From e03c21238ff0deea1aeeae79c166e80821cddbbf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Remko=20Tron=C3=A7on?= <remko@el-tramo.be>
Date: Sat, 20 Jan 2024 18:12:47 +0100
Subject: [PATCH] Revert "thurtle: Add lzw & ulz compression"

This reverts commit 49f0b8f6e6315ede5df42e70de04bb508d7aa10c.
---
 src/web/thurtle/lzw.ts |  46 ------------------
 src/web/thurtle/ulz.ts | 104 -----------------------------------------
 2 files changed, 150 deletions(-)
 delete mode 100644 src/web/thurtle/lzw.ts
 delete mode 100644 src/web/thurtle/ulz.ts

diff --git a/src/web/thurtle/lzw.ts b/src/web/thurtle/lzw.ts
deleted file mode 100644
index 4043902..0000000
--- a/src/web/thurtle/lzw.ts
+++ /dev/null
@@ -1,46 +0,0 @@
-export function lzwEncode(data: Uint8Array) {
-  const dict = new Map<string, number>();
-  const out: Array<number> = [];
-  let phrase = String.fromCharCode(data[0]);
-  let code = 256;
-  for (let i = 1; i < data.length; i++) {
-    const chr = String.fromCharCode(data[i]);
-    const nphrase = phrase + chr;
-    if (dict.has(nphrase)) {
-      phrase = nphrase;
-    } else {
-      out.push(phrase.length > 1 ? dict.get(phrase)! : phrase.charCodeAt(0));
-      dict.set(nphrase, code);
-      code++;
-      phrase = chr;
-    }
-  }
-  out.push(phrase.length > 1 ? dict.get(phrase)! : phrase.charCodeAt(0));
-  return new TextEncoder().encode(
-    out.map((c) => String.fromCharCode(c)).join("")
-  );
-}
-
-export function lzwDecode(rdata: Uint8Array) {
-  const data = [...new TextDecoder().decode(rdata)].map((c) => c.charCodeAt(0));
-  let dict = new Map<number, number[]>();
-  var curChar = data[0];
-  var curPhrase = [curChar];
-  var out = [curChar];
-  var code = 256;
-  for (var i = 1; i < data.length; i++) {
-    const c = data[i];
-    const phrase =
-      c < 256
-        ? [data[i]]
-        : dict.has(c)
-        ? dict.get(c)!
-        : curPhrase.concat(curChar);
-    out.push(...phrase);
-    curChar = phrase[0];
-    dict.set(code, curPhrase.concat(curChar));
-    code++;
-    curPhrase = phrase;
-  }
-  return new Uint8Array(out);
-}
diff --git a/src/web/thurtle/ulz.ts b/src/web/thurtle/ulz.ts
deleted file mode 100644
index 3e0775f..0000000
--- a/src/web/thurtle/ulz.ts
+++ /dev/null
@@ -1,104 +0,0 @@
-export function ulzDecode(src: Uint8Array) {
-  const dst: Array<number> = [];
-  let sp = 0;
-  while (sp < src.length) {
-    const c = src[sp++];
-    if (c & 0x80) {
-      // CPY
-      let length;
-      if (c & 0x40) {
-        if (sp >= src.length) {
-          throw new Error(`incomplete CPY2`);
-        }
-        length = ((c & 0x3f) << 8) | src[sp++];
-      } else {
-        length = c & 0x3f;
-      }
-      if (sp >= src.length) {
-        throw new Error(`incomplete CPY`);
-      }
-      let cp = dst.length - (src[sp++] + 1);
-      if (cp < 0) {
-        throw new Error(`CPY underflow`);
-      }
-      for (let i = 0; i < length + 4; i++) {
-        dst.push(dst[cp++]);
-      }
-    } else {
-      // LIT
-      if (sp + c >= src.length) {
-        throw new Error(`LIT out of bounds: ${sp} + ${c} >= ${src.length}`);
-      }
-      for (let i = 0; i < c + 1; i++) {
-        dst.push(src[sp++]);
-      }
-    }
-  }
-  return new Uint8Array(dst);
-}
-
-const MIN_MAX_LENGTH = 4;
-
-function findBestMatch(
-  src: Uint8Array,
-  sp: number,
-  dlen: number,
-  slen: number
-) {
-  let bmlen = 0;
-  let bmp = 0;
-  let dp = sp - dlen;
-  for (; dlen; dp++, dlen--) {
-    let i = 0;
-    for (; ; i++) {
-      if (i == slen) {
-        return [dp, i];
-      }
-      if (src[sp + i] != src[dp + (i % dlen)]) {
-        break;
-      }
-    }
-    if (i > bmlen) {
-      bmlen = i;
-      bmp = dp;
-    }
-  }
-  return [bmp, bmlen];
-}
-
-export function ulzEncode(src: Uint8Array) {
-  let dst: Array<number> = [];
-  let sp = 0;
-  let litp = -1;
-  while (sp < src.length) {
-    const dlen = Math.min(sp, 256);
-    const slen = Math.min(src.length - sp, 0x3fff + MIN_MAX_LENGTH);
-    const [bmp, bmlen] = findBestMatch(src, sp, dlen, slen);
-    if (bmlen >= MIN_MAX_LENGTH) {
-      // CPY
-      const bmctl = bmlen - MIN_MAX_LENGTH;
-      if (bmctl > 0x3f) {
-        // 	CPY2
-        dst.push((bmctl >> 8) | 0xc0);
-        dst.push(bmctl & 0xff);
-      } else {
-        dst.push(bmctl | 0x80);
-      }
-      dst.push(sp - bmp - 1);
-      sp += bmlen;
-      litp = -1;
-    } else {
-      // LIT
-      if (litp >= 0) {
-        if ((dst[litp] += 1) == 127) {
-          litp = -1;
-        }
-      } else {
-        dst.push(0);
-        litp = dst.length - 1;
-      }
-      dst.push(src[sp++]);
-    }
-  }
-  return new Uint8Array(dst);
-}