The C language tool code commonly used in embedded development is indeed very important.Below are some sword-level C language tool code examples, along with brief explanations.1 Circular Buffer
typedef struct {int buffer[SIZE];int head;int tail;int count;} CircularBuffer;
void push(CircularBuffer *cb, int data) {if (cb->count < SIZE) { cb->buffer[cb->head] = data; cb->head = (cb->head + 1) % SIZE; cb->count++; }}
int pop(CircularBuffer *cb) {if (cb->count > 0) {int data = cb->buffer[cb->tail]; cb->tail = (cb->tail + 1) % SIZE; cb->count--;return data; }return -1; // Buffer is empty}
A circular buffer is an efficient data structure suitable for buffering and data stream applications, such as serial communication receive buffers.2 Assertion
#define assert(expression) ((void)0)
#ifndef NDEBUG
#undef assert
#define assert(expression) ((expression) ? (void)0 : assert_failed(__FILE__, __LINE__))
#endif
void assert_failed(const char *file, int line) {printf("Assertion failed at %s:%d\n", file, line);// Additional error handling or logging can be added here}
Assertions are used to check whether specific conditions are met in the program; if the condition is false, it triggers an assertion failure and outputs relevant information.3 Bit Reversal
unsigned int reverse_bits(unsigned int num) {unsigned int numOfBits = sizeof(num) * 8;unsigned int reverseNum = 0;
for (unsigned int i = 0; i < numOfBits; i++) {if (num & (1 << i)) { reverseNum |= (1 << ((numOfBits - 1) - i)); }}return reverseNum;}
This function reverses the bits of a given unsigned integer and can be used for bit-level operations in certain embedded systems.4 Fixed-Point Arithmetic
typedef int16_t fixed_t;
#define FIXED_SHIFT 8
#define FLOAT_TO_FIXED(f) ((fixed_t)((f) * (1 << FIXED_SHIFT)))
#define FIXED_TO_FLOAT(f) ((float)(f) / (1 << FIXED_SHIFT))
fixed_t fixed_multiply(fixed_t a, fixed_t b) {return (fixed_t)(((int32_t)a * (int32_t)b) >> FIXED_SHIFT);}
In some embedded systems, floating-point operations can be slow or unsupported. Therefore, using fixed-point arithmetic can provide an efficient approximation solution for floating-point numbers.5 Endianness Conversion
uint16_t swap_bytes(uint16_t value) { return (value >> 8) | (value << 8); }
// Function for converting between big-endian and little-endian byte order.
6 Bit Masks
#define BIT_MASK(bit) (1 << (bit))
This is used to create a bit mask with only the specified bit set, which can be used for bit manipulation.7 Timer Counting
#include <avr/io.h>
void setup_timer() {// Configure timer settings}
uint16_t read_timer() {return TCNT1;}
In AVR embedded systems, timers are used to implement time measurement and timed tasks.8 Binary Search
int binary_search(int arr[], int size, int target) { int left = 0, right = size - 1;
while (left <= right) { int mid = left + (right - left) / 2;if (arr[mid] == target) {return mid; } else if (arr[mid] < target) {left = mid + 1; } else {right = mid - 1; }}return -1; // Not found}
This function performs a binary search in a sorted array.9 Bitset
#include <stdint.h>
typedef struct {uint32_t bits;} Bitset;
void set_bit(Bitset *bitset, int bit) {bitset->bits |= (1U << bit);}
int get_bit(Bitset *bitset, int bit) {return (bitset->bits >> bit) & 1U;}
Implements a simple bitset data structure for managing the state of a set of bits.These code examples represent some sword-level C language tool codes commonly used in embedded development. They have wide applications in embedded system development, helping to optimize performance, save resources, and improve code maintainability.Source:https://zhuanlan.zhihu.com/p/653484840