Dag-Erling Smørgrav
a09cdc6318
Fix equality predicates.
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The count we passed to memcmp() in mpi_eq() and mpi_eq_abs() was actually the number of significant words in the MPI, rather than the number of bytes we wanted to compare. Multiply by 4 to get the correct value.
To make the intent of the code more apparent, introduce a private MPI_MSW() macro which evaluates to the number of significant words (or 1-based index of the most significant word). This also comes in handy in mpi_{add,sub,mul}_abs().
Add a couple of test cases which not only demonstrate the bug we fixed here but also demonstrate why we must compare whole words: on a big-endian machine, we would be comparing the unused upper bytes of the first and only word instead of the lower bytes which actually hold a value...
2017-04-22 05:32:25 +02:00
Dag-Erling Smørgrav
c556bc0aa8
Implement MPI division.
2017-04-06 19:52:23 +02:00
Dag-Erling Smørgrav
3c2b134fe4
Implement fast increment / decrement functions.
2017-04-06 19:52:23 +02:00
Dag-Erling Smørgrav
111efcb949
Correct function descriptions.
2017-04-06 19:52:23 +02:00
Dag-Erling Smørgrav
2a66f62078
Implement MPI multiplication.
2017-04-06 19:52:23 +02:00
Dag-Erling Smørgrav
206c6ffc85
Implement ffs() / fls() and use the latter to compute the MSB.
2017-04-06 19:52:23 +02:00
Dag-Erling Smørgrav
8477c4ae0b
Slightly improve function descriptions.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
094635f394
Remove debugging code.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
b4eb918dad
Implement GCD using Stein's binary algorithm.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
a11c52e896
Refactor the comparison predicates, check for identity first.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
47a0bf838f
Add functions for comparing an MPI to an integer.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
26e434d64b
Add functions that return the LSB and MSB of an MPI.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
7e05fe419a
Remove unused headers.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
895d1eb539
Constify where possible.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
9ee45d4e34
Fix sign bug in special cases in mpi_{add,sub}_abs().
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We failed to clear the negative flag when handling trivial cases, so if one of the terms was 0 and the other was negative, the result would be an exact copy of the non-zero term instead of its absolute value.
2017-04-06 19:51:47 +02:00
Dag-Erling Smørgrav
fbf69f31cb
Start using pkg-config / pkgconf.
2017-03-07 00:54:46 +01:00
Dag-Erling Smørgrav
f70dac496f
Mechanically bump copyright dates to the date of the latest commit.
2017-02-19 20:07:43 +01:00
Dag-Erling Smørgrav
f6905c8edb
Fix bugs in cryb_mpi_{add,sub}_abs() caused by assuming that the target is initally positive zero.
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If its operands were identical, cryb_mpi_add_abs() would leave the target untouched. Explicitly call mpi_zero() before returning. While there, extend the “identical operands” shortcut to also cover equality.
Both cryb_mpi_add_abs() and cryb_mpi_sub_abs() would leave the target's negative flag untouched. Explicitly clear it before returning.
2017-02-19 17:20:40 +01:00
Dag-Erling Smørgrav
f612ea1b14
Add dependencies on libcryb-core to all other libraries, as already enforced in the configure script.
2016-11-14 12:59:13 +01:00
Dag-Erling Smørgrav
dc43296a47
Centralize most of .gitignore.
2016-09-17 21:38:54 +02:00
Dag-Erling Smørgrav
06a757e878
Big reorganization and cleanup
2016-09-04 14:56:39 +02:00
Dag-Erling Smørgrav
4d7893004c
Prepare for moving to Github
2015-12-14 15:55:38 +01:00
Dag-Erling Smørgrav
94471e9923
Always clear the negative flag in mpi_zero()
2015-10-03 14:23:32 +00:00
Dag-Erling Smørgrav
a33f58cad7
Fix equality predicate.
2015-01-07 19:23:38 +00:00
Dag-Erling Smørgrav
d0fb2359f1
Implement mpi_{add,sub}() in terms of mpi_{add,sub}_abs().
2015-01-07 18:59:44 +00:00
Dag-Erling Smørgrav
7a90ca7b42
Since X may point to the same MPI as either G or L (or even both), we
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can't set the carry flag based on the contents of G or L after having
modified X. Instead, compute and stash the new carry value first.
2014-12-30 19:14:59 +00:00
Dag-Erling Smørgrav
0d483f20ab
Fix msb calculation. We may have to backtrack quite a bit, for
...
instance when subtracting two nearly equal large numbers.
2014-12-30 16:45:18 +00:00
Dag-Erling Smørgrav
1c024928f9
Fix off-by-one bug in mpi_cmp() which could cause it to read past the
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end of the buffer.
2014-12-30 16:35:13 +00:00
Dag-Erling Smørgrav
43b870dc83
WIP: implement subtraction correctly. The actual result is now correct
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most of the time, but the MSB calculation is not.
2014-12-30 11:23:30 +00:00
Dag-Erling Smørgrav
7524a14386
comment nit
2014-12-30 11:15:28 +00:00
Dag-Erling Smørgrav
c5b962387c
Add mpi_eq_abs() and mpi_eq() predicates.
2014-12-30 11:12:11 +00:00
Dag-Erling Smørgrav
bc8e9d67ba
In both mpi_add_abs() and mpi_sub_abs(), make sure that the target is
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untouched if the operation fails. Also ensure that A = A +/- A works.
2014-12-29 23:44:34 +00:00
Dag-Erling Smørgrav
98c6349d4a
In mpi_zero(), save a memset() if the target is already zero.
2014-12-29 23:22:54 +00:00
Dag-Erling Smørgrav
1412dac680
Shifting any number by zero places is a no-op, but so is shifting zero by
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any number of places.
2014-12-29 23:20:26 +00:00
Dag-Erling Smørgrav
8228f19d5a
In mpi_copy(), any failure should leave the target untouched.
2014-12-29 23:18:57 +00:00
Dag-Erling Smørgrav
82f5c5cf77
In mpi_load(), use be32dec() when possible.
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In mpi_set(), it is impossible for the value being loaded to exceed
the minimum size of an mpi; thus, there is no need for mpi_grow().
2014-12-29 15:08:09 +00:00
Dag-Erling Smørgrav
d4fd9a1958
rm unused variable
2014-08-12 07:33:30 +00:00
Dag-Erling Smørgrav
be31515f5e
Start of a multiple-precision integer arithmetic library.
2014-08-12 07:30:31 +00:00
