Re: fletcher's checksum

Thanks for the reply. I do have the C code that does this. If anybody can easily translate it to PHP, it would be very apriciated. Here is the C code. There is a decode function, but I don't need it in PHP because I have a C program listening to serial port on the other end that will validate the checksum. /* * operator fletcher_encode */ fletcher_encode( buffer, count ) unsigned char* buffer; long count; { int i; unsigned char c0 = 0; unsigned char c1 = 0; * ( buffer + count - 1 ) = 0; * ( buffer + count - 2 ) = 0; for( i = 0; i < count; i++) {

    c0 = c0 + * ( buffer + i );
    c1 =c1 +c0;

} * ( buffer + count - 2 ) = c0 - c1; * ( buffer + count - 1 ) = c1 - 2*c0; } My problem with PHP was with the unsigned char. Thanks again, Dave Gervais Ford, Mike [LSS] wrote:

-----Original Message----- From: Dave Gervais [mailto:dag27dsl@magma.ca] Sent: 08 January 2003 19:11 Does anybody know how to implement the 8 and 16 bit versions of Fletcher's checksum using PHP? I hit google and came up dry. It's easy enough to find how to do it in C, but PHP if a different story.

Well, I have no idea what Fletcher's checksum is, but if you have a version in C that's not too long (<20 lines of code, say), it shouldn't be too difficult to convert it into PHP. There should be enough people here sufficiently proficient in both C and PHP to at least give you a pointer in the right direction! Cheers! Mike --------------------------------------------------------------------- Mike Ford, Electronic Information Services Adviser, Learning Support Services, Learning & Information Services, JG125, James Graham Building, Leeds Metropolitan University, Beckett Park, LEEDS, LS6 3QS, United Kingdom Email: m.ford@lmu.ac.uk

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