1240ac558d
The lookup table for power-of-two sizes was added in commit 540b849261
for the purpose of having convenient shortcuts for these sizes in cases
when the literal number has to be present at compile time, and
expressions as '(1 * KiB)' can not be used. One such case is the
stringification of sizes. Beyond that, it is convenient to use these
shortcuts for all power-of-two sizes, even if they don't have to be
literal numbers.
Despite its convenience, this table introduced 55 lines of "dumb" code,
the purpose and origin of which are obscure without reading the message
of the commit which introduced it. This patch fixes that by adding a
comment to the code itself with a brief explanation for the reasoning
behind this table. This comment includes the short AWK script that
generated the table, so that anyone who's interested could make sure
that the values in it are correct (otherwise these values look as if
they were typed manually).
Signed-off-by: Leonid Bloch <lbloch@janustech.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
94 lines
3 KiB
C
94 lines
3 KiB
C
/*
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* IEC binary prefixes definitions
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*
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* Copyright (C) 2015 Nikunj A Dadhania, IBM Corporation
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* Copyright (C) 2018 Philippe Mathieu-Daudé <f4bug@amsat.org>
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#ifndef QEMU_UNITS_H
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#define QEMU_UNITS_H
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#define KiB (INT64_C(1) << 10)
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#define MiB (INT64_C(1) << 20)
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#define GiB (INT64_C(1) << 30)
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#define TiB (INT64_C(1) << 40)
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#define PiB (INT64_C(1) << 50)
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#define EiB (INT64_C(1) << 60)
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/*
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* The following lookup table is intended to be used when a literal string of
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* the number of bytes is required (for example if it needs to be stringified).
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* It can also be used for generic shortcuts of power-of-two sizes.
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* This table is generated using the AWK script below:
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*
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* BEGIN {
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* suffix="KMGTPE";
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* for(i=10; i<64; i++) {
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* val=2**i;
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* s=substr(suffix, int(i/10), 1);
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* n=2**(i%10);
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* pad=21-int(log(n)/log(10));
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* printf("#define S_%d%siB %*d\n", n, s, pad, val);
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* }
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* }
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*/
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#define S_1KiB 1024
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#define S_2KiB 2048
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#define S_4KiB 4096
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#define S_8KiB 8192
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#define S_16KiB 16384
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#define S_32KiB 32768
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#define S_64KiB 65536
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#define S_128KiB 131072
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#define S_256KiB 262144
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#define S_512KiB 524288
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#define S_1MiB 1048576
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#define S_2MiB 2097152
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#define S_4MiB 4194304
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#define S_8MiB 8388608
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#define S_16MiB 16777216
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#define S_32MiB 33554432
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#define S_64MiB 67108864
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#define S_128MiB 134217728
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#define S_256MiB 268435456
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#define S_512MiB 536870912
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#define S_1GiB 1073741824
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#define S_2GiB 2147483648
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#define S_4GiB 4294967296
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#define S_8GiB 8589934592
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#define S_16GiB 17179869184
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#define S_32GiB 34359738368
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#define S_64GiB 68719476736
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#define S_128GiB 137438953472
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#define S_256GiB 274877906944
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#define S_512GiB 549755813888
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#define S_1TiB 1099511627776
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#define S_2TiB 2199023255552
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#define S_4TiB 4398046511104
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#define S_8TiB 8796093022208
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#define S_16TiB 17592186044416
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#define S_32TiB 35184372088832
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#define S_64TiB 70368744177664
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#define S_128TiB 140737488355328
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#define S_256TiB 281474976710656
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#define S_512TiB 562949953421312
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#define S_1PiB 1125899906842624
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#define S_2PiB 2251799813685248
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#define S_4PiB 4503599627370496
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#define S_8PiB 9007199254740992
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#define S_16PiB 18014398509481984
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#define S_32PiB 36028797018963968
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#define S_64PiB 72057594037927936
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#define S_128PiB 144115188075855872
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#define S_256PiB 288230376151711744
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#define S_512PiB 576460752303423488
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#define S_1EiB 1152921504606846976
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#define S_2EiB 2305843009213693952
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#define S_4EiB 4611686018427387904
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#define S_8EiB 9223372036854775808
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#endif
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