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-rw-r--r--src/lzio.js81
1 files changed, 81 insertions, 0 deletions
diff --git a/src/lzio.js b/src/lzio.js
new file mode 100644
index 0000000..919ed44
--- /dev/null
+++ b/src/lzio.js
@@ -0,0 +1,81 @@
+"use strict";
+
+const assert = require('assert');
+
+
+class MBuffer {
+ constructor() {
+ this.buffer = null;
+ this.n = 0;
+ }
+}
+
+class ZIO {
+ constructor(L, reader, data) {
+ this.L = L; /* Lua state (for reader) */
+ assert(typeof reader == "function", "ZIO requires a reader");
+ this.reader = reader; /* reader function */
+ this.data = data; /* additional data */
+ this.n = 0; /* bytes still unread */
+ this.buffer = null;
+ this.off = 0; /* current position in buffer */
+ }
+
+ zgetc () {
+ return ((this.n--) > 0) ? this.buffer[this.off++] : luaZ_fill(this);
+ }
+}
+
+const EOZ = -1;
+
+const luaZ_fill = function(z) {
+ let size;
+ let buff = z.reader(z.L, z.data);
+ if (buff === null)
+ return EOZ;
+ if (buff instanceof DataView) {
+ z.buffer = new Uint8Array(buff.buffer, buff.byteOffset, buff.byteLength);
+ z.off = 0;
+ size = buff.byteLength - buff.byteOffset;
+ } else {
+ assert(typeof buff !== "string", "Should only load binary of array of bytes");
+ z.buffer = buff;
+ z.off = 0;
+ size = buff.length;
+ }
+ if (size === 0)
+ return EOZ;
+ z.n = size - 1;
+ return z.buffer[z.off++];
+};
+
+/* b should be an array-like that will be set to bytes
+ * b_offset is the offset at which to start filling */
+const luaZ_read = function(z, b, b_offset, n) {
+ while (n) {
+ if (z.n === 0) { /* no bytes in buffer? */
+ if (luaZ_fill(z) === EOZ)
+ return n; /* no more input; return number of missing bytes */
+ else {
+ z.n++; /* luaZ_fill consumed first byte; put it back */
+ z.off--;
+ }
+ }
+ let m = (n <= z.n) ? n : z.n; /* min. between n and z->n */
+ for (let i=0; i<m; i++) {
+ b[b_offset++] = z.buffer[z.off++];
+ }
+ z.n -= m;
+ if (z.n === 0) // remove reference to input so it can get freed
+ z.buffer = null;
+ n -= m;
+ }
+
+ return 0;
+};
+
+module.exports.EOZ = EOZ;
+module.exports.luaZ_fill = luaZ_fill;
+module.exports.luaZ_read = luaZ_read;
+module.exports.MBuffer = MBuffer;
+module.exports.ZIO = ZIO;