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0865492 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 | "use strict";
/**
* GEAR hash WASM - Runtime bytecode generation
*
* Generates a tiny WebAssembly module with a single `nextMatch` function
* that performs the gear hash rolling scan using native i64 arithmetic.
*
* Memory layout (all little-endian):
* 0-2047: Gear lookup table (256 × 8 bytes)
* 2048-2055: Hash state (u64, persists across calls)
* 2056-2063: Mask (u64, set per-hasher before each call)
* 4096+: Input buffer
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.MAX_INPUT_SIZE = exports.INPUT_OFFSET = exports.MASK_OFFSET = exports.HASH_OFFSET = exports.TABLE_OFFSET = void 0;
exports.initWasm = initWasm;
exports.wasmNextMatch = wasmNextMatch;
exports.getView = getView;
const table_js_1 = require("./table.js");
exports.TABLE_OFFSET = 0;
exports.HASH_OFFSET = 2048;
exports.MASK_OFFSET = 2056;
exports.INPUT_OFFSET = 4096;
const PAGES = 8; // 512 KB
exports.MAX_INPUT_SIZE = PAGES * 65536 - exports.INPUT_OFFSET;
let wasmMemory = null;
let wasmView = null;
let wasmFn = null;
function toSignedLeb128(n) {
const bytes = [];
let value = n | 0;
for (;;) {
const byte = value & 0x7f;
value >>= 7;
if ((value === 0 && (byte & 0x40) === 0) || (value === -1 && (byte & 0x40) !== 0)) {
bytes.push(byte);
return bytes;
}
bytes.push(byte | 0x80);
}
}
function toLebU32Padded5(n) {
return [
(n & 0x7f) | 0x80,
((n >>> 7) & 0x7f) | 0x80,
((n >>> 14) & 0x7f) | 0x80,
((n >>> 21) & 0x7f) | 0x80,
(n >>> 28) & 0x0f,
];
}
/**
* Generate the WASM module bytecode.
*
* Exports one function:
* nextMatch(inputStart: i32, inputLen: i32) -> i32
*
* Reads hash/mask from fixed memory offsets, scans from `inputStart`
* for `inputLen` bytes, writes updated hash back.
* Returns 1-based match position within the scanned range, or -1.
*/
function generateWasmBytes() {
const code = [];
function emit(...bytes) {
code.push(...bytes);
}
// ── Module header ──
emit(0x00, 0x61, 0x73, 0x6d); // magic
emit(0x01, 0x00, 0x00, 0x00); // version 1
// ── Type section: (i32, i32) -> (i32) ──
emit(0x01, 0x07, 0x01, 0x60, 0x02, 0x7f, 0x7f, 0x01, 0x7f);
// ── Import section: memory "js"."mem" min=PAGES ──
emit(0x02, 0x0b, 0x01, 0x02, 0x6a, 0x73, 0x03, 0x6d, 0x65, 0x6d, 0x02, 0x00, PAGES);
// ── Function section: 1 function, type 0 ──
emit(0x03, 0x02, 0x01, 0x00);
// ── Export section: "nextMatch" -> func 0 ──
emit(0x07, 0x0d, 0x01, 0x09, 0x6e, 0x65, 0x78, 0x74, 0x4d, 0x61, 0x74, 0x63, 0x68, 0x00, 0x00);
// ── Code section ──
emit(0x0a);
const sectionSizeOff = code.length;
emit(0x00, 0x00, 0x00, 0x00, 0x00);
emit(0x01); // 1 function body
const funcSizeOff = code.length;
emit(0x00, 0x00, 0x00, 0x00, 0x00);
const bodyStart = code.length;
// Locals: $0 = inputStart (param), $1 = inputLen (param)
// $2 = hash (i64), $3 = mask (i64)
// $4 = ptr (i32), $5 = end (i32)
emit(0x02, 0x02, 0x7e, 0x02, 0x7f);
// Load hash from memory[HASH_OFFSET]
emit(0x41, ...toSignedLeb128(exports.HASH_OFFSET));
emit(0x29, 0x03, 0x00);
emit(0x21, 0x02);
// Load mask from memory[MASK_OFFSET]
emit(0x41, ...toSignedLeb128(exports.MASK_OFFSET));
emit(0x29, 0x03, 0x00);
emit(0x21, 0x03);
// ptr = inputStart
emit(0x20, 0x00);
emit(0x21, 0x04);
// end = inputStart + inputLen
emit(0x20, 0x00);
emit(0x20, 0x01);
emit(0x6a);
emit(0x21, 0x05);
// block $done
emit(0x02, 0x40);
// loop $loop
emit(0x03, 0x40);
// if ptr >= end → break
emit(0x20, 0x04);
emit(0x20, 0x05);
emit(0x4e);
emit(0x0d, 0x01);
// hash = (hash << 1) + table[mem[ptr] * 8]
emit(0x20, 0x02);
emit(0x42, 0x01);
emit(0x86);
emit(0x20, 0x04);
emit(0x2d, 0x00, 0x00);
emit(0x41, 0x03);
emit(0x74);
emit(0x29, 0x03, 0x00);
emit(0x7c);
emit(0x22, 0x02);
// if (hash & mask) == 0 → match
emit(0x20, 0x03);
emit(0x83);
emit(0x50);
emit(0x04, 0x40);
// Store updated hash
emit(0x41, ...toSignedLeb128(exports.HASH_OFFSET));
emit(0x20, 0x02);
emit(0x37, 0x03, 0x00);
// Return: ptr - inputStart + 1
emit(0x20, 0x04);
emit(0x20, 0x00);
emit(0x6b);
emit(0x41, 0x01);
emit(0x6a);
emit(0x0f);
emit(0x0b); // end if
// ptr++
emit(0x20, 0x04);
emit(0x41, 0x01);
emit(0x6a);
emit(0x21, 0x04);
emit(0x0c, 0x00); // br $loop
emit(0x0b); // end loop
emit(0x0b); // end block
// no match: store hash, return -1
emit(0x41, ...toSignedLeb128(exports.HASH_OFFSET));
emit(0x20, 0x02);
emit(0x37, 0x03, 0x00);
emit(0x41, 0x7f);
emit(0x0b); // end function
// Backpatch sizes
const bodySize = code.length - bodyStart;
const bsPatch = toLebU32Padded5(bodySize);
for (let i = 0; i < 5; i++)
code[funcSizeOff + i] = bsPatch[i];
const secSize = code.length - sectionSizeOff - 5;
const ssPatch = toLebU32Padded5(secSize);
for (let i = 0; i < 5; i++)
code[sectionSizeOff + i] = ssPatch[i];
return new Uint8Array(code);
}
function initWasm() {
if (wasmFn)
return;
const bytes = generateWasmBytes();
wasmMemory = new WebAssembly.Memory({ initial: PAGES });
const module = new WebAssembly.Module(bytes);
const instance = new WebAssembly.Instance(module, { js: { mem: wasmMemory } });
wasmFn = instance.exports.nextMatch;
wasmView = new Uint8Array(wasmMemory.buffer);
const dv = new DataView(wasmMemory.buffer);
for (let i = 0; i < 256; i++) {
dv.setBigUint64(exports.TABLE_OFFSET + i * 8, table_js_1.GEAR_TABLE[i], true);
}
}
function wasmNextMatch(inputStart, inputLen) {
return wasmFn(inputStart, inputLen);
}
function getView() {
return wasmView;
}
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