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Merge pull request #17710 from benpicco/sys/bitfield-ops

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sys/bitfield: add support for bit-wise bitfield operations
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benpicco 2022-03-09 22:09:34 +01:00 committed by GitHub
commit 60fb36eb1e
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3 changed files with 118 additions and 5 deletions
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6
sys/bitfield/bitfield.c
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@ -21,11 +21,11 @@
#include "bitfield.h"
#include "irq.h"
int bf_get_unset(uint8_t field[], int size)
int bf_get_unset(uint8_t field[], size_t size)
{
int result = -1;
int nbytes = (size + 7) / 8;
int i = 0;
size_t i = 0;
unsigned state = irq_disable();
@ -43,5 +43,5 @@ int bf_get_unset(uint8_t field[], int size)
}
irq_restore(state);
return(result);
return result;
}

91
sys/include/bitfield.h
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@ -89,18 +89,105 @@ static inline bool bf_isset(uint8_t field[], size_t idx)
return (field[idx / 8] & (1u << (7 - (idx % 8))));
}
/**
* @brief Perform a bitwise OR operation on two bitfields
* `out = a | b`
*
* @pre The size of @p a, @p b and @p out must be at least @p len bits
*
* @note This operation will also affect unused bits of the bytes that make up
* the bitfield.
*
* @param[out] out The resulting bitfield
* @param[in] a The first bitfield
* @param[in] b The second bitfield
* @param[in] len The number of bits in the bitfields
*/
static inline void bf_or(uint8_t out[], const uint8_t a[], const uint8_t b[], size_t len)
{
len = (len + 7) / 8;
while (len--) {
out[len] = a[len] | b[len];
}
}
/**
* @brief Perform a bitwise AND operation on two bitfields
* `out = a & b`
*
* @pre The size of @p a, @p b and @p out must be at least @p len bits
*
* @note This operation will also affect unused bits of the bytes that make up
* the bitfield.
*
* @param[out] out The resulting bitfield
* @param[in] a The first bitfield
* @param[in] b The second bitfield
* @param[in] len The number of bits in the bitfields
*/
static inline void bf_and(uint8_t out[], const uint8_t a[], const uint8_t b[], size_t len)
{
len = (len + 7) / 8;
while (len--) {
out[len] = a[len] & b[len];
}
}
/**
* @brief Perform a bitwise XOR operation on two bitfields
* `out = a ^ b`
*
* @pre The size of @p a, @p b and @p out must be at least @p len bits
*
* @note This operation will also affect unused bits of the bytes that make up
* the bitfield.
*
* @param[out] out The resulting bitfield
* @param[in] a The first bitfield
* @param[in] b The second bitfield
* @param[in] len The number of bits in the bitfields
*/
static inline void bf_xor(uint8_t out[], const uint8_t a[], const uint8_t b[], size_t len)
{
len = (len + 7) / 8;
while (len--) {
out[len] = a[len] ^ b[len];
}
}
/**
* @brief Perform a bitwise NOT operation on a bitfield
* `out = ~a`
*
* @pre The size of @p a and @p out must be at least @p len bits
*
* @note This operation will also affect unused bits of the bytes that make up
* the bitfield.
*
* @param[out] out The resulting bitfield
* @param[in] a The bitfield to invert
* @param[in] len The number of bits in the bitfield
*/
static inline void bf_inv(uint8_t out[], const uint8_t a[], size_t len)
{
len = (len + 7) / 8;
while (len--) {
out[len] = ~a[len];
}
}
/**
* @brief Atomically get the number of an unset bit and set it
*
* This function can be used to record e.g., empty entries in an array.
*
* @param[in,out] field The bitfield
* @param[in] size The size of the bitfield
* @param[in] len The number of bits in the bitfield to consider
*
* @return number of bit that was set
* @return -1 if no bit was unset
*/
int bf_get_unset(uint8_t field[], int size);
int bf_get_unset(uint8_t field[], size_t len);
#ifdef __cplusplus
}

26
tests/unittests/tests-bitfield/tests-bitfield.c
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@ -197,6 +197,31 @@ static void test_bf_get_unset_lastbyte(void)
TEST_ASSERT_EQUAL_INT(39, res);
}
static void test_bf_ops(void)
{
const uint8_t zero[3] = {0};
const uint8_t set[3] = { 0xFF, 0xFF, 0xFF };
uint8_t a[3] = { 0xAA, 0x55, 0xF0 };
uint8_t b[3] = { 0x55, 0xAA, 0x0F };
uint8_t c[3];
bf_or(c, a, b, 24);
TEST_ASSERT_EQUAL_INT(0, memcmp(c, set, sizeof(c)));
bf_inv(c, c, 24);
TEST_ASSERT_EQUAL_INT(0, memcmp(c, zero, sizeof(c)));
bf_and(c, a, b, 24);
TEST_ASSERT_EQUAL_INT(0, memcmp(c, zero, sizeof(c)));
bf_inv(c, c, 24);
TEST_ASSERT_EQUAL_INT(0, memcmp(c, set, sizeof(c)));
bf_xor(c, c, a, 24);
TEST_ASSERT_EQUAL_INT(0, memcmp(c, b, sizeof(c)));
}
Test *tests_bitfield_tests(void)
{
EMB_UNIT_TESTFIXTURES(fixtures) {
@ -208,6 +233,7 @@ Test *tests_bitfield_tests(void)
new_TestFixture(test_bf_get_unset_firstbyte),
new_TestFixture(test_bf_get_unset_middle),
new_TestFixture(test_bf_get_unset_lastbyte),
new_TestFixture(test_bf_ops),
};
EMB_UNIT_TESTCALLER(bitfield_tests, NULL, NULL, fixtures);