it works

src/zippy/compress.nim

@@ -281,13 +281,23 @@ func compress*(src: seq[uint8]): seq[uint8] =
       b.addBits(bitLensRle[k], 7)
     inc k
 
+  for i in 0 ..< encoded.len:
+    let symbol = encoded[i]
+    b.addBitsReverse(codesLitLen[symbol], depthsLitLen[symbol])
+
   if depthsLitLen[256] == 0:
     failCompress()
 
-  b.addBits(0, 8)
-  b.addBits(0, 8)
-  b.addBits(0, 8)
-  b.addBits(0, 8)
+  b.addBitsReverse(codesLitLen[256], depthsLitLen[256]) # End of block
+
+  b.skipRemainingBitsInCurrentByte()
+  b.data.setLen(b.data.len + 1)
+
+  let checksum = cast[array[4, uint8]](adler32(src))
+  b.addBits(checkSum[3], 8)
+  b.addBits(checkSum[2], 8)
+  b.addBits(checkSum[1], 8)
+  b.addBits(checkSum[0], 8)
 
   b.data
 

src/zippy/uncompress.nim

@@ -138,8 +138,8 @@ func decodeSymbol(b: var BitStream, h: Huffman): uint16 {.inline.} =
       code = code or (bits and 1).int
       bits = bits shr 1
       count = h.counts[len].int
-      debugEcho code, " ", toBin(code.int, 8), " ", len, " ", count, " ", first, " ", index
-      debugEcho code - count
+      # debugEcho code, " ", toBin(code.int, 8), " ", len, " ", count, " ", first, " ", index
+      # debugEcho code - count
       if code - count < first:
         fastSkip(i)
         return h.symbols[index + (code - first)]

tests/test.nim

@@ -38,8 +38,8 @@ const golds = [
 
 let c = cast[seq[uint8]](compress("A_DEAD_DAD_CEDED_A_BAD_BABE_A_BEADED_ABACA_BED"))
 # let c = cast[seq[uint8]](compress("aaaaaaaaaabcccccccccccccccddddddd"))
-# echo c
-echo uncompress(c)
+echo c
+echo cast[string](uncompress(c))
 # import random, fidget/opengl/perf, algorithm
 
 # include zippy/compress