实现指令编解码与反汇编，冻结 disasm 格式。

- Encode.h/Encode.cpp：encode/decode 往返 + disasm 一行文本
- 指令与映像.md 新增反汇编格式表（9 种形态 + 未知操作码）
- Op.h STORE_* 注释对齐 disasm（rs, slot 寄存器在前）

Doc/isa/指令与映像.md

@@ -107,6 +107,25 @@ RET
 `I`/`Q`/`M` 走映像指令，不是通用寄存器。  
 FB 实例固定布局，字段偏移编译期算死。
 
+### 反汇编格式（disasm）
+
+`disasm` 输出一条指令的一行文本，格式冻结：
+
+| 形态 | 格式 | 示例 |
+|---|---|---|
+| 二寄存器 | `MOVE rd, rs` / `NOT rd, rs` | `MOVE r1, r2` |
+| 三寄存器 | `OP rd, ra, rb`（逻辑 / 算术 / 比较） | `ADD r1, r2, r3` |
+| 常量 | `LOADK rd, imm` | `LOADK r0, 3` |
+| 无条件跳转 | `JMP off` | `JMP +4` |
+| 条件跳转 | `JT rd, off` / `JF rd, off` | `JT r0, -1` |
+| I/Q/M/全局 | `LOAD_I rd, slot` 等；STORE 同形 `STORE_Q rs, slot` | `LOAD_I r0, 2` |
+| FB 内置 | `CAL_TON instance` 等 | `CAL_TON 0` |
+| 调用 | `CALL fn_id` | `CALL 1` |
+| 返回 | `RET` | `RET` |
+| 未知操作码 | `??? 0x<hex>` | — |
+
+跳转偏移带符号、恒显正负号（`%+d`）；寄存器一律 `r<n>`；常量/槽号/`fn_id` 无符号十进制。
+
 ---
 
 ## 映像

isa/include/isa/Encode.h

@@ -0,0 +1,31 @@
+/**
+ * @file Encode.h
+ * @brief 指令编解码与反汇编
+ * @author 
+ * @date 2026-08-19
+ */
+
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+
+#include "isa/Instr.h"
+#include "isa/Op.h"
+
+namespace isa {
+    // 解码后的字段视图
+    struct Decoded {
+        Op op;
+        uint8_t rd;
+        uint8_t a;
+        uint8_t b;
+    };
+
+    // 编解码往返：encode(decode(w)) == w
+    Instr encode(Decoded d);
+    Decoded decode(Instr w);
+
+    // 反汇编一行文本，写入 out，至多 cap 字节（含 '\0'）。格式见 Doc/isa/指令与映像.md。
+    void disasm(Instr w, char* out, size_t cap);
+}

isa/include/isa/Op.h

@@ -32,11 +32,11 @@ namespace isa {
         JT = 16,           // JT r, offset
         JF = 17,           // JF r, offset
         LOAD_I = 18,       // LOAD_I rd, slot
-        STORE_Q = 19,      // STORE_Q slot, rs
+        STORE_Q = 19,      // STORE_Q rs, slot
         LOAD_M = 20,       // LOAD_M rd, slot
-        STORE_M = 21,      // STORE_M slot, rs
+        STORE_M = 21,      // STORE_M rs, slot
         LOAD_GLOBAL = 22,  // LOAD_GLOBAL rd, slot
-        STORE_GLOBAL = 23, // STORE_GLOBAL slot, rs
+        STORE_GLOBAL = 23, // STORE_GLOBAL rs, slot
         CAL_TON = 24,      // CAL_TON instance_slot
         CAL_TOF = 25,      // CAL_TOF instance_slot
         CAL_CTU = 26,      // CAL_CTU instance_slot

isa/src/Encode.cpp

@@ -0,0 +1,96 @@
+/**
+ * @file Encode.cpp
+ * @brief 指令编解码与反汇编
+ * @author 
+ * @date 2026-08-19
+ */
+
+#include "isa/Encode.h"
+
+#include <cstdio>
+
+namespace isa {
+
+Instr encode(Decoded d) {
+    return pack(d.op, d.rd, d.a, d.b);
+}
+
+Decoded decode(Instr w) {
+    Decoded d;
+    d.op = op(w);
+    d.rd = rd(w);
+    d.a = a(w);
+    d.b = b(w);
+    return d;
+}
+
+void disasm(Instr w, char* out, size_t cap) {
+    if (cap == 0) {
+        return;
+    }
+    out[0] = '\0';
+
+    const Op o = op(w);
+    const int idx = static_cast<int>(o);
+    if (idx < 0 || idx >= kOpCount) {
+        snprintf(out, cap, "??? 0x%08x", static_cast<unsigned>(w));
+        return;
+    }
+    const char* m = mnemonic(o);
+
+    switch (o) {
+        case Op::MOVE:
+        case Op::NOT:
+            snprintf(out, cap, "%s r%u, r%u", m,
+                     static_cast<unsigned>(rd(w)), static_cast<unsigned>(a(w)));
+            break;
+        case Op::AND:
+        case Op::OR:
+        case Op::ADD:
+        case Op::SUB:
+        case Op::MUL:
+        case Op::DIV:
+        case Op::CMP_EQ:
+        case Op::CMP_NE:
+        case Op::CMP_LT:
+        case Op::CMP_LE:
+        case Op::CMP_GT:
+        case Op::CMP_GE:
+            snprintf(out, cap, "%s r%u, r%u, r%u", m,
+                     static_cast<unsigned>(rd(w)), static_cast<unsigned>(a(w)),
+                     static_cast<unsigned>(b(w)));
+            break;
+        case Op::LOADK:
+            snprintf(out, cap, "%s r%u, %u", m,
+                     static_cast<unsigned>(rd(w)), static_cast<unsigned>(imm16(w)));
+            break;
+        case Op::JMP:
+            snprintf(out, cap, "%s %+d", m, static_cast<int>(off16(w)));
+            break;
+        case Op::JT:
+        case Op::JF:
+            snprintf(out, cap, "%s r%u, %+d", m,
+                     static_cast<unsigned>(rd(w)), static_cast<int>(off16(w)));
+            break;
+        case Op::LOAD_I:
+        case Op::STORE_Q:
+        case Op::LOAD_M:
+        case Op::STORE_M:
+        case Op::LOAD_GLOBAL:
+        case Op::STORE_GLOBAL:
+            snprintf(out, cap, "%s r%u, %u", m,
+                     static_cast<unsigned>(rd(w)), static_cast<unsigned>(imm16(w)));
+            break;
+        case Op::CAL_TON:
+        case Op::CAL_TOF:
+        case Op::CAL_CTU:
+        case Op::CALL:
+            snprintf(out, cap, "%s %u", m, static_cast<unsigned>(imm16(w)));
+            break;
+        case Op::RET:
+            snprintf(out, cap, "%s", m);
+            break;
+    }
+}
+
+}  // namespace isa