tools: add zbuf_decode.py

tools/zbuf_decode.py

@@ -0,0 +1,38 @@
+import sys
+import struct
+
+with open(sys.argv[1], 'rb') as f:
+    buf = memoryview(f.read())
+
+print("P2")
+print("1600 1200")
+print("65535")
+
+min_n = None
+max_n = None
+
+for i in range(len(buf) // 4):
+    b = buf[i*4:i*4+4]
+
+    num, = struct.unpack("<I", b)
+    assert (num & 0xff) == 0, (hex(i*4), hex(num))
+    depth24 = num >> 8
+    depth16 = num >> 16
+
+    if i == 0:
+        min_n = depth24
+        max_n = depth24
+
+    if min_n == 0 or (depth24 < min_n and depth24 != 0):
+        min_n = depth24
+    if depth24 > max_n:
+        max_n = depth24
+
+    print(depth16, end='')
+    if i % 128 == 127:
+        print("", end='\n')
+    else:
+        print("", end=" ")
+
+
+print(min_n, max_n, file=sys.stderr)