[sdcc-devel] [ sdcc-Patches-2762462 ] Z80: faster/smaller _mullong

[SourceForge.net <no...@so...>]

Patches item #2762462, was opened at 2009-04-14 18:43
Message generated for change (Settings changed) made by parerga
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=300599&aid=2762462&group_id=599

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
>Category: z80 port
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Marco Bodrato (parerga)
Assigned to: Nobody/Anonymous (nobody)
Summary: Z80: faster/smaller _mullong

Initial Comment:
The best should be to write a (small) asm replacement, but I do not know exactly how to do it (I can write the mullong.s, but how to convince the compiler to use it?)

Meanwhile I cleaned the C code for the long integer product (32x32->32), it uses a smaller local variable and replaces six 8x8->16 products (four of them should be 8x8->8, because the high byte is discarder) with two 16x16->16 multiplication.

The C code obviously works on all the ports, but it was developed with Z80 limitations in mind, that's why an #ifdef limits its use to the z80 environment. On the other ports this code MAY show a small gain in code size, but it SHOULD NOT give any speed improvement (or may be it slow down the library), that's why it is disabled.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=300599&aid=2762462&group_id=599