On Thu, Aug 18, 2016 at 20:55 (+0200), Slávek Banko wrote:
On Wednesday 17 of August 2016 16:26:26 Jim wrote:
On Wed, Aug 17, 2016 at 03:00 (+0200), Slávek Banko wrote:
Hi all,
Various irrelevancies <snip>ed...
However, one serious problem is here.
In the 'kjs' and 'tdehtml/ecma' is used HashEntry structure that contains the item 'value' of type short int - see 'kjs/lookup.h'. Into this item was stored values DOM::NodeFilter::ShowCode::SHOW_ALL = 0xFFFFFFFF (see tdehtml/dom/dom2_traversal.h) and kjs event CHANGE with value 32768 (see tdehtml/ecma/kjs_events.cpp). Both are therefore outside the range of short int.
Changing the type of 'value' in HashEntry from short to long would apparently cause a change in ABI - kjs/lookup.h is part of the public includes. That's why I made the change values 0xFFFFFFFF and 32768 to -1. I think that GCC compilers version less than 6 will store these values in the same way. Therefore, I believe that the proposed patch would not cause problems == can be pushed. What is your opinion?
Is anyone compiling this for a 1's complement hardware platform? If so, that could be an issue (now or in the future).
I don't have any gcc 6.0 machine to play with, so here are some alternative thoughts, for what they are worth.
how about ~0 (or ~(short)0) to get all 1 bits?
Format ~0 looks good, but I'm afraid of possible complications:
- hash tables are generated by kjs/create_hash_table (perl script) - it
would have to verify what would be the behavior with expressions instead of simple values.
Is that verification difficult?
- enum values can be used in the code for the bindings to other
languages - such as python. Use expressions instead of simple values could cause problems.
Is it difficult to check that?
Therefore, I believe that the use of the simple value -1 makes more sense.
(FWIW) Wikipedia says The representation used in most current computing devices is two's complement, although the Unisys ClearPath Dorado series mainframes use ones' complement. Putting a -1 in there will not give you 0xFFFF on such machines. Maybe no one cares...
Jim