Bitwise assumptions ensure correctness of low-level binary operations and data representations. They allow verification of individual bits, bitmasks, and bit positions, as well as counting set bits and validating properties like power-of-two values. Additional macros cover equality of bit patterns and correctness of bitwise operations such as AND, OR, XOR, shifts, and rotations. These assumptions are particularly valuable in systems programming, embedded development, protocol implementation, and performance-critical code where precise control over bits is required.
Code reference for C, C++, or Python APIs for a respective Fossil Logic Project.
C, C++ REFERENCE #
// **************************************************
// Bitwise assumptions
// ************************************************
/**
* @brief Assumes that the given bit flag is set in the value.
*
* @param value The value to check.
* @param flag The bit flag to check for.
*/
#define ASSUME_ITS_BIT_SET(value, flag) \
FOSSIL_TEST_ASSUME(((value) & (flag)) != 0, _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit flag " #flag " to be set in value " #value " of value 0x%llx", (uint64_t)(value)))
/**
* @brief Assumes that the given bit flag is not set in the value.
*
* @param value The value to check.
* @param flag The bit flag to check for.
*/
#define ASSUME_NOT_BIT_SET(value, flag) \
FOSSIL_TEST_ASSUME(((value) & (flag)) == 0, _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit flag " #flag " to not be set in value " #value " of value 0x%llx", (uint64_t)(value)))
/**
* @brief Assumes that all bits in the mask are set in the value.
*
* @param value The value to check.
* @param mask The bitmask to check for.
*/
#define ASSUME_ITS_BITMASK_SET(value, mask) \
FOSSIL_TEST_ASSUME((((value) & (mask)) == (mask)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bitmask " #mask " of value 0x%llx to be fully set in value " #value " of value 0x%llx", (uint64_t)(mask), (uint64_t)(value)))
/**
* @brief Assumes that all bits in the mask are not set in the value.
*
* @param value The value to check.
* @param mask The bitmask to check for.
*/
#define ASSUME_NOT_BITMASK_SET(value, mask) \
FOSSIL_TEST_ASSUME((((value) & (mask)) == 0), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bitmask " #mask " of value 0x%llx to not be set in value " #value " of value 0x%llx", (uint64_t)(mask), (uint64_t)(value)))
/**
* @brief Assumes that the given bit position is set in the value.
*
* @param value The value to check.
* @param bit The bit position (0-based) to check.
*/
#define ASSUME_ITS_BIT_POSITION_SET(value, bit) \
FOSSIL_TEST_ASSUME((((value) >> (bit)) & 1U) != 0, _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit at position " #bit " to be set in value " #value " of value 0x%llx", (uint64_t)(value)))
/**
* @brief Assumes that the given bit position is not set in the value.
*
* @param value The value to check.
* @param bit The bit position (0-based) to check.
*/
#define ASSUME_NOT_BIT_POSITION_SET(value, bit) \
FOSSIL_TEST_ASSUME((((value) >> (bit)) & 1U) == 0, _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit at position " #bit " to not be set in value " #value " of value 0x%llx", (uint64_t)(value)))
/**
* @brief Assumes that the bit count in the value equals the expected count.
*
* @param value The value to check.
* @param expected_count The expected number of set bits.
*/
#define ASSUME_ITS_BIT_COUNT(value, expected_count) \
FOSSIL_TEST_ASSUME(__builtin_popcountll((uint64_t)(value)) == (expected_count), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit count in value " #value " to be " #expected_count ", but got %d", __builtin_popcountll((uint64_t)(value))))
/**
* @brief Assumes that the bit count in the value does not equal the expected count.
*
* @param value The value to check.
* @param expected_count The expected number of set bits.
*/
#define ASSUME_NOT_BIT_COUNT(value, expected_count) \
FOSSIL_TEST_ASSUME(__builtin_popcountll((uint64_t)(value)) != (expected_count), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit count in value " #value " to not be " #expected_count ", but got %d", __builtin_popcountll((uint64_t)(value))))
/**
* @brief Assumes that the given value is a power of two.
*
* @param value The value to check (must be unsigned and non-zero).
*/
#define ASSUME_ITS_POWER_OF_TWO(value) \
FOSSIL_TEST_ASSUME(((value) != 0) && (((value) & ((value) - 1)) == 0), _FOSSIL_TEST_ASSUME_MESSAGE("Expected value " #value " of value 0x%llx to be a power of two", (uint64_t)(value)))
/**
* @brief Assumes that the given value is not a power of two.
*
* @param value The value to check (must be unsigned).
*/
#define ASSUME_NOT_POWER_OF_TWO(value) \
FOSSIL_TEST_ASSUME(((value) == 0) || (((value) & ((value) - 1)) != 0), _FOSSIL_TEST_ASSUME_MESSAGE("Expected value " #value " of value 0x%llx to not be a power of two", (uint64_t)(value)))
/**
* @brief Assumes that two values have the same bit pattern.
*
* @param actual The actual value.
* @param expected The expected value.
*/
#define ASSUME_ITS_EQUAL_BITS(actual, expected) \
FOSSIL_TEST_ASSUME((actual) == (expected), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit pattern " #actual " of value 0x%llx to equal " #expected " of value 0x%llx", (uint64_t)(actual), (uint64_t)(expected)))
/**
* @brief Assumes that two values have different bit patterns.
*
* @param actual The actual value.
* @param expected The expected value.
*/
#define ASSUME_NOT_EQUAL_BITS(actual, expected) \
FOSSIL_TEST_ASSUME((actual) != (expected), _FOSSIL_TEST_ASSUME_MESSAGE("Expected bit pattern " #actual " of value 0x%llx to not equal " #expected " of value 0x%llx", (uint64_t)(actual), (uint64_t)(expected)))
/**
* @brief Assumes that a bitwise AND operation produces the expected result.
*
* @param value The value to AND.
* @param mask The mask to AND with.
* @param expected The expected result.
*/
#define ASSUME_ITS_BITWISE_AND_EQUAL(value, mask, expected) \
FOSSIL_TEST_ASSUME((((value) & (mask)) == (expected)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected ((value " #value " & mask " #mask ") to equal " #expected ", got 0x%llx", (uint64_t)((value) & (mask))))
/**
* @brief Assumes that a bitwise OR operation produces the expected result.
*
* @param value The value to OR.
* @param mask The mask to OR with.
* @param expected The expected result.
*/
#define ASSUME_ITS_BITWISE_OR_EQUAL(value, mask, expected) \
FOSSIL_TEST_ASSUME((((value) | (mask)) == (expected)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected (value " #value " | mask " #mask ") to equal " #expected ", got 0x%llx", (uint64_t)((value) | (mask))))
/**
* @brief Assumes that a bitwise XOR operation produces the expected result.
*
* @param value The value to XOR.
* @param mask The mask to XOR with.
* @param expected The expected result.
*/
#define ASSUME_ITS_BITWISE_XOR_EQUAL(value, mask, expected) \
FOSSIL_TEST_ASSUME((((value) ^ (mask)) == (expected)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected (value " #value " ^ mask " #mask ") to equal " #expected ", got 0x%llx", (uint64_t)((value) ^ (mask))))
/**
* @brief Assumes that a left shift operation produces the expected result.
*
* Only works with unsigned types to avoid undefined behavior.
*
* @param value The unsigned value to shift (must be unsigned type).
* @param shift The number of positions to shift left.
* @param expected The expected result.
*/
#define ASSUME_ITS_SHIFT_LEFT_EQUAL(value, shift, expected) \
FOSSIL_TEST_ASSUME(((value) << (shift)) == (expected), _FOSSIL_TEST_ASSUME_MESSAGE("Expected (value " #value " << " #shift ") to equal " #expected ", got 0x%llx", (uint64_t)((value) << (shift))))
/**
* @brief Assumes that a right shift operation produces the expected result.
*
* Only works with unsigned types to avoid implementation-defined behavior.
*
* @param value The unsigned value to shift (must be unsigned type).
* @param shift The number of positions to shift right.
* @param expected The expected result.
*/
#define ASSUME_ITS_SHIFT_RIGHT_EQUAL(value, shift, expected) \
FOSSIL_TEST_ASSUME(((value) >> (shift)) == (expected), _FOSSIL_TEST_ASSUME_MESSAGE("Expected (value " #value " >> " #shift ") to equal " #expected ", got 0x%llx", (uint64_t)((value) >> (shift))))
/**
* @brief Assumes that rotating left produces the expected result.
*
* Performs a left rotate on unsigned 64-bit values.
*
* @param value The unsigned value to rotate.
* @param n The number of positions to rotate.
* @param expected The expected result.
*/
#define ASSUME_ITS_ROTATE_LEFT_EQUAL(value, n, expected) \
FOSSIL_TEST_ASSUME(((((uint64_t)(value) << ((uint64_t)(n) & 63)) | ((uint64_t)(value) >> (64 - ((uint64_t)(n) & 63)))) == (expected)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected rotate_left(value " #value ", " #n ") to equal " #expected ", got 0x%llx", (((uint64_t)(value) << ((uint64_t)(n) & 63)) | ((uint64_t)(value) >> (64 - ((uint64_t)(n) & 63))))))
/**
* @brief Assumes that rotating right produces the expected result.
*
* Performs a right rotate on unsigned 64-bit values.
*
* @param value The unsigned value to rotate.
* @param n The number of positions to rotate.
* @param expected The expected result.
*/
#define ASSUME_ITS_ROTATE_RIGHT_EQUAL(value, n, expected) \
FOSSIL_TEST_ASSUME(((((uint64_t)(value) >> ((uint64_t)(n) & 63)) | ((uint64_t)(value) << (64 - ((uint64_t)(n) & 63)))) == (expected)), _FOSSIL_TEST_ASSUME_MESSAGE("Expected rotate_right(value " #value ", " #n ") to equal " #expected ", got 0x%llx", (((uint64_t)(value) >> ((uint64_t)(n) & 63)) | ((uint64_t)(value) << (64 - ((uint64_t)(n) & 63))))))
PYTHON REFERENCE #
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