shaba/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2025-01-12 13:18:14 +03:00
Code

basic/logarithm: add popcount() wrapper

Browse Source 
__builtin_popcount() is a bit of a mouthful, so let's provide a helper.
Using _Generic has the advantage that if a type other then the ones on
the list is given, compilation will fail. This is nice, because if by any
change we pass a wider type, it is rejected immediately instead of being
truncated.

log.h is also needed. It is included transitively, but let's include it
directly.

macro.h is *not* needed.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2023-04-03 14:32:39 +02:00
parent 6eccc3cfa9
commit a12bc99ef0
4 changed files with 37 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/boot/efi/splash.c
View File

@ -1,6 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "graphics.h"
#include "logarithm.h"
#include "proto/graphics-output.h"
#include "splash.h"
#include "unaligned-fundamental.h"
@ -141,14 +142,14 @@ static void read_channel_maks(
channel_shift[R] = __builtin_ctz(dib->channel_mask_r);
channel_shift[G] = __builtin_ctz(dib->channel_mask_g);
channel_shift[B] = __builtin_ctz(dib->channel_mask_b);
channel_scale[R] = 0xff / ((1 << __builtin_popcount(dib->channel_mask_r)) - 1);
channel_scale[G] = 0xff / ((1 << __builtin_popcount(dib->channel_mask_g)) - 1);
channel_scale[B] = 0xff / ((1 << __builtin_popcount(dib->channel_mask_b)) - 1);
channel_scale[R] = 0xff / ((1 << popcount(dib->channel_mask_r)) - 1);
channel_scale[G] = 0xff / ((1 << popcount(dib->channel_mask_g)) - 1);
channel_scale[B] = 0xff / ((1 << popcount(dib->channel_mask_b)) - 1);
if (dib->size >= SIZEOF_BMP_DIB_RGBA && dib->channel_mask_a != 0) {
channel_mask[A] = dib->channel_mask_a;
channel_shift[A] = __builtin_ctz(dib->channel_mask_a);
channel_scale[A] = 0xff / ((1 << __builtin_popcount(dib->channel_mask_a)) - 1);
channel_scale[A] = 0xff / ((1 << popcount(dib->channel_mask_a)) - 1);
} else {
channel_mask[A] = 0;
channel_shift[A] = 0;

10
src/basic/logarithm.h → src/fundamental/logarithm.h
View File

@ -3,8 +3,6 @@
#include <stdint.h>
#include "macro.h"
/* Note: log2(0) == log2(1) == 0 here and below. */
#define CONST_LOG2ULL(x) ((x) > 1 ? (unsigned) __builtin_clzll(x) ^ 63U : 0)
@ -30,6 +28,14 @@ static inline unsigned u32ctz(uint32_t n) {
#endif
}
#define popcount(n) \
_Generic((n), \
unsigned char: __builtin_popcount(n), \
unsigned short: __builtin_popcount(n), \
unsigned: __builtin_popcount(n), \
unsigned long: __builtin_popcountl(n), \
unsigned long long: __builtin_popcountll(n))
#define CONST_LOG2U(x) ((x) > 1 ? __SIZEOF_INT__ * 8 - __builtin_clz(x) - 1 : 0)
#define NONCONST_LOG2U(x) ({ \
unsigned _x = (x); \

4
src/shared/tpm2-util.c
View File

@ -14,6 +14,8 @@
#include "hexdecoct.h"
#include "hmac.h"
#include "lock-util.h"
#include "log.h"
#include "logarithm.h"
#include "memory-util.h"
#include "openssl-util.h"
#include "parse-util.h"
@ -773,7 +775,7 @@ size_t tpm2_tpms_pcr_selection_weight(const TPMS_PCR_SELECTION *s) {
uint32_t mask;
tpm2_tpms_pcr_selection_to_mask(s, &mask);
return (size_t)__builtin_popcount(mask);
return popcount(mask);
}
/* Utility functions for TPML_PCR_SELECTION. */

21
src/test/test-logarithm.c
View File

@ -71,4 +71,25 @@ TEST(log2i) {
assert_se(log2i(INT_MAX) == sizeof(int)*8-2);
}
TEST(popcount) {
uint16_t u16a = 0x0000;
uint16_t u16b = 0xFFFF;
uint32_t u32a = 0x00000010;
uint32_t u32b = 0xFFFFFFFF;
uint64_t u64a = 0x0000000000000010;
uint64_t u64b = 0x0100000000100010;
assert_se(popcount(u16a) == 0);
assert_se(popcount(u16b) == 16);
assert_se(popcount(u32a) == 1);
assert_se(popcount(u32b) == 32);
assert_se(popcount(u64a) == 1);
assert_se(popcount(u64b) == 3);
/* This would fail:
* error: ‘_Generic’ selector of type ‘int’ is not compatible with any association
* assert_se(popcount(0x10) == 1);
*/
}
DEFINE_TEST_MAIN(LOG_INFO);