bizhawk_write16

Instructions

Implementation Reference

• src/tools.ts:171-188 (registration)

  Tool registration definition for 'bizhawk_write16' — declares the tool name, description, and inputSchema (address, value, domain).

  {
    name: "bizhawk_write16",
    description:
      "PURPOSE: Write an unsigned 16-bit little-endian value to emulator memory at the given address. " +
      "USAGE: Use for 16-bit cheats and pokes (HP, score, coordinates). For single bytes use bizhawk_write8; for 32-bit use bizhawk_write32; for big-endian fields, byteswap and use bizhawk_write_range; for cart save RAM seeding, use bizhawk_load_state. " +
      "BEHAVIOR: DESTRUCTIVE: overwrites two bytes (low byte at `address`, high byte at `address+1`) with no undo. Direct memory write — no MBC/mapper/DMA mediation, see bizhawk_write8 notes. Returns an error if the domain is unknown, address+2 exceeds the domain, value < 0 or > 65535, or the core lacks memory.write_u16_le. " +
      "RETURNS: Single line 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX (DOMAIN)'.",
    inputSchema: {
      type: "object",
      required: ["address", "value"],
      properties: {
        address: { type: "integer", minimum: 0, description: ADDRESS_PARAM_DESC(2) },
        value:   { type: "integer", minimum: 0, maximum: 65535, description: "16-bit value to write. Must be 0-65535 (0x0000-0xFFFF). LSB is written to `address`, MSB to `address+1`. Values outside this range return an error." },
        domain:  { type: "string", description: DOMAIN_PARAM_DESC },
      },
      additionalProperties: false,
    },
  },

• src/tools.ts:551-554 (handler)

  Handler that executes bizhawk_write16: calls bh.call('write16', ...) with address, value, and optional domain, then returns success message.

  case "bizhawk_write16": {
    await bh.call("write16", { address: a(), value: p.value, ...dom() });
    return ok(`Wrote ${fmtHex(p.value)} → ${addrHex(a())}${p.domain ? ` (${p.domain})` : ""}`);
  }

• src/tools.ts:178-188 (schema)

  Input schema for bizhawk_write16: requires address (integer >=0) and value (integer 0-65535), optional domain (string).

    inputSchema: {
      type: "object",
      required: ["address", "value"],
      properties: {
        address: { type: "integer", minimum: 0, description: ADDRESS_PARAM_DESC(2) },
        value:   { type: "integer", minimum: 0, maximum: 65535, description: "16-bit value to write. Must be 0-65535 (0x0000-0xFFFF). LSB is written to `address`, MSB to `address+1`. Values outside this range return an error." },
        domain:  { type: "string", description: DOMAIN_PARAM_DESC },
      },
      additionalProperties: false,
    },
  },

• src/tools.ts:482-484 (helper)

  addrHex helper used by the bizhawk_write16 handler to format the address as hex in the output.

  function addrHex(n: number): string {
    return `0x${n.toString(16).toUpperCase().padStart(4, "0")}`;
  }

• src/tools.ts:478-481 (helper)

  fmtHex helper used by the bizhawk_write16 handler to format the written value as decimal + hex in the output.

  function fmtHex(n: unknown): string {
    if (typeof n !== "number") return String(n);
    return `${n} (0x${n.toString(16).toUpperCase()})`;
  }