Add zstd support for blend files.

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "libs/pixie"]
 	path = libs/pixie
 	url = https://git.myou.dev/MyouProject/pixie
+[submodule "libs/nim_zstd"]
+	path = libs/nim_zstd
+	url = https://github.com/DiThi/nim_zstd

libs/nim_zstd

@@ -0,0 +1 @@
+Subproject commit feeac7b6931ff2d8dc8cc76918de5d10d150bd09

src/loaders/blend_format.nim

@@ -32,10 +32,11 @@
 
 {.experimental: "dotOperators".}
 
-import strutils, tables, algorithm, sequtils, strformat, bitops
-import memfiles
+import std/[strutils, tables, algorithm, sequtils, strformat, bitops]
+import std/memfiles
 # import sugar
-import hashes
+import std/hashes
+import zstd/decompress
 
 # TODO!! ADD BOUND CHECKS TO ALL FNODES AND DNA1 PARSING!
 # TODO: implement big endian, test 32 bit
@@ -56,6 +57,8 @@ type
         old_mem_ptr: pointer
         # end pointer for bounds checking
         endp: pointer
+        # byte seq in case we used zstd
+        byte_seq: seq[byte]
     
     BlendFile* = ref BlendFileVal
 
@@ -142,13 +145,16 @@ template `-`(p, q: pointer): int = cast[int](cast[int](p) -% cast[int](q))
 template `+=`(p: pointer, i: Natural) = p = cast[pointer](cast[int](p) +% cast[int](i))
 
 # this is for getting a string that may not be null terminated
-# otherwise you can just do $cast[cstring](x.addr)
+# otherwise you could just do $cast[cstring](x.addr)
 proc getString(data: pointer, max_size: Natural): string =
     let u8 = cast[ptr UncheckedArray[char]](data)
-    for i in 0 ..< max_size:
+    var i = 0
+    while i < max_size:
         if u8[i] == '\0':
             break
-        result &= u8[i]
+        inc(i)
+    result.setLen i
+    copyMem(result.cstring, data, i)
 
 proc build_dna_table(dna_table: ptr FBlock64): (TypeAttrsRef, StructToTypeMap, seq[cstring], TypeLengths)  =
     var type_attrs = new TypeAttrsRef
@@ -230,25 +236,21 @@ proc build_dna_table(dna_table: ptr FBlock64): (TypeAttrsRef, StructToTypeMap, s
             )
             aoffset += asize
             offset += 4
-        # if true:
-        # # if lengths[type_id] != aoffset:
-        #     echo &"{types[type_id]}: {lengths[type_id]}, {aoffset}"
-        #     var offsets = toSeq(type_attrs[type_id].pairs)
-        #     for _,(k,v) in offsets.sortedByIt(it[1].offset):
-        #         echo &"{types[type_id]}.{k}:\t\t{v.offset}"
         assert lengths[type_id] == aoffset
         # type_attrs[type_id]["(size)"] = AttrOffset(offset: lengths[type_id])
     return (type_attrs, struct_to_type, types, lengths)
 
 proc openBlendFile*(path: string, data: pointer, len: int): BlendFile =
     result = new BlendFile
-    # result.mem_file = memfiles.open(path, mode=fmRead)
     result.file_path = path
-    # let mem = result.mem_file.mem
-    # result.mem = mem
-    # let file_length = result.mem_file.size
-    let mem = data
-    let file_length = len
+    let (mem, file_length) = if cast[ptr uint32](data)[] == 0xFD2FB528'u32:
+        # Zstandard compressed file
+        # TODO: store offsets of each zstd frame so we can semi-random access
+        # big files later
+        result.byte_seq = decompress cast[ptr UncheckedArray[byte]](data).toOpenArray(0, len-1)
+        (result.byte_seq[0].addr.pointer, result.byte_seq.len)
+    else:
+        (data, len)
     assert file_length > 32, "Invalid file size"
     result.endp = mem + file_length
     let u8 = cast[ptr UncheckedArray[uint8]](mem)