5.10 GDSII 輸出#

┌────────────┬────────────┬─────────────────────────┐
│ len: u16   │ rt: u16    │ payload（偶數 byte）      │
│ (big-end)  │ = 高 byte  │                         │
│  含自身 4B │  = 型別    │                         │
└────────────┴────────────┴─────────────────────────┘

// veryl-eda/src/asic/gds.rs
struct W(Vec<u8>);
impl W {
    fn rec(&mut self, rt: u16, data: &[u8]) {
        let len = (4 + data.len() + data.len() % 2) as u16;   // 補 pad 到偶數
        self.0.extend(len.to_be_bytes());
        self.0.extend(rt.to_be_bytes());
        self.0.extend(data);
        if data.len() % 2 == 1 { self.0.push(0); }            // pad byte
    }
    fn i16s(&mut self, rt: u16, v: &[i16]) { ... }   // 資料型別 0x02
    fn i32s(&mut self, rt: u16, v: &[i32]) { ... }   // 資料型別 0x03
    fn s(&mut self, rt: u16, s: &str) { ... }        // ASCII，型別 0x06
    fn real8(&mut self, rt: u16, v: &[f64]) { ... }  // 8-byte real，型別 0x05
}

// veryl-eda/src/asic/gds.rs
pub fn real8(v: f64) -> [u8; 8] {
    if v == 0.0 { return [0; 8]; }
    let (sign, mut m) = (v < 0.0, v.abs());
    let mut e: i32 = 64;
    while m >= 1.0 { m /= 16.0; e += 1; }
    while m < 1.0 / 16.0 { m *= 16.0; e -= 1; }
    let mant = (m * (1u64 << 56) as f64).round() as u64;
    let mut out = [0u8; 8];
    out[0] = (if sign { 0x80 } else { 0 }) | (e as u8 & 0x7f);
    for k in 0..7 { out[1 + k] = (mant >> (8 * (6 - k))) as u8; }
    out
}

// veryl-eda/src/asic/gds.rs（tests）
assert_eq!(super::real8(0.001), [0x3e, 0x41, 0x89, 0x37, 0x4b, 0xc6, 0xa7, 0xf0]);
assert_eq!(super::real8(1e-9),  [0x39, 0x44, 0xb8, 0x2f, 0xa0, 0x9b, 0x5a, 0x54]);

// veryl-eda/src/asic/gds.rs（節錄）
w.i16s(0x0002, &[600]);              // HEADER：GDS 版本 6.0
w.i16s(0x0102, &date);               // BGNLIB（修改/存取時間戳各 6 個 i16）
w.s(0x0206, design);                 // LIBNAME
w.real8(0x0305, &[0.001, 1e-9]);     // UNITS

// veryl-eda/src/asic/gds.rs
/// the structures of a GDS file by name (their raw records, BGNSTR .. ENDSTR)
pub fn structures(gds: &[u8]) -> HashMap<String, Vec<u8>> {
    let mut out = HashMap::new();
    let mut i = 0;
    let mut start = None;
    let mut name = String::new();
    while i + 4 <= gds.len() {
        let len = u16::from_be_bytes([gds[i], gds[i + 1]]) as usize;
        if len < 4 { break; }
        let rt = gds[i + 2];
        match rt {
            0x05 => start = Some(i),                       // BGNSTR
            0x06 => name = ...(STRNAME),                   // 0x0606
            0x07 => { if let Some(s) = start.take() { out.insert(name.clone(), gds[s..i + len].to_vec()); } }
            _ => {}
        }
        i += len;
    }
    out
}

// veryl-eda/src/asic/gds.rs（節錄）
let mut need: Vec<String> = l.insts.iter().map(|i| i.cell.clone()).collect::<HashSet<_>>().into_iter().collect();
need.sort();
let mut done: HashSet<String> = HashSet::new();
while let Some(n) = need.pop() {
    if !done.insert(n.clone()) { continue; }
    let s = lib.get(&n).ok_or_else(|| format!("cell {} is not in the GDS library", n))?;
    let mut i = 0;
    while i + 4 <= s.len() {
        let len = ...;
        if s[i + 2] == 0x12 { need.push(...SNAME...); }   // 遞迴依賴
        i += len;
    }
    w.0.extend(s);                                        // 原樣複製
}

// veryl-eda/src/asic/gds.rs（節錄）
for inst in &l.insts {
    w.rec(0x0A00, &[]);                 // SREF
    w.s(0x1206, &inst.cell);            // SNAME
    if inst.flip {
        // mirrored about the x axis, then moved up by the cell height
        w.rec(0x1A01, &0x8000u16.to_be_bytes());          // STRANS：bit15 = 鏡射
        w.i32s(0x1003, &[inst.x as i32, (inst.y + inst.h) as i32]);  // XY
    } else {
        w.i32s(0x1003, &[inst.x as i32, inst.y as i32]);
    }
    w.rec(0x1100, &[]);                 // ENDEL
}

// veryl-eda/src/asic/gds.rs（節錄）
for s in &l.shapes {
    let Some((layer, dt, _)) = sky130_layer(&l.layers[s.layer as usize]) else { continue };
    w.rec(0x0800, &[]);                              // BOUNDARY
    w.i16s(0x0D02, &[layer]);                        // LAYER
    w.i16s(0x0E02, &[dt]);                           // DATATYPE
    let (x0, y0, x1, y1) = (s.x0 as i32, s.y0 as i32, s.x1 as i32, s.y1 as i32);
    w.i32s(0x1003, &[x0, y0, x1, y0, x1, y1, x0, y1, x0, y0]);   // XY，5 點閉合
    w.rec(0x1100, &[]);                              // ENDEL
}

// veryl-eda/src/asic/gds.rs（節錄）
pub fn sky130_layer(name: &str) -> Option<(i16, i16, i16)> {
    Some(match name {
        "li1"  => (67, 20, 16),
        "mcon" => (67, 44, 44),
        "met1" => (68, 20, 16),
        "via"  => (68, 44, 44),
        "met2" => (69, 20, 16),
        ...
    })
}

// veryl-eda/src/asic/gds.rs（節錄）
w.i16s(0x0E02, &[pin]);      // pin datatype（16）
...
w.i16s(0x1602, &[5]);        // TEXTTYPE = 5（label）
w.i32s(0x1003, &[x, y]);
w.s(0x1906, name);           // STRING 記錄（0x1906）

w.rec(0x0700, &[]);          // ENDSTR（頂層 structure 結束）
w.rec(0x0400, &[]);          // ENDLIB

// veryl-eda/src/pdk/mod.rs
pub const SKY130_GDS: &[u8] = include_bytes!("../../pdk/sky130hd/sky130_fd_sc_hd.gds");

# tools/gds_check.py（節錄）
tops = [c for c in ly.top_cells()]
if len(tops) != 1 or tops[0].name != design: bad.append(...)
insts = list(top.each_inst())
if len(insts) != n_inst: bad.append(...)
for i in insts:
    c = ly.cell(i.cell_index)
    if c.bbox().empty(): bad.append("cell %s has no geometry" % c.name)
...
boxes = texts = 0
for li in ly.layer_indexes():
    for s in top.shapes(li).each():
        if s.is_text(): texts += 1
        elif s.is_box() or s.is_polygon(): boxes += 1