machines with oddball char * formats

William E. Westfield billw at navajo.STANFORD.EDU
Thu Nov 20 10:48:25 AEST 1986


In article <1534 at batcomputer.tn.cornell.edu>, garry at batcomputer) writes:
> 
> Forgive my ignorance, but why don't the compiler writers on these "odd"
> machines just designate a "char" and a "byte" to be the identical width
> to a "short" ?   What will go wrong ?  
> 
> (Would very many real-life application programs actually be hurt by the 
> added memory usage? - I'm excluding text editors!)
> 
> It seems so simple - give some memory, get a lot more speed.
> 

this is a word addressable machine.  A short is 36 bits.  Giving up
some memory for the sake of speed is one thing, but you are talking
about wasting 77% of the memory.  Given paging, it probably wouldn't
even be faster.  For typical C code dealing with character stings or
arrays, the byte operations asren't that much slower than individual
memory moves, given cache, and the fact that the byte instructions
auto-increment, and memory instructions don't.

BillW



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