//
//   CRC_32 Checksum
//
//  FutureBasic 7.0.34, August 2025 R.W
//----------------------------------------------

// Get CRC_32 checksum from a CFstring
// using the standard bits reversed 0x04C11DB7

// Verified accuracy using the site
// https://codeshack.io/crc32-checksum-generator/

local fn getCRC_32 (textStr As CFStringRef) As UInt32
  UInt32 i, j, crc, byte
  crc = 0xFFFFFFFF

  for i = 0 to len(textStr) -1
    byte = ucc(textStr, i)
    crc = crc XOR byte
    for j = 0 to 7
      if ( crc AND 1 )
        crc = (crc >> 1) XOR 0xEDB88320
      else
        crc = crc >> 1
      end if
    next
  next
  crc = crc XOR 0xFFFFFFFF
end fn = crc


window 1,@"CRC checksum"

CFStringRef testString
testString = @"The quick brown fox jumps over the lazy dog"

UInt32 checksum
checksum = fn getCRC_32(testString)

print
print @" ";testString
print @" has a checksum of ";hex(checksum)

handleEvents

//