help with c translation

[Lars T. Kyllingstad]

robby wrote:
> can anybody help me translate this c function to d, im having a problem with the data types. thanks.
> 
> 
> //-------------------------
> unsigned int BLZCC blz_pack(const void *source,
>                             void *destination,
>                             unsigned int length,
>                             void *workmem)
> {
>    BLZPACKDATA ud;
>    const unsigned char **lookup = workmem;
>    const unsigned char *backptr = source;
> 
>    /* check for length == 0 */
>    if (length == 0) return 0;
> 
>    /* init lookup[] */
>    {
>       int i;
>       for (i = 0; i < BLZ_WORKMEM_SIZE/4; ++i) lookup[i] = 0;
>    }
> 
>    ud.source = source;
>    ud.destination = destination;
> 
>    /* first byte verbatim */
>    *ud.destination++ = *ud.source++;
> 
>    /* check for length == 1 */
>    if (--length == 0) return 1;
> 
>    /* init first tag */
>    ud.tagpos = ud.destination;
>    ud.destination += 2;
>    ud.tag = 0;
>    ud.bitcount = 16;
> 
>    /* main compression loop */
>    while (length > 4)
>    {
>       const unsigned char *ppos;
>       unsigned int len = 0;
> 
>       /* update lookup[] up to current position */
>       while (backptr < ud.source)
>       {
> 	 lookup[blz_hash4(backptr)] = backptr;
> 	 backptr++;
>       }
> 
>       /* look up current position */
>       ppos = lookup[blz_hash4(ud.source)];
> 
>       /* check match */
>       if (ppos)
>       {
> 	 while ((len < length) &&
> 		(*(ppos + len) == *(ud.source + len))) ++len;
>       }
> 
>       /* output match or literal */
>       if (len > 3)
>       {
> 	 unsigned int pos = ud.source - ppos - 1;
> 
> 	 /* output match tag */
> 	 blz_putbit(&ud, 1);
> 
> 	 /* output length */
> 	 blz_putgamma(&ud, len - 2);
> 
> 	 /* output position */
> 	 blz_putgamma(&ud, (pos >> 8) + 2);
> 	 *ud.destination++ = pos & 0x00ff;
> 
> 	 ud.source += len;
> 	 length -= len;
> 
>       } else {
> 
> 	 /* output literal tag */
> 	 blz_putbit(&ud, 0);
> 
> 	 /* copy literal */
> 	 *ud.destination++ = *ud.source++;
> 	 length--;
>       }
>    }
> 
>    /* output any remaining literals */
>    while (length > 0)
>    {
>       /* output literal tag */
>       blz_putbit(&ud, 0);
> 
>       /* copy literal */
>       *ud.destination++ = *ud.source++;
>       length--;
>    }
> 
>    /* shift last tag into position and store */
>    ud.tag <<= ud.bitcount;
>    ud.tagpos[0] = ud.tag & 0x00ff;
>    ud.tagpos[1] = (ud.tag >> 8) & 0x00ff;
> 
>    /* return compressed length */
>    return ud.destination - (unsigned char *)destination;
> }


I'm no C expert, but I'll give it a shot.

     unsigned int -> uint  (or size_t, if it is the length of an array)
     unsigned char -> ubyte

For future reference, a handy table of C-to-D type correspondences can 
be found here:
     http://www.digitalmars.com/d/2.0/htomodule.html

You didn't say whether you use D1 or D2. If it is D1 I believe you 
should also replace "const void *" by just "void*" in the function 
declaration.

Hope this helps,
-Lars