionValue#(Bit#(8)) next()) ValFn;
+
+function ValFn constant_value(Integer cnst);
+   function ActionValue#(Bit#(8)) next();
+      return (actionvalue
+                 return fromInteger(cnst);
+              endactionvalue);
+   endfunction
+
+   return next;
+endfunction
+
+module mkIncrementingValue(ValFn);
+   Reg#(Bit#(8)) val <- mkReg(0);
+
+   function ActionValue#(Bit#(8)) next();
+      return (actionvalue
+                 val <= val+1;
+                 return val;
+              endactionvalue);
+   endfunction
+
+   return next;
+endmodule
+
+module mkWriter(Server#(VRAMRequest, VRAMResponse) dut, ValFn next_value, Machine ifc);
+   let flags <- mkTestFlags();
+   let cycles <- mkCycleCounter();
+   let write_cycle_time <- mkCycleCounter();
+
+   Reg#(VRAMAddr) total <- mkReg(0);
+   Reg#(VRAMAddr) remaining <- mkReg(0);
+   Reg#(VRAMAddr) idx <- mkReg(0);
+
+   rule write (remaining > 0);
+      dynamicAssert(write_cycle_time == 1, "write didn't happen every cycle");
+      write_cycle_time.reset();
+
+      let data <- next_value();
+      let req = VRAMRequest{
+         addr: idx,
+         data: tagged Valid data
+      };
+      dut.request.put(req);
+
+      if (flags.verbose)
+         $display("%0d: write(%0d, %0d)", cycles.all, idx, data);
+
+      if (remaining == 1)
+         $display("Wrote %0d values in %0d cycles", total, cycles);
+      remaining <= remaining-1;
+      idx <= idx+1;
+   endrule
+
+   method Action start(VRAMAddr start_addr, VRAMAddr count) if (remaining == 0);
+      cycles.reset();
+      write_cycle_time.reset();
+      total <= count;
+      remaining <= count;
+      idx <= start_addr;
+   endmethod
+
+   method Bool done();
+      return remaining == 0;
+   endmethod
+endmodule
+
+module mkReader(Server#(VRAMRequest, VRAMResponse) dut, ValFn next_value, Machine ifc);
+   let flags <- mkTestFlags();
+   let cycles <- mkCycleCounter();
+
+   Reg#(VRAMAddr) total <- mkReg(0);
+
+   Reg#(VRAMAddr) issue_remaining <- mkReg(0);
+   Reg#(VRAMAddr) issue_idx <- mkReg(0);
+
+   Reg#(VRAMAddr) verify_remaining <- mkReg(0);
+   Reg#(VRAMAddr) verify_idx <- mkReg(0);
+
+   rule issue_read (issue_remaining > 0);
+      let req = VRAMRequest{
+         addr: issue_idx,
+         data: tagged Invalid
+      };
+      dut.request.put(req);
+
+      if (flags.verbose)
+         $display("%0d: issue_read(%0d)", cycles.all, issue_idx);
+
+      if (issue_remaining == 1)
+         $display("Issued %0d reads in %0d cycles", total, cycles);
+      issue_remaining <= issue_remaining-1;
+      issue_idx <= issue_idx+1;
+   endrule
+
+   rule verify_read (verify_remaining > 0);
+      let got <- dut.response.get();
+      let want <- next_value();
+      dynamicAssert(got.data == want, "wrong value seen during read");
+
+      if (flags.verbose)
+         $display("%0d: verify_read(%0d) = %0d, want %0d", cycles.all, verify_idx, got, want);
+
+      if (verify_remaining == 1)
+         $display("Verified %0d reads in %0d cycles", total, cycles);
+      verify_remaining <= verify_remaining-1;
+      verify_idx <= verify_idx+1;
+   endrule
+
+   method Action start(VRAMAddr start_addr, VRAMAddr count) if (issue_remaining == 0 && verify_remaining == 0);
+      cycles.reset();
+      total <= count;
+      issue_remaining <= count;
+      verify_remaining <= count;
+      issue_idx <= start_addr;
+      verify_idx <= start_addr;
+   endmethod
+
+   method Bool done();
+      return issue_remaining == 0 && verify_remaining == 0;
+   endmethod
+endmodule
+
+(* descending_urgency="writer.write,reader.issue_read" *)
+module mkSimpleTest(VRAMCore dut, Stmt ret);
+   let winc <- mkIncrementingValue();
+   let writer <- mkWriter(dut.portA, winc);
+
+   let rinc <- mkIncrementingValue();
+   let reader <- mkReader(dut.portA, rinc);
+
+   return (seq
+              writer.start(3000, 6000);
+              await(writer.done);
+
+              reader.start(3000, 6000);
+              await(reader.done);
+           endseq);
+endmodule
+
+module mkTwoPortTest(VRAMCore dut, Stmt ret);
+   let winc <- mkIncrementingValue();
+   let writer <- mkWriter(dut.portA, winc);
+
+   let rinc <- mkIncrementingValue();
+   let reader <- mkReader(dut.portB, rinc);
+
+   return (seq
+              writer.start(0, 1000);
+              // Delay a little before starting the reader, so it's
+              // trailing the writer by a few addrs.
+              repeat (2) noAction;
+              reader.start(0, 1000);
+              await(writer.done);
+              await(reader.done);
+           endseq);
+endmodule
+
+(* descending_urgency="simple.reader.issue_read,two_port.writer.write" *)
+module mkTB(Empty);
+   let dut <- mkVRAMCore(112);
+
+   let simple <- mkSimpleTest(dut);
+   let two_port <- mkTwoPortTest(dut);
+
+   runTest(100000,
+      mkTest("VRAMCore", seq
+         mkTest("VRAMCore/simple", simple);
+         mkTest("VRAMCore/two_port", two_port);
+      endseq));
+endmodule
+
+endpackage