awk 'BEGIN{for (i = 0; i < 256; ++i) {ord[sprintf("%c", i)] = i;} }'  ' { print ord['a'];  ord ['b']; }'

-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=18347 $?=0] ; cat foo.awk
#!/bin/awk -f

BEGIN {
    for (ii = 0; ii < 256; ++ii) {
        ch = sprintf("%c", ii);
        ascii[ch] = ii;
    }

    for (ii = 1; ii < ARGC; ii++) {
        print "ord(" ARGV[ii] " = " ascii[ARGV[ii]];
    }
}
-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=18347 $?=0] ; ./foo.awk a b c 1 2 3
ord(a) = 97
ord(b) = 98
ord(c) = 99
ord(1) = 49
ord(2) = 50
ord(3) = 51
-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=18347 $?=0] ; bye