methods used by compilers for switch{ case } statements?

Can someone please point me to an online reference which describes the
mechanism(s) compilers use to implement the switch/case statement in
C? Specifically, which method or methods does the object code
implement? I'm also interested in references to any discussion
comparing the speed of a small switch statment (say 2-3 cases ) versus
the equivalent logic implemented with if statements. At what N does:


switch (a){
    case 0:
        /* code */
    case 1:
        /* code */
    ...
    case N:
        /* code */
    default:
        /* code */
}


become faster than


if(a==0){
    /* code */
}
else {
    if(a==1){
        /* code */
    }
    else {
      /* etc. ... */
    }
}


Thanks,


David Mathog
mathog@seqaxp.bio.caltech.edu
Manager, sequence analysis facility, biology division, Caltech

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