Implemented vm memory using external 23LCV512 chip.

Todo: implement extended registers

arduino/arduino.ino

@@ -21,16 +21,48 @@ limitations under the License.
 
 #include "vm.h"
 #include "console.h"
+#include "memory.h"
 
 VM vm;
 Console console(&vm);
 
+//Expecting a Microchip 23LCV512 connected over MOSI/MISO/MCLK
+Memory mem(20000000, MSBFIRST, SPI_MODE0, 4);
+
 void setup() {
+  //Setup VM
   vm_reset(&vm);
   vm.error = vm_print_error;
   vm.syscall = vm_syscall;
-  Serial.begin(1200);
+  vm.readAddr = vm_read_addr;
+  vm.writeAddr = vm_write_addr;
+
+  //Start serial
+  Serial.begin(9600);
   console.setSerial(&Serial);
+
+  //Init memory
+  SPI.begin();
+  mem.setSize(VM_MEM_SIZE);
+  if (!mem.init()) {
+    Serial.println("Memory failed to init!");
+  } else {
+    mem.writeRange(0x55, 0, VM_MEM_SIZE);
+#ifdef TEST_DESTRUCTIVE
+    Serial.print("Testing ");
+    Serial.print(mem.getSize(), DEC);
+    Serial.print(" bytes memory... ");
+    unsigned long startTime = millis();
+    if (mem.test()) {
+      Serial.println("OK");
+    } else {
+      Serial.println("ERROR!");
+    }
+    Serial.print("Tested in ");
+    Serial.print(millis() - startTime, DEC);
+    Serial.println("ms");
+#endif
+  }
 }
 
 void loop() {
@@ -45,7 +77,8 @@ void vm_print_error(uint8_t err) {
       Serial.println("Halted. PC misaligned.");
       break;
     case VM_ERR_UNKNOWN_OP:
-      Serial.println("Halted. Unknown instruction. (this should never happen)");
+      //Will only happen if an instruction is not handled in the vm
+      Serial.println("Halted. Unknown instruction.");
       break;
     case VM_ERR_OUT_OF_BOUNDS:
       Serial.println("Halted. Operation out of bounds.");
@@ -80,3 +113,10 @@ uint8_t vm_syscall(VM* vm, uint8_t callno, uint8_t imm) {
   return 0;
 }
 
+uint8_t vm_read_addr(uint16_t addr) {
+  return mem.read(addr);
+}
+void vm_write_addr(uint16_t addr, uint8_t data) {
+  mem.write(addr, data);
+}
+

arduino/console.cpp

@@ -83,7 +83,7 @@ void Console::printMemory(uint16_t from, uint16_t to) {
       serial->print(i, HEX);
       serial->print(" ");
     }
-    uint8_t m = this->vm->M[i];
+    uint8_t m = this->vm->readAddr(i);
     if (m < 0x10) {
       serial->print("0");
     }
@@ -95,8 +95,8 @@ void Console::printMemory(uint16_t from, uint16_t to) {
 
 void Console::loop() {
   HardwareSerial * serial = this->serial;
-  int i;
-      
+  uint32_t i;
+  
   switch(this->state) {
     case CONSOLE_NONE:
       serial->println("Press Enter to activate console.");
@@ -155,7 +155,7 @@ void Console::loop() {
     case CONSOLE_CLEAR:
       vm_reset(this->vm);
       for(i = 0; i < VM_MEM_SIZE; i++) {
-        this->vm->M[i] = 0;
+        this->vm->writeAddr(i, 0);
       }
       serial->println("VM Reset & Memory Cleared");
       this->state = CONSOLE_ACTIVATE;
@@ -315,7 +315,7 @@ void Console::stateExamine() {
             for(int i = 0; i < x.length(); i += 2) {
               value = this->hexToDec(x.substring(i, i+2));
               if (value >= 0 && value <= 255) {
-                this->vm->M[location++] = value;
+                this->vm->writeAddr(location++, value);
               } else {
                 serial->println(i);
                 serial->println(x.substring(i, i+2));

arduino/memory.cpp

@@ -0,0 +1,127 @@
+/*
+Copyright 2018 Sam Stevens
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+ */
+
+#include "memory.h"
+
+Memory::Memory(uint32_t clock, uint8_t bitOrder, uint8_t dataMode, uint8_t csPin) {
+  //Set cs pin high
+  this->csPin = csPin;
+  pinMode(csPin, OUTPUT);
+  digitalWrite(csPin, HIGH);
+  //Default to 64k ram
+  this->memSize = 0xFFFF;
+  //Store spi setting
+  this->setting = SPISettings(clock, bitOrder, dataMode);
+}
+
+void Memory::start() {
+  digitalWrite(this->csPin, LOW);
+  SPI.beginTransaction(this->setting);
+}
+void Memory::end() {
+  SPI.endTransaction();
+  digitalWrite(this->csPin, HIGH);
+}
+
+bool Memory::init() {
+  //Set mode to sequential access (should be default mode)
+  this->start();
+  SPI.transfer(INSTR_WRMR);
+  SPI.transfer(MODE_SEQ);
+  this->end();
+
+  //Verify that it was set
+  this->start();
+  SPI.transfer(INSTR_RDMR);
+  uint8_t mode = SPI.transfer(0);
+  this->end();
+  
+  return mode == MODE_SEQ;
+}
+
+uint16_t Memory::getSize() {
+  return this->memSize;
+}
+
+void Memory::setSize(uint16_t memSize) {
+  this->memSize = memSize;
+}
+
+uint8_t Memory::read(uint16_t addr) {
+  this->start();
+  SPI.transfer(INSTR_READ);
+  SPI.transfer16(addr);
+  uint8_t data = SPI.transfer(0);
+  this->end();
+  return data;
+}
+
+void Memory::write(uint16_t addr, uint8_t data) {
+  this->start();
+  SPI.transfer(INSTR_WRITE);
+  SPI.transfer16(addr);
+  SPI.transfer(data);
+  this->end();
+}
+
+void Memory::writeRange(uint8_t data, uint16_t from, uint16_t to) {
+  if (from > to) {
+    return;
+  }
+  this->start();
+  SPI.transfer(INSTR_WRITE);
+  SPI.transfer16(from);
+  for(uint32_t i = from; i < to; i++) {
+    SPI.transfer(data);
+  }
+  this->end();
+}
+
+bool Memory::verifyRange(uint8_t data, uint16_t from, uint16_t to) {
+  if (from > to) {
+    return false;
+  }
+  this->start();
+  SPI.transfer(INSTR_READ);
+  SPI.transfer16(from);
+  bool ok = true;
+  for(uint32_t i = from; i < to; i++) {
+    if (SPI.transfer(0) != data) {
+      ok = false;
+      break;
+    }
+  }
+  this->end();
+  return ok;
+}
+
+bool Memory::test() {
+  //write 0x55 (01010101)
+  this->writeRange(0x55, 0, this->memSize);
+  //verify
+  if (!this->verifyRange(0x55, 0, this->memSize)) {
+    return false;
+  }
+  
+  //write zeros
+  this->writeRange(0, 0, this->memSize);
+  //verify zeros
+  if (!this->verifyRange(0, 0, this->memSize)) {
+    return false;
+  }
+  return true;
+}
+

arduino/memory.h

@@ -0,0 +1,57 @@
+/*
+Copyright 2018 Sam Stevens
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+ */
+
+#ifndef UVM_MEMORY_H
+#define UVM_MEMORY_H
+
+#include <SPI.h>
+
+enum MemoryMode_t {
+  MODE_BYTE = 0x00,
+  MODE_PAGE = 0x80,
+  MODE_SEQ  = 0x40
+};
+typedef enum MemoryMode_t MemoryMode;
+
+enum MemoryInstruction_t {
+  INSTR_READ  = 0x03,
+  INSTR_WRITE = 0x02,
+  INSTR_EDIO  = 0x3B,
+  INSTR_RESIO = 0xFF,
+  INSTR_RDMR  = 0x05,
+  INSTR_WRMR  = 0x01
+};
+typedef enum MemoryInstruction_t MemoryInstruction;
+
+class Memory {
+    SPISettings setting;
+    uint8_t csPin;
+    uint16_t memSize;
+    void start();
+    void end();
+  public:
+    Memory(uint32_t clock, uint8_t bitOrder, uint8_t dataMode, uint8_t csPin);
+    uint16_t getSize();
+    void setSize(uint16_t memSize);
+    bool init();
+    uint8_t read(uint16_t addr);
+    void write(uint16_t addr, uint8_t data);
+    void writeRange(uint8_t data, uint16_t from, uint16_t to) ;
+    bool verifyRange(uint8_t data, uint16_t from, uint16_t to);
+    bool test();
+};
+
+#endif //UVM_MEMORY_H

arduino/vm.c

@@ -36,7 +36,6 @@ void vm_reset(VM *vm) {
 
 void vm_clear(VM *vm) {
     vm_reset(vm);
-    memset(&vm->M, 0, VM_MEM_SIZE);
 }
 
 inline uint8_t vm_get_r(VM *vm, uint8_t r) {
@@ -99,7 +98,7 @@ void vm_step(VM *vm) {
         vm->halted = true;
         return;
     }
-    uint16_t raw = (vm->M[PC] << 8) + vm->M[PC + 1];
+    uint16_t raw = (vm->readAddr(PC) << 8) + vm->readAddr(PC + 1);
     vm->PC += 2;
     inst.op = (uint8_t) (raw >> 12);
 
@@ -118,7 +117,7 @@ void vm_step(VM *vm) {
             temp16 = x;
             temp16 += inst.imm;
             if (temp16 < VM_MEM_SIZE) {
-              d = vm->M[temp16];
+              d = vm->readAddr(temp16);
             } else {
               if (vm->error != NULL) {
                 vm->error(VM_ERR_OUT_OF_BOUNDS);
@@ -132,7 +131,7 @@ void vm_step(VM *vm) {
             temp16 = vm_get_r(vm, inst.rd);
             temp16 += inst.imm;
             if (temp16 < VM_MEM_SIZE) {
-              vm->M[temp16] = x;
+              vm->writeAddr(temp16, x);
             } else {
               if (vm->error != NULL) {
                 vm->error(VM_ERR_OUT_OF_BOUNDS);

arduino/vm.h

@@ -20,7 +20,7 @@ limitations under the License.
 #include <stdint.h>
 #include <stdbool.h>
 
-#define VM_MEM_SIZE 256
+#define VM_MEM_SIZE 0xFFFF
 #define VM_REG_SIZE 16
 
 #define OP_HLT 0x0
@@ -60,9 +60,10 @@ typedef struct VM_Instruction_t VM_Instruction;
 struct VM_t {
     uint8_t R[VM_REG_SIZE];
     uint8_t PC;
-    uint8_t M[VM_MEM_SIZE];
     uint8_t carry;
     bool halted;
+    uint8_t (*readAddr)(uint16_t addr);
+    void (*writeAddr)(uint16_t addr, uint8_t data);
     uint8_t (*syscall)(struct VM_t* vm, uint8_t callno, uint8_t imm);
     void (*error)(uint8_t err);
 };