// Expect retcode = 0

// SPL VM 机器码容器（移植自 stage0/spl_mcode.c 的构建/序列化/dump 部分）。
// 只负责「内存中的 prog」与「写入 .sir」，不包含反序列化（由 C 侧 spl_cli 读）。
//
// 字符串一律是 ByteView（借用上层 IR/attr 的名称，本模块不复制、不释放）；
// gdata 条目是 ByteBuffer，由本模块拥有并释放。
//
// 二进制格式（元数据字段均为 u64 小端）：
//   [HEADER]  magic(8) nfuncs(8) ninsns(8) nnatives(8) nstrs(8) ndata(8)
//   [FUNCS]   每项: name_len(8) name(pad8, 含结尾 NUL) idx_of_strtab(8)
//                   nargs(8) ninsns(8) address(8)
//   [INSTRS]  每项: opcode(2) type(2) imm(8) = 12 字节
//   [NATIVES] 每项: name_len(8) name(pad8, 含结尾 NUL) idx_of_strtab(8)
//   [STRTAB]  每项: slen(8) str(pad8)
//   [GDATA]   每项: dsize(8) data(pad8)

type .{ .Error, .Status, .make } = @import("utils/error.spl");
type .{ .Vec } = @import("utils/vec.spl");
type .{ .ByteView } = @import("utils/byte_view.spl");
type .{ .ByteBuffer } = @import("utils/byte_buffer.spl");
type .{ .append_usize, .append_i64 } = @import("utils/fmt.spl");
type Mem = @import("sys/mem.spl");
type File = @import("sys/file.spl");
type .{ .open_cstr, .write_all, .read_all } = @import("utils/io.spl");

type Op = enum {
    Error,
    Push,
    Dup,
    Drop,
    Swap,
    Pick,
    Rot,
    Add,
    Sub,
    Mul,
    DivS,
    DivU,
    RemS,
    RemU,
    Neg,
    And,
    Or,
    Xor,
    Not,
    Shl,
    ShrU,
    ShrS,
    Eq,
    Ne,
    Slt,
    Sle,
    Ult,
    Ule,
    Sgt,
    Sge,
    Ugt,
    Uge,
    Trunc,
    Sext,
    Zext,
    Jmp,
    Bz,
    Bnz,
    Halt,
    Call,
    Calli,
    Ret,
    Alloc,
    Laddr,
    Gaddr,
    Load,
    Store,
    Ncall,
    Nlib,
    Bk,
    Dbg,
}

type VmKind = enum {
    Void,
    Bool,
    I8,
    U8,
    I16,
    U16,
    I32,
    U32,
    I64,
    U64,
    Isize,
    Usize,
    F32,
    F64,
    Ptr,
}

type VmIns = struct {
    opcode: Op,
    ty: VmKind,
    imm: usize,
}

type VmFunc = struct {
    name: ByteView,
    idx_of_strtab: usize,
    nargs: usize,
    ninsns: usize,
    address: usize,
}

type VmNative = struct {
    name: ByteView,
    idx_of_strtab: usize,
}

type Prog = @self;

insns: Vec,   // VmIns
funcs: Vec,   // VmFunc
natives: Vec, // VmNative
strtab: Vec,  // ByteView
gdata: Vec,   // ByteBuffer（索引 0 为占位项）

type ProgResult = enum {
    Ok: Prog,
    Err: Error,
}

fn op_name(op: Op): []u8 {
    match op {
        .Error => { ret "error"; },
        .Push => { ret "push"; },
        .Dup => { ret "dup"; },
        .Drop => { ret "drop"; },
        .Swap => { ret "swap"; },
        .Pick => { ret "pick"; },
        .Rot => { ret "rot"; },
        .Add => { ret "add"; },
        .Sub => { ret "sub"; },
        .Mul => { ret "mul"; },
        .DivS => { ret "div_s"; },
        .DivU => { ret "div_u"; },
        .RemS => { ret "rem_s"; },
        .RemU => { ret "rem_u"; },
        .Neg => { ret "neg"; },
        .And => { ret "and"; },
        .Or => { ret "or"; },
        .Xor => { ret "xor"; },
        .Not => { ret "not"; },
        .Shl => { ret "shl"; },
        .ShrU => { ret "shr_u"; },
        .ShrS => { ret "shr_s"; },
        .Eq => { ret "eq"; },
        .Ne => { ret "ne"; },
        .Slt => { ret "slt"; },
        .Sle => { ret "sle"; },
        .Ult => { ret "ult"; },
        .Ule => { ret "ule"; },
        .Sgt => { ret "sgt"; },
        .Sge => { ret "sge"; },
        .Ugt => { ret "ugt"; },
        .Uge => { ret "uge"; },
        .Trunc => { ret "trunc"; },
        .Sext => { ret "sext"; },
        .Zext => { ret "zext"; },
        .Jmp => { ret "jmp"; },
        .Bz => { ret "bz"; },
        .Bnz => { ret "bnz"; },
        .Halt => { ret "halt"; },
        .Call => { ret "call"; },
        .Calli => { ret "calli"; },
        .Ret => { ret "ret"; },
        .Alloc => { ret "alloc"; },
        .Laddr => { ret "laddr"; },
        .Gaddr => { ret "gaddr"; },
        .Load => { ret "load"; },
        .Store => { ret "store"; },
        .Ncall => { ret "ncall"; },
        .Nlib => { ret "nlib"; },
        .Bk => { ret "breakpoint"; },
        .Dbg => { ret "dbg"; },
    }
    ret "error";
}

fn kind_name(k: VmKind): []u8 {
    match k {
        .Void => { ret "void"; },
        .Bool => { ret "bool"; },
        .I8 => { ret "i8"; },
        .U8 => { ret "u8"; },
        .I16 => { ret "i16"; },
        .U16 => { ret "u16"; },
        .I32 => { ret "i32"; },
        .U32 => { ret "u32"; },
        .I64 => { ret "i64"; },
        .U64 => { ret "u64"; },
        .Isize => { ret "isize"; },
        .Usize => { ret "usize"; },
        .F32 => { ret "f32"; },
        .F64 => { ret "f64"; },
        .Ptr => { ret "ptr"; },
    }
    ret "???";
}

// ---- 生命周期 ----

fn new(): ProgResult {
    var prog = Prog {
        .insns = Vec.blank(@sizeof(VmIns), @alignof(VmIns)),
        .funcs = Vec.blank(@sizeof(VmFunc), @alignof(VmFunc)),
        .natives = Vec.blank(@sizeof(VmNative), @alignof(VmNative)),
        .strtab = Vec.blank(@sizeof(ByteView), @alignof(ByteView)),
        .gdata = Vec.blank(@sizeof(ByteBuffer), @alignof(ByteBuffer)),
    };
    // 索引 0 占位，使真实数据地址非零。
    var placeholder = ByteBuffer.new();
    match Vec.push(&prog.gdata, &placeholder as *u8) {
        .Ok => {},
        .Err(error) => {
            Vec.drop(&prog.gdata);
            Vec.drop(&prog.strtab);
            Vec.drop(&prog.natives);
            Vec.drop(&prog.funcs);
            Vec.drop(&prog.insns);
            ret .Err(error);
        },
    }
    ret .Ok(prog);
}

fn gdata_at(self: *Prog, i: usize): *ByteBuffer {
    match Vec.get(&self.gdata, i) {
        .Ok(ptr) => { ret ptr as *ByteBuffer; },
        .Err(error) => { ret null; },
    }
    ret null;
}

fn native_at(self: *Prog, i: usize): *VmNative {
    match Vec.get(&self.natives, i) {
        .Ok(ptr) => { ret ptr as *VmNative; },
        .Err(error) => { ret null; },
    }
    ret null;
}

fn drop(self: *Prog) {
    var i: usize = 0;
    while i < self.gdata.len {
        var e = gdata_at(self, i);
        if e != null { ByteBuffer.drop(e); }
        i = i + 1;
    }
    Vec.drop(&self.gdata);
    Vec.drop(&self.strtab);
    Vec.drop(&self.natives);
    Vec.drop(&self.funcs);
    Vec.drop(&self.insns);
}

// ---- 构建 ----

fn add_instr(self: *Prog, op: Op, ty: VmKind, imm: usize): usize {
    var i = self.insns.len;
    if i < self.insns.cap {
        var p = (self.insns.data as *VmIns) + i;
        p.opcode = op;
        p.ty = ty;
        p.imm = imm;
        self.insns.len = i + 1;
        ret i + 1;
    }
    var ins = VmIns { .opcode = op, .ty = ty, .imm = imm };
    if !Vec.push_raw(&self.insns, &ins as *u8) { ret 0; }
    ret self.insns.len;
}

fn add_func(self: *Prog, name: ByteView, nargs: usize, address: usize): usize {
    var f = VmFunc {
        .name = name,
        .idx_of_strtab = 0,
        .nargs = nargs,
        .ninsns = 0,
        .address = address,
    };
    match Vec.push(&self.funcs, &f as *u8) {
        .Ok => {},
        .Err(error) => { ret 0; },
    }
    ret self.funcs.len;
}

// 复制 size 字节到新的 gdata 条目；返回其索引（0 表示失败）。
// ptr 是上层（Ast/Ast2Ir）拥有的稳定字节，调用期间保持有效。
fn add_data(self: *Prog, ptr: usize, size: usize): usize {
    var entry = ByteBuffer.new();
    match ByteBuffer.reserve(&entry, size) {
        .Ok => {},
        .Err(error) => { ByteBuffer.drop(&entry); ret 0; },
    }
    if size != 0 {
        if ptr == 0 { ByteBuffer.drop(&entry); ret 0; }
        ignore_ptr(Mem.copy(entry.storage.data as *any, ptr as *any, size));
        entry.storage.len = size;
    }
    match Vec.push(&self.gdata, &entry as *u8) {
        .Ok => {},
        .Err(error) => { ByteBuffer.drop(&entry); ret 0; },
    }
    ret self.gdata.len - 1;
}

// 返回 name 对应的 native 索引；不存在则登记。name 为空指针时返回 -1。
fn get_or_add_native(self: *Prog, name: ByteView): isize {
    if name.ptr == null { ret -1; }
    var i: usize = 0;
    while i < self.natives.len {
        var n = native_at(self, i);
        if n != null && ByteView.eq(n.name, name) { ret i as isize; }
        i = i + 1;
    }
    var nat = VmNative { .name = name, .idx_of_strtab = 0 };
    match Vec.push(&self.natives, &nat as *u8) {
        .Ok => {},
        .Err(error) => { ret -1; },
    }
    ret (self.natives.len - 1) as isize;
}

// ---- dump（输出必须与 stage0 spl_prog_dump 逐字节一致）----

fn out_s(out: *ByteBuffer, s: []u8): bool {
    match ByteBuffer.append(out, s) { .Ok => { ret true; }, .Err(error) => { ret false; } }
    ret false;
}

fn out_u(out: *ByteBuffer, v: usize): bool {
    match append_usize(out, v, 10, false) { .Ok => { ret true; }, .Err(error) => { ret false; } }
    ret false;
}

fn out_i(out: *ByteBuffer, v: i64): bool {
    match append_i64(out, v, 10, false) { .Ok => { ret true; }, .Err(error) => { ret false; } }
    ret false;
}

// %4zd：右对齐、最小宽度 4 的有符号十进制。
fn out_width4_i(out: *ByteBuffer, v: i64): bool {
    var width: usize = 0;
    if v < 0 {
        if v >= -9 { width = 2; }
        else if v >= -99 { width = 3; }
        else { width = 4; }
    } else {
        if v < 10 { width = 1; }
        else if v < 100 { width = 2; }
        else if v < 1000 { width = 3; }
        else { width = 4; }
    }
    var pad: usize = 0;
    if width < 4 { pad = 4 - width; }
    if !out_s(out, "    "[0..pad]) { ret false; }
    ret out_i(out, v);
}

fn dump(self: *Prog, out: *ByteBuffer): bool {
    if !out_s(out, ";; SPL bytecode dump: \n") { ret false; }
    if !out_s(out, ";; ninsns=") { ret false; }
    if !out_u(out, self.insns.len) { ret false; }
    if !out_s(out, " nfuncs=") { ret false; }
    if !out_u(out, self.funcs.len) { ret false; }
    if !out_s(out, " nnatives=") { ret false; }
    if !out_u(out, self.natives.len) { ret false; }
    if !out_s(out, " nstrs=") { ret false; }
    if !out_u(out, self.strtab.len) { ret false; }
    if !out_s(out, "\n\n") { ret false; }

    if self.funcs.len > 0 {
        if !out_s(out, ";; --- functions ---\n") { ret false; }
        var i: usize = 0;
        while i < self.funcs.len {
            var f = func_at(self, i);
            if f == null {
                @assert(false, "func missing in dump");
                ret false;
            }
            if !out_s(out, "  ") { ret false; }
            if !out_s(out, ByteView.as_slice(f.name)) { ret false; }
            if !out_s(out, "  nargs=") { ret false; }
            if !out_u(out, f.nargs) { ret false; }
            if !out_s(out, " ninsns=") { ret false; }
            if !out_u(out, f.ninsns) { ret false; }
            if !out_s(out, " addr=") { ret false; }
            if !out_u(out, f.address) { ret false; }
            if !out_s(out, "\n") { ret false; }
            i = i + 1;
        }
        if !out_s(out, "\n") { ret false; }
    }

    if self.natives.len > 0 {
        if !out_s(out, ";; --- natives ---\n") { ret false; }
        var i: usize = 0;
        while i < self.natives.len {
            var n = native_at(self, i);
            if n == null {
                @assert(false, "native missing in dump");
                ret false;
            }
            if !out_s(out, "  ") { ret false; }
            if !out_s(out, ByteView.as_slice(n.name)) { ret false; }
            if !out_s(out, "\n") { ret false; }
            i = i + 1;
        }
        if !out_s(out, "\n") { ret false; }
    }

    if self.strtab.len > 0 {
        if !out_s(out, ";; --- string table ---\n") { ret false; }
        var i: usize = 0;
        while i < self.strtab.len {
            var s = str_at(self, i);
            if !out_s(out, "  ") { ret false; }
            if !out_i(out, i as i64) { ret false; }
            if !out_s(out, ": \"") { ret false; }
            if !out_s(out, ByteView.as_slice(s)) { ret false; }
            if !out_s(out, "\"\n") { ret false; }
            i = i + 1;
        }
        if !out_s(out, "\n") { ret false; }
    }

    if !out_s(out, ";; --- instructions ---\n") { ret false; }
    var i: usize = 0;
    while i < self.insns.len {
        var ins = ins_at(self, i);
        if !out_width4_i(out, i as i64) { ret false; }
        if !out_s(out, ": ") { ret false; }
        if !out_s(out, op_name(ins.opcode)) { ret false; }
        if @enum2int(ins.ty) != @enum2int(VmKind.Void) {
            if !out_s(out, " ") { ret false; }
            if !out_s(out, kind_name(ins.ty)) { ret false; }
        }
        if !out_s(out, " ") { ret false; }
        if !out_i(out, ins.imm as i64) { ret false; }

        if @enum2int(ins.opcode) == @enum2int(Op.Jmp) ||
           @enum2int(ins.opcode) == @enum2int(Op.Bz) ||
           @enum2int(ins.opcode) == @enum2int(Op.Bnz) {
            if !out_s(out, "  ; -> ") { ret false; }
            if !out_u(out, i + 1 + ins.imm) { ret false; }
        } else if @enum2int(ins.opcode) == @enum2int(Op.Call) {
            if !out_s(out, "  ; nargs=") { ret false; }
            if !out_u(out, ins.imm) { ret false; }
            if !out_s(out, ", from stack") { ret false; }
        } else if @enum2int(ins.opcode) == @enum2int(Op.Calli) {
            if !out_s(out, "  ; indirect call") { ret false; }
        } else if @enum2int(ins.opcode) == @enum2int(Op.Gaddr) {
            if !out_s(out, "  ; gdata[") { ret false; }
            if !out_u(out, ins.imm) { ret false; }
            if !out_s(out, "]") { ret false; }
        }
        if !out_s(out, "\n") { ret false; }
        i = i + 1;
    }
    ret true;
}

fn ins_at(self: *Prog, i: usize): VmIns {
    if i >= self.insns.len { ret VmIns { .opcode = .Error, .ty = .Void, .imm = 0 }; }
    ret ((self.insns.data as *VmIns) + i).*;
}

fn func_at(self: *Prog, i: usize): *VmFunc {
    match Vec.get(&self.funcs, i) {
        .Ok(ptr) => { ret ptr as *VmFunc; },
        .Err(error) => { ret null; },
    }
    ret null;
}

fn str_at(self: *Prog, i: usize): ByteView {
    match Vec.get(&self.strtab, i) {
        .Ok(ptr) => { ret (ptr as *ByteView).*; },
        .Err(error) => { ret ByteView.empty(); },
    }
    ret ByteView.empty();
}

// ---- 序列化 ----

fn align8(n: usize): usize {
    ret (n + 7) & (~(7 as usize));
}

// 说明：以下 put_* 直接写入已预留容量的 ByteBuffer 存储（store 已按精确总大小 reserve），
// 跳过 ByteBuffer.append → Vec.append 的校验/拷贝路径。若容量不足会越界，故 store 先校验容量。

fn put_u8(out: *ByteBuffer, b: u8): bool {
    out.storage.data[out.storage.len] = b;
    out.storage.len = out.storage.len + 1;
    ret true;
}

// 直接按小端整型写（x86 小端；VM 的 STORE 用 memcpy，未对齐也安全）。
fn put_u16(out: *ByteBuffer, v: usize): bool {
    var d = out.storage.data + out.storage.len;
    (d as *u16).* = v as u16;
    out.storage.len = out.storage.len + 2;
    ret true;
}

fn put_u64(out: *ByteBuffer, v: usize): bool {
    var d = out.storage.data + out.storage.len;
    (d as *u64).* = v as u64;
    out.storage.len = out.storage.len + 8;
    ret true;
}

fn put_zeros(out: *ByteBuffer, n: usize): bool {
    if n != 0 {
        ignore_ptr(Mem.set((out.storage.data + out.storage.len) as *any, 0, n));
        out.storage.len = out.storage.len + n;
    }
    ret true;
}

fn put_view(out: *ByteBuffer, v: ByteView): bool {
    if v.len == 0 { ret true; }
    Mem.copy((out.storage.data + out.storage.len) as *any, v.ptr as *any, v.len);
    out.storage.len = out.storage.len + v.len;
    ret true;
}

// 写入「带结尾 NUL、再按 8 对齐」的名称字段（对应 C 侧 nlen = strlen+1）。
fn put_name_field(out: *ByteBuffer, name: ByteView): bool {
    var nlen = name.len + 1;
    if !put_u64(out, nlen) { ret false; }
    if !put_view(out, name) { ret false; }
    if !put_u8(out, 0) { ret false; }
    ret put_zeros(out, align8(nlen) - nlen);
}

// 把 prog 序列化为二进制写入 out（不落盘，供内嵌 VM 直接用）。
fn encode(self: *Prog, out: *ByteBuffer): Status {
    // 精确预估输出大小并一次性预留，避免大文件逐字节增长导致的重复拷贝。
    var total: usize = 48;
    var fi: usize = 0;
    while fi < self.funcs.len {
        var f = func_at(self, fi);
        if f != null {
            var nlen = f.name.len + 1;
            total = total + 8 + align8(nlen) + 32;
        }
        fi = fi + 1;
    }
    total = total + self.insns.len * 12;
    fi = 0;
    while fi < self.natives.len {
        var n = native_at(self, fi);
        if n != null {
            var nlen = n.name.len + 1;
            total = total + 8 + align8(nlen) + 8;
        }
        fi = fi + 1;
    }
    fi = 0;
    while fi < self.strtab.len {
        total = total + 8 + align8(str_at(self, fi).len);
        fi = fi + 1;
    }
    fi = 1;
    while fi < self.gdata.len {
        var e = gdata_at(self, fi);
        if e != null { total = total + 8 + align8(e.storage.len); }
        fi = fi + 1;
    }
    match ByteBuffer.reserve(out, total) { .Ok => {}, .Err(error) => {} }
    if out.storage.cap < total || out.storage.data == null { ret .Err(make(.Io)); }

    if !put_view(out, ByteView.from_slice("SPLBIN")) { ret .Err(make(.Io)); }
    if !put_zeros(out, 2) { ret .Err(make(.Io)); }

    var nfuncs = self.funcs.len;
    var ninsns = self.insns.len;
    var nnatives = self.natives.len;
    var nstrs = self.strtab.len;
    var ndata: usize = 0;
    if self.gdata.len > 0 { ndata = self.gdata.len - 1; }

    if !put_u64(out, nfuncs) { ret .Err(make(.Io)); }
    if !put_u64(out, ninsns) { ret .Err(make(.Io)); }
    if !put_u64(out, nnatives) { ret .Err(make(.Io)); }
    if !put_u64(out, nstrs) { ret .Err(make(.Io)); }
    if !put_u64(out, ndata) { ret .Err(make(.Io)); }

    var i: usize = 0;
    while i < nfuncs {
        var f = func_at(self, i);
        if f == null { ret .Err(make(.Io)); }
        if !put_name_field(out, f.name) { ret .Err(make(.Io)); }
        if !put_u64(out, f.idx_of_strtab) { ret .Err(make(.Io)); }
        if !put_u64(out, f.nargs) { ret .Err(make(.Io)); }
        if !put_u64(out, f.ninsns) { ret .Err(make(.Io)); }
        if !put_u64(out, f.address) { ret .Err(make(.Io)); }
        i = i + 1;
    }

    i = 0;
    while i < ninsns {
        var ins = ins_at(self, i);
        var d = out.storage.data + out.storage.len;
        (d as *u16).* = @enum2int(ins.opcode) as u16;
        ((d + 2) as *u16).* = @enum2int(ins.ty) as u16;
        ((d + 4) as *u64).* = ins.imm as u64;
        out.storage.len = out.storage.len + 12;
        i = i + 1;
    }

    i = 0;
    while i < nnatives {
        var n = native_at(self, i);
        if n == null { ret .Err(make(.Io)); }
        if !put_name_field(out, n.name) { ret .Err(make(.Io)); }
        if !put_u64(out, n.idx_of_strtab) { ret .Err(make(.Io)); }
        i = i + 1;
    }

    i = 0;
    while i < nstrs {
        var s = str_at(self, i);
        if !put_u64(out, s.len) { ret .Err(make(.Io)); }
        if !put_view(out, s) { ret .Err(make(.Io)); }
        if !put_zeros(out, align8(s.len) - s.len) { ret .Err(make(.Io)); }
        i = i + 1;
    }

    i = 1;
    while i < self.gdata.len {
        var e = gdata_at(self, i);
        if e == null { ret .Err(make(.Io)); }
        var dsize = e.storage.len;
        if !put_u64(out, dsize) { ret .Err(make(.Io)); }
        if !put_view(out, ByteView.from_slice(ByteBuffer.as_slice(e.*))) { ret .Err(make(.Io)); }
        if !put_zeros(out, align8(dsize) - dsize) { ret .Err(make(.Io)); }
        i = i + 1;
    }
    ret .Ok;
}

fn store(self: *Prog, path: ByteView): Status {
    var out = ByteBuffer.new();
    defer { ByteBuffer.drop(&out); }

    match encode(self, &out) {
        .Ok => {},
        .Err(error) => { ret .Err(error); },
    }

    var f = open_cstr(path, ByteView.from_slice("wb"));
    if !File.valid(&f) { ret .Err(make(.Io)); }
    var w = write_all(&f, ByteBuffer.as_slice(out));
    var closed = File.close(&f);
    match w {
        .Ok => {},
        .Err(error) => { ret .Err(error); },
    }
    if closed != 0 { ret .Err(make(.Io)); }
    ret .Ok;
}

fn ignore_ptr(p: *any) {}
fn ignore_usize(v: usize) {}

// ---- 测试 ----

fn test_dump_basic() {
    var pr: Prog = undefined;
    match new() {
        .Ok(v) => { pr = v; },
        .Err(error) => { @assert(false, "prog init"); ret; },
    }
    defer { drop(&pr); }

    ignore_usize(add_instr(&pr, .Halt, .Void, 0));

    var out = ByteBuffer.new();
    defer { ByteBuffer.drop(&out); }
    if !dump(&pr, &out) { @assert(false, "dump"); ret; }

    var expected: [69]u8 = .[
        ';', ';', ' ', 'S', 'P', 'L', ' ', 'b',
        'y', 't', 'e', 'c', 'o', 'd', 'e', ' ',
        'd', 'u', 'm', 'p', ':', ' ', 10,
        ';', ';', ' ', 'n', 'i', 'n', 's', 'n',
        's', '=', '1', ' ', 'n', 'f', 'u', 'n',
        'c', 's', '=', '0', ' ', 'n', 'n', 'a',
        't', 'i', 'v', 'e', 's', '=', '0', ' ',
        'n', 's', 't', 'r', 's', '=', '0', 10, 10,
        ';', ';', ' ', '-', '-', '-',
    ];
    var got = ByteBuffer.as_slice(out);
    @assert(got.len > expected.len, "dump longer than header prefix");
    var i: usize = 0;
    while i < expected.len {
        @assert(got.ptr[i] == expected[i], "dump header bytes");
        i = i + 1;
    }
}

fn test_native_dedup() {
    var pr: Prog = undefined;
    match new() {
        .Ok(v) => { pr = v; },
        .Err(error) => { @assert(false, "prog init"); ret; },
    }
    defer { drop(&pr); }

    var vm = ByteView.from_slice("vm_printf");
    @assert(get_or_add_native(&pr, vm) == 0, "first native idx");
    @assert(get_or_add_native(&pr, vm) == 0, "dedup native idx");
    @assert(pr.natives.len == 1, "native count");
}

fn test_store_roundtrip() {
    var pr: Prog = undefined;
    match new() {
        .Ok(v) => { pr = v; },
        .Err(error) => { @assert(false, "prog init"); ret; },
    }
    defer { drop(&pr); }

    ignore_usize(add_func(&pr, ByteView.from_slice("main"), 0, 0));
    ignore_usize(add_instr(&pr, .Halt, .Void, 0));

    var path = ByteView.from_slice("build/_mcode_roundtrip.tmp");
    match store(&pr, path) {
        .Ok => {},
        .Err(error) => { @assert(false, "store to file"); ret; },
    }

    var data = ByteBuffer.new();
    defer { ByteBuffer.drop(&data); }
    match read_all(path, &data) {
        .Ok => {},
        .Err(error) => { @assert(false, "read back"); ret; },
    }
    var b = ByteBuffer.as_slice(data);
    // header(48) + 一个函数项(8 + 8 + 4*8 = 48) + 一条指令(12) = 108
    @assert(b.len == 108, "serialized size");
    @assert(b.ptr[0] == 'S' && b.ptr[1] == 'P' && b.ptr[2] == 'L' && b.ptr[3] == 'B' &&
            b.ptr[4] == 'I' && b.ptr[5] == 'N' && b.ptr[6] == 0 && b.ptr[7] == 0,
            "magic");
    @assert(b.ptr[8] == 1, "nfuncs");
    @assert(b.ptr[16] == 1, "ninsns");
    @assert(b.ptr[24] == 0 && b.ptr[32] == 0 && b.ptr[40] == 0, "nnatives/nstrs/ndata");
    // 函数项起始：name_len(5) + "main\0" + pad(3)
    @assert(b.ptr[48] == 5, "name_len");
    @assert(b.ptr[56] == 'm' && b.ptr[57] == 'a' && b.ptr[58] == 'i' && b.ptr[59] == 'n' &&
            b.ptr[60] == 0, "name bytes");
    @assert(b.ptr[61] == 0 && b.ptr[62] == 0 && b.ptr[63] == 0, "name padding");
    // 指令：opcode(2)=halt(38) type(2)=void(0) imm(8)=0
    var ins_off: usize = 96;
    @assert(b.ptr[ins_off + 0] == 38 && b.ptr[ins_off + 1] == 0, "opcode bytes");
    @assert(b.ptr[ins_off + 2] == 0 && b.ptr[ins_off + 3] == 0, "type bytes");
    @assert(b.ptr[ins_off + 4] == 0 && b.ptr[ins_off + 11] == 0, "imm bytes");
}

fn main() {
    test_dump_basic();
    test_native_dedup();
    test_store_roundtrip();
}