V4/man/man3/qsort.3

.th QSORT III 6/12/72
.sh NAME
qsort \*- quicker sort
.sh SYNOPSIS
.nf
(end+1 of data in r2)
(element width in r3)
.ft B
jsr pc,qsort
.s3
qsort(base, nel, width, compar)
char *base;
int (*compar)( );
.fi
.ft R
.sh DESCRIPTION
.it Qsort
is an implementation
of the quicker-sort algorithm.
The assembly-language version
is designed to sort equal length
elements.
Registers r1 and r2 delimit the region of
core containing the array of byte strings to be sorted:
r1 points to the start of the first string, r2 to the first
location above the last string.
Register r3 contains the length of each string.
r2\*-r1 should be a multiple of r3.
On return, r0, r1, r2, r3 are destroyed.
.s3
The routine compar (q.v.) is called to compare elements
and may be replaced by the user.
.s3
The C version has somewhat different arguments
and the user must supply a comparison routine.
The first argument is to the base of the data;
the second is the number of elements;
the third is the width of an element
in bytes;
the last is the name of the comparison routine.
It is called with two arguments which are pointers
to the elements being compared.
The routine must return a negative integer if the
first element is to be considered less than
the second, a positive integer if the second
element is smaller than the first, and 0
if the elements are equal.
.sh "SEE ALSO"
compar (III)
.sh BUGS