16 bit signed division

[Robb Bates]

I don't know why, but it's almost impossible to find a fast compact 16 bit signed division assembly routine.

Yes, I know just use an unsigned one after getting the ABS of both values and negating the result if needed.

But mine is a slow, big and bloated brute force method.  If anyone has a nice small routine already crafted, can you post it?

Ideally, HL=DE/HL with DE=remainder.  But I'll take anything.

Thanks,

Robb

[Willy De la Court]

https://wikiti.brandonw.net/index.php?title=Z80_Routines:Math:Division
Not tested these but this I think are valid.

[Willy De la Court]

Some other links
https://learn.cemetech.net/index.php/Z80:Math_Routines
https://map.grauw.nl/articles/mult_div_shifts.php
https://tutorials.eeems.ca/Z80ASM/part4.htm

[Robb Bates]

Yeah, I've seen those and I'll probably end up using one of them.  I was hoping someone had one already pre-rolled and ready to go.  All the register shuffling that I have to do adds bloat.

The ac/de one is nice and small, but I'll have to see if it leaves the remainder somewhere.  I need a MOD function as well.

Robb

[Phillip Stevens]

Here is the z88dk small implementation, which follows the C standard of the remainder taking the sign of the dividend.

https://github.com/z88dk/z88dk/blob/master/libsrc/math/integer/small/l_small_divs_16_16x16.asm

 

[Phillip Stevens]

I don't know why, but it's almost impossible to find a fast compact 16 bit signed division assembly routine.

Ideally, HL=DE/HL with DE=remainder.  But I'll take anything.

Here is the z88dk small implementation, which follows the C standard of the remainder taking the sign of the dividend.

https://github.com/z88dk/z88dk/blob/master/libsrc/math/integer/small/l_small_divs_16_16x16.asm

There are fast versions too, if you prefer that path.

https://github.com/z88dk/z88dk/tree/master/libsrc/math/integer/fast