_SPEEDY BUFFERING_
by Bruce Tonkin

[LISTING ONE]

DEFINT A-Z
CLS
LINE INPUT "Name of file to read: "; filename$
INPUT "Record length: "; rl
buffersize = (1 + 16384 \ rl) * rl     '16K, rounded up.
blocks = buffersize \ rl
DIM chunk$(1 TO blocks)      'each chunk will be one record.

'open the random file with a record length of buffersize
OPEN "r", 1, filename$, buffersize
filesize& = CLNG(LOF(1)) \ rl

'set up the buffer in record-length sized chunks
FOR i = 1 TO blocks
   FIELD #1, dummy AS dummy$, rl AS chunk$(i)
   dummy = dummy + rl
NEXT i

'open up a dummy buffer to hold the actual records
OPEN "r", 2, "real.$$$", rl
FIELD #2, rl AS all$

t1! = TIMER
FOR i = 1 TO filesize&
   GOSUB getrec    'read the buffered records
NEXT i
t1! = TIMER - t1!  'save the time taken
CLOSE              'close the files and delete the dummy file.
KILL "real.$$$"

OPEN "r", 1, filename$, rl   'now open and read unbuffered
FIELD #1, rl AS all$
t2! = TIMER
FOR i = 1 TO filesize&
   GET 1, i
NEXT i
t2! = TIMER - t2!
CLOSE
PRINT "Buffered time: "; t1!
PRINT "Unbuffered time: "; t2!
END

getrec:
whichblock = 1 + (i - 1) \ blocks
IF whichblock <> lastblock THEN
    GET 1, whichblock
    lastblock = whichblock
    end if
whichchunk = 1 + i MOD blocks
LSET all$ = chunk$(whichchunk)
RETURN