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Bug Fixes

Two problems are fixed in V2.5.5. NBS has hitherto allocated the data for primitive noticeboard items using exactly the data size supplied in the item definition. In V2.5.5 this size is rounded up to a multiple of the size of a double precision number. This ensures that items composed of types likely to mapped using NBS_GET_POINTER or nbc_get_pointer will be correctly aligned.

The second problem concerns the algorithm used to generate UNIX shared memory identifiers (4 byte integers) from memory section names. The method used in previous releases simply copied the values of the first three characters into an integer. The new algorithm adds the value of each character code in the name shifted leftwards by a number of bits equal to its position in the string. This means that all the characters in the name are significant (only 16 are allowed, which means all the bits in the last character are significant if used), and that anagrams of names map on to different key values.



next up previous 372
Next: Description of Individual NBS Routines
Up: Omissions and Future Plans
Previous: New Features

NBS The Noticeboard System
Starlink User Note 77
D.J. Allan
11 September 1995
E-mail:ussc@star.rl.ac.uk