lab7 & final project

branchpred.py

+import math
+
+class PHT:
+    def __init__(self, bits):
+        self.pht = {}
+        self.bits = bits
+        self.size = 2 ** bits
+        self.history = (1 << self.bits) - 1
+        self.predCorrect = 0
+        self.inpredCorrect = 0
+        self.phtInit()
+
+    def phtInit(self):
+        for k in range(self.size):
+            self.pht[k] = 1
+
+    def update(self, pc, taken):
+        if self.pht[self.history] == 1:
+            if taken: 
+                self.predCorrect += 1
+            else:
+                self.inpredCorrect += 1
+                self.pht[self.history] -= 1
+        else:
+            if taken != 1: 
+                self.predCorrect += 1
+            else:
+                self.inpredCorrect += 1
+                self.pht[self.history] += 1
+        self.history = (self.history >> 1) | (int(taken) << (self.bits - 1))
+
+    def display(self):
+        print(f"PHT")
+        accuracy = self.predCorrect / (self.predCorrect+self.inpredCorrect)
+        print(f"Prediction Accurancy is:\n {accuracy:.2f}\n")
+
+class BHT:
+    def __init__(self, size, bits, wSize):
+        self.bht = {}
+        self.size = size
+        self.bits = bits
+        self.byteOffset = int(math.log(wSize, 2))
+        self.indexBits = int(math.log(size, 2))
+        self.predCorrect = 0
+        self.inpredCorrect = 0
+        self.bhtInit()
+    
+    def bhtInit(self):
+        for key in range(self.size):
+            self.bht[key] = (1 << self.bits) - 1
+    
+    def index(self, pc):
+        return (pc >> self.byteOffset) & ((1 << self.indexBits) - 1)
+    
+    def update(self, pc, taken):
+        i = self.index(pc)
+        if self.bits == 1:
+            if self.bht[i] == 1:
+                if taken: 
+                    self.predCorrect += 1
+                else:
+                    self.inpredCorrect += 1
+                    self.bht[i] -= 1
+            else:
+                if taken != 1: 
+                    self.predCorrect += 1
+                else:
+                    self.inpredCorrect += 1
+                    self.bht[i] += 1
+        elif self.bits == 2:
+            if (self.bht[i] == 2) or (self.bht[i] == 3):
+                if taken: 
+                    self.predCorrect += 1
+                    if self.bht[i] == 2: 
+                        self.bht[i] += 1
+                else:
+                    self.inpredCorrect += 1
+                    self.bht[i] -= 1
+            else:
+                if taken != 1: 
+                    self.predCorrect += 1
+                    if self.bht[i] == 1: 
+                        self.bht[i] -= 1
+                else:
+                    self.inpredCorrect += 1
+                    self.bht[i] += 1
+
+    def display(self):
+        print(f"BHT")
+        accuracy = self.predCorrect / (self.predCorrect+self.inpredCorrect)
+        print(f"Prediction Accurancy is:\n {accuracy:.2f}\n")
\ No newline at end of file

onestage_elf.py

@@ -12,6 +12,7 @@ from riscv_isa import Instruction, decoder
 from regfile import RegFile
 from mux import make_mux
 from alu import alu
+from branchpred import BHT, PHT
 
 control = decoder.control
 ALU = lambda op1, op2, alu_fun: alu(op1, op2, alu_fun)
@@ -23,6 +24,9 @@ imem = elfMem
 PC = Register()
 RF = RegFile()
 DM = Memory(elfMem)
+# branch predictors
+bht = BHT(8, 2, 4)
+pht = PHT(4)
 
 #RF.clock(2, 0xEFFFF, True)
 #RF.regs[2] = 0xeffff #pointer
@@ -149,6 +153,9 @@ for t in itertools.count():
         pc_des = 3
     PC.clock(pc_change[pc_des])
 
+    bht.update(pc_val, takeBranch)
+    pht.update(pc_val, takeBranch)
+
     # memory
     rData = None
     if (mem_em):
@@ -165,12 +172,15 @@ for t in itertools.count():
                 print(f"{t:20d}:", display())
                 status = "TEST PASS" if RF.read(10) == 0 else "TEST FAIL"
                 print(status)
+                bht.display()
+                pht.display()
                 if status == "TEST FAIL":
                     exit(1)
                 if status == "TEST PASS":
                     exit(0)
                 RF.display()
                 print (f"SYSCALL: exit ({val>>1})")
+                
                 sys.exit(val>>1)
             else:
                 which = DM.mem[DM.mem[symbolTable['tohost']]]
@@ -198,6 +208,9 @@ for t in itertools.count():
             print(f"ECALL({RF.read(10)}): {RF.read(11)}\n")
             status = "TEST PASS" if RF.read(10) == 0 else "TEST FAIL"
             print(status)
+            RF.display()
+            bht.display()
+            pht.display()
             if status == "TEST FAIL":
                 exit(1)
             if status == "TEST PASS":
@@ -207,6 +220,8 @@ for t in itertools.count():
             status = "TEST PASS" if RF.read(10) == 0 else "TEST FAIL"
             print(status)
             RF.display()
+            bht.display()
+            pht.display()
             if status == "TEST FAIL":
                 exit(1)
             if status == "TEST PASS":
@@ -216,9 +231,14 @@ for t in itertools.count():
             strr = f"ECALL({RF.read(10)}): "
             if RF.read(10) == 10:
                 print(strr + 'EXIT\n')
+                RF.display()
+                bht.display()
+                pht.display()
             else:
                 print(strr + 'HALT\n')
                 RF.display()
+                bht.display()
+                pht.display()
                 break
 ###################################################################################
    
@@ -229,11 +249,14 @@ for t in itertools.count():
     if imem[PC.out()] == 0:
         status = "TEST PASS" if RF.read(10) == 0 else "TEST FAIL"
         print(status)
+        bht.display()
+        pht.display()
         if status == "TEST FAIL":
             exit(1)
         if status == "TEST PASS":
             exit(0)
         #print("Done -- end of program.")
+        
         print("------------------------------<  Final reg values  >------------------------------")
         RF.display()
         break
\ No newline at end of file