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.TH LIBJ2_J2I_LSH 3 LIBJ2
.SH NAME
libj2_j2i_lsh \- Left-shift bits
.SH SYNOPSIS
.nf
#include <libj2.h>
void \fBlibj2_j2i_lsh\fP(struct libj2_j2i *\fIa\fP, unsigned \fIb\fP);
void \fBlibj2_j2i_lsh_to_j2i\fP(const struct libj2_j2i *\fIa\fP, unsigned \fIb\fP, struct libj2_j2i *\fIr\fP);
void \fBlibj2_ji_lsh_to_j2i\fP(intmax_t \fIa\fP, unsigned \fIb\fP, struct libj2_j2i *\fIr\fP);
void \fBlibj2_j2u_lsh\fP(struct libj2_j2u *\fIa\fP, unsigned \fIb\fP);
void \fBlibj2_j2u_lsh_to_j2u\fP(const struct libj2_j2u *\fIa\fP, unsigned \fIb\fP, struct libj2_j2u *\fIr\fP);
void \fBlibj2_ju_lsh_to_j2u\fP(uintmax_t \fIa\fP, unsigned \fIb\fP, struct libj2_j2u *\fIr\fP);
int \fBlibj2_j2i_lsh_overflow\fP(struct libj2_j2i *\fIa\fP, unsigned \fIb\fP);
int \fBlibj2_j2i_lsh_to_j2i_overflow\fP(const struct libj2_j2i *\fIa\fP, unsigned \fIb\fP, struct libj2_j2i *\fIr\fP);
int \fBlibj2_ji_lsh_to_j2i_overflow\fP(intmax_t \fIa\fP, unsigned \fIb\fP, struct libj2_j2i *\fIr\fP);
int \fBlibj2_j2u_lsh_overflow\fP(struct libj2_j2u *\fIa\fP, unsigned \fIb\fP);
int \fBlibj2_j2u_lsh_to_j2u_overflow\fP(const struct libj2_j2u *\fIa\fP, unsigned \fIb\fP, struct libj2_j2u *\fIr\fP);
int \fBlibj2_ju_lsh_to_j2u_overflow\fP(uintmax_t \fIa\fP, unsigned \fIb\fP, struct libj2_j2u *\fIr\fP);
int \fBlibj2_j2i_lsh_overflow_p\fP(const struct libj2_j2i *\fIa\fP, unsigned \fIb\fP);
int \fBlibj2_ji_lsh_overflow_p\fP(intmax_t \fIa\fP, unsigned \fIb\fP);
int \fBlibj2_j2u_lsh_overflow_p\fP(const struct libj2_j2u *\fIa\fP, unsigned \fIb\fP);
int \fBlibj2_ju_lsh_overflow_p\fP(uintmax_t \fIa\fP, unsigned \fIb\fP);
.fi
.PP
Link with
.IR -lj2 .
.SH DESCRIPTION
The above listed functions discard the
.I b
most significant bits in
.IR a ,
shift all bits to
.I b
more significant positions, and clears the
.I b
least significant bits, effectively multiplying
.I a
by 2 to the power of
.IR b .
The functions with the parameter
.I r
store the result in
.IR r ,
the other functions store the result in
.IR a ,
except the functions
.BR libj2_j2i_lsh_overflow_p (),
.BR libj2_ji_lsh_overflow_p (),
.BR libj2_j2u_lsh_overflow_p (),
and
.BR libj2_ju_lsh_overflow_p (),
only predict overflow, and do not perform
any bit-shifting, and therefore does store
it anywhere.
.PP
The value-returning functions (that is, those
with word
.B overflow
in their name), detect overflow, that is,
if any discarded bit (any of the
.I b
most significant bits) was set.
.PP
The result is truncated to the least significant
bits, as many as can be stored, in case of overflow;
that is, modular arithmetics is used.
.PP
The arguments are assumed to be
.RI non- NULL .
.SH RETURN VALUE
For functions with a return value, the functions
return +1 if any discarded bit was set and
.I a
was positive, -1 if any discarded bit was set and
.I a
was negative,
and 0 otherwise.
.SH ERRORS
The above listed functions cannot fail.
.SH HISTORY
The
.BR libj2_j2u_lsh (),
.BR libj2_j2u_lsh_to_j2u (),
.BR libj2_ju_lsh_to_j2u (),
.BR libj2_j2u_lsh_overflow (),
.BR libj2_j2u_lsh_to_j2u_overflow (),
.BR libj2_ju_lsh_to_j2u_overflow (),
.BR libj2_j2u_lsh_overflow_p (),
and
.BR libj2_ju_lsh_overflow_p ()
functions were added in version 1.0 of
.BR libj2 .
.PP
The
.BR libj2_j2i_lsh (),
.BR libj2_j2i_lsh_to_j2i (),
.BR libj2_ji_lsh_to_j2i (),
.BR libj2_j2i_lsh_overflow (),
.BR libj2_j2i_lsh_to_j2i_overflow (),
.BR libj2_ji_lsh_to_j2i_overflow (),
.BR libj2_j2i_lsh_overflow_p (),
and
.BR libj2_ji_lsh_overflow_p ()
functions were added in version 1.1 of
.BR libj2 .
.SH SEE ALSO
.BR libj2 (7),
.BR libj2_j2i_rsh_j2i (3),
.BR libj2_j2i_lrot_j2i (3),
.BR libj2_j2i_rrot_j2i (3)
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