.TH sub_of 3
.SH NAME
sub_of \- subtract two integers, check for arithmetic overflow
.SH SYNTAX
.B #include <libowfat/rangecheck.h>

int \fBsub_of\fP(dest,a,b);
.SH DESCRIPTION
If calculating a-b is possible without causing undefined behavior or an
arithmetic overflow in C, and the result fits into the destination
integer type, do dest=a-b and return 0.

Otherwise, return 1.

Note: This is a macro, so dest does not have to be a pointer.
.SH BUGS
In the multiplication functions, a return value of 1 signals success and
0 failure. In add_of, sub_of and assign it's the other way around.
.SH "SEE ALSO"
add_of(3), assign(3), imult16(3), umult16(3), imult32(3), umult32(3),
imult64(3), umult64(3)