ldiv.3

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th LDIV III 5/7/73
.sh NAME
ldiv, lrem \*- long division
.sh SYNOPSIS
.ft B
ldiv(hidividend, lodividend, divisor)
.s3
lrem(hidividend, lodividend, divisor)
.ft R
.sh DESCRIPTION
The
concatenation of the signed
16-bit
.it hidividend
and the unsigned 16-bit
.it lodividend
is divided by
\fIdivisor\fR.
The 16-bit signed quotient is returned by
.it ldiv
and the 16-bit signed remainder is returned by
.it lrem.
Divide check and erroneous results
will occur
unless the magnitude of the
divisor is greater than that of the high-order
dividend.
.s3
An integer division of an unsigned
dividend by a signed divisor may
be accomplished by
.s3
	quo = ldiv(0, dividend, divisor);
.s3
and similarly for the remainder operation.
.s3
Often both the quotient and the remainder are wanted.
Therefore
.it ldiv
leaves a remainder in the external cell
.it ldivr.
.sh BUGS
No divide check check.