From fb5790302186502ee87cc8f7ca4e93bd6cd895ae Mon Sep 17 00:00:00 2001
From: David Anderson <dave@natulte.net>
Date: Sun, 8 Sep 2024 09:26:59 -0700
Subject: [PATCH] vram/VRAMCore: make simulatable in Bluesim, tidy up

---
 vram/VRAMCore.bsv | 98 +++++++++++++++++++++++++++--------------------
 1 file changed, 56 insertions(+), 42 deletions(-)

diff --git a/vram/VRAMCore.bsv b/vram/VRAMCore.bsv
index bad4d92..bc120d6 100644
--- a/vram/VRAMCore.bsv
+++ b/vram/VRAMCore.bsv
@@ -1,15 +1,9 @@
 package VRAMCore;
 
-import Connectable::*;
 import GetPut::*;
 import ClientServer::*;
-import DReg::*;
-import BRAM::*;
-import Vector::*;
-import FIFOF::*;
-import SpecialFIFOs::*;
+import BRAMCore::*;
 import Real::*;
-import Printf::*;
 
 import DelayLine::*;
 import ECP5_RAM::*;
@@ -18,31 +12,71 @@ export VRAMAddr;
 export VRAMData;
 export VRAMRequest(..);
 export VRAMResponse(..);
-export VRAMClient(..);
-export VRAMServer(..);
 export VRAMCore(..);
 export mkVRAMCore;
 
 typedef Bit#(8) VRAMData;
 
-// Each byte RAM we build below can address 4096 bytes, which is 12
-// address bits.
-typedef UInt#(12) ByteAddr;
-
+typedef UInt#(17) VRAMAddr;
+typedef UInt#(2) ArrayAddr;
 typedef UInt#(3) ChipAddr;
+typedef UInt#(12) ByteAddr;
 
 // ByteRAM is two EBRs glued together to make a whole-byte memory.
 typedef EBR#(ByteAddr, VRAMData, ByteAddr, VRAMData) ByteRAM;
 
+typedef struct {
+   VRAMAddr addr;
+   Maybe#(VRAMData) data;
+} VRAMRequest deriving (Bits, Eq);
+
+typedef struct {
+   VRAMData data;
+} VRAMResponse deriving (Bits, Eq);
+
+module mkNibbleRAM_ECP5(ChipAddr chip_addr, EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) ifc);
+   EBRPortConfig cfg = defaultValue;
+   cfg.chip_select_addr = chip_addr;
+   let _ret <- mkEBRCore(cfg, cfg);
+   return _ret;
+endmodule
+
+module mkNibbleRAM_Sim(ChipAddr chip_addr, EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) ifc);
+   BRAM_DUAL_PORT#(ByteAddr, Bit#(4)) ram <- mkBRAMCore2(4096, False);
+
+   interface EBRPort portA;
+      method Action put(UInt#(3) chip_select, Bool write, ByteAddr address, Bit#(4) datain);
+         if (chip_select == chip_addr)
+            ram.a.put(write, address, datain);
+      endmethod
+      method read = ram.a.read;
+   endinterface
+
+   interface EBRPort portB;
+      method Action put(UInt#(3) chip_select, Bool write, ByteAddr address, Bit#(4) datain);
+         if (chip_select == chip_addr)
+            ram.b.put(write, address, datain);
+      endmethod
+      method read = ram.b.read;
+   endinterface
+endmodule
+
+module mkNibbleRAM(ChipAddr chip_addr, EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) ifc);
+   let _ret;
+   if (genC())
+      _ret <- mkNibbleRAM_Sim(chip_addr);
+   else
+      _ret <- mkNibbleRAM_ECP5(chip_addr);
+   return _ret;
+endmodule
+
 // mkByteRAM glues two ECP5 EBRs together to make a 4096x8b memory
 // block. Like the underlying ECP5 EBRs, callers must bring their own
 // flow control to read out responses one cycle after putting a read
 // request.
 module mkByteRAM(ChipAddr chip_addr, ByteRAM ifc);
-   EBRPortConfig cfg = defaultValue;
-   cfg.chip_select_addr = chip_addr;
-   EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) upper <- mkEBRCore(cfg, cfg);
-   EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) lower <- mkEBRCore(cfg, cfg);
+   EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) upper <- mkNibbleRAM(chip_addr);
+   EBR#(ByteAddr, Bit#(4), ByteAddr, Bit#(4)) lower <- mkNibbleRAM(chip_addr);
 
    interface EBRPort portA;
       method Action put(ChipAddr chip_select, Bool write, ByteAddr addr, VRAMData data_in);
@@ -119,25 +153,9 @@ module mkByteRAMArray(Integer num_chips, ByteRAM ifc);
    endinterface
 endmodule
 
-typedef UInt#(2) ArrayAddr;
-
-typedef UInt#(17) VRAMAddr;
-
-typedef struct {
-   VRAMAddr addr;
-   Maybe#(VRAMData) data;
-} VRAMRequest deriving (Bits, Eq);
-
-typedef struct {
-   VRAMData data;
-} VRAMResponse deriving (Bits, Eq);
-
-typedef Server#(VRAMRequest, VRAMResponse) VRAMServer;
-typedef Client#(VRAMRequest, VRAMResponse) VRAMClient;
-
 interface VRAMCore;
-   interface VRAMServer portA;
-   interface VRAMServer portB;
+   interface Server#(VRAMRequest, VRAMResponse) portA;
+   interface Server#(VRAMRequest, VRAMResponse) portB;
 endinterface
 
 // mkVRAMCore creates a dual port VRAM of the specified size, using
@@ -163,11 +181,7 @@ module mkVRAMCore(Integer num_kilobytes, VRAMCore ifc);
    let num_arrays = ceil(fromInteger(num_byterams) / 8);
 
    function Tuple3#(ArrayAddr, ChipAddr, ByteAddr) split_addr(VRAMAddr a);
-      if (num_bytes < 128*1024)
-         a = a % fromInteger(num_bytes);
-      match {.top, .byteaddr} = split(pack(a));
-      Tuple2#(Bit#(SizeOf#(ArrayAddr)), Bit#(SizeOf#(ChipAddr))) route = split(top);
-      return tuple3(unpack(tpl_1(route)), unpack(tpl_2(route)), unpack(byteaddr));
+      return unpack(pack(a));
    endfunction
 
    ByteRAM arrays[num_arrays];
@@ -179,7 +193,7 @@ module mkVRAMCore(Integer num_kilobytes, VRAMCore ifc);
    Reg#(Maybe#(ArrayAddr)) inflight_A[2] <- mkCReg(2, tagged Invalid);
    Reg#(Maybe#(ArrayAddr)) inflight_B[2] <- mkCReg(2, tagged Invalid);
 
-   interface VRAMServer portA;
+   interface Server portA;
       interface Put request;
          method Action put(VRAMRequest req) if (inflight_A[1] matches tagged Invalid);
             match {.array, .chip, .byteaddr} = split_addr(req.addr);
@@ -196,7 +210,7 @@ module mkVRAMCore(Integer num_kilobytes, VRAMCore ifc);
       endinterface
    endinterface
 
-   interface VRAMServer portB;
+   interface Server portB;
       interface Put request;
          method Action put(VRAMRequest req) if (inflight_B[1] matches tagged Invalid);
             match {.array, .chip, .byteaddr} = split_addr(req.addr);