50 lines
1.1 KiB
Plaintext
50 lines
1.1 KiB
Plaintext
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#ifndef AWS_COMMON_ZERO_INL
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#define AWS_COMMON_ZERO_INL
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/**
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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* SPDX-License-Identifier: Apache-2.0.
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*/
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#include <aws/common/stdbool.h>
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#include <aws/common/stdint.h>
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#include <aws/common/zero.h>
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#include <string.h>
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AWS_EXTERN_C_BEGIN
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/**
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* Returns whether each byte is zero.
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*/
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AWS_STATIC_IMPL
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bool aws_is_mem_zeroed(const void *buf, size_t bufsize) {
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/* Optimization idea: vectorized instructions to check more than 64 bits at a time. */
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/* Check 64 bits at a time */
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const uint64_t *buf_u64 = (const uint64_t *)buf;
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const size_t num_u64_checks = bufsize / 8;
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size_t i;
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for (i = 0; i < num_u64_checks; ++i) {
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if (buf_u64[i]) {
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return false;
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}
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}
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/* Update buf to where u64 checks left off */
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buf = buf_u64 + num_u64_checks;
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bufsize = bufsize % 8;
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/* Check 8 bits at a time */
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const uint8_t *buf_u8 = (const uint8_t *)buf;
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for (i = 0; i < bufsize; ++i) {
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if (buf_u8[i]) {
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return false;
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}
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}
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return true;
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}
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AWS_EXTERN_C_END
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#endif /* AWS_COMMON_ZERO_INL */
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