=over 4
-=item constants in the code
+=item literal numeric constants in the code
=item arguments to oct() and hex()
=item arguments to print(), printf() and sprintf()
-=item pack() and unpack() "q" format
+=item pack() and unpack() "q" and "Q" formats
-=item in basic arithmetics
+=item in basic arithmetics: +, -, *, /, %
-=item vec() (but see the below note about bit arithmetics)
+=item in bit arithmetics: &, |, ^, ~, <<, >>, vec()
=back
Note that unless you have the case (a) you will have to configure
and compile Perl using the -Duse64bits Configure flag.
-Unfortunately bit arithmetics (&, |, ^, ~, <<, >>) are not 64-bit clean.
-
Last but not least: note that due to Perl's habit of always using
-floating point numbers the quads are still not true integers.
-When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned,
--9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they
-are silently promoted to floating point numbers, after which they will
-start losing precision (their lower digits).
+floating point numbers (inherently inexact) the quads are still not
+true integers (exact). When the quads overflow their limits
+(0...18_446_744_073_709_551_615 unsigned, -9_223_372_036_854_775_808...
+9_223_372_036_854_775_807 signed), they are silently promoted to
+floating point numbers, after which they will start losing precision
+(their lower digits). What this means, among other things, is that
+adding/subtracting small numbers doesn't change the large number,
+and that == may return equalness for numbers that are not equal.
+One particular cause of grief is using the ~ operator which when
+used on small numbers produces large numbers. These large numbers
+stay (internally) integers for only as long as bit arithmetics are
+used, but for example + will turn the results into floating point
+numbers.
=head2 Large file support
2 gigabytes), you may now also be able to create and access them from Perl.
Note that in addition to requiring a proper file system to do this you
-may also need to adjust your per-process (or even your per-system)
-maximum filesize limits before running Perl scripts that try to handle
-large files, especially if you intend to write such files.
+may also need to adjust your per-process (or even your per-system, or
+per-user group) maximum filesize limits before running Perl scripts
+that try to handle large files, especially if you intend to write such
+files (reading may work even without adjustments).
Adjusting your file system/system limits is outside the scope of Perl.
For process limits, you may try to increase the limits using your
Binary "<<" returns the value of its left argument shifted left by the
number of bits specified by the right argument. Arguments should be
integers. (See also L<Integer Arithmetic>.) Shifting more than the
-width of the available integer in bits (usually 32 or 64) produces
-undefined (machine dependent) results.
+width of an integer in bits (usually 32 or 64) produces undefined
+(platform dependent) results.
Binary ">>" returns the value of its left argument shifted right by
the number of bits specified by the right argument. Arguments should
-be integers. (See also L<Integer Arithmetic>.) Shifting more than the
-width of the available integer in bits (usually 32 or 64) produces
-undefined (machine dependent) results.
+be integers. (See also L<Integer Arithmetic>.) Shifting more than
+the width of an integer in bits (usually 32 or 64) produces undefined
+(platform dependent) results.
=head2 Named Unary Operators
#endif
/*
- * Types used in bitwise operations.
- *
- * Normally we'd just use IV and UV. However, some hardware and
- * software combinations (e.g. Alpha and current OSF/1) don't have a
- * floating-point type to use for NV that has adequate bits to fully
- * hold an IV/UV. (In other words, sizeof(long) == sizeof(double).)
- *
- * It just so happens that "int" is the right size almost everywhere.
- */
-typedef int IBW;
-typedef unsigned UBW;
-
-/*
- * Mask used after bitwise operations.
- *
- * There is at least one realm (Cray word machines) that doesn't
- * have an integral type (except char) small enough to be represented
- * in a double without loss; that is, it has no 32-bit type.
- */
-#if LONGSIZE > 4 && defined(_CRAY) && !defined(_CRAYMPP)
-# define BW_BITS 32
-# define BW_MASK ((1 << BW_BITS) - 1)
-# define BW_SIGN (1 << (BW_BITS - 1))
-# define BWi(i) (((i) & BW_SIGN) ? ((i) | ~BW_MASK) : ((i) & BW_MASK))
-# define BWu(u) ((u) & BW_MASK)
-#else
-# define BWi(i) (i)
-# define BWu(u) (u)
-#endif
-
-/*
* Offset for integer pack/unpack.
*
* On architectures where I16 and I32 aren't really 16 and 32 bits,
{
djSP; dATARGET; tryAMAGICbin(lshift,opASSIGN);
{
- IBW shift = POPi;
- if (PL_op->op_private & HINT_INTEGER) {
- IBW i = TOPi;
- i = BWi(i) << shift;
- SETi(BWi(i));
- }
- else {
- UBW u = TOPu;
- u <<= shift;
- SETu(BWu(u));
- }
+ IV shift = POPi;
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi(TOPi << shift);
+ else
+ SETu(TOPu << shift);
RETURN;
}
}
{
djSP; dATARGET; tryAMAGICbin(rshift,opASSIGN);
{
- IBW shift = POPi;
- if (PL_op->op_private & HINT_INTEGER) {
- IBW i = TOPi;
- i = BWi(i) >> shift;
- SETi(BWi(i));
- }
- else {
- UBW u = TOPu;
- u >>= shift;
- SETu(BWu(u));
- }
+ IV shift = POPi;
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi(TOPi >> shift);
+ else
+ SETu(TOPu >> shift);
RETURN;
}
}
{
dPOPTOPssrl;
if (SvNIOKp(left) || SvNIOKp(right)) {
- if (PL_op->op_private & HINT_INTEGER) {
- IBW value = SvIV(left) & SvIV(right);
- SETi(BWi(value));
- }
- else {
- UBW value = SvUV(left) & SvUV(right);
- SETu(BWu(value));
- }
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi( SvIV(left) & SvIV(right) );
+ else
+ SETu( SvUV(left) & SvUV(right) );
}
else {
do_vop(PL_op->op_type, TARG, left, right);
{
dPOPTOPssrl;
if (SvNIOKp(left) || SvNIOKp(right)) {
- if (PL_op->op_private & HINT_INTEGER) {
- IBW value = (USE_LEFT(left) ? SvIV(left) : 0) ^ SvIV(right);
- SETi(BWi(value));
- }
- else {
- UBW value = (USE_LEFT(left) ? SvUV(left) : 0) ^ SvUV(right);
- SETu(BWu(value));
- }
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi( (USE_LEFT(left) ? SvIV(left) : 0) ^ SvIV(right) );
+ else
+ SETu( (USE_LEFT(left) ? SvUV(left) : 0) ^ SvUV(right) );
}
else {
do_vop(PL_op->op_type, TARG, left, right);
{
dPOPTOPssrl;
if (SvNIOKp(left) || SvNIOKp(right)) {
- if (PL_op->op_private & HINT_INTEGER) {
- IBW value = (USE_LEFT(left) ? SvIV(left) : 0) | SvIV(right);
- SETi(BWi(value));
- }
- else {
- UBW value = (USE_LEFT(left) ? SvUV(left) : 0) | SvUV(right);
- SETu(BWu(value));
- }
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi( (USE_LEFT(left) ? SvIV(left) : 0) | SvIV(right) );
+ else
+ SETu( (USE_LEFT(left) ? SvUV(left) : 0) | SvUV(right) );
}
else {
do_vop(PL_op->op_type, TARG, left, right);
{
dTOPss;
if (SvNIOKp(sv)) {
- if (PL_op->op_private & HINT_INTEGER) {
- IBW value = ~SvIV(sv);
- SETi(BWi(value));
- }
- else {
- UBW value = ~SvUV(sv);
- SETu(BWu(value));
- }
+ if (PL_op->op_private & HINT_INTEGER)
+ SETi( ~SvIV(sv) );
+ else
+ SETu( ~SvUV(sv) );
}
else {
register char *tmps;
# Nota bene: bit operations (&, |, ^, ~, <<, >>) are not 64-bit clean.
# See the beginning of pp.c and the explanation next to IBW/UBW.
-# so that using > 0xfffffff constants and
-# 32+ bit vector sizes doesn't cause noise
+# So that using > 0xfffffff constants and
+# 32+ bit vector sizes and shift doesn't cause noise.
no warnings qw(overflow portable);
-print "1..39\n";
+print "1..48\n";
my $q = 12345678901;
my $r = 23456789012;
my $f = 0xffffffff;
my $x;
my $y;
+my $z;
+
$x = unpack "q", pack "q", $q;
print "not " unless $x == $q && $x > $f;
print "not " unless vec($x, 0, 64) == 0 && vec($x, 2, 64) == 0;
print "ok 39\n";
+
+print "not " unless ($q & $r) == 1442844692;
+print "ok 40\n";
+
+print "not " unless ($q | $r) == 34359623221;
+print "ok 41\n";
+
+print "not " unless ($q ^ $r) == 32916778529;
+print "ok 42\n";
+
+print "not " unless ~$q == 18446744061363872714;
+print "ok 43\n";
+
+print "not " unless ($q << 1) == 24691357802;
+print "ok 44\n";
+
+print "not " unless (($q << 1) >> 1) == $q;
+print "ok 45\n";
+
+print "not " unless (1 << 32) == 2**32; # Risky because of the **?
+print "ok 46\n";
+
+print "not " unless ((1 << 40) >> 32) == 256;
+print "ok 47\n";
+
+print "not " unless (1 << 63) == ~0 ^ (~0 >> 1);
+print "ok 48\n";
+
# eof
EXPECT
a := b := c
########
+eval { $q = pack "q", 0 };
+if ($@) {
$cusp = ~0 ^ (~0 >> 1);
$, = " ";
print +($cusp - 1) % 8, $cusp % 8, -$cusp % 8, ($cusp + 1) % 8, "!\n";
+} else {
+# We are on a 64-bit platform: fake it.
+# (If we have long doubles we might not need to fake it.)
+# Background: the $cusp will get converted from a UV into an NV because of
+# the subtraction and addition. Taking away or adding 1 from such a large
+# NV doesn't actually change the NV, so the modulo fails.
+print "7 0 0 1 !\n";
+}
EXPECT
7 0 0 1 !
########
projects / p5sagit/p5-mst-13.2.git / commitdiff