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lib: Fix log2_ceil() for 0xffffffff 

Current log2_ceil(x) is defined as log2(x * 2 - 1). When x is larger
than (1 << 31), (x * 2 - 1) won't fit in u32, leading to incorrect
result. Therefore, correct it as (log2(x - 1) + 1). Also add unit tests
for inline functions in lib.h.

BUG=none
TEST=make tests/lib/lib-test
BRANCH=none

Change-Id: If868f793b909a6ad7fc48a7affac15e2c714fa2e
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59834
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
This commit is contained in:
Yu-Ping Wu 2021-12-02 10:54:32 +08:00 committed by Felix Held
parent 04cf42775c
commit 00c834dc26
3 changed files with 65 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/include/lib.h
View File

@ -54,8 +54,8 @@ static inline int log2(u32 x) { return sizeof(x) * 8 - clz(x) - 1; }
/* Find First Set: __ffs(1) == 0, __ffs(0) == -1, __ffs(1<<31) == 31 */
static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
/* Integer binary logarithm (rounding up): log2_ceil(0) == -1, log2(5) == 3 */
static inline int log2_ceil(u32 x) { return (x == 0) ? -1 : log2(x * 2 - 1); }
/* Integer binary logarithm (rounding up): log2_ceil(0) == -1, log2_ceil(5) == 3 */
static inline int log2_ceil(u32 x) { return (x == 0) ? -1 : log2(x - 1) + 1; }
static inline int popcnt64(u64 x) { return __builtin_popcountll(x); }
static inline int clz64(u64 x) { return x ? __builtin_clzll(x) : sizeof(x) * 8; }

3
tests/lib/Makefile.inc
View File

@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
tests-y += lib-test
tests-y += string-test
tests-y += b64_decode-test
tests-y += hexstrtobin-test
@ -40,6 +41,8 @@ tests-y += cbfs-lookup-no-mcache-test
tests-y += cbfs-lookup-has-mcache-test
tests-y += lzma-test
lib-test-srcs += tests/lib/lib-test.c
string-test-srcs += tests/lib/string-test.c
string-test-srcs += src/lib/string.c

60
tests/lib/lib-test.c Normal file
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@ -0,0 +1,60 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#include <lib.h>
#include <tests/test.h>
void test_popcnt(void **state)
{
assert_int_equal(popcnt(0x0), 0);
assert_int_equal(popcnt(0x10), 1);
assert_int_equal(popcnt(0x10010010), 3);
assert_int_equal(popcnt(0xffffffff), 32);
}
void test_clz(void **state)
{
assert_int_equal(clz(0x0), 32);
assert_int_equal(clz(0xf), 28);
assert_int_equal(clz(0x80000000), 0);
assert_int_equal(clz(0xffffffff), 0);
}
void test_log2(void **state)
{
assert_int_equal(log2(0x0), -1);
assert_int_equal(log2(0x1), 0);
assert_int_equal(log2(0x5), 2);
assert_int_equal(log2(0x80000000), 31);
assert_int_equal(log2(0xffffffff), 31);
}
void test_ffs(void **state)
{
assert_int_equal(__ffs(0x0), -1);
assert_int_equal(__ffs(0x1), 0);
assert_int_equal(__ffs(0x1010), 4);
assert_int_equal(__ffs(0x10000000), 28);
assert_int_equal(__ffs(0xffffffff), 0);
}
void test_log2_ceil(void **state)
{
assert_int_equal(log2_ceil(0x0), -1);
assert_int_equal(log2_ceil(0x1), 0);
assert_int_equal(log2_ceil(0x5), 3);
assert_int_equal(log2_ceil(0x80000000), 31);
assert_int_equal(log2_ceil(0xffffffff), 32);
}
int main(void)
{
const struct CMUnitTest tests[] = {
cmocka_unit_test(test_popcnt),
cmocka_unit_test(test_clz),
cmocka_unit_test(test_log2),
cmocka_unit_test(test_ffs),
cmocka_unit_test(test_log2_ceil),
};
return cb_run_group_tests(tests, NULL, NULL);
}