feat(avm): implement addressing modes for MOV (#4490)

Creates `Addressing` class to handle addressing modes.
I might later change the instruction constructors to take/accept `Addressing`.

Closes: #4266.

yarn-project/simulator/src/avm/opcodes/addressing_mode.test.ts

@@ -0,0 +1,49 @@
+import { TaggedMemory, Uint32 } from '../avm_memory_types.js';
+import { Addressing, AddressingMode } from './addressing_mode.js';
+
+describe('Addressing', () => {
+  it('should reserialize correctly', () => {
+    const addressingMode = Addressing.fromWire(0b10101010);
+    const wireModes = addressingMode.toWire();
+    expect(wireModes).toBe(0b10101010);
+  });
+
+  it('should convert to wire format correctly', () => {
+    const addressingMode = new Addressing([
+      AddressingMode.INDIRECT,
+      AddressingMode.DIRECT,
+      AddressingMode.INDIRECT,
+      AddressingMode.DIRECT,
+    ]);
+    const wireModes = addressingMode.toWire();
+    expect(wireModes).toBe(0b00000101);
+  });
+
+  it('should convert from wire format correctly', () => {
+    const addressingMode = Addressing.fromWire(0b00011001);
+    const expected = new Addressing([
+      AddressingMode.INDIRECT,
+      AddressingMode.DIRECT,
+      AddressingMode.DIRECT,
+      AddressingMode.INDIRECT,
+      AddressingMode.INDIRECT,
+      AddressingMode.DIRECT,
+      AddressingMode.DIRECT,
+      AddressingMode.DIRECT,
+    ]);
+
+    expect(addressingMode).toStrictEqual(expected);
+  });
+
+  it('should resolve offsets correctly', () => {
+    const addressingMode = Addressing.fromWire(0b00011001);
+    const offsets = [10, 20, 30];
+    const mem = new TaggedMemory();
+    mem.set(10, new Uint32(100));
+    mem.set(20, new Uint32(200));
+    mem.set(30, new Uint32(300));
+
+    const resolved = addressingMode.resolve(offsets, mem);
+    expect(resolved).toEqual([100, 20, 30]);
+  });
+});

yarn-project/simulator/src/avm/opcodes/addressing_mode.ts

@@ -0,0 +1,66 @@
+import { strict as assert } from 'assert';
+
+import { TaggedMemory, TypeTag } from '../avm_memory_types.js';
+
+export enum AddressingMode {
+  DIRECT,
+  INDIRECT,
+  INDIRECT_PLUS_CONSTANT, // Not implemented yet.
+}
+
+/** A class to represent the addressing mode of an instruction. */
+export class Addressing {
+  public constructor(
+    /** The addressing mode for each operand. The length of this array is the number of operands of the instruction. */
+    private readonly modePerOperand: AddressingMode[],
+  ) {
+    assert(modePerOperand.length <= 8, 'At most 8 operands are supported');
+  }
+
+  public static fromWire(wireModes: number): Addressing {
+    // The modes are stored in the wire format as a byte, with each bit representing the mode for an operand.
+    // The least significant bit represents the zeroth operand, and the most significant bit represents the last operand.
+    const modes = new Array<AddressingMode>(8);
+    for (let i = 0; i < 8; i++) {
+      modes[i] = (wireModes & (1 << i)) === 0 ? AddressingMode.DIRECT : AddressingMode.INDIRECT;
+    }
+    return new Addressing(modes);
+  }
+
+  public toWire(): number {
+    // The modes are stored in the wire format as a byte, with each bit representing the mode for an operand.
+    // The least significant bit represents the zeroth operand, and the least significant bit represents the last operand.
+    let wire: number = 0;
+    for (let i = 0; i < 8; i++) {
+      if (this.modePerOperand[i] === AddressingMode.INDIRECT) {
+        wire |= 1 << i;
+      }
+    }
+    return wire;
+  }
+
+  /**
+   * Resolves the offsets using the addressing mode.
+   * @param offsets The offsets to resolve.
+   * @param mem The memory to use for resolution.
+   * @returns The resolved offsets. The length of the returned array is the same as the length of the input array.
+   */
+  public resolve(offsets: number[], mem: TaggedMemory): number[] {
+    assert(offsets.length <= this.modePerOperand.length);
+    const resolved = new Array(offsets.length);
+    for (const [i, offset] of offsets.entries()) {
+      switch (this.modePerOperand[i]) {
+        case AddressingMode.INDIRECT:
+          mem.checkTag(TypeTag.UINT32, offset);
+          resolved[i] = Number(mem.get(offset).toBigInt());
+          break;
+        case AddressingMode.DIRECT:
+          resolved[i] = offset;
+          break;
+        default:
+          throw new Error(`Unimplemented addressing mode: ${AddressingMode[this.modePerOperand[i]]}`);
+      }
+    }
+    return resolved;
+  }
+}

yarn-project/simulator/src/avm/opcodes/memory.test.ts

@@ -4,6 +4,7 @@ import { AvmContext } from '../avm_context.js';
 import { Field, TypeTag, Uint8, Uint16, Uint32, Uint64, Uint128 } from '../avm_memory_types.js';
 import { InstructionExecutionError } from '../errors.js';
 import { initContext, initExecutionEnvironment } from '../fixtures/index.js';
+import { Addressing, AddressingMode } from './addressing_mode.js';
 import { CMov, CalldataCopy, Cast, Mov, Set } from './memory.js';
 
 describe('Memory instructions', () => {
@@ -304,6 +305,16 @@ describe('Memory instructions', () => {
       expect(tag).toEqual(TypeTag.UINT16);
     });
 
+    it('Should support INDIRECT addressing', async () => {
+      context.machineState.memory.set(0, new Uint16(55));
+      context.machineState.memory.set(10, new Uint32(20));
+      const addressing = new Addressing([/*srcOffset*/ AddressingMode.DIRECT, /*dstOffset*/ AddressingMode.INDIRECT]);
+      await new Mov(/*indirect=*/ addressing.toWire(), /*srcOffset=*/ 0, /*dstOffset=*/ 10).execute(context);
+
+      expect(context.machineState.memory.get(1)).toBeUndefined();
+      expect(context.machineState.memory.get(20)).toEqual(new Uint16(55n));
+    });
+
     it('Should move field elements on different memory cells', async () => {
       context.machineState.memory.set(0, new Field(27));
       await new Mov(/*indirect=*/ 0, /*srcOffset=*/ 0, /*dstOffset=*/ 1).execute(context);

yarn-project/simulator/src/avm/opcodes/memory.ts

@@ -3,6 +3,7 @@ import { Field, TaggedMemory, TypeTag } from '../avm_memory_types.js';
 import { InstructionExecutionError } from '../errors.js';
 import { BufferCursor } from '../serialization/buffer_cursor.js';
 import { Opcode, OperandType, deserialize, serialize } from '../serialization/instruction_serialization.js';
+import { Addressing } from './addressing_mode.js';
 import { Instruction } from './instruction.js';
 import { TwoOperandInstruction } from './instruction_impl.js';
 
@@ -152,9 +153,14 @@ export class Mov extends Instruction {
   }
 
   async execute(context: AvmContext): Promise<void> {
-    const a = context.machineState.memory.get(this.srcOffset);
+    const [srcOffset, dstOffset] = Addressing.fromWire(this.indirect).resolve(
+      [this.srcOffset, this.dstOffset],
+      context.machineState.memory,
+    );
 
-    context.machineState.memory.set(this.dstOffset, a);
+    const a = context.machineState.memory.get(srcOffset);
+
+    context.machineState.memory.set(dstOffset, a);
 
     context.machineState.incrementPc();
   }