Dennis Castleman
-----Original Message-----
From: Dennis
Castleman [mailto:DennisCastleman@oaktech.com]
Sent: Monday, April 14,
2003 9:53 AM
To: 'Ralf Baechle';
linux-mips@linux-mips.org
Cc: Gus Fernandez
Subject: Soft
floating point on 5K
ALL
I'm trying to run soft-floating point functions on a r5000 core with a FPU.
Without having to take the overhead of using a trap. Using the files fp-bit.c and dp-bit.c
from the gcc source as a floating point lib. This implementation lack in accuracy in
the least signeficant bit multiplication in division operations.Using the floating point validation test from UCB(ucbtest), which validates
single and double precision operations for addition, subtraction, division
and multiplication. This test tests all difficult cases and edge conditions
(like combination of infinities, Nan etc.).Here is the result with our soft-float library:-
Single precision Addition: Passed all 344 tests.
Single precision Subtraction: Passed all 316 tests
Single precision multiplication: Total: 334 Passed:313 Failed: 21
Single precision division: Total: 379 Passed: 375 Failed: 4
Double precision Addition: Passed all 352 tests.
Double precision Subtraction: Passed all 321 tests
Double precision multiplication: Total: 340 Passed: 319 Failed: 21
Double precision division: Total: 383 Passed: 379 Failed: 4However, in all the failed cases there is only 1 bit different in the mantissa.
Essentially for some cases, it's less accurate by the minimum distance.
Any ideas in how to make this work or improve soft-floating point on a mips 5Kc?
Value error: divd n eq xu
Input: 000FFFFF FFFFFFFE 3FEFFFFF FFFFFFFE
Computed: 000FFFFF FFFFFFFE
Expected: 000FFFFF FFFFFFFF xu
Value error: divd n eq xu
Input: 000FFFFF FFFFFFF7 3FEFFFFF FFFFFFFE
Computed: 000FFFFF FFFFFFF7
Expected: 000FFFFF FFFFFFF8 xu
Value error: divd n eq xu
Input: 800FFFFF FFFFFFF8 3FEFFFFF FFFFFFFE
Computed: 800FFFFF FFFFFFF8
Expected: 800FFFFF FFFFFFF9 xu
Value error: divd n eq xu
Input: 001FFFFF FFFFFFFF 40000000 00000000
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 xu
Total 383 tests: pass 379, flags err 0, value err 4, divd
ucbtest UCBFAIL in divd at line 701 for double
Value error: divs n eq xu
Input: 007FFFFE 3F7FFFFE
Computed: 007FFFFE
Expected: 007FFFFF xu
Value error: divs n eq xu
Input: 007FFFF7 3F7FFFFE
Computed: 007FFFF7
Expected: 007FFFF8 xu
Value error: divs n eq xu
Input: 807FFFF8 3F7FFFFE
Computed: 807FFFF8
Expected: 807FFFF9 xu
Value error: divs n eq xu
Input: 00FFFFFF 40000000
Computed: 007FFFFF
Expected: 00800000 xu
Total 379 tests: pass 375, flags err 0, value err 4, divs
ucbtest UCBFAIL in divs at line 701 for floatValue error: muld n eq x?u
Input: 000FFFFF FFFFFFF8 3FF00000 00000008
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 x?u
Value error: muld n eq x?u
Input: 000FFFFF FFFFFFF8 BFF00000 00000008
Computed: 800FFFFF FFFFFFFF
Expected: 80100000 00000000 x?u
Value error: muld n eq x?u
Input: 000FFFFF FFFFFFFF 3FF00000 00000001
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 x?u
Value error: muld n eq x?u
Input: 00100000 00000001 3FEFFFFF FFFFFFFE
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 x?u
Value error: muld n eq x?u
Input: 00100000 00000002 3FEFFFFF FFFFFFFC
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 x?u
Value error: muld n eq x?u
Input: 20000000 02000000 1FFFFFFF FC000000
Computed: 00000000 00000000
Expected: 00100000 00000000 x?u
Value error: muld n eq x?u
Input: 800FFFFF FFFFFFFF 3FF00000 00000001
Computed: 800FFFFF FFFFFFFF
Expected: 80100000 00000000 x?u
Value error: muld n eq xu
Input: 00000000 00000001 3FEFFFFF FFFFFFFF
Computed: 00000000 00000000
Expected: 00000000 00000001 xu
Value error: muld n eq xu
Input: 00000000 00000001 BFEFFFFF FFFFFFFF
Computed: 80000000 00000000
Expected: 80000000 00000001 xu
Value error: muld n eq xu
Input: 000FFFFF FFFFFFF8 3FF00000 00000001
Computed: 000FFFFF FFFFFFF8
Expected: 000FFFFF FFFFFFF9 xu
Value error: muld n eq xu
Input: 000FFFFF FFFFFFF8 BFF00000 00000001
Computed: 800FFFFF FFFFFFF8
Expected: 800FFFFF FFFFFFF9 xu
Value error: muld n eq xu
Input: 000FFFFF FFFFFFFE 3FF00000 00000001
Computed: 000FFFFF FFFFFFFE
Expected: 000FFFFF FFFFFFFF xu
Value error: muld n eq xu
Input: 000FFFFF FFFFFFFE BFF00000 00000001
Computed: 800FFFFF FFFFFFFE
Expected: 800FFFFF FFFFFFFF xu
Value error: muld n eq xu
Input: 00100000 00000001 3FEFFFFF FFFFFFFA
Computed: 000FFFFF FFFFFFFD
Expected: 000FFFFF FFFFFFFE xu
Value error: muld n eq xu
Input: 001FFFFF FFFFFFFF 3FE00000 00000000
Computed: 000FFFFF FFFFFFFF
Expected: 00100000 00000000 xu
Value error: muld n eq xu
Input: 001FFFFF FFFFFFFF BFE00000 00000000
Computed: 800FFFFF FFFFFFFF
Expected: 80100000 00000000 xu
Value error: muld n eq xu
Input: 800FFFFF FFFFFFF7 3FF00000 00000001
Computed: 800FFFFF FFFFFFF7
Expected: 800FFFFF FFFFFFF8 xu
Value error: muld n eq xu
Input: BFE00000 00000001 00000000 00000001
Computed: 80000000 00000000
Expected: 80000000 00000001 xu
Value error: muld n eq xu
Input: BFF80000 00000000 80000000 00000001
Computed: 00000000 00000001
Expected: 00000000 00000002 xu
Value error: muld n eq xu
Input: C0040000 00000001 00000000 00000001
Computed: 80000000 00000002
Expected: 80000000 00000003 xu
Value error: muld n eq xu
Input: C00C0000 00000000 80000000 00000001
Computed: 00000000 00000003
Expected: 00000000 00000004 xu
Total 340 tests: pass 319, flags err 0, value err 21, muld
ucbtest UCBFAIL in muld at line 701 for double
