From d65fd681617ca30d7568b14eb518ea7a67e074e3 Mon Sep 17 00:00:00 2001
From: Ryan Oldenburg <ryan@guzba.com>
Date: Tue, 25 Jan 2022 16:48:01 -0600
Subject: [PATCH] zippy 0.8.1

---
 pixie.nimble                  |  4 ++--
 src/pixie/fileformats/gif.nim |  9 ++++++---
 src/pixie/fileformats/png.nim | 30 +++++++++++++++++++++++-------
 3 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/pixie.nimble b/pixie.nimble
index d8cf7b3..66a5c04 100644
--- a/pixie.nimble
+++ b/pixie.nimble
@@ -5,10 +5,10 @@ license     = "MIT"
 
 srcDir = "src"
 
-requires "nim >= 1.4.0"
+requires "nim >= 1.4.8"
 requires "vmath >= 1.1.0"
 requires "chroma >= 0.2.5"
-requires "zippy >= 0.7.4"
+requires "zippy >= 0.8.1"
 requires "flatty >= 0.2.2"
 requires "nimsimd >= 1.0.0"
 requires "bumpy >= 1.0.3"
diff --git a/src/pixie/fileformats/gif.nim b/src/pixie/fileformats/gif.nim
index b2ee795..1b89302 100644
--- a/src/pixie/fileformats/gif.nim
+++ b/src/pixie/fileformats/gif.nim
@@ -101,7 +101,10 @@ proc decodeGif*(data: string): Image {.raises: [PixieError].} =
 
       # Turn full lzw data into bit stream.
       var
-        bs = initBitStream(lzwData)
+        bs = BitStreamReader(
+          src: cast[ptr UncheckedArray[uint8]](lzwData[0].addr),
+          len: lzwData.len
+        )
         bitSize = lzwMinBitSize + 1
         currentCodeTableMax = (1 shl (bitSize)) - 1
         codeLast: int = -1
@@ -110,10 +113,10 @@ proc decodeGif*(data: string): Image {.raises: [PixieError].} =
 
       # Main decode loop.
       while codeLast != endCode:
-        if bs.pos + bitSize.int > bs.data.len * 8: failInvalid()
+        if bs.pos + bitSize.int > bs.len * 8: failInvalid()
         var
           # Read variable bits out of the table.
-          codeId = bs.readBits(bitSize).int
+          codeId = bs.readBits(bitSize.int).int
           # Some time we need to carry over table information.
           carryOver: seq[int]
 
diff --git a/src/pixie/fileformats/png.nim b/src/pixie/fileformats/png.nim
index cfd65a2..fb96177 100644
--- a/src/pixie/fileformats/png.nim
+++ b/src/pixie/fileformats/png.nim
@@ -165,14 +165,31 @@ proc unfilter(
       discard # Not possible, parseHeader validates
 
 proc decodeImageData(
+  data: string,
   header: PngHeader,
   palette: seq[ColorRGB],
-  transparency, data: string
+  transparency: string,
+  idats: seq[(int, int)]
 ): seq[ColorRGBA] =
+  if idats.len == 0:
+    failInvalid()
+
   result.setLen(header.width * header.height)
 
   let
-    uncompressed = try: uncompress(data) except ZippyError: failInvalid()
+    uncompressed =
+      if idats.len > 1:
+        var imageData: string
+        for (start, len) in idats:
+          let op = imageData.len
+          imageData.setLen(imageData.len + len)
+          copyMem(imageData[op].addr, data[start].unsafeAddr, len)
+        try: uncompress(imageData) except ZippyError: failInvalid()
+      else:
+        let
+          (start, len) = idats[0]
+          p = data[start].unsafeAddr
+        try: uncompress(p, len) except ZippyError: failInvalid()
     valuesPerPixel =
       case header.colorType:
       of 0: 1
@@ -340,7 +357,8 @@ proc decodePngRaw*(data: string): Png {.raises: [PixieError].} =
     counts = ChunkCounts()
     header: PngHeader
     palette: seq[ColorRGB]
-    transparency, imageData: string
+    transparency: string
+    idats: seq[(int, int)]
     prevChunkType: string
 
   # First chunk must be IHDR
@@ -402,9 +420,7 @@ proc decodePngRaw*(data: string): Png {.raises: [PixieError].} =
         failInvalid()
       if header.colorType == 3 and counts.PLTE == 0:
         failInvalid()
-      let op = imageData.len
-      imageData.setLen(imageData.len + chunkLen)
-      copyMem(imageData[op].addr, data[pos].unsafeAddr, chunkLen)
+      idats.add((pos, chunkLen))
     of "IEND":
       if chunkLen != 0:
         failInvalid()
@@ -432,7 +448,7 @@ proc decodePngRaw*(data: string): Png {.raises: [PixieError].} =
   result.width = header.width
   result.height = header.height
   result.channels = 4
-  result.data = decodeImageData(header, palette, transparency, imageData)
+  result.data = decodeImageData(data, header, palette, transparency, idats)
 
 proc decodePng*(data: string): Image {.raises: [PixieError].} =
   ## Decodes the PNG data into an Image.