CHCKSM - compute a checksum using add with carry.
Alternate Entry Name: CHK.SM
Usage:
B:
checksum = chcksm( array, count [, awcc, initial] );
C:
int chcksm(void *array, int count [, int awcc,
int initial] );
Where:
- array
- points to the vector to be checksummed.
- count
- is the number of words to checksum. This is usually the
number of words in "array".
- awcc
- is the number of trailing adds with carries of zero to
do. The possible values of "awcc" are listed
below, along with descriptions of the sort of
applications for each value. If no "awcc" is
specified, the default is zero.
- 0
- is used for object decks
- 1
- is used for file system control blocks, and hstar
files
- 2
- is used for all but the last chunk when you
checksum something by chunks. It may also be used
to prepare a Multics-style checksum.
- initial
- is the starting value of the checksum. The default is
zero.
Description:
CHCKSM is used to compute system-compatible checksums.
At times it is not possible to hold the entire item to be
checksummed in memory. In this case, you should checksum the file
in chunks, using the checksum from one chunk as the
"initial" value for the next. When using this chunk
checksumming method, you should specify the value of two for
"awcc" for all chunks but the last.
Copyright © 1996, Thinkage Ltd.