Formatting.

pipelined/src/cache/cache.sv

@@ -1,10 +1,11 @@
 ///////////////////////////////////////////
 // cache 
 //
-// Written: ross1728@gmail.com July 07, 2021
+// Written: Ross Thompson ross1728@gmail.com
-//          Implements the L1 instruction/data cache
+// Created: 7 July 2021
+// Modified: 20 January 2023
 //
-// Purpose: Storage for data and meta data.
+// Purpose: Implements the I$ and D$. Interfaces with requests from IEU and HPTW and ahbcacheinterface
 //
 // Documentation: RISC-V System on Chip Design Chapter 7 (Figures 7.9, 7.11, and 7.20)
 //

pipelined/src/cache/cacheLRU.sv

@@ -1,10 +1,13 @@
 ///////////////////////////////////////////
 // dcache (data cache)
 //
-// Written: ross1728@gmail.com July 20, 2021
+// Written: Ross Thompson ross1728@gmail.com
-//          Implements Pseudo LRU
+// Created: 20 July 2021
-//          Tested for Powers of 2.
+// Modified: 20 January 2023
 //
+// Purpose: Implements Pseudo LRU. Tested for Powers of 2.
+//
+// Documentation: RISC-V System on Chip Design Chapter 7 (Figures 7.8 and 7.16 to 7.19)
 //
 // A component of the CORE-V-WALLY configurable RISC-V project.
 //
@@ -28,18 +31,19 @@
 
 module cacheLRU
   #(parameter NUMWAYS = 4, SETLEN = 9, OFFSETLEN = 5, NUMLINES = 128) (
-  input  logic                clk, reset, 
+  input  logic                clk, 
-  input  logic                CacheEn, 
+  input  logic                reset, 
-  input  logic                FlushStage,
+  input  logic                FlushStage,      // Pipeline flush of second stage (prevent writes and bus operations)
-  input  logic [NUMWAYS-1:0]  HitWay,
+  input  logic                CacheEn,         // Enable the cache memory arrays.  Disable hold read data constant
-  input  logic [NUMWAYS-1:0]  ValidWay,
+  input  logic [NUMWAYS-1:0]  HitWay,          // Which way is valid and matches PAdr's tag
-  input  logic [SETLEN-1:0]   CAdr,
+  input  logic [NUMWAYS-1:0]  ValidWay,        // Which ways for a particular set are valid, ignores tag
-  input  logic [SETLEN-1:0]   PAdr,
+  input  logic [SETLEN-1:0]   CAdr,            // Cache address, the output of the address select mux, NextAdr, PAdr, or FlushAdr
-  input  logic                LRUWriteEn, 
+  input  logic [SETLEN-1:0]   PAdr,            // Physical address 
-  input  logic                SetValid, 
+  input  logic                LRUWriteEn,      // Update the LRU state
-  input  logic                InvalidateCache, 
+  input  logic                SetValid,        // Set the dirty bit in the selected way and set
-  input  logic                FlushCache,
+  input  logic                InvalidateCache, // Clear all valid bits
-  output logic [NUMWAYS-1:0]  VictimWay
+  input  logic                FlushCache,      // Flush all dirty lines back to memory
+  output logic [NUMWAYS-1:0]  VictimWay        // LRU selects a victim to evict
 );
 
   localparam                           LOGNUMWAYS = $clog2(NUMWAYS);

pipelined/src/cache/cachefsm.sv

@@ -1,11 +1,14 @@
 ///////////////////////////////////////////
 // dcache (data cache) fsm
 //
-// Written: ross1728@gmail.com August 25, 2021
+// Written: Ross Thompson ross1728@gmail.com
-//          Implements the L1 data cache fsm
+// Created: 25 August 2021
+// Modified: 20 January 2023
 //
 // Purpose: Controller for the dcache fsm
 //
+// Documentation: RISC-V System on Chip Design Chapter 7 (Figure 7.15 and Table 7.1)
+//
 // A component of the CORE-V-WALLY configurable RISC-V project.
 //
 // Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
@@ -39,33 +42,31 @@ module cachefsm (
   input  logic [1:0] CacheAtomic,       // Atomic operation
   input  logic       FlushCache,        // Flush all dirty lines back to memory
   input  logic       InvalidateCache,   // Clear all valid bits
-  // cache internals
-  input  logic       CacheHit,          // Exactly 1 way hits
-  input  logic       LineDirty,         // The selected line and way is dirty
-  input  logic       FlushAdrFlag,      // On last set of a cache flush
-  input  logic       FlushWayFlag,      // On the last way for any set of a cache flush
   // Bus controls
   input  logic       CacheBusAck,       // Bus operation completed
   output logic [1:0] CacheBusRW,        // [1] Read (cache line fetch) or [0] write bus (cache line writeback)
   // performance counter outputs
   output logic       CacheMiss,         // Cache miss  
   output logic       CacheAccess,		// Cache access
-  // Bus outputs
 
-  // dcache internals
+  // cache internals
-  output logic       SelAdr,
+  input  logic       CacheHit,          // Exactly 1 way hits
-  output logic       ClearValid,
+  input  logic       LineDirty,         // The selected line and way is dirty
-  output logic       ClearDirty,
+  input  logic       FlushAdrFlag,      // On last set of a cache flush
-  output logic       SetDirty,
+  input  logic       FlushWayFlag,      // On the last way for any set of a cache flush
-  output logic       SetValid,
+  output logic       SelAdr,            // [0] SRAM reads from NextAdr, [1] SRAM reads from PAdr
-  output logic       SelWriteback,
+  output logic       ClearValid,        // Clear the valid bit in the selected way and set
-  output logic       LRUWriteEn,
+  output logic       ClearDirty,        // Clear the dirty bit in the selected way and set
-  output logic       SelFlush,
+  output logic       SetValid,          // Set the dirty bit in the selected way and set
-  output logic       FlushAdrCntEn,
+  output logic       SetDirty,          // Set the dirty bit in the selected way and set
-  output logic       FlushWayCntEn, 
+  output logic       SelWriteback,      // Overrides cached tag check to select a specific way and set for writeback
-  output logic       FlushCntRst,
+  output logic       LRUWriteEn,        // Update the LRU state
-  output logic       SelFetchBuffer, 
+  output logic       SelFlush,          // [0] Use SelAdr, [1] SRAM reads/writes from FlushAdr
-  output logic       CacheEn
+  output logic       FlushAdrCntEn,     // Enable the counter for Flush Adr
+  output logic       FlushWayCntEn,     // Enable the way counter during a flush
+  output logic       FlushCntRst,       // Reset both flush counters
+  output logic       SelFetchBuffer,    // Bypass the SRAM for a load hit by directly using the read data from the ahbcacheinterface's FetchBuffer
+  output logic       CacheEn            // Enable the cache memory arrays.  Disable hold read data constant
 );
   
   logic               resetDelay;