D3AA simulator

1 files changed, 119 insertions, 0 deletions

diff --git a/src/peripherals/avrdx-nvmctrl.ts b/src/peripherals/avrdx-nvmctrl.ts
new file mode 100644
index 0000000..2321023
--- /dev/null
+++ b/src/peripherals/avrdx-nvmctrl.ts
@@ -0,0 +1,119 @@
+// AVR-Dx NVMCTRL + Mapped EEPROM
+// EEPROM is memory-mapped at 0x1400-0x14FF and accessed via NVMCTRL commands.
+
+import type { CPU } from 'avr8js/cpu/cpu';
+import type { AVRDxCCP } from './avrdx-ccp';
+
+const CTRLA    = 0x0000;
+// const CTRLB    = 0x0001;
+// const STATUS   = 0x0002;
+// const INTCTRL  = 0x0003;
+// const INTFLAGS = 0x0004;
+// const DATAL    = 0x0006;
+// const DATAH    = 0x0007;
+// const ADDR0    = 0x0008;
+// const ADDR1    = 0x0009;
+// const ADDR2    = 0x000A;
+// const ADDR3    = 0x000B;
+
+// CMD values
+const CMD_NONE_gc           = 0x00;
+const CMD_NOOP_gc           = 0x01;
+// const CMD_FLWR_gc           = 0x02;
+// const CMD_FLPER_gc          = 0x08;
+// const CMD_FLMPER2_gc        = 0x09;
+// const CMD_FLMPER4_gc        = 0x0A;
+// const CMD_FLMPER8_gc        = 0x0B;
+// const CMD_FLMPER16_gc       = 0x0C;
+// const CMD_FLMPER32_gc       = 0x0D;
+const CMD_EEWR_gc           = 0x12;
+const CMD_EEERWR_gc         = 0x13;
+const CMD_EEBER_gc          = 0x18;
+// const CMD_EEMBER2_gc        = 0x19;
+// const CMD_EEMBER4_gc        = 0x1A;
+// const CMD_EEMBER8_gc        = 0x1B;
+// const CMD_EEMBER16_gc       = 0x1C;
+// const CMD_EEMBER32_gc       = 0x1D;
+
+export class AVRDxNVMCTRL {
+  readonly eeprom: Uint8Array;
+  /** Page buffer for EEPROM writes (tracks which bytes have been written) */
+  private pageBuffer: Uint8Array;
+  private pageBufferDirty: Uint8Array;
+
+  constructor(cpu: CPU, base: number, start: number, private size: number, private ccp: AVRDxCCP, init: undefined | Uint8Array = undefined) {
+    this.eeprom = new Uint8Array(size);
+    this.pageBuffer = new Uint8Array(size);
+    this.pageBufferDirty = new Uint8Array(size);
+
+    this.eeprom.fill(0xFF);
+    if (init) this.loadEeprom(init);
+
+    // CTRLA - CCP protected, executes NVM commands
+    cpu.writeHooks[base + CTRLA] = (value: number) => {
+      if (this.ccp.isUnlocked()) {
+        cpu.data[base + CTRLA] = value;
+        this.executeCommand(value);
+      }
+      return true;
+    };
+
+    // Mapped EEPROM read hooks (0x1400-0x14FF)
+    for (let i = 0; i < size; i++) {
+      cpu.readHooks[start + i] = () => this.eeprom[i];
+
+      // Writes to mapped EEPROM go to the page buffer
+      cpu.writeHooks[start + i] = (value: number) => {
+        this.pageBuffer[i] = value;
+        this.pageBufferDirty[i] = 1;
+
+        // Check the current active command
+        const cmd = cpu.data[base + CTRLA];
+
+        if (cmd === CMD_EEERWR_gc) {
+          // Erase+write: replace byte directly
+          this.eeprom[i] = value;
+          this.pageBufferDirty[i] = 0;
+        } else if (cmd === CMD_EEWR_gc) {
+          // Write-only: AND with existing data (can only clear bits)
+          this.eeprom[i] &= value;
+          this.pageBufferDirty[i] = 0;
+        }
+        return true;
+      };
+    }
+  }
+
+  loadEeprom(data: Uint8Array) {
+    this.eeprom.set(data.subarray(0, this.size));
+  }
+
+  private executeCommand(cmd: number) {
+    switch (cmd) {
+      case CMD_NONE_gc:
+      case CMD_NOOP_gc:
+        this.pageBufferDirty.fill(0);
+        break;
+      case CMD_EEWR_gc:
+        // Write-only mode: subsequent mapped EEPROM writes AND with existing data.
+        // Actual writes happen in the mapped EEPROM write hooks.
+        // Don't clear command — it stays active until NONE/NOOP.
+        break;
+      case CMD_EEERWR_gc:
+        // Erase+write mode: subsequent mapped EEPROM writes replace data directly.
+        // Actual writes happen in the mapped EEPROM write hooks.
+        // Don't clear command — it stays active until NONE/NOOP.
+        break;
+      case CMD_EEBER_gc:
+        // Erase EEPROM page (the page containing the address in ADDR)
+        // For simplicity, erase the whole EEPROM
+        // TODO: figure out page size
+        this.eeprom.fill(0xFF);
+        this.pageBufferDirty.fill(0);
+        break;
+      default:
+        // TODO: implement other commands (if needed)
+        break;
+    }
+  }
+}