6502.org

Hello everyone.

i'm developing a floating point unit for 65C816 compliant with IEEE754 quadruple precision.
At this time these functions are full implemented:
- fpadd, fpsub, fpmult, fpdiv (basic operations)
- fprexp (extract exponent), fscale (scale by a power of two), scale10 (scale by a power of ten), fsquare
- fpack (store in memory in ieee format), funpack (get from memory)
- Roundup functions: ftrunc, fceil, floor, fround, fmod
- str2int, str2fp (convert string to binary)
- fp2str: convert a float to string (compliant with sprintf() function)
- int2dec, uint2dec: convert a 128 bit integer to string
- fsqrt, fcbrt: square root and cube root
- flog, flog10, flog2 (logarithm functions)
- flogp1, flog10p1, flog2p1: computes lognn(1+x) whenn x is very close to 1.0
- fexp, fexp2, fexp10: exponential functions
- fexpm1: computes exp(x)-1 with greater accuracy when x is close to 0.0
- fpown: computes x raised at n (n integer)
- frootn: computes the n-th root
- fpowxy: computes x raised to y (both float)

For future i plan to implement circular functions and hyperbolics functions.

Source code is available HERE: http://65xx.unet.bz/fpu.txt

- Marco

Oh, this is wonderful. I'm going to try it out RIGHT NOW.
...and thank you.

Hello everyone,

i updated the fpu implementation with a new version: http://65xx.unet.bz/fpu.txt

Some minor bugs was fixed (one in str2fp function, one in fexp function) and some improvements was done.
Added a function int2str compliant with format of sprintf() function (hex. formatting, a flag to Group thousand in decimal format).

The function that extract integral part and fractionary part was renamed from fmod to fpfrac.

Added two "remainders" functions: fpmod & fprem (work as the same functions in C).

Finally, added circular & hyperbolics functions:

fsin, fcos, ftan, fcotan (max. absolute value of argument: 2^56)
fasin, facos, fatan, fatanyx (this last function compute fatan(y/x) but return value in interval [0, 2pi] useful for computes phase angle)
fsinh, fcosh, ftanh
fasinh, facosh, fatanh

For implementation details and algorithms look at source code.

Greetings,
Marco

For those who haven't had a peek at Granati's source code, it runs to 9838 lines, which is a substantial piece of work (the entire firmware in my POC is about 11,300 lines). I hope to look more closely into it in the near future, after I recover from my next ( ) eye surgery.

Whishes for a quick and good recovery.

Many lines on fpu.asm are just comments, assembled code is about 16k (many bytes used for store float constants).

The main goal is build a "virtual numeric co-processor" with some internal pseudo-registers stack-oriented, interfaced by 'cop' instruction.

Thank you.
I include comments in the line count because they have to be typed in, just like the actual instructions, and hence represent code editing time.

The constants tables should help a lot in what are computationally-intensive operations. This is a classic tradeoff between memory consumption and compute-bound performance. Given the much greater addressing capabilities of the 65C816 over the 65C02, memory consumption of this sort should not be a problem.
The BIOS in POC V2 (which is awaiting construction once I regain full use of both eyes) will be called via software interrupts using COP. It'll be an interesting exercise to integrate your floating point package into such an environment.

Glanced over the code. Thank you for writing it. Looks good.

Is anyone aware whether 32 and 64 bit versions of this code exist?

32,64,128 bit

why not, ieee754-16 (half single)

https://en.wikipedia.org/wiki/Half-prec ... int_format

(Welcome, tebe6502!)

The link seems to be dead now. Did anyone save a copy?

Can see it here:
https://web.archive.org/web/20170923012 ... 80/fpu.txt

Sorry for dead link, soon i put again online. Happened when i changed hosting (i restored an old version of the web site).

Marco

p.s.: the source code is available in the downloadable archive in my site

Great to know you're still active!

Is that http://65xx.unet.bz/ ? (It's not in your profile or signature line, but it's the base of your link above which gives a 404 error message.) I cannot find the source code in that domain. It is archived though at https://web.archive.org/web/20170923012 ... 80/fpu.txt .