GMP Questions (Lucien Hayen)

Jim White mathimagics at
Tue Oct 18 14:07:30 CEST 2005

> Q1.
>   a. Can anyone tell me where to find a more up to 
>      date manual, if there is one, and 
>   b. if there are any differences with the manual 
>      I have.

a. Section 1 (Introduction) p2: "For up-to-date
   information, please see ...."

b. Section 2.1, p9. Note the very last entry. 
   Utilities such as "diff" may be useful.

> Q2.
>    Chapter 3, section 3.8 (page 19) mentions the
>    variable mp_bits_per_limb.... Chapter 8, section
>    8.1 (page 62) mentions GMP_LIMB_BITS. What is the
>    difference between the two ?

GMP_LIMB_BITS is just an alias for the global comstant
mp_bits_per_limb. The alias is convenient for the
purposes of the Nails discussion.

> Q3.
>   In gmp.h I found : #define GMP_LIMB_BITS  32 where
>   I would have expected something more like ...
>   .. Is there a special reason for avoiding such
>   definitions ?

Since the header file is itself generated by the
config process, and this macro is used in a particular
context, the question really is why would you make the
macro more complicated than it needs to be?
> Q4.
>   Is there no portable way to obtain pointers to the
>   active memory functions?

On the same page you refer to above (p19), you will
also find this:

"mp_set_memory_functions uses global variables to
store the selected memory allocation functions" 

These are found in gmp.h, eg "__gmp_allocate_func". 

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