---------
> From: FrankT <gymna@COMPUSERVE.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: 2 bytes into unsigned long
> Date: Monday, 21 April 1997 22:16
>
> Via I2c I receive 2 bytes HighByte and LowByte.
>
> What is the fastest way (with MPLABC) to convert them into a unsigned
long
> variable?

Well, using CCS's C I do this -

put this in your h file

struct two_byte {
        BYTE lsb;
        BYTE msb;
};

typedef union split_tag {
        long L;   // note!  a long in CCS is 16 bits
        struct two_byte TB;
} split_type;

then declare

split_type a, b;
a.TB.lsb = 123; // manipulate as 8 bit vars
a.TB.msb = 456;

b.L = a.L; // manipulate as 16 bit vars


Advantage is that there is no arithmetic ops involved.  Things to check are
whether your C is big or little endian, and whether it supports structs /
unions.

MikeS
<mikesmith_oz@relaymail.net>