[libre-riscv-dev] [Bug 74] preliminary exploratory software emulation of FP SQRT

[bugzilla-daemon at libre-riscv.org]

http://bugs.libre-riscv.org/show_bug.cgi?id=74

--- Comment #28 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Aleksandar Kostovic from comment #27)
> >theeeeennn... you can do sq_test = x.sqrt() above... and on the answer,
> >use the function decodefp32(sq_test)...
> >
> >and print those out next to the answer from using main().
> 
> Okay so i am confused by the thing i should do but tried to understand, so 
> added:
> 
> +    sq_test = x.sqrt()
> +    e, m = decode_fp32(sq_test)
> +    print(main(e, m))
> 
> and get an error:
> File "/home/aleksandar/projects/ieee754fpu/src/add/fsqrt.py", line 64, in
> get_sign
>     return ((x & 0x80000000) >> 31)
> TypeError: unsupported operand type(s) for &: 'sfpy.float.Float32' and 'int'

you did exactly the same thing, doh!  you passed in sq_test (an object)
*NOT* the bits *OF* the object, which are an integer.

-    sq_test = x.sqrt()
+    sq_test = x.sqrt.bits

also, decode_fp32 returns a tuple of 3 items: sign, exponent, mantissa.
you can't assign a tuple of length 3 to a tuple of length 2 (e, m)

-    e, m = decode_fp32(sq_test.bits)
+    s, e, m = decode_fp32(sq_test.bits)

try git pull.

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