Summary of routines in numio.i:

(3000)   .1 <- character from input
(3001)   Prints .2 as a character
(3010)   ,1 <- a string of input from the user, no longer than .1, and
         excluding the terminating newline.
         .2 <- the real length of the user input.
         .3 <- #1 if .2 <= .1 (i.e., no characters were lost).
         Otherwise, .3 <- #2.
(3020)   ,1 <- a string of input from the user, no longer than .1,
         translated (where possible) into indices into ,2
         .3 <- the real length of the user input.
         .4 <- #1 if .3 <= .1 and all characters in the input are
         listed in ,2. Otherwise, .4 <- #2.
(3080)   .1 <- a 16-bit number from the user
(3089)   .1 <- a 16-bit number from the user, with an error message if
         non-digits are encountered
(3090)   Displays the value in .1
(3099)   Displays the value in .1 and prints a newline
(3180)   :1 <- a 32-bit number from the user
(3189)   :1 <- a 32-bit number from the user, with an error message if
         non-digits are encountered
(3190)   Displays the value in :1
(3199)   Displays the value in :1 and prints a newline
(3990)   Initializes internal arrays.

numio.i reserves the use of two arrays - ,3000 and ,3001 - for input
and output respectively. Each array has one dimension of one element,
and they are used to provide a getchar routine, at (3000), and a
putchar routine, (3001). Note that (3001) expects that the character
values have already been bit-reversed.

The arrays are initialized by routine (3990); this should be called
before using any other routines in this library.

Routines (3010) and (3020) provide line input capabilities. The
routines write in characters until they see a newline (or
end-of-file), and store them in ,1. They are called with .1 being the
number of characters to save; any input after that is thrown
away. (Already they're better than C's gets()!)

(3010) returns the actual number of characters that were input in .2,
and .3 is set to #2 if characters were lost (i.e., if .2 is longer
than .1). I decided to add .3, even though the caller could check for
this themselves, as inequal comparisons are a bit painful in INTERCAL.
Or, to be accurate, they're more painful than equal comparisons. Note
also that if .1 is #0, the routine becomes a press-Enter-to-continue
type of function, and ,1 need not actually be defined.

(3020) is a filtering, or translating, input routine. When called, the
array ,2 should contain a set of "approved" characters that are
expected to be in the input, and .2 should contain the number of
characters in ,2. As input is retrieved, the routine tries to look up
each character in ,2. If the character is found, the routine stores in
,1 the index of the character instead. (Otherwise the actual character
number is stored, as with (3010).) Upon return, .3 has the number of
characters that were input, and .4 is set to #2 if characters were
lost OR if any characters in the input were not in the set of approved
characters.

The remaining routines are for doing "wimpmode"-style I/O - or in
other words, the C-INTERCAL equivalent of atoi and itoa. (3080) and
(3090) translate the ASCII input as a number (yes, a number as in
[0-9]*), and (3090) and (3190) do the same for displaying numbers in
ASCII. (By the way, the routines can also be made to support EBCDIC:
simply replace #3 with #15 on lines 119, 159, and 185.)

Each routine also has a "niner" variation. For itoa, (3099) and (3190)
print a newline at the end of the number. In the case of atoi, (3089)
and (3189) make sure that the number ends with a newline. In other
words, they ensure there are no other non-numeric characters in the
input line. If there are, a typically snide INTERCAL error message is
displayed. (The regular versions work like C's atoi in that they
return as soon as they see any non-digit.)

There's not too much to note about these routines. The atoi routines
use the shift-and-add trick to avoid multiplying by 10, so they should
be pretty efficient (snort). itoa has no such shortcuts, and the
routines use modified division routines which also returns the
remainder. The 16-bit version is at (2030), and is the familiar one
created by Louis Howell, copied from lib2.i. The 32-bit version is at
(2530), and is just a copy of the standard library routine without the
lines that throw away the remainder at the end.

Note also that for these routines to work properly, they must be used
more or less exclusively in regards to other array I/O. Otherwise, the
getchar and putchar subroutines will get out of sync with the
Turing-text character loop. If you do want to do other I/O while using
these routines, you can use (3000) and (3001) as a getchar and
putchar. Or, you can simply re-initialize the ,3000 and/or ,3001
values after you are done, by storing in them the bit-reversed ASCII
value of the last character that you wrote in and/or read out. For
example, if you READ OUT some strings and the last thing to be printed
was a newline, then:

	DO ,3001SUB#1 <- #80

would then allow you to safely call the itoa routines.