forked from mirrors/linux
1635e62e75
Verify that edge cases produce proper results, and some more. [npitre@baylibre.com: avoid undefined shift value] Link: https://lkml.kernel.org/r/7rrs9pn1-n266-3013-9q6n-1osp8r8s0rrn@syhkavp.arg Link: https://lkml.kernel.org/r/20240707190648.1982714-3-nico@fluxnic.net Signed-off-by: Nicolas Pitre <npitre@baylibre.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Cc: Biju Das <biju.das.jz@bp.renesas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
99 lines
4 KiB
C
99 lines
4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2024 BayLibre SAS
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/printk.h>
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#include <linux/math64.h>
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typedef struct { u64 a; u64 b; u64 c; u64 result; } test_params;
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static test_params test_values[] = {
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/* this contains many edge values followed by a couple random values */
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{ 0xb, 0x7, 0x3, 0x19 },
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{ 0xffff0000, 0xffff0000, 0xf, 0x1110eeef00000000 },
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{ 0xffffffff, 0xffffffff, 0x1, 0xfffffffe00000001 },
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{ 0xffffffff, 0xffffffff, 0x2, 0x7fffffff00000000 },
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{ 0x1ffffffff, 0xffffffff, 0x2, 0xfffffffe80000000 },
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{ 0x1ffffffff, 0xffffffff, 0x3, 0xaaaaaaa9aaaaaaab },
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{ 0x1ffffffff, 0x1ffffffff, 0x4, 0xffffffff00000000 },
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{ 0xffff000000000000, 0xffff000000000000, 0xffff000000000001, 0xfffeffffffffffff },
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{ 0x3333333333333333, 0x3333333333333333, 0x5555555555555555, 0x1eb851eb851eb851 },
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{ 0x7fffffffffffffff, 0x2, 0x3, 0x5555555555555554 },
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{ 0xffffffffffffffff, 0x2, 0x8000000000000000, 0x3 },
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{ 0xffffffffffffffff, 0x2, 0xc000000000000000, 0x2 },
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{ 0xffffffffffffffff, 0x4000000000000004, 0x8000000000000000, 0x8000000000000007 },
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{ 0xffffffffffffffff, 0x4000000000000001, 0x8000000000000000, 0x8000000000000001 },
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{ 0xffffffffffffffff, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000001 },
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{ 0xfffffffffffffffe, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000000 },
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{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffe, 0x8000000000000001 },
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{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffd, 0x8000000000000002 },
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{ 0x7fffffffffffffff, 0xffffffffffffffff, 0xc000000000000000, 0xaaaaaaaaaaaaaaa8 },
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{ 0xffffffffffffffff, 0x7fffffffffffffff, 0xa000000000000000, 0xccccccccccccccca },
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{ 0xffffffffffffffff, 0x7fffffffffffffff, 0x9000000000000000, 0xe38e38e38e38e38b },
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{ 0x7fffffffffffffff, 0x7fffffffffffffff, 0x5000000000000000, 0xccccccccccccccc9 },
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{ 0xffffffffffffffff, 0xfffffffffffffffe, 0xffffffffffffffff, 0xfffffffffffffffe },
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{ 0xe6102d256d7ea3ae, 0x70a77d0be4c31201, 0xd63ec35ab3220357, 0x78f8bf8cc86c6e18 },
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{ 0xf53bae05cb86c6e1, 0x3847b32d2f8d32e0, 0xcfd4f55a647f403c, 0x42687f79d8998d35 },
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{ 0x9951c5498f941092, 0x1f8c8bfdf287a251, 0xa3c8dc5f81ea3fe2, 0x1d887cb25900091f },
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{ 0x374fee9daa1bb2bb, 0x0d0bfbff7b8ae3ef, 0xc169337bd42d5179, 0x03bb2dbaffcbb961 },
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{ 0xeac0d03ac10eeaf0, 0x89be05dfa162ed9b, 0x92bb1679a41f0e4b, 0xdc5f5cc9e270d216 },
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};
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/*
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* The above table can be verified with the following shell script:
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*
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* #!/bin/sh
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* sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4/p' \
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* lib/math/test_mul_u64_u64_div_u64.c |
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* while read a b c r; do
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* expected=$( printf "obase=16; ibase=16; %X * %X / %X\n" $a $b $c | bc )
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* given=$( printf "%X\n" $r )
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* if [ "$expected" = "$given" ]; then
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* echo "$a * $b / $c = $r OK"
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* else
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* echo "$a * $b / $c = $r is wrong" >&2
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* echo "should be equivalent to 0x$expected" >&2
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* exit 1
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* fi
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* done
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*/
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static int __init test_init(void)
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{
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int i;
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pr_info("Starting mul_u64_u64_div_u64() test\n");
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for (i = 0; i < ARRAY_SIZE(test_values); i++) {
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u64 a = test_values[i].a;
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u64 b = test_values[i].b;
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u64 c = test_values[i].c;
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u64 expected_result = test_values[i].result;
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u64 result = mul_u64_u64_div_u64(a, b, c);
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if (result != expected_result) {
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pr_err("ERROR: 0x%016llx * 0x%016llx / 0x%016llx\n", a, b, c);
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pr_err("ERROR: expected result: %016llx\n", expected_result);
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pr_err("ERROR: obtained result: %016llx\n", result);
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}
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}
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pr_info("Completed mul_u64_u64_div_u64() test\n");
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return 0;
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}
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static void __exit test_exit(void)
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{
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}
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module_init(test_init);
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module_exit(test_exit);
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MODULE_AUTHOR("Nicolas Pitre");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("mul_u64_u64_div_u64() test module");
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