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#ifndef AWS_COMMON_MATH_FALLBACK_INL
#define AWS_COMMON_MATH_FALLBACK_INL
/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
/*
* This header is already included, but include it again to make editor
* highlighting happier.
*/
#include <aws/common/common.h>
#include <aws/common/math.h>
AWS_EXTERN_C_BEGIN
/**
* Multiplies a * b. If the result overflows, returns 2^64 - 1.
*/
AWS_STATIC_IMPL uint64_t aws_mul_u64_saturating(uint64_t a, uint64_t b) {
if (a > 0 && b > 0 && a > (UINT64_MAX / b))
return UINT64_MAX;
return a * b;
}
/**
* If a * b overflows, returns AWS_OP_ERR; otherwise multiplies
* a * b, returns the result in *r, and returns AWS_OP_SUCCESS.
*/
AWS_STATIC_IMPL int aws_mul_u64_checked(uint64_t a, uint64_t b, uint64_t *r) {
if (a > 0 && b > 0 && a > (UINT64_MAX / b))
return aws_raise_error(AWS_ERROR_OVERFLOW_DETECTED);
*r = a * b;
return AWS_OP_SUCCESS;
}
/**
* Multiplies a * b. If the result overflows, returns 2^32 - 1.
*/
AWS_STATIC_IMPL uint32_t aws_mul_u32_saturating(uint32_t a, uint32_t b) {
if (a > 0 && b > 0 && a > (UINT32_MAX / b))
return UINT32_MAX;
return a * b;
}
/**
* If a * b overflows, returns AWS_OP_ERR; otherwise multiplies
* a * b, returns the result in *r, and returns AWS_OP_SUCCESS.
*/
AWS_STATIC_IMPL int aws_mul_u32_checked(uint32_t a, uint32_t b, uint32_t *r) {
if (a > 0 && b > 0 && a > (UINT32_MAX / b))
return aws_raise_error(AWS_ERROR_OVERFLOW_DETECTED);
*r = a * b;
return AWS_OP_SUCCESS;
}
/**
* Adds a + b. If the result overflows returns 2^64 - 1.
*/
AWS_STATIC_IMPL uint64_t aws_add_u64_saturating(uint64_t a, uint64_t b) {
if ((b > 0) && (a > (UINT64_MAX - b)))
return UINT64_MAX;
return a + b;
}
/**
* If a + b overflows, returns AWS_OP_ERR; otherwise adds
* a + b, returns the result in *r, and returns AWS_OP_SUCCESS.
*/
AWS_STATIC_IMPL int aws_add_u64_checked(uint64_t a, uint64_t b, uint64_t *r) {
if ((b > 0) && (a > (UINT64_MAX - b)))
return aws_raise_error(AWS_ERROR_OVERFLOW_DETECTED);
*r = a + b;
return AWS_OP_SUCCESS;
}
/**
* Adds a + b. If the result overflows returns 2^32 - 1.
*/
AWS_STATIC_IMPL uint32_t aws_add_u32_saturating(uint32_t a, uint32_t b) {
if ((b > 0) && (a > (UINT32_MAX - b)))
return UINT32_MAX;
return a + b;
}
/**
* If a + b overflows, returns AWS_OP_ERR; otherwise adds
* a + b, returns the result in *r, and returns AWS_OP_SUCCESS.
*/
AWS_STATIC_IMPL int aws_add_u32_checked(uint32_t a, uint32_t b, uint32_t *r) {
if ((b > 0) && (a > (UINT32_MAX - b)))
return aws_raise_error(AWS_ERROR_OVERFLOW_DETECTED);
*r = a + b;
return AWS_OP_SUCCESS;
}
/*
* These are pure C implementations of the count leading/trailing zeros calls
* They should not be necessary unless using a really esoteric compiler with
* no intrinsics for these functions whatsoever.
*/
#if !defined(__clang__) && !defined(__GNUC__)
/**
* Search from the MSB to LSB, looking for a 1
*/
AWS_STATIC_IMPL size_t aws_clz_u32(uint32_t n) {
return aws_clz_i32((int32_t)n);
}
AWS_STATIC_IMPL size_t aws_clz_i32(int32_t n) {
size_t idx = 0;
if (n == 0) {
return sizeof(n) * 8;
}
/* sign bit is the first bit */
if (n < 0) {
return 0;
}
while (n >= 0) {
++idx;
n <<= 1;
}
return idx;
}
AWS_STATIC_IMPL size_t aws_clz_u64(uint64_t n) {
return aws_clz_i64((int64_t)n);
}
AWS_STATIC_IMPL size_t aws_clz_i64(int64_t n) {
size_t idx = 0;
if (n == 0) {
return sizeof(n) * 8;
}
/* sign bit is the first bit */
if (n < 0) {
return 0;
}
while (n >= 0) {
++idx;
n <<= 1;
}
return idx;
}
AWS_STATIC_IMPL size_t aws_clz_size(size_t n) {
# if SIZE_BITS == 64
return aws_clz_u64(n);
# else
return aws_clz_u32(n);
# endif
}
/**
* Search from the LSB to MSB, looking for a 1
*/
AWS_STATIC_IMPL size_t aws_ctz_u32(uint32_t n) {
return aws_ctz_i32((int32_t)n);
}
AWS_STATIC_IMPL size_t aws_ctz_i32(int32_t n) {
int32_t idx = 0;
const int32_t max_bits = (int32_t)(SIZE_BITS / sizeof(uint8_t));
if (n == 0) {
return sizeof(n) * 8;
}
while (idx < max_bits) {
if (n & (1 << idx)) {
break;
}
++idx;
}
return (size_t)idx;
}
AWS_STATIC_IMPL size_t aws_ctz_u64(uint64_t n) {
return aws_ctz_i64((int64_t)n);
}
AWS_STATIC_IMPL size_t aws_ctz_i64(int64_t n) {
int64_t idx = 0;
const int64_t max_bits = (int64_t)(SIZE_BITS / sizeof(uint8_t));
if (n == 0) {
return sizeof(n) * 8;
}
while (idx < max_bits) {
if (n & (1ULL << idx)) {
break;
}
++idx;
}
return (size_t)idx;
}
AWS_STATIC_IMPL size_t aws_ctz_size(size_t n) {
# if SIZE_BITS == 64
return aws_ctz_u64(n);
# else
return aws_ctz_u32(n);
# endif
}
#endif
AWS_EXTERN_C_END
#endif /* AWS_COMMON_MATH_FALLBACK_INL */
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