Essential C Language Tool Codes in Embedded Development

The commonly used C language tool codes in embedded development are 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
}

The 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 provides an efficient approximation solution for floating-point numbers.

5. Endianness Conversion:

uint16_t swap_bytes(uint16_t value) { return (value >> 8) | (value << 8); }

This function is used to convert between big-endian and little-endian byte orders.

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 scheduled 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;
}

This implements a simple bitset data structure for managing the state of a set of bits.

These code examples represent some of the commonly used sword-level C language tool codes in embedded development. They have wide applications in embedded system development, helping to optimize performance, save resources, and improve code maintainability.

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