From 13c309667b3b45404421bde8402bfc5b9495d918 Mon Sep 17 00:00:00 2001
From: MihailRis <mexaruc@gmail.com>
Date: Mon, 17 Mar 2025 02:17:32 +0300
Subject: [PATCH] add crc32 function

---
 res/scripts/stdmin.lua | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/res/scripts/stdmin.lua b/res/scripts/stdmin.lua
index 1366966a..9a1de9b4 100644
--- a/res/scripts/stdmin.lua
+++ b/res/scripts/stdmin.lua
@@ -26,6 +26,38 @@ function __vc_Canvas_set_data(self, data)
     self:_set_data(tostring(_ffi.cast("uintptr_t", canvas_ffi_buffer)))
 end
 
+_ffi.cdef([[
+    unsigned long crc32(unsigned long crc, const char *buf, unsigned len);
+]])
+
+local zlib
+if _ffi.os == "Windows" then
+    zlib = _ffi.load("zlib1")
+elseif _ffi.os == "OSX" then
+    zlib = _ffi.load("z")
+elseif _ffi.os == "Linux" then
+    zlib = _ffi.load("libz.so.1")
+else
+    error("platform does not support zlib " .. _ffi.os)
+end
+
+function crc32(bytes, chksum)
+    local chksum = chksum or 0
+
+    local length = #bytes
+    if type(bytes) == "string" then
+        return zlib.crc32(chksum, bytes, length)
+    elseif type(bytes) == "table" then
+        local buffer = _ffi.new(
+            string.format("char[%s]", length)
+        )
+        for i=1, length do
+            buffer[i - 1] = bytes[i]
+        end
+        return zlib.crc32(chksum, buffer, length)
+    end
+end
+
 -- Check if given table is an array
 function is_array(x)
     if #x > 0 then