New version of tac.c

[Ralf Friedl]

Jean-Christophe Dubois wrote:
> just a few comments:
>
> On Tuesday 08 January 2008 22:42:23 Tito wrote:
>   
>>                                 llist_add_to(&list, memcpy(size, &i, sizeof(int))); 
>>     
>>                                 llist_add_to(&list, line); 
>>     
> More generally would it make sense to define a structure holding both the 
> string size and the string pointer? This would allow to call llist_add_to() 
> only once per line instead of twice (same for llist_pop) ...
>   
I agree that it would be more efficient to use a structure for the 
length and and the content of the line, for memory usage and for run time.
And because llist_add_to() allocates a new llist_t element for each list 
element, it would use even less memory and less calls to malloc() to use 
a struct that contains the list pointer, the line length and the line 
content. It might even result in a little smaller code size. A malloc() 
is necessary anyways, and the code to inser an element in a single 
linked list may be smaller that the code to call a function to do it.

Also, "size" has been allocated with malloc(), so it should be properly 
aligned to be accessed as an int.
Therefor
  memcpy(size, &i, sizeof(int))
could be written as
  *size = i

which is better readable and most likely produces shorter code, 
especially on machines where unaligned writes are not possible.

Regards
Ralf Friedl