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Minor correctness and warning fixes #1

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Minor correctness and warning fixes #1

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c920527
Avoid format warnings on systems where uint64_t is not long int
ehntoo Jul 16, 2024
14ce9a2
Fix an issue under clang on ARM64 where 64-bit CRCs were breaking
ehntoo Jul 16, 2024
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12 changes: 8 additions & 4 deletions crcfactory.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
#ifndef __CRCFACTORY_H__
#define __CRCFACTORY_H__

#include <limits.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
Expand Down Expand Up @@ -101,10 +102,13 @@ CRCFACTORY_INLINE CRCFACTORY_CRC_TYPE _crcfactory_mask(int width, bool reflected
if (!reflected && width <= 8) {
return value & 0xff;
}
// The following if statement is due to a bug under x86_64:
// "1ULL << 64" evaluates to 0 (expected), but
// "1ULL << x" when x==64 evaluates to 1 (wrong).
if ((1ULL << width) == 1) return value;

// Avoid undefined behavior if a shift to generate the mask would exceed
// the size of the type. Just return the value unmasked, since the mask
// would cover all bits anyway. Strictly speaking we probably want a
// limits-based check here in case CRC_TYPE is signed, but signed types
// would likely break other things anyway.
if ((size_t)width >= (CHAR_BIT * sizeof(CRCFACTORY_CRC_TYPE))) return value;
return value & ((1ULL << width) - 1);
}

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3 changes: 2 additions & 1 deletion test/crclist2test.py
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Expand Up @@ -6,6 +6,7 @@
CFILE_TEMPLATE = r"""
/* NOTE: This file was auto-generated by crclist2test.py */
#include <stdio.h>
#include <inttypes.h>

#define CRCFACTORY_CRC_TYPE <<crc_datatype>>
#define CRCFACTORY_CRCTABLE_TYPE <<table_datatype>>
Expand All @@ -20,7 +21,7 @@
func##_t_init(crctable); \
uint64_t r = func((uint8_t *)TESTDATA, TESTDATA_LEN); \
uint64_t r_t = func##_t(crctable, (uint8_t *)TESTDATA, TESTDATA_LEN); \
printf("%-20s: %-16lx %-6s : %-16lx %-6s\n", desc, r, (r == check) ? "(OK)" : "(FAIL)", r_t, (r_t == check) ? "(OK)" : "(FAIL)"); \
printf("%-20s: %-16" PRIx64 " %-6s : %-16" PRIx64 " %-6s\n", desc, r, (r == check) ? "(OK)" : "(FAIL)", r_t, (r_t == check) ? "(OK)" : "(FAIL)"); \
test_count += 2; \
test_failures += (r == check) ? 0 : 1; \
test_failures += (r_t == check) ? 0 : 1; \
Expand Down